feat: add JavaScript learning section with starter lessons and sidebar section headers

Implementation following plan: - S01: Foundation: schema, section config, and router - S02: Install CodeMirror JavaScript language support - S03: Create JavaScript lesson JSON files (variables, DOM, events) - S04: Register JavaScript lessons in module stores - S05: Add JavaScript validation logic - S06: Add JavaScript mode to LessonEngine preview rendering - S07: Add JavaScript mode to CodeEditor - S08: Update app.js for JavaScript mode support - S09: Update navigation HTML and CSS theming for JavaScript section - S10: Add section grouping headers in sidebar navigation - S11: Update and write tests
Merge pull request 'fix: rewrite flexbox tasks to describe outcomes instead of answers' (#5 ) from 003-flexbox-task-wording into main
2026-03-28 20:22:50 +01:00 · 2026-03-28 19:59:24 +01:00 · 2026-03-28 19:25:32 +01:00 · 2026-03-28 19:17:48 +01:00 · 2026-03-28 17:01:32 +01:00 · 2026-03-28 16:38:56 +01:00
53 changed files with 9660 additions and 401 deletions
--- a/.claude/settings.json
+++ b/.claude/settings.json
@@ -1,15 +1,6 @@
 {
 	"permissions": {
 		"allow": [
-			"Bash(git add:*)",
-			"Bash(git commit:*)",
-			"Bash(git push:*)",
-			"Bash(npm run build:*)",
-			"Bash(grep:*)",
-			"Bash(npm run format.lessons:*)",
-			"Bash(xargs:*)",
-			"Bash(cat:*)",
-			"Bash(prettier --write:*)"
 		],
 		"deny": ["Read(./.env)", "Read(./.env.*)", "Read(./secrets/**)"]
 	},
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,19 @@
 node_modules
 dist
 coverage
+.env
+.env.local

 # Claude Code local settings (user-specific)
-.claude/settings.local.json
+.claude/settings.local.json
+.claude_settings.json
+
+# Auto-Claude
+.auto-claude
+.worktrees
+
+# Wave ephemeral data
+.wave/workspaces
+.wave/traces
+.wave/artifacts
+.wave/output
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -0,0 +1,297 @@
+# Code Crispies Roadmap
+
+## Current State (Updated)
+
+**Total Active Lessons:** 101 (excluding welcome, goodbye, playground)
+**Target:** 100 lessons for milestone system ✅ ACHIEVED
+
+### Current Module Breakdown
+
+| Module | Lessons | Category | Status |
+|--------|---------|----------|--------|
+| Basic Selectors | 10 | CSS | ✅ |
+| Colors | 4 | CSS | ✅ |
+| **Gradients** | 3 | CSS | ✅ NEW |
+| Typography | 6 | CSS | ✅ +2 |
+| Box Model | 8 | CSS | ✅ |
+| Flexbox | 6 | CSS | ✅ |
+| Grid | 6 | CSS | ✅ |
+| **Positioning** | 4 | CSS | ✅ NEW |
+| Units & Variables | 4 | CSS | ✅ |
+| Responsive | 4 | CSS | ✅ |
+| Transitions & Animations | 4 | CSS | ✅ |
+| **Filters** | 4 | CSS | ✅ NEW |
+| **Pseudo-elements** | 4 | CSS | ✅ NEW |
+| HTML Elements | 2 | HTML | ✅ |
+| **Semantic HTML** | 3 | HTML | ✅ NEW |
+| Figure | 3 | HTML | ✅ |
+| SVG | 3 | HTML | ✅ |
+| Details/Summary | 3 | HTML | ✅ |
+| Dialog | 2 | HTML | ✅ |
+| Progress/Meter | 3 | HTML | ✅ |
+| Forms Basic | 3 | HTML | ✅ |
+| Forms Validation | 1 | HTML | ✅ |
+| Fieldset | 3 | HTML | ✅ |
+| Datalist | 2 | HTML | ✅ |
+| Tables | 3 | HTML | ✅ +2 |
+| **Total** | **101** | | ✅ |
+
+---
+
+## Phase 1: Milestone Progress System ✅ COMPLETED
+
+### Design
+
+Replace percentage-based progress with milestone markers:
+
+```
+[1] [5] [10] [20] [30] [50] [75] [100]
+ ●   ●    ◐    ○    ○    ○    ○    ○
+```
+
+**Milestones:**
+- 1 lesson - First Step
+- 5 lessons - Getting Started
+- 10 lessons - Rookie
+- 20 lessons - Learner
+- 30 lessons - Intermediate
+- 50 lessons - Halfway Hero
+- 75 lessons - Advanced
+- 100 lessons - Master
+
+### Implementation ✅
+
+1. **Update `LessonEngine.getProgressStats()`** ✅
+   - Added `currentMilestone` and `nextMilestone` fields
+   - Added `milestonesReached: number[]`
+   - Added `progressToNext` percentage
+
+2. **Update Progress UI** ✅
+   - Added milestone dots with visual states (reached, current, next)
+   - Animate milestone completion
+   - Show current milestone badge
+
+3. **Add Milestone Celebration**
+   - Confetti/animation on reaching milestones
+   - Achievement unlocks in sidebar
+
+---
+
+## Phase 2: New Lessons (34 needed to reach 100)
+
+### Priority 1: Expand Existing Modules (+15 lessons)
+
+#### CSS Colors (+3)
+- Gradients (linear-gradient)
+- Color functions (hsl, rgb)
+- Opacity and transparency
+
+#### Typography (+3)
+- Web fonts (@font-face)
+- Text shadows
+- Letter/word spacing
+
+#### Responsive (+3)
+- Container queries
+- Aspect ratio
+- Clamp() for fluid typography
+
+#### Transitions & Animations (+3)
+- Keyframe animations
+- Animation timing functions
+- Transform origin
+
+#### Tables (+3)
+- Table styling (borders, spacing)
+- Responsive tables
+- Table accessibility
+
+### Priority 2: New CSS Modules (+12 lessons)
+
+#### Filters & Effects (4 lessons)
+- CSS filters (blur, brightness, contrast)
+- Backdrop filters
+- Mix-blend-mode
+- Box shadows advanced
+
+#### Positioning (4 lessons)
+- Relative positioning
+- Absolute positioning
+- Fixed/sticky positioning
+- Z-index stacking
+
+#### Pseudo-elements (4 lessons)
+- ::before and ::after
+- ::first-letter and ::first-line
+- ::marker for lists
+- Content property
+
+### Priority 3: New HTML Modules (+7 lessons)
+
+#### Semantic Structure (3 lessons)
+- Article vs Section
+- Header/Footer/Main
+- Nav and Aside
+
+#### Media Elements (2 lessons)
+- Picture element (responsive images)
+- Audio/Video basics
+
+#### Accessibility (2 lessons)
+- ARIA labels
+- Skip links
+- Focus management
+
+---
+
+## MDN Topics Reference
+
+### CSS Topics from MDN (prioritized for interactive lessons)
+
+**Layout Systems:**
+- [x] Flexbox (covered)
+- [x] Grid (covered)
+- [ ] Multi-column layout
+- [ ] Positioned layout (z-index, stacking)
+
+**Visual Effects:**
+- [x] Colors (partially covered)
+- [ ] Filters (blur, brightness, contrast, drop-shadow)
+- [ ] Blend modes (mix-blend-mode, background-blend-mode)
+- [ ] Masking and clipping
+- [ ] Shapes (shape-outside)
+
+**Typography:**
+- [x] Basic text (covered)
+- [ ] Web fonts (@font-face)
+- [ ] Variable fonts
+- [ ] Text decoration advanced
+
+**Animations:**
+- [x] Transitions (covered)
+- [ ] Keyframe animations
+- [ ] Scroll-driven animations (experimental)
+- [ ] View transitions
+
+**Advanced:**
+- [x] Custom properties (covered in units-variables)
+- [ ] Container queries
+- [ ] Anchor positioning (new)
+- [ ] Logical properties (for RTL support)
+
+### HTML Topics from MDN
+
+**Structural:**
+- [x] Basic elements (covered)
+- [x] Figure/figcaption (covered)
+- [ ] Article vs section semantics
+- [ ] Template element
+
+**Interactive:**
+- [x] Details/Summary (covered)
+- [x] Dialog (have JSON, not active)
+- [ ] Datalist (have JSON, not active)
+- [ ] Progress/Meter (have JSON, not active)
+
+**Forms:**
+- [x] Basic forms (covered)
+- [x] Validation (covered)
+- [x] Fieldset (have JSON, not active)
+- [ ] Input types exploration
+
+**Media:**
+- [x] SVG basics (covered)
+- [ ] Picture element
+- [ ] srcset and sizes
+- [ ] Audio/Video
+
+---
+
+## Inactive Lesson Files (Ready to Activate)
+
+These lesson files exist but aren't in the active module list:
+
+| File | Lessons | Topic |
+|------|---------|-------|
+| 24-html-progress-meter.json | 3 | Progress/Meter elements |
+| 25-html-datalist.json | 2 | Datalist for autocomplete |
+| 27-html-dialog.json | 2 | Native dialog element |
+| 28-html-forms-fieldset.json | 3 | Fieldset/legend grouping |
+| 31-html-marquee.json | 3 | Marquee (deprecated but fun) |
+| **Total** | **13** | |
+
+**Quick Win:** Activating these adds 13 lessons immediately → 79 total
+
+---
+
+## Implementation Order
+
+### Week 1: Foundation
+1. Design milestone UI component
+2. Implement milestone progress system
+3. Add milestone celebrations
+
+### Week 2: Quick Wins
+4. Activate 5 inactive HTML modules (+13 lessons)
+5. Test and fix translations
+
+### Week 3-4: New Content
+6. Create Filters & Effects module (+4)
+7. Create Positioning module (+4)
+8. Expand existing modules (+7)
+
+### Final Polish
+9. Reach 100 lessons milestone
+10. Add milestone achievements to sidebar
+11. Update landing page messaging
+
+---
+
+## Technical Notes
+
+### Milestone Data Structure
+
+```js
+const MILESTONES = [1, 5, 10, 20, 30, 50, 75, 100];
+
+function getMilestoneProgress(completed) {
+  const reached = MILESTONES.filter(m => completed >= m);
+  const current = reached[reached.length - 1] || 0;
+  const next = MILESTONES.find(m => m > completed) || 100;
+
+  return {
+    current,
+    next,
+    reached,
+    percentToNext: ((completed - current) / (next - current)) * 100
+  };
+}
+```
+
+### Progress Display Update
+
+```html
+<div class="milestone-progress">
+  <div class="milestones">
+    <span class="milestone reached" data-value="1">1</span>
+    <span class="milestone reached" data-value="5">5</span>
+    <span class="milestone current" data-value="10">10</span>
+    <span class="milestone" data-value="20">20</span>
+    <!-- ... -->
+  </div>
+  <div class="progress-bar">
+    <div class="progress-fill" style="width: 35%"></div>
+  </div>
+  <span class="progress-label">12 of 100 lessons</span>
+</div>
+```
+
+---
+
+## Success Metrics
+
+- [ ] 100 total lessons
+- [ ] Milestone system implemented
+- [ ] All 6 languages have translations
+- [ ] Achievement celebrations working
+- [ ] Mobile responsive milestone UI
--- a/flake.lock
+++ b/flake.lock
@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1768564909,
+        "narHash": "sha256-Kell/SpJYVkHWMvnhqJz/8DqQg2b6PguxVWOuadbHCc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e4bae1bd10c9c57b2cf517953ab70060a828ee6f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
--- a/flake.nix
+++ b/flake.nix
@@ -9,13 +9,14 @@
  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = import nixpkgs { inherit system; config.allowUnfree = true; };
      in {
        devShells.default = pkgs.mkShell {
          buildInputs = with pkgs; [
            nodejs_20
            nodePackages.npm
            gnumake
+            claude-code
          ];

          shellHook = ''
--- a/lessons/00-welcome.json
+++ b/lessons/00-welcome.json
@@ -3,7 +3,7 @@
 	"id": "welcome",
 	"title": "Welcome",
 	"description": "Get started with Code Crispies",
-	"mode": "html",
+	"mode": "css",
 	"difficulty": "beginner",
 	"excludeFromProgress": true,
 	"lessons": [
--- a/lessons/04-typography.json
+++ b/lessons/04-typography.json
@@ -98,6 +98,53 @@
 					"message": "Set letter-spacing to <kbd>1px</kbd>"
 				}
 			]
+		},
+		{
+			"id": "text-decoration",
+			"title": "Text Decoration",
+			"description": "The <kbd>text-decoration</kbd> property adds lines to text. Common values:<br><br>• <kbd>underline</kbd> — line below text<br>• <kbd>line-through</kbd> — strikethrough<br>• <kbd>none</kbd> — removes decoration (useful for links)<br><br>You can also style decorations with <kbd>text-decoration-color</kbd> and <kbd>text-decoration-style</kbd>.",
+			"task": "Show the old price with a strikethrough. Add <kbd>text-decoration: line-through</kbd>.",
+			"previewHTML": "<div class=\"price-box\"><span class=\"old-price\">$49.99</span><span class=\"new-price\">$29.99</span></div>",
+			"previewBaseCSS": "body { font-family: system-ui; padding: 1rem; } .price-box { display: flex; gap: 1rem; align-items: center; } .old-price { color: #999; font-size: 1rem; } .new-price { color: coral; font-size: 1.5rem; font-weight: bold; }",
+			"sandboxCSS": "",
+			"codePrefix": ".old-price {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"previewContainer": "preview-area",
+			"solution": "text-decoration: line-through;",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "text-decoration", "expected": "line-through" },
+					"message": "Set text-decoration to <kbd>line-through</kbd>"
+				}
+			]
+		},
+		{
+			"id": "text-shadow",
+			"title": "Text Shadow",
+			"description": "The <kbd>text-shadow</kbd> property adds shadow effects to text. The syntax is:<br><br><pre>text-shadow: x-offset y-offset blur color;</pre><br>Example: <kbd>text-shadow: 2px 2px 4px gray</kbd> creates a soft shadow offset down and right.",
+			"task": "Add depth to the heading with <kbd>text-shadow: 2px 2px 4px gray</kbd>.",
+			"previewHTML": "<h1 class=\"hero-title\">Welcome</h1>",
+			"previewBaseCSS": "body { font-family: system-ui; padding: 2rem; background: linear-gradient(135deg, #667eea, #764ba2); } .hero-title { margin: 0; font-size: 3rem; color: white; text-align: center; }",
+			"sandboxCSS": "",
+			"codePrefix": ".hero-title {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"previewContainer": "preview-area",
+			"solution": "text-shadow: 2px 2px 4px gray;",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "text-shadow",
+					"message": "Use <kbd>text-shadow</kbd> property"
+				},
+				{
+					"type": "contains",
+					"value": "2px 2px",
+					"message": "Set offset to <kbd>2px 2px</kbd>"
+				}
+			]
 		}
 	]
 }
--- a/lessons/09-gradients.json
+++ b/lessons/09-gradients.json
@@ -0,0 +1,92 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "css-gradients",
+	"title": "CSS Gradients",
+	"description": "Create smooth color transitions with CSS gradients.",
+	"difficulty": "intermediate",
+	"lessons": [
+		{
+			"id": "gradients-1",
+			"title": "Linear Gradient",
+			"description": "Gradients create smooth transitions between colors. The <kbd>linear-gradient()</kbd> function creates a gradient along a straight line.<br><br><strong>Basic syntax:</strong><br><pre>background: linear-gradient(color1, color2);</pre><br>By default, gradients flow from top to bottom.",
+			"task": "Add a gradient background from <kbd>coral</kbd> to <kbd>gold</kbd>.",
+			"previewHTML": "<div class=\"card\"><h3>Summer Sale</h3><p>Up to 50% off</p></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .card { padding: 2rem; border-radius: 12px; color: white; text-shadow: 0 1px 2px rgba(0,0,0,0.2); } .card h3 { margin: 0 0 8px; font-size: 1.5rem; } .card p { margin: 0; opacity: 0.9; }",
+			"sandboxCSS": "",
+			"codePrefix": ".card {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "background: linear-gradient(coral, gold);",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "linear-gradient",
+					"message": "Use <kbd>linear-gradient()</kbd>"
+				},
+				{
+					"type": "contains",
+					"value": "coral",
+					"message": "Include <kbd>coral</kbd> as the first color"
+				},
+				{
+					"type": "contains",
+					"value": "gold",
+					"message": "Include <kbd>gold</kbd> as the second color"
+				}
+			]
+		},
+		{
+			"id": "gradients-2",
+			"title": "Gradient Direction",
+			"description": "Control the gradient direction by adding an angle or keyword before the colors.<br><br><strong>Keywords:</strong> <kbd>to right</kbd>, <kbd>to left</kbd>, <kbd>to bottom right</kbd><br><strong>Angles:</strong> <kbd>45deg</kbd>, <kbd>90deg</kbd>, <kbd>180deg</kbd><br><br><pre>background: linear-gradient(to right, blue, purple);</pre>",
+			"task": "Make the gradient flow from left to right using <kbd>to right</kbd>.",
+			"previewHTML": "<button class=\"btn\">Get Started</button>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 2rem; } .btn { padding: 1rem 2rem; border: none; border-radius: 8px; font-size: 1rem; font-weight: 600; color: white; cursor: pointer; }",
+			"sandboxCSS": "",
+			"codePrefix": ".btn {\n  background: linear-gradient(",
+			"initialCode": "",
+			"codeSuffix": ", steelblue, mediumseagreen);\n}",
+			"solution": "to right",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "to right",
+					"message": "Add <kbd>to right</kbd> to set the direction"
+				}
+			]
+		},
+		{
+			"id": "gradients-3",
+			"title": "Radial Gradient",
+			"description": "The <kbd>radial-gradient()</kbd> function creates a gradient that radiates from a center point outward in a circular or elliptical pattern.<br><br><pre>background: radial-gradient(circle, white, steelblue);</pre><br>Add <kbd>circle</kbd> for a perfect circular gradient.",
+			"task": "Create a radial gradient from <kbd>white</kbd> to <kbd>steelblue</kbd>.",
+			"previewHTML": "<div class=\"orb\"></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 2rem; display: flex; justify-content: center; } .orb { width: 150px; height: 150px; border-radius: 50%; box-shadow: 0 8px 32px rgba(70, 130, 180, 0.4); }",
+			"sandboxCSS": "",
+			"codePrefix": ".orb {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "background: radial-gradient(circle, white, steelblue);",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "radial-gradient",
+					"message": "Use <kbd>radial-gradient()</kbd>"
+				},
+				{
+					"type": "contains",
+					"value": "white",
+					"message": "Start with <kbd>white</kbd>"
+				},
+				{
+					"type": "contains",
+					"value": "steelblue",
+					"message": "End with <kbd>steelblue</kbd>"
+				}
+			]
+		}
+	]
+}
--- a/lessons/11-filters.json
+++ b/lessons/11-filters.json
@@ -0,0 +1,108 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "css-filters",
+	"title": "CSS Filters",
+	"description": "Apply visual effects like blur, brightness, and shadows with CSS filters.",
+	"difficulty": "intermediate",
+	"lessons": [
+		{
+			"id": "filters-1",
+			"title": "Blur Filter",
+			"description": "The <kbd>filter</kbd> property applies visual effects to elements. The <kbd>blur()</kbd> function creates a Gaussian blur effect.<br><br><pre>filter: blur(4px);</pre><br>Higher values create more blur. This is great for backgrounds or creating depth.",
+			"task": "Blur the background image using <kbd>filter: blur(4px)</kbd>.",
+			"previewHTML": "<div class=\"bg\"></div><div class=\"content\"><h2>Welcome</h2></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; margin: 0; height: 200px; position: relative; overflow: hidden; } .bg { position: absolute; inset: 0; background: linear-gradient(45deg, coral, gold, steelblue); } .content { position: relative; z-index: 1; display: flex; align-items: center; justify-content: center; height: 100%; } .content h2 { color: white; text-shadow: 0 2px 8px rgba(0,0,0,0.3); margin: 0; }",
+			"sandboxCSS": "",
+			"codePrefix": ".bg {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "filter: blur(4px);",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "filter", "expected": "blur(4px)" },
+					"message": "Set <kbd>filter: blur(4px)</kbd>"
+				}
+			]
+		},
+		{
+			"id": "filters-2",
+			"title": "Grayscale Filter",
+			"description": "The <kbd>grayscale()</kbd> function removes color from an element. Use values from <kbd>0%</kbd> (full color) to <kbd>100%</kbd> (fully grayscale).<br><br><pre>filter: grayscale(100%);</pre><br>Great for hover effects or disabled states.",
+			"task": "Make the image grayscale with <kbd>filter: grayscale(100%)</kbd>.",
+			"previewHTML": "<div class=\"photo\"></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .photo { width: 200px; height: 150px; background: linear-gradient(135deg, coral 0%, gold 50%, steelblue 100%); border-radius: 8px; }",
+			"sandboxCSS": "",
+			"codePrefix": ".photo {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "filter: grayscale(100%);",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "grayscale",
+					"message": "Use <kbd>grayscale()</kbd> filter"
+				},
+				{
+					"type": "contains",
+					"value": "100%",
+					"message": "Set to <kbd>100%</kbd> for full grayscale"
+				}
+			]
+		},
+		{
+			"id": "filters-3",
+			"title": "Brightness Filter",
+			"description": "The <kbd>brightness()</kbd> function adjusts how bright an element appears. Values below <kbd>100%</kbd> darken, above <kbd>100%</kbd> brighten.<br><br><pre>filter: brightness(150%);</pre>",
+			"task": "Brighten the card with <kbd>filter: brightness(120%)</kbd>.",
+			"previewHTML": "<div class=\"card\"><span>Featured</span></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; background: #1a1a2e; } .card { padding: 2rem; background: linear-gradient(135deg, #4a4a6a, #2a2a4a); border-radius: 12px; text-align: center; } .card span { color: gold; font-weight: 600; text-transform: uppercase; letter-spacing: 2px; }",
+			"sandboxCSS": "",
+			"codePrefix": ".card {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "filter: brightness(120%);",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "brightness",
+					"message": "Use <kbd>brightness()</kbd> filter"
+				},
+				{
+					"type": "contains",
+					"value": "120%",
+					"message": "Set to <kbd>120%</kbd>"
+				}
+			]
+		},
+		{
+			"id": "filters-4",
+			"title": "Drop Shadow",
+			"description": "The <kbd>drop-shadow()</kbd> filter creates a shadow that follows the shape of the element, including transparency. Unlike <kbd>box-shadow</kbd>, it works on images with transparent backgrounds.<br><br><pre>filter: drop-shadow(2px 4px 6px black);</pre>",
+			"task": "Add a drop shadow with <kbd>filter: drop-shadow(4px 4px 8px gray)</kbd>.",
+			"previewHTML": "<div class=\"icon\">★</div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 2rem; display: flex; justify-content: center; } .icon { font-size: 4rem; color: gold; }",
+			"sandboxCSS": "",
+			"codePrefix": ".icon {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "filter: drop-shadow(4px 4px 8px gray);",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "drop-shadow",
+					"message": "Use <kbd>drop-shadow()</kbd> filter"
+				},
+				{
+					"type": "contains",
+					"value": "4px 4px 8px",
+					"message": "Set shadow offset and blur"
+				}
+			]
+		}
+	]
+}
--- a/lessons/12-positioning.json
+++ b/lessons/12-positioning.json
@@ -0,0 +1,98 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "css-positioning",
+	"title": "CSS Positioning",
+	"description": "Control element placement with CSS positioning properties.",
+	"difficulty": "intermediate",
+	"lessons": [
+		{
+			"id": "position-1",
+			"title": "Relative Position",
+			"description": "The <kbd>position</kbd> property controls how elements are placed. <kbd>relative</kbd> keeps the element in normal flow but allows you to offset it with <kbd>top</kbd>, <kbd>right</kbd>, <kbd>bottom</kbd>, <kbd>left</kbd>.<br><br><pre>.box {\n  position: relative;\n  top: 10px;\n}</pre>",
+			"task": "Make the badge position relative so we can offset it.",
+			"previewHTML": "<div class=\"card\"><span class=\"badge\">NEW</span><h3>Product</h3></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .card { padding: 1rem; background: white; border: 2px solid #eee; border-radius: 8px; } .card h3 { margin: 0; } .badge { display: inline-block; padding: 2px 8px; background: coral; color: white; font-size: 0.7rem; font-weight: bold; border-radius: 4px; }",
+			"sandboxCSS": "",
+			"codePrefix": ".badge {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "position: relative;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "position", "expected": "relative" },
+					"message": "Set <kbd>position: relative</kbd>"
+				}
+			]
+		},
+		{
+			"id": "position-2",
+			"title": "Offset Properties",
+			"description": "With <kbd>position: relative</kbd>, use offset properties to nudge the element from its original position:<br><br><kbd>top</kbd> - pushes down from top<br><kbd>left</kbd> - pushes right from left<br><br>Negative values move in the opposite direction.",
+			"task": "Move the badge up with <kbd>top: -8px</kbd>.",
+			"previewHTML": "<div class=\"card\"><span class=\"badge\">NEW</span><h3>Product</h3></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .card { padding: 1rem; background: white; border: 2px solid #eee; border-radius: 8px; } .card h3 { margin: 0; } .badge { display: inline-block; padding: 2px 8px; background: coral; color: white; font-size: 0.7rem; font-weight: bold; border-radius: 4px; position: relative; }",
+			"sandboxCSS": "",
+			"codePrefix": ".badge {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "top: -8px;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "top", "expected": "-8px" },
+					"message": "Set <kbd>top: -8px</kbd>"
+				}
+			]
+		},
+		{
+			"id": "position-3",
+			"title": "Absolute Position",
+			"description": "<kbd>position: absolute</kbd> removes the element from normal flow and positions it relative to its nearest positioned ancestor (or the viewport if none exists).<br><br>Always set a parent to <kbd>position: relative</kbd> to contain absolute children.",
+			"task": "Position the close button absolutely.",
+			"previewHTML": "<div class=\"modal\"><button class=\"close\">×</button><h3>Modal</h3><p>Content here</p></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .modal { position: relative; padding: 2rem; background: white; border-radius: 12px; box-shadow: 0 4px 24px rgba(0,0,0,0.15); max-width: 250px; } .modal h3 { margin: 0 0 8px; } .modal p { margin: 0; color: #666; } .close { width: 32px; height: 32px; border: none; background: #f5f5f5; border-radius: 50%; font-size: 1.2rem; cursor: pointer; }",
+			"sandboxCSS": "",
+			"codePrefix": ".close {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "position: absolute;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "position", "expected": "absolute" },
+					"message": "Set <kbd>position: absolute</kbd>"
+				}
+			]
+		},
+		{
+			"id": "position-4",
+			"title": "Placing Absolute Elements",
+			"description": "Combine <kbd>position: absolute</kbd> with offset properties to place elements precisely.<br><br><pre>.close {\n  position: absolute;\n  top: 8px;\n  right: 8px;\n}</pre>",
+			"task": "Move the close button to the top right corner with <kbd>top: 8px</kbd> and <kbd>right: 8px</kbd>.",
+			"previewHTML": "<div class=\"modal\"><button class=\"close\">×</button><h3>Modal</h3><p>Content here</p></div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .modal { position: relative; padding: 2rem; background: white; border-radius: 12px; box-shadow: 0 4px 24px rgba(0,0,0,0.15); max-width: 250px; } .modal h3 { margin: 0 0 8px; } .modal p { margin: 0; color: #666; } .close { position: absolute; width: 32px; height: 32px; border: none; background: #f5f5f5; border-radius: 50%; font-size: 1.2rem; cursor: pointer; }",
+			"sandboxCSS": "",
+			"codePrefix": ".close {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "top: 8px;\n  right: 8px;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "top", "expected": "8px" },
+					"message": "Set <kbd>top: 8px</kbd>"
+				},
+				{
+					"type": "property_value",
+					"value": { "property": "right", "expected": "8px" },
+					"message": "Set <kbd>right: 8px</kbd>"
+				}
+			]
+		}
+	]
+}
--- a/lessons/13-pseudo-elements.json
+++ b/lessons/13-pseudo-elements.json
@@ -0,0 +1,113 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "css-pseudo-elements",
+	"title": "CSS Pseudo-elements",
+	"description": "Create decorative elements and style specific parts of content with pseudo-elements.",
+	"difficulty": "intermediate",
+	"lessons": [
+		{
+			"id": "pseudo-1",
+			"title": "The ::before Element",
+			"description": "Pseudo-elements let you style specific parts of an element. <kbd>::before</kbd> creates a virtual element as the first child.<br><br>It requires the <kbd>content</kbd> property to display anything (even if empty).<br><br><pre>.item::before {\n  content: \"→ \";\n}</pre>",
+			"task": "Add a bullet before each list item using <kbd>::before</kbd> with <kbd>content: \"• \"</kbd>.",
+			"previewHTML": "<ul class=\"list\"><li>First item</li><li>Second item</li><li>Third item</li></ul>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .list { list-style: none; padding: 0; margin: 0; } .list li { padding: 8px 0; }",
+			"sandboxCSS": "",
+			"codePrefix": ".list li::before {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "content: \"• \";",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "content",
+					"message": "Use the <kbd>content</kbd> property"
+				},
+				{
+					"type": "contains",
+					"value": "•",
+					"message": "Add a bullet character <kbd>•</kbd>"
+				}
+			]
+		},
+		{
+			"id": "pseudo-2",
+			"title": "Styling ::before",
+			"description": "Pseudo-elements can be styled like any element. Add color, size, margins, and more.<br><br><pre>.item::before {\n  content: \"★\";\n  color: gold;\n  margin-right: 8px;\n}</pre>",
+			"task": "Style the bullet with <kbd>color: coral</kbd>.",
+			"previewHTML": "<ul class=\"list\"><li>First item</li><li>Second item</li><li>Third item</li></ul>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .list { list-style: none; padding: 0; margin: 0; } .list li { padding: 8px 0; } .list li::before { content: \"• \"; }",
+			"sandboxCSS": "",
+			"codePrefix": ".list li::before {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "color: coral;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "color", "expected": "coral" },
+					"message": "Set <kbd>color: coral</kbd>"
+				}
+			]
+		},
+		{
+			"id": "pseudo-3",
+			"title": "The ::after Element",
+			"description": "<kbd>::after</kbd> works like <kbd>::before</kbd> but inserts content as the last child. Common uses include badges, icons, or decorative elements.<br><br><pre>.new::after {\n  content: \" ✓\";\n  color: green;\n}</pre>",
+			"task": "Add a checkmark after completed items with <kbd>content: \" ✓\"</kbd>.",
+			"previewHTML": "<ul class=\"list\"><li class=\"done\">Buy groceries</li><li class=\"done\">Walk the dog</li><li>Read a book</li></ul>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .list { list-style: none; padding: 0; margin: 0; } .list li { padding: 8px 0; }",
+			"sandboxCSS": "",
+			"codePrefix": ".done::after {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "content: \" ✓\";",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "content",
+					"message": "Use the <kbd>content</kbd> property"
+				},
+				{
+					"type": "contains",
+					"value": "✓",
+					"message": "Add a checkmark <kbd>✓</kbd>"
+				}
+			]
+		},
+		{
+			"id": "pseudo-4",
+			"title": "Decorative Lines",
+			"description": "Pseudo-elements with <kbd>content: \"\"</kbd> can create decorative shapes when combined with width, height, and background.<br><br><pre>.title::after {\n  content: \"\";\n  display: block;\n  width: 50px;\n  height: 3px;\n  background: coral;\n}</pre>",
+			"task": "Create an underline decoration with <kbd>width: 40px</kbd>, <kbd>height: 3px</kbd>, and <kbd>background: steelblue</kbd>.",
+			"previewHTML": "<h2 class=\"title\">About Us</h2><p>We build great things.</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .title { margin: 0 0 1rem; } .title::after { content: \"\"; display: block; margin-top: 8px; } p { margin: 0; color: #666; }",
+			"sandboxCSS": "",
+			"codePrefix": ".title::after {\n  ",
+			"initialCode": "",
+			"codeSuffix": "\n}",
+			"solution": "width: 40px;\n  height: 3px;\n  background: steelblue;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "property_value",
+					"value": { "property": "width", "expected": "40px" },
+					"message": "Set <kbd>width: 40px</kbd>"
+				},
+				{
+					"type": "property_value",
+					"value": { "property": "height", "expected": "3px" },
+					"message": "Set <kbd>height: 3px</kbd>"
+				},
+				{
+					"type": "property_value",
+					"value": { "property": "background", "expected": "steelblue" },
+					"message": "Set <kbd>background: steelblue</kbd>"
+				}
+			]
+		}
+	]
+}
--- a/lessons/30-html-tables.json
+++ b/lessons/30-html-tables.json
@@ -39,6 +39,54 @@
 					"message": "Add 3 rows (1 header + 2 data rows)"
 				}
 			]
+		},
+		{
+			"id": "table-sections",
+			"title": "Table Sections",
+			"description": "Semantic table sections improve accessibility and allow for separate styling:<br><br>• <kbd>&lt;thead&gt;</kbd> — header section<br>• <kbd>&lt;tbody&gt;</kbd> — main content<br>• <kbd>&lt;tfoot&gt;</kbd> — footer (totals, summaries)",
+			"task": "Wrap the header row in <kbd>&lt;thead&gt;</kbd> and data rows in <kbd>&lt;tbody&gt;</kbd>.",
+			"previewHTML": "",
+			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; } table { border-collapse: collapse; width: 100%; max-width: 350px; background: white; border-radius: 8px; overflow: hidden; box-shadow: 0 2px 8px rgba(0,0,0,0.1); } th, td { padding: 12px 16px; text-align: left; } thead { background: steelblue; color: white; } tbody tr:nth-child(even) { background: #f8f9fa; }",
+			"sandboxCSS": "",
+			"initialCode": "<table>\n  <tr>\n    <th>Name</th>\n    <th>Score</th>\n  </tr>\n  <tr>\n    <td>Alice</td>\n    <td>95</td>\n  </tr>\n  <tr>\n    <td>Bob</td>\n    <td>87</td>\n  </tr>\n</table>",
+			"solution": "<table>\n  <thead>\n    <tr>\n      <th>Name</th>\n      <th>Score</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <td>Alice</td>\n      <td>95</td>\n    </tr>\n    <tr>\n      <td>Bob</td>\n      <td>87</td>\n    </tr>\n  </tbody>\n</table>",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "element_exists",
+					"value": "thead",
+					"message": "Add a <kbd>&lt;thead&gt;</kbd> section for the header"
+				},
+				{
+					"type": "element_exists",
+					"value": "tbody",
+					"message": "Add a <kbd>&lt;tbody&gt;</kbd> section for the data"
+				}
+			]
+		},
+		{
+			"id": "table-colspan",
+			"title": "Spanning Columns",
+			"description": "The <kbd>colspan</kbd> attribute lets a cell span multiple columns. This is useful for headers that group multiple columns or footer totals.<br><br><pre>&lt;td colspan=\"2\"&gt;...&lt;/td&gt;</pre>",
+			"task": "Add a footer row that spans both columns using <kbd>colspan=\"2\"</kbd>.",
+			"previewHTML": "",
+			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; } table { border-collapse: collapse; width: 100%; max-width: 350px; background: white; border-radius: 8px; overflow: hidden; box-shadow: 0 2px 8px rgba(0,0,0,0.1); } th, td { padding: 12px 16px; text-align: left; border-bottom: 1px solid #eee; } thead { background: steelblue; color: white; } tfoot { background: #f0f0f0; font-weight: 600; }",
+			"sandboxCSS": "",
+			"initialCode": "<table>\n  <thead>\n    <tr>\n      <th>Item</th>\n      <th>Price</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <td>Coffee</td>\n      <td>$4</td>\n    </tr>\n    <tr>\n      <td>Cake</td>\n      <td>$6</td>\n    </tr>\n  </tbody>\n</table>",
+			"solution": "<table>\n  <thead>\n    <tr>\n      <th>Item</th>\n      <th>Price</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <td>Coffee</td>\n      <td>$4</td>\n    </tr>\n    <tr>\n      <td>Cake</td>\n      <td>$6</td>\n    </tr>\n  </tbody>\n  <tfoot>\n    <tr>\n      <td colspan=\"2\">Total: $10</td>\n    </tr>\n  </tfoot>\n</table>",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "element_exists",
+					"value": "tfoot",
+					"message": "Add a <kbd>&lt;tfoot&gt;</kbd> section"
+				},
+				{
+					"type": "contains",
+					"value": "colspan",
+					"message": "Use <kbd>colspan</kbd> to span columns"
+				}
+			]
 		}
 	]
 }
--- a/lessons/33-html-semantic.json
+++ b/lessons/33-html-semantic.json
@@ -0,0 +1,88 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "html-semantic",
+	"title": "Semantic HTML",
+	"mode": "html",
+	"description": "Use meaningful HTML elements to structure content properly.",
+	"difficulty": "beginner",
+	"lessons": [
+		{
+			"id": "semantic-1",
+			"title": "The <article> Element",
+			"description": "The <kbd>&lt;article&gt;</kbd> element represents self-contained content that could be distributed independently, like a blog post, news article, or comment.<br><br><pre>&lt;article&gt;\n  &lt;h2&gt;Article Title&lt;/h2&gt;\n  &lt;p&gt;Article content...&lt;/p&gt;\n&lt;/article&gt;</pre>",
+			"task": "Wrap the blog post content in an <kbd>&lt;article&gt;</kbd> element.",
+			"previewHTML": "",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } article { padding: 1rem; background: #f9f9f9; border-left: 4px solid steelblue; border-radius: 4px; } h2 { margin: 0 0 8px; color: steelblue; } p { margin: 0; color: #555; line-height: 1.5; }",
+			"sandboxCSS": "",
+			"codePrefix": "",
+			"initialCode": "<h2>My First Post</h2>\n<p>This is a blog post about learning HTML.</p>",
+			"codeSuffix": "",
+			"solution": "<article>\n<h2>My First Post</h2>\n<p>This is a blog post about learning HTML.</p>\n</article>",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "<article>",
+					"message": "Add an opening <kbd>&lt;article&gt;</kbd> tag"
+				},
+				{
+					"type": "contains",
+					"value": "</article>",
+					"message": "Add a closing <kbd>&lt;/article&gt;</kbd> tag"
+				}
+			]
+		},
+		{
+			"id": "semantic-2",
+			"title": "The <section> Element",
+			"description": "The <kbd>&lt;section&gt;</kbd> element represents a thematic grouping of content, typically with a heading. Use it to divide a page into logical sections.<br><br><pre>&lt;section&gt;\n  &lt;h2&gt;Features&lt;/h2&gt;\n  &lt;p&gt;Our product features...&lt;/p&gt;\n&lt;/section&gt;</pre>",
+			"task": "Wrap the features content in a <kbd>&lt;section&gt;</kbd> element.",
+			"previewHTML": "",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } section { padding: 1rem; background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%); border-radius: 8px; } h2 { margin: 0 0 12px; } ul { margin: 0; padding-left: 1.5rem; } li { margin: 4px 0; color: #444; }",
+			"sandboxCSS": "",
+			"codePrefix": "",
+			"initialCode": "<h2>Features</h2>\n<ul>\n  <li>Fast performance</li>\n  <li>Easy to use</li>\n</ul>",
+			"codeSuffix": "",
+			"solution": "<section>\n<h2>Features</h2>\n<ul>\n  <li>Fast performance</li>\n  <li>Easy to use</li>\n</ul>\n</section>",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "<section>",
+					"message": "Add an opening <kbd>&lt;section&gt;</kbd> tag"
+				},
+				{
+					"type": "contains",
+					"value": "</section>",
+					"message": "Add a closing <kbd>&lt;/section&gt;</kbd> tag"
+				}
+			]
+		},
+		{
+			"id": "semantic-3",
+			"title": "The <aside> Element",
+			"description": "The <kbd>&lt;aside&gt;</kbd> element represents content tangentially related to the main content, like sidebars, pull quotes, or related links.<br><br><pre>&lt;aside&gt;\n  &lt;h3&gt;Related&lt;/h3&gt;\n  &lt;ul&gt;...&lt;/ul&gt;\n&lt;/aside&gt;</pre>",
+			"task": "Wrap the related links in an <kbd>&lt;aside&gt;</kbd> element.",
+			"previewHTML": "",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } aside { padding: 1rem; background: #fff8e7; border: 1px solid #ffe0a6; border-radius: 8px; } h3 { margin: 0 0 8px; color: #b8860b; font-size: 0.9rem; text-transform: uppercase; } ul { margin: 0; padding-left: 1.2rem; } li { margin: 4px 0; } a { color: #b8860b; }",
+			"sandboxCSS": "",
+			"codePrefix": "",
+			"initialCode": "<h3>Related Posts</h3>\n<ul>\n  <li><a href=\"#\">CSS Basics</a></li>\n  <li><a href=\"#\">HTML Tips</a></li>\n</ul>",
+			"codeSuffix": "",
+			"solution": "<aside>\n<h3>Related Posts</h3>\n<ul>\n  <li><a href=\"#\">CSS Basics</a></li>\n  <li><a href=\"#\">HTML Tips</a></li>\n</ul>\n</aside>",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "<aside>",
+					"message": "Add an opening <kbd>&lt;aside&gt;</kbd> tag"
+				},
+				{
+					"type": "contains",
+					"value": "</aside>",
+					"message": "Add a closing <kbd>&lt;/aside&gt;</kbd> tag"
+				}
+			]
+		}
+	]
+}
--- a/lessons/40-markdown-basics.json
+++ b/lessons/40-markdown-basics.json
@@ -0,0 +1,197 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "markdown-basics",
+	"title": "Markdown Basics",
+	"description": "Learn to format text documents with Markdown, a simple and readable markup language used everywhere from GitHub to note-taking apps.",
+	"mode": "markdown",
+	"difficulty": "beginner",
+	"lessons": [
+		{
+			"id": "md-headings",
+			"title": "Headings",
+			"description": "Markdown uses hash symbols <kbd>#</kbd> to create headings. One <kbd>#</kbd> creates the largest heading (h1), two <kbd>##</kbd> creates a smaller heading (h2), and so on up to six levels.<br><br><pre># Main Title\n## Section\n### Subsection</pre>",
+			"task": "Create a main heading by typing <kbd># Hello</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"solution": "# Hello",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "^#\\s+.+",
+					"message": "Start with <kbd>#</kbd> followed by a space and your heading text"
+				},
+				{
+					"type": "contains",
+					"value": "Hello",
+					"message": "Your heading should contain <kbd>Hello</kbd>"
+				}
+			]
+		},
+		{
+			"id": "md-heading-levels",
+			"title": "Heading Levels",
+			"description": "Use more <kbd>#</kbd> symbols for smaller headings. <kbd>##</kbd> creates an h2, <kbd>###</kbd> an h3. This creates a clear document structure with visual hierarchy.",
+			"task": "Create an h2 heading with <kbd>## About</kbd> followed by an h3 heading with <kbd>### Details</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"solution": "## About\n\n### Details",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "^##\\s+About",
+					"message": "Start with <kbd>## About</kbd>"
+				},
+				{
+					"type": "regex",
+					"value": "###\\s+Details",
+					"message": "Add <kbd>### Details</kbd> for the h3 heading"
+				}
+			]
+		},
+		{
+			"id": "md-bold",
+			"title": "Bold Text",
+			"description": "Wrap text in double asterisks <kbd>**</kbd> or double underscores <kbd>__</kbd> to make it <strong>bold</strong>. This emphasizes important words or phrases.",
+			"task": "Make the word <kbd>important</kbd> bold by wrapping it with <kbd>**</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "This is important text.",
+			"solution": "This is **important** text.",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "\\*\\*important\\*\\*",
+					"message": "Wrap <kbd>important</kbd> with double asterisks: <kbd>**important**</kbd>"
+				}
+			]
+		},
+		{
+			"id": "md-italic",
+			"title": "Italic Text",
+			"description": "Wrap text in single asterisks <kbd>*</kbd> or single underscores <kbd>_</kbd> to make it <em>italic</em>. Use this for subtle emphasis or titles of works.",
+			"task": "Make the word <kbd>elegant</kbd> italic by wrapping it with <kbd>*</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "A simple and elegant solution.",
+			"solution": "A simple and *elegant* solution.",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "\\*elegant\\*",
+					"message": "Wrap <kbd>elegant</kbd> with single asterisks: <kbd>*elegant*</kbd>"
+				},
+				{
+					"type": "not_contains",
+					"value": "**elegant**",
+					"message": "Use single asterisks for italic, not double"
+				}
+			]
+		},
+		{
+			"id": "md-unordered-list",
+			"title": "Bullet Lists",
+			"description": "Create bullet lists using <kbd>-</kbd>, <kbd>*</kbd>, or <kbd>+</kbd> at the start of each line. Each item goes on its own line.",
+			"task": "Create a bullet list with three items: <kbd>Apple</kbd>, <kbd>Banana</kbd>, <kbd>Cherry</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"solution": "- Apple\n- Banana\n- Cherry",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "^[-*+]\\s+Apple",
+					"message": "Start with a dash, asterisk, or plus followed by <kbd>Apple</kbd>"
+				},
+				{
+					"type": "regex",
+					"value": "[-*+]\\s+Banana",
+					"message": "Add <kbd>Banana</kbd> as a list item"
+				},
+				{
+					"type": "regex",
+					"value": "[-*+]\\s+Cherry",
+					"message": "Add <kbd>Cherry</kbd> as a list item"
+				}
+			]
+		},
+		{
+			"id": "md-ordered-list",
+			"title": "Numbered Lists",
+			"description": "Create numbered lists by starting lines with <kbd>1.</kbd>, <kbd>2.</kbd>, etc. Markdown automatically numbers them in sequence.",
+			"task": "Create a numbered list: <kbd>Wake up</kbd>, <kbd>Eat breakfast</kbd>, <kbd>Start coding</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"solution": "1. Wake up\n2. Eat breakfast\n3. Start coding",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "\\d+\\.\\s+Wake up",
+					"message": "Start with a number and period: <kbd>1. Wake up</kbd>"
+				},
+				{
+					"type": "regex",
+					"value": "\\d+\\.\\s+Eat breakfast",
+					"message": "Add <kbd>Eat breakfast</kbd> as a numbered item"
+				},
+				{
+					"type": "regex",
+					"value": "\\d+\\.\\s+Start coding",
+					"message": "Add <kbd>Start coding</kbd> as a numbered item"
+				}
+			]
+		},
+		{
+			"id": "md-links",
+			"title": "Links",
+			"description": "Create links with <kbd>[text](url)</kbd>. The text in brackets is what readers see; the URL in parentheses is where they go when clicked.",
+			"task": "Create a link that shows <kbd>Google</kbd> and goes to <kbd>https://google.com</kbd>",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"solution": "[Google](https://google.com)",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "\\[Google\\]\\(https?://google\\.com\\)",
+					"message": "Use the format <kbd>[Google](https://google.com)</kbd>"
+				}
+			]
+		},
+		{
+			"id": "md-inline-code",
+			"title": "Inline Code",
+			"description": "Wrap text in backticks <kbd>`</kbd> to format it as code. This is useful for variable names, commands, or short code snippets in your text.",
+			"task": "Format <kbd>npm install</kbd> as inline code using backticks",
+			"previewHTML": "",
+			"previewBaseCSS": "",
+			"sandboxCSS": "",
+			"initialCode": "Run npm install to install dependencies.",
+			"solution": "Run `npm install` to install dependencies.",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "`npm install`",
+					"message": "Wrap <kbd>npm install</kbd> with backticks: <kbd>`npm install`</kbd>"
+				}
+			]
+		}
+	]
+}
--- a/lessons/50-js-variables.json
+++ b/lessons/50-js-variables.json
@@ -0,0 +1,139 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "js-variables",
+	"title": "JS Variables",
+	"description": "Learn to declare variables with let and const, and work with basic data types in JavaScript.",
+	"mode": "javascript",
+	"difficulty": "beginner",
+	"lessons": [
+		{
+			"id": "js-const",
+			"title": "Constants",
+			"description": "Use <kbd>const</kbd> to declare a variable that cannot be reassigned. Constants are the default choice for most values in modern JavaScript.",
+			"task": "Declare a constant named <kbd>name</kbd> with the value <kbd>\"Alice\"</kbd>",
+			"previewHTML": "<p id=\"out\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "\ndocument.getElementById('out').textContent = name;",
+			"solution": "const name = \"Alice\";",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "const",
+					"message": "Use <kbd>const</kbd> to declare the variable"
+				},
+				{
+					"type": "regex",
+					"value": "const\\s+name\\s*=",
+					"message": "Declare a constant called <kbd>name</kbd>"
+				},
+				{
+					"type": "regex",
+					"value": "\"Alice\"|'Alice'|`Alice`",
+					"message": "Set the value to <kbd>\"Alice\"</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-let",
+			"title": "Let Variables",
+			"description": "Use <kbd>let</kbd> to declare variables that you plan to reassign later. Unlike <kbd>const</kbd>, a <kbd>let</kbd> variable can change its value.",
+			"task": "Declare a variable <kbd>count</kbd> with <kbd>let</kbd> set to <kbd>0</kbd>, then reassign it to <kbd>5</kbd>",
+			"previewHTML": "<p id=\"out\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "\ndocument.getElementById('out').textContent = count;",
+			"solution": "let count = 0;\ncount = 5;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "let\\s+count\\s*=\\s*0",
+					"message": "Start with <kbd>let count = 0;</kbd>"
+				},
+				{
+					"type": "regex",
+					"value": "count\\s*=\\s*5",
+					"message": "Reassign count to <kbd>5</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-string",
+			"title": "Template Literals",
+			"description": "Template literals use backticks <kbd>`</kbd> and <kbd>${}</kbd> to embed expressions inside strings. This makes building dynamic text much easier than string concatenation.",
+			"task": "Create a constant <kbd>msg</kbd> using a template literal: <kbd>`Hello, ${name}!`</kbd>",
+			"previewHTML": "<p id=\"out\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "const name = \"World\";\n",
+			"codeSuffix": "\ndocument.getElementById('out').textContent = msg;",
+			"solution": "const msg = `Hello, ${name}!`;",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "const\\s+msg\\s*=",
+					"message": "Declare a constant called <kbd>msg</kbd>"
+				},
+				{
+					"type": "contains",
+					"value": "${name}",
+					"message": "Use <kbd>${name}</kbd> inside backticks to embed the variable"
+				},
+				{
+					"type": "regex",
+					"value": "`.*\\$\\{name\\}.*`",
+					"message": "Wrap the whole string in backticks <kbd>`</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-array",
+			"title": "Arrays",
+			"description": "Arrays store ordered lists of values in square brackets. Access items by index (starting at 0) and use <kbd>.length</kbd> to get the count.",
+			"task": "Create a constant <kbd>colors</kbd> with an array: <kbd>[\"red\", \"green\", \"blue\"]</kbd>",
+			"previewHTML": "<p id=\"out\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "\ndocument.getElementById('out').textContent = colors.join(', ');",
+			"solution": "const colors = [\"red\", \"green\", \"blue\"];",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "regex",
+					"value": "const\\s+colors\\s*=",
+					"message": "Declare a constant called <kbd>colors</kbd>"
+				},
+				{
+					"type": "contains",
+					"value": "[",
+					"message": "Use square brackets <kbd>[</kbd> to create an array"
+				},
+				{
+					"type": "regex",
+					"value": "(\"red\"|'red'|`red`)",
+					"message": "Include <kbd>\"red\"</kbd> in the array"
+				},
+				{
+					"type": "regex",
+					"value": "(\"green\"|'green'|`green`)",
+					"message": "Include <kbd>\"green\"</kbd> in the array"
+				},
+				{
+					"type": "regex",
+					"value": "(\"blue\"|'blue'|`blue`)",
+					"message": "Include <kbd>\"blue\"</kbd> in the array"
+				}
+			]
+		}
+	]
+}
--- a/lessons/51-js-dom.json
+++ b/lessons/51-js-dom.json
@@ -0,0 +1,139 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "js-dom",
+	"title": "JS DOM",
+	"description": "Learn to select and modify HTML elements using JavaScript DOM methods like querySelector and textContent.",
+	"mode": "javascript",
+	"difficulty": "beginner",
+	"lessons": [
+		{
+			"id": "js-query",
+			"title": "querySelector",
+			"description": "Use <kbd>document.querySelector()</kbd> to find the first element matching a CSS selector. It returns a single element you can then modify.",
+			"task": "Select the <kbd>h1</kbd> element and store it in a constant called <kbd>title</kbd>",
+			"previewHTML": "<h1>Hello</h1><p id=\"out\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "\ndocument.getElementById('out').textContent = title.tagName;",
+			"solution": "const title = document.querySelector('h1');",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "querySelector",
+					"message": "Use <kbd>document.querySelector()</kbd> to select an element"
+				},
+				{
+					"type": "regex",
+					"value": "querySelector\\(['\"`]h1['\"`]\\)",
+					"message": "Pass <kbd>'h1'</kbd> as the selector"
+				},
+				{
+					"type": "regex",
+					"value": "const\\s+title\\s*=",
+					"message": "Store the result in a constant called <kbd>title</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-text",
+			"title": "textContent",
+			"description": "The <kbd>textContent</kbd> property lets you read or change the text inside an element. Setting it replaces all existing text.",
+			"task": "Select the <kbd>.msg</kbd> element and set its <kbd>textContent</kbd> to <kbd>\"Done!\"</kbd>",
+			"previewHTML": "<p class=\"msg\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "",
+			"solution": "document.querySelector('.msg').textContent = \"Done!\";",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "querySelector",
+					"message": "Use <kbd>querySelector</kbd> to find the element"
+				},
+				{
+					"type": "contains",
+					"value": "textContent",
+					"message": "Use the <kbd>textContent</kbd> property to change the text"
+				},
+				{
+					"type": "regex",
+					"value": "(\"Done!\"|'Done!'|`Done!`)",
+					"message": "Set the text to <kbd>\"Done!\"</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-style",
+			"title": "Inline Styles",
+			"description": "Access the <kbd>style</kbd> property to set inline CSS on an element. CSS properties with dashes become camelCase: <kbd>background-color</kbd> becomes <kbd>backgroundColor</kbd>.",
+			"task": "Select the <kbd>.box</kbd> element and set its <kbd>style.color</kbd> to <kbd>\"coral\"</kbd>",
+			"previewHTML": "<p class=\"box\">Style me!</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .box { font-size: 1.5rem; font-weight: bold; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "",
+			"solution": "document.querySelector('.box').style.color = \"coral\";",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "querySelector",
+					"message": "Use <kbd>querySelector</kbd> to find the element"
+				},
+				{
+					"type": "contains",
+					"value": ".style.",
+					"message": "Use the <kbd>.style</kbd> property to set CSS"
+				},
+				{
+					"type": "regex",
+					"value": "style\\.color\\s*=",
+					"message": "Set <kbd>style.color</kbd> on the element"
+				},
+				{
+					"type": "regex",
+					"value": "(\"coral\"|'coral'|`coral`)",
+					"message": "Set the color to <kbd>\"coral\"</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-classlist",
+			"title": "classList",
+			"description": "The <kbd>classList</kbd> property provides methods to add, remove, or toggle CSS classes on an element without touching other classes.",
+			"task": "Select the <kbd>.card</kbd> element and add the class <kbd>\"active\"</kbd> using <kbd>classList.add()</kbd>",
+			"previewHTML": "<div class=\"card\">Toggle me</div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .card { padding: 1rem; border: 2px solid gray; border-radius: 8px; } .active { border-color: coral; background: #fff0ee; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "",
+			"codeSuffix": "",
+			"solution": "document.querySelector('.card').classList.add(\"active\");",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "classList",
+					"message": "Use the <kbd>classList</kbd> property"
+				},
+				{
+					"type": "regex",
+					"value": "classList\\.add\\(",
+					"message": "Call <kbd>classList.add()</kbd> to add a class"
+				},
+				{
+					"type": "regex",
+					"value": "(\"active\"|'active'|`active`)",
+					"message": "Add the class <kbd>\"active\"</kbd>"
+				}
+			]
+		}
+	]
+}
--- a/lessons/52-js-events.json
+++ b/lessons/52-js-events.json
@@ -0,0 +1,118 @@
+{
+	"$schema": "../schemas/code-crispies-module-schema.json",
+	"id": "js-events",
+	"title": "JS Events",
+	"description": "Learn to respond to user interactions with addEventListener for clicks, input changes, and keyboard events.",
+	"mode": "javascript",
+	"difficulty": "beginner",
+	"lessons": [
+		{
+			"id": "js-click",
+			"title": "Click Events",
+			"description": "Use <kbd>addEventListener('click', ...)</kbd> to run code when a user clicks an element. The first argument is the event name, the second is a callback function.",
+			"task": "Add a click listener to the <kbd>.btn</kbd> element that sets the <kbd>.msg</kbd> text to <kbd>\"Clicked!\"</kbd>",
+			"previewHTML": "<button class=\"btn\">Click me</button><p class=\"msg\">Waiting...</p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .btn { padding: 0.5rem 1rem; border: none; background: steelblue; color: white; border-radius: 4px; cursor: pointer; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "const btn = document.querySelector('.btn');\nconst msg = document.querySelector('.msg');\n\n",
+			"codeSuffix": "",
+			"solution": "btn.addEventListener('click', () => {\n  msg.textContent = \"Clicked!\";\n});",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "addEventListener",
+					"message": "Use <kbd>addEventListener</kbd> to listen for events"
+				},
+				{
+					"type": "regex",
+					"value": "addEventListener\\(['\"`]click['\"`]",
+					"message": "Listen for the <kbd>'click'</kbd> event"
+				},
+				{
+					"type": "contains",
+					"value": "textContent",
+					"message": "Use <kbd>textContent</kbd> to update the text"
+				},
+				{
+					"type": "regex",
+					"value": "(\"Clicked!\"|'Clicked!'|`Clicked!`)",
+					"message": "Set the text to <kbd>\"Clicked!\"</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-toggle",
+			"title": "Toggle Classes",
+			"description": "Combine events with <kbd>classList.toggle()</kbd> to switch a class on and off. Each click adds the class if missing, or removes it if present.",
+			"task": "Add a click listener to <kbd>.btn</kbd> that toggles the class <kbd>\"on\"</kbd> on <kbd>.lamp</kbd>",
+			"previewHTML": "<button class=\"btn\">Toggle</button><div class=\"lamp\">💡</div>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; text-align: center; } .btn { padding: 0.5rem 1rem; border: none; background: steelblue; color: white; border-radius: 4px; cursor: pointer; } .lamp { font-size: 3rem; margin-top: 1rem; opacity: 0.3; transition: opacity 0.3s; } .lamp.on { opacity: 1; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "const btn = document.querySelector('.btn');\nconst lamp = document.querySelector('.lamp');\n\n",
+			"codeSuffix": "",
+			"solution": "btn.addEventListener('click', () => {\n  lamp.classList.toggle('on');\n});",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "addEventListener",
+					"message": "Use <kbd>addEventListener</kbd> to listen for events"
+				},
+				{
+					"type": "regex",
+					"value": "addEventListener\\(['\"`]click['\"`]",
+					"message": "Listen for the <kbd>'click'</kbd> event"
+				},
+				{
+					"type": "regex",
+					"value": "classList\\.toggle\\(",
+					"message": "Use <kbd>classList.toggle()</kbd> to switch the class"
+				},
+				{
+					"type": "regex",
+					"value": "(\"on\"|'on'|`on`)",
+					"message": "Toggle the class <kbd>\"on\"</kbd>"
+				}
+			]
+		},
+		{
+			"id": "js-input",
+			"title": "Input Events",
+			"description": "The <kbd>input</kbd> event fires every time the value of an input field changes. Use <kbd>event.target.value</kbd> to read the current value.",
+			"task": "Add an input listener to <kbd>.field</kbd> that sets <kbd>.out</kbd> text to the input's value",
+			"previewHTML": "<input class=\"field\" placeholder=\"Type here...\"><p class=\"out\">Echo: </p>",
+			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .field { padding: 0.5rem; border: 2px solid #ccc; border-radius: 4px; font-size: 1rem; width: 100%; box-sizing: border-box; }",
+			"sandboxCSS": "",
+			"initialCode": "",
+			"codePrefix": "const field = document.querySelector('.field');\nconst out = document.querySelector('.out');\n\n",
+			"codeSuffix": "",
+			"solution": "field.addEventListener('input', (event) => {\n  out.textContent = event.target.value;\n});",
+			"previewContainer": "preview-area",
+			"validations": [
+				{
+					"type": "contains",
+					"value": "addEventListener",
+					"message": "Use <kbd>addEventListener</kbd> to listen for events"
+				},
+				{
+					"type": "regex",
+					"value": "addEventListener\\(['\"`]input['\"`]",
+					"message": "Listen for the <kbd>'input'</kbd> event"
+				},
+				{
+					"type": "contains",
+					"value": "textContent",
+					"message": "Use <kbd>textContent</kbd> to update the output"
+				},
+				{
+					"type": "regex",
+					"value": "(event|e|evt)\\.target\\.value",
+					"message": "Read the input value with <kbd>event.target.value</kbd>"
+				}
+			]
+		}
+	]
+}
--- a/lessons/ar/00-welcome.json
+++ b/lessons/ar/00-welcome.json
@@ -3,7 +3,7 @@
 	"id": "welcome",
 	"title": "مرحباً",
 	"description": "ابدأ مع Code Crispies",
-	"mode": "html",
+	"mode": "css",
 	"difficulty": "beginner",
 	"excludeFromProgress": true,
 	"lessons": [
--- a/lessons/de/00-welcome.json
+++ b/lessons/de/00-welcome.json
@@ -3,7 +3,7 @@
 	"id": "welcome",
 	"title": "Willkommen",
 	"description": "Erste Schritte mit Code Crispies",
-	"mode": "html",
+	"mode": "css",
 	"difficulty": "beginner",
 	"excludeFromProgress": true,
 	"lessons": [
--- a/lessons/es/00-welcome.json
+++ b/lessons/es/00-welcome.json
@@ -3,7 +3,7 @@
 	"id": "welcome",
 	"title": "Bienvenido",
 	"description": "Comienza con Code Crispies",
-	"mode": "html",
+	"mode": "css",
 	"difficulty": "beginner",
 	"excludeFromProgress": true,
 	"lessons": [
--- a/lessons/flexbox.json
+++ b/lessons/flexbox.json
@@ -9,7 +9,7 @@
 			"id": "flexbox-1",
 			"title": "Container",
 			"description": "Before flexbox, creating even simple layouts required floats, positioning hacks, or table-based layouts. Flexbox (Flexible Box Layout) revolutionized CSS by providing a one-dimensional layout system designed specifically for distributing space and aligning content.<br><br><strong>How it works:</strong> When you set <kbd>display: flex</kbd> on an element, it becomes a <em>flex container</em>. Its direct children automatically become <em>flex items</em> that flow along a main axis (horizontal by default). This single property transforms stacked block elements into a horizontal row.<br><br><strong>The two axes:</strong><br>• <em>Main axis</em> – The primary direction items flow (row = left→right)<br>• <em>Cross axis</em> – Perpendicular to main (row = top→bottom)<br><br><pre>.nav {\n  display: flex;\n}</pre>",
-			"task": "This navigation menu stacks vertically. Add <kbd>display: flex</kbd> to <kbd>.nav</kbd> to arrange the links horizontally.",
+			"task": "The navigation links are stacking vertically. Make them display side by side in a horizontal row.",
 			"previewHTML": "<nav class=\"nav\"><a href=\"#\">Home</a><a href=\"#\">Products</a><a href=\"#\">About</a><a href=\"#\">Contact</a></nav>",
 			"previewBaseCSS": "body { font-family: system-ui, sans-serif; margin: 0; } .nav { background: #1a1a2e; padding: 1rem; } .nav a { color: white; text-decoration: none; padding: 8px 1rem; border-radius: 4px; } .nav a:hover { background: rgba(255,255,255,0.1); }",
 			"sandboxCSS": "",
@@ -22,7 +22,7 @@
 				{
 					"type": "property_value",
 					"value": { "property": "display", "expected": "flex" },
-					"message": "Set <kbd>display: flex</kbd>"
+					"message": "Try changing the display mode to create a flex container"
 				}
 			]
 		},
@@ -30,7 +30,7 @@
 			"id": "flexbox-2",
 			"title": "Gap",
 			"description": "The <kbd>gap</kbd> property adds consistent spacing between flex items without needing margins. It only creates space between items, not around the edges.",
-			"task": "Add <kbd>gap: 1rem</kbd> to space out the navigation links evenly.",
+			"task": "The navigation links are crammed together with no breathing room. Add 1rem of spacing between them.",
 			"previewHTML": "<nav class=\"nav\"><a href=\"#\">Home</a><a href=\"#\">Products</a><a href=\"#\">About</a><a href=\"#\">Contact</a></nav>",
 			"previewBaseCSS": "body { font-family: system-ui, sans-serif; margin: 0; } .nav { background: #1a1a2e; padding: 1rem; display: flex; } .nav a { color: white; text-decoration: none; padding: 8px 1rem; border-radius: 4px; background: rgba(255,255,255,0.1); }",
 			"sandboxCSS": "",
@@ -43,7 +43,7 @@
 				{
 					"type": "property_value",
 					"value": { "property": "gap", "expected": "1rem" },
-					"message": "Set <kbd>gap: 1rem</kbd>"
+					"message": "Use the property that adds spacing between flex items"
 				}
 			]
 		},
@@ -51,7 +51,7 @@
 			"id": "flexbox-3",
 			"title": "Justify Content",
 			"description": "<kbd>justify-content</kbd> distributes items along the main axis. Common values:<br>• <kbd>flex-start</kbd> – pack items at the start<br>• <kbd>flex-end</kbd> – pack at the end<br>• <kbd>center</kbd> – center items<br>• <kbd>space-between</kbd> – equal space between items<br>• <kbd>space-around</kbd> – equal space around items",
-			"task": "Push the \"Login\" button to the right by setting <kbd>justify-content: space-between</kbd> on the nav.",
+			"task": "The Login button should sit on the far right, with the other links staying on the left. Distribute the space between them.",
 			"previewHTML": "<nav class=\"nav\"><div class=\"links\"><a href=\"#\">Home</a><a href=\"#\">Products</a><a href=\"#\">About</a></div><a href=\"#\" class=\"login\">Login</a></nav>",
 			"previewBaseCSS": "body { font-family: system-ui, sans-serif; margin: 0; } .nav { background: #1a1a2e; padding: 1rem; display: flex; } .links { display: flex; gap: 8px; } .nav a { color: white; text-decoration: none; padding: 8px 1rem; border-radius: 4px; } .nav a:hover { background: rgba(255,255,255,0.1); } .login { background: steelblue; }",
 			"sandboxCSS": "",
@@ -64,7 +64,7 @@
 				{
 					"type": "property_value",
 					"value": { "property": "justify-content", "expected": "space-between" },
-					"message": "Set <kbd>justify-content: space-between</kbd>"
+					"message": "Use the property that distributes items along the main axis"
 				}
 			]
 		},
@@ -72,7 +72,7 @@
 			"id": "flexbox-4",
 			"title": "Align Items",
 			"description": "<kbd>align-items</kbd> controls alignment on the cross axis (vertical when flex-direction is row). Values include:<br>• <kbd>stretch</kbd> – stretch to fill (default)<br>• <kbd>flex-start</kbd> – align to top<br>• <kbd>flex-end</kbd> – align to bottom<br>• <kbd>center</kbd> – center vertically",
-			"task": "The logo and nav links have different heights. Center them vertically with <kbd>align-items: center</kbd>.",
+			"task": "The logo and nav links sit at different heights. Center them vertically so they line up.",
 			"previewHTML": "<header class=\"header\"><div class=\"logo\">ACME</div><nav><a href=\"#\">Products</a><a href=\"#\">Pricing</a><a href=\"#\">Docs</a></nav></header>",
 			"previewBaseCSS": "body { font-family: system-ui, sans-serif; margin: 0; } .header { background: white; padding: 1rem 2rem; display: flex; justify-content: space-between; border-bottom: 1px solid #eee; } .logo { font-size: 1.5rem; font-weight: bold; color: steelblue; } nav { display: flex; gap: 1rem; } nav a { color: #333; text-decoration: none; font-size: 0.9rem; }",
 			"sandboxCSS": "",
@@ -85,7 +85,7 @@
 				{
 					"type": "property_value",
 					"value": { "property": "align-items", "expected": "center" },
-					"message": "Set <kbd>align-items: center</kbd>"
+					"message": "Use the property that controls cross-axis alignment"
 				}
 			]
 		},
@@ -93,7 +93,7 @@
 			"id": "flexbox-5",
 			"title": "Flex Wrap",
 			"description": "By default, flex items squeeze onto one line. <kbd>flex-wrap: wrap</kbd> allows items to flow onto multiple lines when they run out of space.",
-			"task": "These cards overflow the container. Add <kbd>flex-wrap: wrap</kbd> to allow them to wrap to new rows.",
+			"task": "The cards overflow the container instead of fitting within it. Allow the items to flow onto new rows when they run out of space.",
 			"previewHTML": "<div class=\"cards\"><article class=\"card\">Card 1</article><article class=\"card\">Card 2</article><article class=\"card\">Card 3</article><article class=\"card\">Card 4</article><article class=\"card\">Card 5</article><article class=\"card\">Card 6</article></div>",
 			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; background: #f5f5f5; } .cards { display: flex; gap: 1rem; } .card { background: white; padding: 2rem; border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.1); min-width: 120px; text-align: center; }",
 			"sandboxCSS": "",
@@ -106,7 +106,7 @@
 				{
 					"type": "property_value",
 					"value": { "property": "flex-wrap", "expected": "wrap" },
-					"message": "Set <kbd>flex-wrap: wrap</kbd>"
+					"message": "Use the property that allows flex items to wrap onto new lines"
 				}
 			]
 		},
@@ -114,7 +114,7 @@
 			"id": "flexbox-6",
 			"title": "Flex Grow",
 			"description": "The <kbd>flex</kbd> property on items controls how they grow and shrink. <kbd>flex: 1</kbd> makes an item grow to fill available space. Multiple items with <kbd>flex: 1</kbd> share space equally.",
-			"task": "Make the search input expand to fill available space by setting <kbd>flex: 1</kbd> on <kbd>.search</kbd>.",
+			"task": "The search input is too narrow. Make it stretch to fill all the remaining space in the toolbar.",
 			"previewHTML": "<div class=\"toolbar\"><input class=\"search\" type=\"text\" placeholder=\"Search...\"><button class=\"btn\">Search</button><button class=\"btn\">Filters</button></div>",
 			"previewBaseCSS": "body { font-family: system-ui, sans-serif; padding: 1rem; } .toolbar { display: flex; gap: 8px; padding: 1rem; background: #f5f5f5; border-radius: 8px; } .search { padding: 8px 1rem; border: 1px solid #ddd; border-radius: 4px; font-size: 1rem; } .btn { padding: 8px 1rem; background: steelblue; color: white; border: none; border-radius: 4px; cursor: pointer; }",
 			"sandboxCSS": "",
@@ -125,9 +125,9 @@
 			"previewContainer": "preview-area",
 			"validations": [
 				{
-					"type": "property_value",
-					"value": { "property": "flex", "expected": "1" },
-					"message": "Set <kbd>flex: 1</kbd>"
+					"type": "regex",
+					"value": "(flex\\s*:\\s*1|flex-grow\\s*:\\s*1)",
+					"message": "Use the property that makes a flex item grow to fill available space"
 				}
 			]
 		}
--- a/lessons/pl/00-welcome.json
+++ b/lessons/pl/00-welcome.json
@@ -3,7 +3,7 @@
 	"id": "welcome",
 	"title": "Witaj",
 	"description": "Rozpocznij przygodę z Code Crispies",
-	"mode": "html",
+	"mode": "css",
 	"difficulty": "beginner",
 	"excludeFromProgress": true,
 	"lessons": [
--- a/lessons/uk/00-welcome.json
+++ b/lessons/uk/00-welcome.json
@@ -3,7 +3,7 @@
 	"id": "welcome",
 	"title": "Ласкаво просимо",
 	"description": "Почніть з Code Crispies",
-	"mode": "html",
+	"mode": "css",
 	"difficulty": "beginner",
 	"excludeFromProgress": true,
 	"lessons": [
--- a/package-lock.json
+++ b/package-lock.json
@@ -7,17 +7,21 @@
 		"": {
 			"name": "code-crispies",
 			"version": "1.0.0",
-			"license": "Copyright 2025 (c) Michael Czechowski",
+			"license": "Copyright 2026 (c) Michael Czechowski",
 			"dependencies": {
 				"@codemirror/autocomplete": "^6.20.0",
 				"@codemirror/commands": "^6.10.1",
 				"@codemirror/lang-css": "^6.3.1",
 				"@codemirror/lang-html": "^6.4.11",
+				"@codemirror/lang-javascript": "^6.2.5",
+				"@codemirror/lang-markdown": "^6.5.0",
 				"@codemirror/state": "^6.5.2",
 				"@codemirror/theme-one-dark": "^6.1.3",
 				"@codemirror/view": "^6.39.4",
 				"@emmetio/codemirror6-plugin": "^0.4.0",
+				"@supabase/supabase-js": "^2.90.1",
 				"codemirror": "^6.0.2",
+				"marked": "^17.0.1",
 				"whatwg-fetch": "^3.6.20"
 			},
 			"devDependencies": {
@@ -155,7 +159,6 @@
 			"resolved": "https://registry.npmjs.org/@codemirror/autocomplete/-/autocomplete-6.20.0.tgz",
 			"integrity": "sha512-bOwvTOIJcG5FVo5gUUupiwYh8MioPLQ4UcqbcRf7UQ98X90tCa9E1kZ3Z7tqwpZxYyOvh1YTYbmZE9RTfTp5hg==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@codemirror/language": "^6.0.0",
 				"@codemirror/state": "^6.0.0",
@@ -168,7 +171,6 @@
 			"resolved": "https://registry.npmjs.org/@codemirror/commands/-/commands-6.10.1.tgz",
 			"integrity": "sha512-uWDWFypNdQmz2y1LaNJzK7fL7TYKLeUAU0npEC685OKTF3KcQ2Vu3klIM78D7I6wGhktme0lh3CuQLv0ZCrD9Q==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@codemirror/language": "^6.0.0",
 				"@codemirror/state": "^6.4.0",
@@ -181,7 +183,6 @@
 			"resolved": "https://registry.npmjs.org/@codemirror/lang-css/-/lang-css-6.3.1.tgz",
 			"integrity": "sha512-kr5fwBGiGtmz6l0LSJIbno9QrifNMUusivHbnA1H6Dmqy4HZFte3UAICix1VuKo0lMPKQr2rqB+0BkKi/S3Ejg==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@codemirror/autocomplete": "^6.0.0",
 				"@codemirror/language": "^6.0.0",
@@ -195,7 +196,6 @@
 			"resolved": "https://registry.npmjs.org/@codemirror/lang-html/-/lang-html-6.4.11.tgz",
 			"integrity": "sha512-9NsXp7Nwp891pQchI7gPdTwBuSuT3K65NGTHWHNJ55HjYcHLllr0rbIZNdOzas9ztc1EUVBlHou85FFZS4BNnw==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@codemirror/autocomplete": "^6.0.0",
 				"@codemirror/lang-css": "^6.0.0",
@@ -209,9 +209,9 @@
 			}
 		},
 		"node_modules/@codemirror/lang-javascript": {
-			"version": "6.2.4",
-			"resolved": "https://registry.npmjs.org/@codemirror/lang-javascript/-/lang-javascript-6.2.4.tgz",
-			"integrity": "sha512-0WVmhp1QOqZ4Rt6GlVGwKJN3KW7Xh4H2q8ZZNGZaP6lRdxXJzmjm4FqvmOojVj6khWJHIb9sp7U/72W7xQgqAA==",
+			"version": "6.2.5",
+			"resolved": "https://registry.npmjs.org/@codemirror/lang-javascript/-/lang-javascript-6.2.5.tgz",
+			"integrity": "sha512-zD4e5mS+50htS7F+TYjBPsiIFGanfVqg4HyUz6WNFikgOPf2BgKlx+TQedI1w6n/IqRBVBbBWmGFdLB/7uxO4A==",
 			"license": "MIT",
 			"dependencies": {
 				"@codemirror/autocomplete": "^6.0.0",
@@ -223,12 +223,26 @@
 				"@lezer/javascript": "^1.0.0"
 			}
 		},
+		"node_modules/@codemirror/lang-markdown": {
+			"version": "6.5.0",
+			"resolved": "https://registry.npmjs.org/@codemirror/lang-markdown/-/lang-markdown-6.5.0.tgz",
+			"integrity": "sha512-0K40bZ35jpHya6FriukbgaleaqzBLZfOh7HuzqbMxBXkbYMJDxfF39c23xOgxFezR+3G+tR2/Mup+Xk865OMvw==",
+			"license": "MIT",
+			"dependencies": {
+				"@codemirror/autocomplete": "^6.7.1",
+				"@codemirror/lang-html": "^6.0.0",
+				"@codemirror/language": "^6.3.0",
+				"@codemirror/state": "^6.0.0",
+				"@codemirror/view": "^6.0.0",
+				"@lezer/common": "^1.2.1",
+				"@lezer/markdown": "^1.0.0"
+			}
+		},
 		"node_modules/@codemirror/language": {
 			"version": "6.11.3",
 			"resolved": "https://registry.npmjs.org/@codemirror/language/-/language-6.11.3.tgz",
 			"integrity": "sha512-9HBM2XnwDj7fnu0551HkGdrUrrqmYq/WC5iv6nbY2WdicXdGbhR/gfbZOH73Aqj4351alY1+aoG9rCNfiwS1RA==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@codemirror/state": "^6.0.0",
 				"@codemirror/view": "^6.23.0",
@@ -265,7 +279,6 @@
 			"resolved": "https://registry.npmjs.org/@codemirror/state/-/state-6.5.2.tgz",
 			"integrity": "sha512-FVqsPqtPWKVVL3dPSxy8wEF/ymIEuVzF1PK3VbUgrxXpJUSHQWWZz4JMToquRxnkw+36LTamCZG2iua2Ptq0fA==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@marijn/find-cluster-break": "^1.0.0"
 			}
@@ -287,7 +300,6 @@
 			"resolved": "https://registry.npmjs.org/@codemirror/view/-/view-6.39.4.tgz",
 			"integrity": "sha512-xMF6OfEAUVY5Waega4juo1QGACfNkNF+aJLqpd8oUJz96ms2zbfQ9Gh35/tI3y8akEV31FruKfj7hBnIU/nkqA==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@codemirror/state": "^6.5.0",
 				"crelt": "^1.0.6",
@@ -383,7 +395,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=18"
 			},
@@ -407,7 +418,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=18"
 			}
@@ -973,9 +983,9 @@
 			}
 		},
 		"node_modules/@lezer/common": {
-			"version": "1.4.0",
-			"resolved": "https://registry.npmjs.org/@lezer/common/-/common-1.4.0.tgz",
-			"integrity": "sha512-DVeMRoGrgn/k45oQNu189BoW4SZwgZFzJ1+1TV5j2NJ/KFC83oa/enRqZSGshyeMk5cPWMhsKs9nx+8o0unwGg==",
+			"version": "1.5.0",
+			"resolved": "https://registry.npmjs.org/@lezer/common/-/common-1.5.0.tgz",
+			"integrity": "sha512-PNGcolp9hr4PJdXR4ix7XtixDrClScvtSCYW3rQG106oVMOOI+jFb+0+J3mbeL/53g1Zd6s0kJzaw6Ri68GmAA==",
 			"license": "MIT"
 		},
 		"node_modules/@lezer/css": {
@@ -1029,6 +1039,16 @@
 				"@lezer/common": "^1.0.0"
 			}
 		},
+		"node_modules/@lezer/markdown": {
+			"version": "1.6.3",
+			"resolved": "https://registry.npmjs.org/@lezer/markdown/-/markdown-1.6.3.tgz",
+			"integrity": "sha512-jpGm5Ps+XErS+xA4urw7ogEGkeZOahVQF21Z6oECF0sj+2liwZopd2+I8uH5I/vZsRuuze3OxBREIANLf6KKUw==",
+			"license": "MIT",
+			"dependencies": {
+				"@lezer/common": "^1.5.0",
+				"@lezer/highlight": "^1.0.0"
+			}
+		},
 		"node_modules/@marijn/find-cluster-break": {
 			"version": "1.0.2",
 			"resolved": "https://registry.npmjs.org/@marijn/find-cluster-break/-/find-cluster-break-1.0.2.tgz",
@@ -1354,6 +1374,86 @@
 				"win32"
 			]
 		},
+		"node_modules/@supabase/auth-js": {
+			"version": "2.90.1",
+			"resolved": "https://registry.npmjs.org/@supabase/auth-js/-/auth-js-2.90.1.tgz",
+			"integrity": "sha512-vxb66dgo6h3yyPbR06735Ps+dK3hj0JwS8w9fdQPVZQmocSTlKUW5MfxSy99mN0XqCCuLMQ3jCEiIIUU23e9ng==",
+			"license": "MIT",
+			"dependencies": {
+				"tslib": "2.8.1"
+			},
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
+		"node_modules/@supabase/functions-js": {
+			"version": "2.90.1",
+			"resolved": "https://registry.npmjs.org/@supabase/functions-js/-/functions-js-2.90.1.tgz",
+			"integrity": "sha512-x9mV9dF1Lam9qL3zlpP6mSM5C9iqMPtF5B/tU1Jj/F0ufX5mjDf9ghVBaErVxmrQJRL4+iMKWKY2GnODkpS8tw==",
+			"license": "MIT",
+			"dependencies": {
+				"tslib": "2.8.1"
+			},
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
+		"node_modules/@supabase/postgrest-js": {
+			"version": "2.90.1",
+			"resolved": "https://registry.npmjs.org/@supabase/postgrest-js/-/postgrest-js-2.90.1.tgz",
+			"integrity": "sha512-jh6vqzaYzoFn3raaC0hcFt9h+Bt+uxNRBSdc7PfToQeRGk7PDPoweHsbdiPWREtDVTGKfu+PyPW9e2jbK+BCgQ==",
+			"license": "MIT",
+			"dependencies": {
+				"tslib": "2.8.1"
+			},
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
+		"node_modules/@supabase/realtime-js": {
+			"version": "2.90.1",
+			"resolved": "https://registry.npmjs.org/@supabase/realtime-js/-/realtime-js-2.90.1.tgz",
+			"integrity": "sha512-PWbnEMkcQRuor8jhObp4+Snufkq8C6fBp+MchVp2qBPY1NXk/c3Iv3YyiFYVzo0Dzuw4nAlT4+ahuPggy4r32w==",
+			"license": "MIT",
+			"dependencies": {
+				"@types/phoenix": "^1.6.6",
+				"@types/ws": "^8.18.1",
+				"tslib": "2.8.1",
+				"ws": "^8.18.2"
+			},
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
+		"node_modules/@supabase/storage-js": {
+			"version": "2.90.1",
+			"resolved": "https://registry.npmjs.org/@supabase/storage-js/-/storage-js-2.90.1.tgz",
+			"integrity": "sha512-GHY+Ps/K/RBfRj7kwx+iVf2HIdqOS43rM2iDOIDpapyUnGA9CCBFzFV/XvfzznGykd//z2dkGZhlZZprsVFqGg==",
+			"license": "MIT",
+			"dependencies": {
+				"iceberg-js": "^0.8.1",
+				"tslib": "2.8.1"
+			},
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
+		"node_modules/@supabase/supabase-js": {
+			"version": "2.90.1",
+			"resolved": "https://registry.npmjs.org/@supabase/supabase-js/-/supabase-js-2.90.1.tgz",
+			"integrity": "sha512-U8KaKGLUgTIFHtwEW1dgw1gK7XrdpvvYo7nzzqPx721GqPe8WZbAiLh/hmyKLGBYQ/mmQNr20vU9tWSDZpii3w==",
+			"license": "MIT",
+			"dependencies": {
+				"@supabase/auth-js": "2.90.1",
+				"@supabase/functions-js": "2.90.1",
+				"@supabase/postgrest-js": "2.90.1",
+				"@supabase/realtime-js": "2.90.1",
+				"@supabase/storage-js": "2.90.1"
+			},
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
 		"node_modules/@testing-library/dom": {
 			"version": "10.4.1",
 			"resolved": "https://registry.npmjs.org/@testing-library/dom/-/dom-10.4.1.tgz",
@@ -1433,6 +1533,30 @@
 			"dev": true,
 			"license": "MIT"
 		},
+		"node_modules/@types/node": {
+			"version": "25.0.9",
+			"resolved": "https://registry.npmjs.org/@types/node/-/node-25.0.9.tgz",
+			"integrity": "sha512-/rpCXHlCWeqClNBwUhDcusJxXYDjZTyE8v5oTO7WbL8eij2nKhUeU89/6xgjU7N4/Vh3He0BtyhJdQbDyhiXAw==",
+			"license": "MIT",
+			"dependencies": {
+				"undici-types": "~7.16.0"
+			}
+		},
+		"node_modules/@types/phoenix": {
+			"version": "1.6.7",
+			"resolved": "https://registry.npmjs.org/@types/phoenix/-/phoenix-1.6.7.tgz",
+			"integrity": "sha512-oN9ive//QSBkf19rfDv45M7eZPi0eEXylht2OLEXicu5b4KoQ1OzXIw+xDSGWxSxe1JmepRR/ZH283vsu518/Q==",
+			"license": "MIT"
+		},
+		"node_modules/@types/ws": {
+			"version": "8.18.1",
+			"resolved": "https://registry.npmjs.org/@types/ws/-/ws-8.18.1.tgz",
+			"integrity": "sha512-ThVF6DCVhA8kUGy+aazFQ4kXQ7E1Ty7A3ypFOe0IcJV8O/M511G99AW24irKrW56Wt44yG9+ij8FaqoBGkuBXg==",
+			"license": "MIT",
+			"dependencies": {
+				"@types/node": "*"
+			}
+		},
 		"node_modules/@vitest/coverage-v8": {
 			"version": "3.2.4",
 			"resolved": "https://registry.npmjs.org/@vitest/coverage-v8/-/coverage-v8-3.2.4.tgz",
@@ -2092,6 +2216,15 @@
 				"node": ">= 14"
 			}
 		},
+		"node_modules/iceberg-js": {
+			"version": "0.8.1",
+			"resolved": "https://registry.npmjs.org/iceberg-js/-/iceberg-js-0.8.1.tgz",
+			"integrity": "sha512-1dhVQZXhcHje7798IVM+xoo/1ZdVfzOMIc8/rgVSijRK38EDqOJoGula9N/8ZI5RD8QTxNQtK/Gozpr+qUqRRA==",
+			"license": "MIT",
+			"engines": {
+				"node": ">=20.0.0"
+			}
+		},
 		"node_modules/iconv-lite": {
 			"version": "0.6.3",
 			"resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.6.3.tgz",
@@ -2222,7 +2355,6 @@
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 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"cssstyle": "^4.2.1",
 				"data-urls": "^5.0.0",
@@ -2319,6 +2451,18 @@
 				"url": "https://github.com/sponsors/sindresorhus"
 			}
 		},
+		"node_modules/marked": {
+			"version": "17.0.1",
+			"resolved": "https://registry.npmjs.org/marked/-/marked-17.0.1.tgz",
+			"integrity": "sha512-boeBdiS0ghpWcSwoNm/jJBwdpFaMnZWRzjA6SkUMYb40SVaN1x7mmfGKp0jvexGcx+7y2La5zRZsYFZI6Qpypg==",
+			"license": "MIT",
+			"bin": {
+				"marked": "bin/marked.js"
+			},
+			"engines": {
+				"node": ">= 20"
+			}
+		},
 		"node_modules/min-indent": {
 			"version": "1.0.1",
 			"resolved": "https://registry.npmjs.org/min-indent/-/min-indent-1.0.1.tgz",
@@ -2465,7 +2609,6 @@
 			"integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=12"
 			},
@@ -2991,13 +3134,24 @@
 				"node": ">=18"
 			}
 		},
+		"node_modules/tslib": {
+			"version": "2.8.1",
+			"resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
+			"integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
+			"license": "0BSD"
+		},
+		"node_modules/undici-types": {
+			"version": "7.16.0",
+			"resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.16.0.tgz",
+			"integrity": "sha512-Zz+aZWSj8LE6zoxD+xrjh4VfkIG8Ya6LvYkZqtUQGJPZjYl53ypCaUwWqo7eI0x66KBGeRo+mlBEkMSeSZ38Nw==",
+			"license": "MIT"
+		},
 		"node_modules/vite": {
 			"version": "6.4.1",
 			"resolved": "https://registry.npmjs.org/vite/-/vite-6.4.1.tgz",
 			"integrity": "sha512-+Oxm7q9hDoLMyJOYfUYBuHQo+dkAloi33apOPP56pzj+vsdJDzr+j1NISE5pyaAuKL4A3UD34qd0lx5+kfKp2g==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"esbuild": "^0.25.0",
 				"fdir": "^6.4.4",
@@ -3096,7 +3250,6 @@
 			"integrity": "sha512-LUCP5ev3GURDysTWiP47wRRUpLKMOfPh+yKTx3kVIEiu5KOMeqzpnYNsKyOoVrULivR8tLcks4+lga33Whn90A==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@types/chai": "^5.2.2",
 				"@vitest/expect": "3.2.4",
@@ -3374,7 +3527,6 @@
 			"version": "8.18.3",
 			"resolved": "https://registry.npmjs.org/ws/-/ws-8.18.3.tgz",
 			"integrity": "sha512-PEIGCY5tSlUt50cqyMXfCzX+oOPqN0vuGqWzbcJ2xvnkzkq46oOpz7dQaTDBdfICb4N14+GARUDw2XV2N4tvzg==",
-			"dev": true,
 			"license": "MIT",
 			"engines": {
 				"node": ">=10.0.0"
--- a/package.json
+++ b/package.json
@@ -37,11 +37,15 @@
 		"@codemirror/commands": "^6.10.1",
 		"@codemirror/lang-css": "^6.3.1",
 		"@codemirror/lang-html": "^6.4.11",
+		"@codemirror/lang-javascript": "^6.2.5",
+		"@codemirror/lang-markdown": "^6.5.0",
 		"@codemirror/state": "^6.5.2",
 		"@codemirror/theme-one-dark": "^6.1.3",
 		"@codemirror/view": "^6.39.4",
 		"@emmetio/codemirror6-plugin": "^0.4.0",
+		"@supabase/supabase-js": "^2.90.1",
 		"codemirror": "^6.0.2",
+		"marked": "^17.0.1",
 		"whatwg-fetch": "^3.6.20"
 	}
 }
--- a/schemas/code-crispies-module-schema.json
+++ b/schemas/code-crispies-module-schema.json
@@ -19,8 +19,8 @@
 		},
 		"mode": {
 			"type": "string",
-			"enum": ["css", "tailwind", "html"],
-			"description": "Whether this module teaches CSS, Tailwind, or HTML"
+			"enum": ["css", "tailwind", "html", "markdown", "javascript"],
+			"description": "Whether this module teaches CSS, Tailwind, HTML, Markdown, or JavaScript"
 		},
 		"difficulty": {
 			"type": "string",
@@ -60,7 +60,7 @@
 					},
 					"mode": {
 						"type": "string",
-						"enum": ["css", "tailwind", "html"],
+						"enum": ["css", "tailwind", "html", "markdown", "javascript"],
 						"description": "Override module mode for individual lessons"
 					},
 					"tailwindConfig": {
--- a/specs/003-flexbox-task-wording/plan.md
+++ b/specs/003-flexbox-task-wording/plan.md
@@ -0,0 +1,76 @@
+# Implementation Plan
+
+## Objective
+
+Rewrite all 6 flexbox lesson task descriptions to describe the desired visual outcome instead of giving the exact CSS declaration. Update validation messages to hint without revealing answers, and accept alternative valid solutions where applicable.
+
+## Approach
+
+This is a content-only change to a single JSON file (`lessons/flexbox.json`). Each lesson needs three edits:
+
+1. **Task text**: Replace copy-pasteable CSS declarations with outcome-oriented descriptions
+2. **Validation messages**: Replace answer-revealing messages with pedagogical hints
+3. **Validations array**: Add alternative accepted solutions where multiple CSS approaches achieve the same visual result
+
+The lesson `description` fields (which teach concepts with code examples) remain unchanged — they are the learning material, not the exercise prompt.
+
+## File Mapping
+
+| File | Action | Description |
+|------|--------|-------------|
+| `lessons/flexbox.json` | modify | Rewrite `task` and validation `message` fields for all 6 lessons; add alternative validations for flexbox-6 |
+
+No new files need to be created. No validator code changes needed — the existing `property_value` and `regex` validation types already support everything required.
+
+## Detailed Changes Per Lesson
+
+### flexbox-1 (Container)
+- **Task**: Describe that nav links stack vertically and should display side by side
+- **Validation msg**: Hint at display property for flex layout
+- **Alt solutions**: None — `display: flex` is the only correct answer (inline-flex changes block behavior)
+
+### flexbox-2 (Gap)
+- **Task**: Describe that links are crammed together and need 1rem of spacing between them
+- **Validation msg**: Hint at the gap property
+- **Alt solutions**: None — `gap: 1rem` is the specific expected value
+
+### flexbox-3 (Justify Content)
+- **Task**: Describe that Login button should be pushed to the far right, with nav links on the left
+- **Validation msg**: Hint at main-axis distribution property
+- **Alt solutions**: None — `justify-content: space-between` is the only property that works when targeting `.nav`
+
+### flexbox-4 (Align Items)
+- **Task**: Describe the visual misalignment and ask for vertical centering
+- **Validation msg**: Hint at cross-axis alignment property
+- **Alt solutions**: None — `align-items: center` is the correct answer
+
+### flexbox-5 (Flex Wrap)
+- **Task**: Describe cards overflowing and needing to flow onto new rows
+- **Validation msg**: Hint at wrapping property
+- **Alt solutions**: None — `flex-wrap: wrap` is the only answer
+
+### flexbox-6 (Flex Grow)
+- **Task**: Describe that the search input should stretch to fill remaining space
+- **Validation msg**: Hint at flex growth property
+- **Alt solutions**: Accept both `flex: 1` and `flex-grow: 1` via regex validation
+
+## Architecture Decisions
+
+1. **No validator code changes**: The existing `regex` validation type can handle alternative solutions for flexbox-6. No need to add a new validation type.
+2. **Keep values in tasks where needed**: Some tasks mention target values like "1rem" since the validator checks exact values and students need to know the amount. The key change is removing the *property name* from the task.
+3. **Solution field unchanged**: The `solution` field is used for the "show solution" feature and should remain as the canonical answer.
+4. **codePrefix unchanged**: The existing codePrefix already shows the selector context (e.g., `.nav {`), which is enough guidance for students.
+
+## Risks
+
+| Risk | Likelihood | Mitigation |
+|------|-----------|------------|
+| Tasks become too vague for beginners | Low | Descriptions still teach the property; tasks describe specific visual outcomes |
+| Alternative regex validation too permissive | Low | Regex will be specific to `flex:\s*1` and `flex-grow:\s*1` patterns |
+| Validation messages too cryptic | Low | Messages will hint at the property category without giving the exact declaration |
+
+## Testing Strategy
+
+1. **Run existing test suite**: `npm run test` — all tests should pass since no code or module structure changes
+2. **Manual verification**: Validate that each rewritten task accurately describes the visual outcome shown in the preview
+3. **JSON schema validation**: Ensure `lessons/flexbox.json` still conforms to the module schema
--- a/specs/003-flexbox-task-wording/spec.md
+++ b/specs/003-flexbox-task-wording/spec.md
@@ -0,0 +1,35 @@
+# fix: remove answers from flexbox task descriptions (copy-paste score 95%)
+
+**Issue**: [libretech/code-crispies#3](https://git.librete.ch/libretech/code-crispies/issues/3)
+**State**: open
+**Author**: libretech
+**Labels**: none
+**Complexity**: simple
+
+## Issue Body
+
+Pedagogy audit: All 6 flexbox exercises give the exact CSS declaration in the task text. Students type without understanding. Rewrite tasks to describe the DESIRED OUTCOME instead of the exact code. Example: 'Add display: flex' → 'The navigation links stack vertically. Make them display side by side.' Accept multiple valid solutions in validations.
+
+## Current State
+
+All 6 lessons in `lessons/flexbox.json` have task descriptions that include the exact CSS declaration students need to type:
+
+| Lesson | Current Task (gives away answer) |
+|--------|----------------------------------|
+| flexbox-1 | "Add `display: flex` to `.nav`" |
+| flexbox-2 | "Add `gap: 1rem` to space out..." |
+| flexbox-3 | "setting `justify-content: space-between` on the nav" |
+| flexbox-4 | "Center them vertically with `align-items: center`" |
+| flexbox-5 | "Add `flex-wrap: wrap` to allow them to wrap" |
+| flexbox-6 | "setting `flex: 1` on `.search`" |
+
+Validation error messages also give away answers (e.g., "Set `display: flex`").
+
+## Acceptance Criteria
+
+1. All 6 flexbox task descriptions rewritten to describe the desired visual outcome, not the exact CSS code
+2. Students cannot copy-paste from the task into the editor to pass
+3. Validation error messages updated to provide hints without revealing the exact declaration
+4. Where applicable, validations accept multiple valid CSS solutions (e.g., `flex: 1` and `flex-grow: 1`)
+5. Existing tests continue to pass
+6. Lesson descriptions (which teach the concepts) remain unchanged
--- a/specs/003-flexbox-task-wording/tasks.md
+++ b/specs/003-flexbox-task-wording/tasks.md
@@ -0,0 +1,13 @@
+# Tasks
+
+## Phase 1: Core Content Changes
+- [X] Task 1.1: Rewrite task text for all 6 flexbox lessons to describe visual outcomes [P]
+- [X] Task 1.2: Rewrite validation error messages to hint without revealing answers [P]
+
+## Phase 2: Alternative Validations
+- [X] Task 2.1: Add regex validation for flexbox-6 to accept both `flex: 1` and `flex-grow: 1`
+
+## Phase 3: Validation
+- [X] Task 3.1: Run existing test suite to confirm no regressions
+- [X] Task 3.2: Verify flexbox.json still conforms to module schema
+- [X] Task 3.3: Run lesson format check (`npm run format.lessons`)
--- a/src/app.js
+++ b/src/app.js
@@ -1,11 +1,12 @@
 import { LessonEngine } from "./impl/LessonEngine.js";
 import { CodeEditor, crispyEditorTheme } from "./impl/CodeEditor.js";
-import { renderLesson, renderModuleList, renderLevelIndicator, updateActiveLessonInSidebar } from "./helpers/renderer.js";
+import { renderLesson, renderModuleList, renderLevelIndicator, updateActiveLessonInSidebar, renderDifficultyBadge } from "./helpers/renderer.js";
 import { loadModules } from "./config/lessons.js";
 import { initI18n, t, getLanguage, setLanguage, applyTranslations } from "./i18n.js";
 import { parseHash, updateHash, replaceHash, getShareableUrl, RouteType, navigateTo } from "./helpers/router.js";
 import { sections, getSection, getModuleSection, getModulesBySection } from "./config/sections.js";
 import { getRandomTemplate } from "./config/playground-templates.js";
+import { initAuth, handleOAuthCallback } from "./auth.js";

 // CodeMirror imports for syntax highlighting
 import { EditorState } from "@codemirror/state";
@@ -17,6 +18,9 @@ import { css } from "@codemirror/lang-css";
 function track(eventName, eventData = {}) {
 	if (typeof umami !== "undefined" && umami.track) {
 		umami.track(eventName, eventData);
+		console.debug("Track:", eventName, eventData);
+	} else {
+		console.debug("Track blocked (umami unavailable):", eventName, eventData);
 	}
 }

@@ -147,6 +151,7 @@ const elements = {
 	previewSection: document.querySelector(".preview-section"),
 	prevBtn: document.getElementById("prev-btn"),
 	nextBtn: document.getElementById("next-btn"),
+	gameControls: document.querySelector(".game-controls"),
 	levelIndicator: document.getElementById("level-indicator"),
 	headerLevelPill: document.getElementById("header-level-pill"),

@@ -156,8 +161,12 @@ const elements = {
 	closeSidebar: document.getElementById("close-sidebar"),
 	moduleList: document.getElementById("module-list"),
 	footerLessonLinks: document.getElementById("footer-lesson-links"),
+	refFooterLessonLinks: document.getElementById("ref-footer-lesson-links"),
+	sectionFooterLessonLinks: document.getElementById("section-footer-lesson-links"),
 	progressFill: document.getElementById("progress-fill"),
-	progressText: document.getElementById("progress-text"),
+	progressCurrent: document.getElementById("progress-current"),
+	progressTotal: document.getElementById("progress-total"),
+	milestonesContainer: document.getElementById("milestones"),
 	resetBtn: document.getElementById("reset-btn"),
 	disableFeedbackToggle: document.getElementById("disable-feedback-toggle"),

@@ -223,6 +232,13 @@ function closeSidebar() {
 function toggleExpectedResult() {
 	state.showExpected = !state.showExpected;

+	const engineState = lessonEngine.getCurrentState();
+	track("expected_toggle", {
+		show: state.showExpected,
+		module: engineState.module?.id,
+		lesson: engineState.lessonIndex
+	});
+
 	if (state.showExpected) {
 		elements.expectedOverlay.classList.add("visible");
 		elements.showExpectedBtn.textContent = t("hideExpected");
@@ -296,14 +312,53 @@ function showSuccessHint(message) {

 // ================= PROGRESS DISPLAY =================

+// Track last milestone to detect new achievements
+let lastMilestoneReached = 0;
+
 function updateProgressDisplay() {
 	const stats = lessonEngine.getProgressStats();
-	elements.progressFill.style.width = `${stats.percentComplete}%`;
-	elements.progressText.textContent = t("progressText", {
-		percent: stats.percentComplete,
-		completed: stats.totalCompleted,
+
+	// Update progress bar - shows progress towards next milestone
+	// CSS variable scales gradient so only first X% of colors show
+	const progressPercent = stats.progressToNext || 1;
+	elements.progressFill.style.width = `${progressPercent}%`;
+	elements.progressFill.style.setProperty('--progress-percent', progressPercent);
+
+	// Update progress current - show progress towards next milestone
+	elements.progressCurrent.textContent = `${stats.totalCompleted}/${stats.nextMilestone}`;
+
+	// Update progress total - show total lessons
+	elements.progressTotal.textContent = t("progressTotal", {
 		total: stats.totalLessons
 	});
+
+	// Update milestone indicators
+	if (elements.milestonesContainer) {
+		const milestoneEls = elements.milestonesContainer.querySelectorAll(".milestone");
+		milestoneEls.forEach((el) => {
+			const value = parseInt(el.dataset.value, 10);
+			el.classList.remove("reached", "current", "next", "just-reached");
+
+			if (stats.milestonesReached.includes(value)) {
+				el.classList.add("reached");
+				// Check if this milestone was just reached
+				if (value > lastMilestoneReached && value === stats.currentMilestone) {
+					el.classList.add("just-reached");
+				}
+			} else if (value === stats.nextMilestone) {
+				el.classList.add("next");
+			}
+
+			if (value === stats.currentMilestone) {
+				el.classList.add("current");
+			}
+		});
+	}
+
+	// Update last milestone for celebration detection
+	if (stats.currentMilestone > lastMilestoneReached) {
+		lastMilestoneReached = stats.currentMilestone;
+	}
 }

 // ================= USER SETTINGS =================
@@ -395,6 +450,9 @@ function initializeModules() {
 		// Use the new renderModuleList function with both callbacks
 		renderModuleList(elements.moduleList, modules, selectModule, selectLesson);

+		// Render footer lesson links (for all pages)
+		renderFooterLessonLinks();
+
 		// Handle route (home, section, or lesson)
 		handleRoute(false);

@@ -456,6 +514,13 @@ function selectLesson(moduleId, lessonIndex) {

 	loadCurrentLesson();

+	// Update section color coding (after loadCurrentLesson to ensure content is loaded first)
+	const newState = lessonEngine.getCurrentState();
+	updateSectionColor(getModuleSection(newState.module));
+
+	// Update nav highlight
+	updateNavHighlight({ type: RouteType.LESSON, moduleId, lessonIndex });
+
 	// Close sidebar after selection on mobile
 	if (window.innerWidth <= 768) {
 		closeSidebar();
@@ -478,6 +543,7 @@ function resetSuccessIndicators() {
 	elements.previewWrapper?.classList.remove("matched");
 	elements.previewWrapper?.classList.remove("completed-glow");
 	elements.previewSection?.classList.remove("matched");
+	elements.previewSection?.classList.remove("completed-glow");

 	// Remove completion badge if present
 	const badge = document.querySelector(".completion-badge");
@@ -507,6 +573,16 @@ function updateEditorForMode(mode) {
 			label: "CSS Editor",
 			cmMode: "css"
 		},
+		markdown: {
+			placeholder: "# Heading\n\nWrite your **Markdown** here...",
+			label: "Markdown Editor",
+			cmMode: "markdown"
+		},
+		javascript: {
+			placeholder: "// Write your JavaScript here...",
+			label: "JavaScript Editor",
+			cmMode: "javascript"
+		},
 		playground: {
 			placeholder: "<style>\n  /* CSS here */\n</style>\n\n<!-- HTML here -->",
 			label: "HTML & CSS",
@@ -540,10 +616,12 @@ function loadCurrentLesson() {
 		elements.instructionsSection?.classList.add("hidden");
 		elements.editorSection?.classList.add("playground-mode");
 		elements.randomTemplateBtn?.classList.remove("hidden");
+		elements.showExpectedBtn?.classList.add("hidden");
 	} else {
 		elements.instructionsSection?.classList.remove("hidden");
 		elements.editorSection?.classList.remove("playground-mode");
 		elements.randomTemplateBtn?.classList.add("hidden");
+		elements.showExpectedBtn?.classList.remove("hidden");
 	}

 	// Add transition class for smooth content swap
@@ -581,40 +659,59 @@ function loadCurrentLesson() {
 		lesson
 	);

+	// Render difficulty badge
+	renderDifficultyBadge(elements.lessonTitleRow, lesson);
+
 	// Set user code in CodeMirror (clear history to prevent undo/redo across lessons)
+	// Pass codePrefix/codeSuffix as read-only zones for CSS mode
 	if (codeEditor) {
-		codeEditor.setValueAndClearHistory(engineState.userCode);
+		const prefix = lesson.codePrefix || "";
+		const suffix = lesson.codeSuffix || "";
+		codeEditor.setValueAndClearHistory(engineState.userCode, prefix, suffix);
 	}

 	// Update Run button text based on completion status
 	if (engineState.isCompleted) {
 		elements.runBtn.querySelector("span").textContent = t("rerun");

-		// Add completion badge if not present
-		if (!document.querySelector(".completion-badge")) {
+		// Add completion badge to difficulty-wrapper if not present
+		const wrapper = document.querySelector(".difficulty-wrapper");
+		if (wrapper && !wrapper.querySelector(".completion-badge")) {
 			const badge = document.createElement("span");
 			badge.className = "completion-badge";
 			badge.textContent = t("completed");
-			elements.lessonTitleRow.appendChild(badge);
+			wrapper.appendChild(badge);
 		}

-		// Show gradient border for completed lessons
+		// Show gradient border and glow for completed lessons
 		elements.previewWrapper?.classList.add("completed-glow");
+		elements.previewSection?.classList.add("completed-glow");
 	} else {
 		elements.runBtn.querySelector("span").textContent = t("run");

-		// Remove completion badge and border if exists
+		// Remove completion badge if exists
 		const badge = document.querySelector(".completion-badge");
 		if (badge) badge.remove();
 		elements.previewWrapper?.classList.remove("completed-glow");
+		elements.previewSection?.classList.remove("completed-glow");
 	}

-	// Update level indicator
-	renderLevelIndicator(elements.levelIndicator, engineState.lessonIndex + 1, engineState.totalLessons);
+	// Update level indicator (hide in playground mode)
+	if (isPlayground) {
+		elements.levelIndicator.classList.add("hidden");
+	} else {
+		elements.levelIndicator.classList.remove("hidden");
+		renderLevelIndicator(elements.levelIndicator, engineState.lessonIndex + 1, engineState.totalLessons);
+	}
 	// Header pill shows module name + level (clickable link to return to lesson)
 	if (elements.headerLevelPill && engineState.module) {
-		const label = t("lessonLabel");
-		elements.headerLevelPill.innerHTML = `<span class="header-module-name">${engineState.module.title}</span> <span class="header-level">${label} ${engineState.lessonIndex + 1} / ${engineState.totalLessons}</span>`;
+		if (isPlayground) {
+			// Playground: just show title, no lesson count
+			elements.headerLevelPill.innerHTML = `<span class="header-module-name">${engineState.module.title}</span>`;
+		} else {
+			const label = t("lessonLabel");
+			elements.headerLevelPill.innerHTML = `<span class="header-module-name">${engineState.module.title}</span> <span class="header-level">${label} ${engineState.lessonIndex + 1} / ${engineState.totalLessons}</span>`;
+		}
 		elements.headerLevelPill.href = `#${engineState.module.id}/${engineState.lessonIndex}`;
 	}

@@ -677,12 +774,13 @@ function handleEditorChange(code) {

 function updateNavigationButtons() {
 	const engineState = lessonEngine.getCurrentState();
+	const isPlayground = engineState.lesson?.mode === "playground";

+	// Update button states
 	elements.prevBtn.disabled = !engineState.canGoPrev;
-	elements.nextBtn.disabled = !engineState.canGoNext;
-
+	elements.nextBtn.disabled = isPlayground || !engineState.canGoNext;
 	elements.prevBtn.classList.toggle("btn-disabled", !engineState.canGoPrev);
-	elements.nextBtn.classList.toggle("btn-disabled", !engineState.canGoNext);
+	elements.nextBtn.classList.toggle("btn-disabled", isPlayground || !engineState.canGoNext);
 }

 function nextLesson() {
@@ -694,16 +792,21 @@ function nextLesson() {
 		// Update URL
 		updateHash(newState.module.id, newState.lessonIndex);

-		if (newState.module.id !== prevModuleId) {
+		const moduleChanged = newState.module.id !== prevModuleId;
+		if (moduleChanged) {
 			updateModuleHighlight(newState.module.id);
-			updateSectionColor(getModuleSection(newState.module));
 		}
 		loadCurrentLesson();
+		if (moduleChanged) {
+			updateSectionColor(getModuleSection(newState.module));
+			updateNavHighlight({ type: RouteType.LESSON, moduleId: newState.module.id, lessonIndex: newState.lessonIndex });
+		}
 	}
 }

 function prevLesson() {
-	const prevModuleId = lessonEngine.getCurrentState().module?.id;
+	const engineState = lessonEngine.getCurrentState();
+	const prevModuleId = engineState.module?.id;
 	const success = lessonEngine.previousLesson();
 	if (success) {
 		const newState = lessonEngine.getCurrentState();
@@ -711,11 +814,15 @@ function prevLesson() {
 		// Update URL
 		updateHash(newState.module.id, newState.lessonIndex);

-		if (newState.module.id !== prevModuleId) {
+		const moduleChanged = newState.module.id !== prevModuleId;
+		if (moduleChanged) {
 			updateModuleHighlight(newState.module.id);
-			updateSectionColor(getModuleSection(newState.module));
 		}
 		loadCurrentLesson();
+		if (moduleChanged) {
+			updateSectionColor(getModuleSection(newState.module));
+			updateNavHighlight({ type: RouteType.LESSON, moduleId: newState.module.id, lessonIndex: newState.lessonIndex });
+		}
 	}
 }

@@ -775,10 +882,12 @@ function loadRandomTemplate() {
 }

 function runCode() {
-	const userCode = codeEditor ? codeEditor.getValue() : "";
+	const userCode = codeEditor ? codeEditor.getEditableValue() : "";
 	const engineState = lessonEngine.getCurrentState();
 	const isPlayground = engineState.lesson?.mode === "playground";

+	track("run_code", { module: engineState.module?.id, lesson: engineState.lessonIndex, playground: isPlayground });
+
 	// Rotate the Run button icon
 	const runButtonImg = document.querySelector("#run-btn img");
 	if (runButtonImg) {
@@ -845,8 +954,9 @@ function runCode() {
 		state.animationTimeout = setTimeout(() => {
 			elements.previewWrapper?.classList.remove("matched");
 			elements.previewSection?.classList.remove("matched");
-			// Keep the gradient border visible after animation
+			// Keep the gradient border and glow visible after animation
 			elements.previewWrapper?.classList.add("completed-glow");
+			elements.previewSection?.classList.add("completed-glow");
 			state.animationTimeout = null;
 		}, 3500);

@@ -1309,6 +1419,143 @@ const sectionContent = {
 				</div>
 			</div>
 		</div>
+	`,
+	markdown: `
+		<div class="section-overview">
+			<p><strong>Markdown</strong> is a lightweight markup language created by John Gruber in 2004. It lets you write formatted text using plain text syntax that's easy to read and write. Markdown is used everywhere—from GitHub READMEs to documentation, note-taking apps, and content management systems.</p>
+			<p>The beauty of Markdown is its simplicity: <code># Heading</code> creates a heading, <code>**bold**</code> makes text bold, and <code>[link](url)</code> creates a link. No complex HTML tags needed. Markdown files can be converted to HTML, PDF, or many other formats.</p>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>Headings & Structure</h2>
+				<p>Create document structure with headings using <code>#</code> symbols. One <code>#</code> for h1, two <code>##</code> for h2, up to six levels. This creates a clear hierarchy in your documents.</p>
+				<p>
+					<a href="#markdown-basics/0" class="topic-link">Practice headings →</a>
+				</p>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code># Main Title
+## Section
+### Subsection
+#### Detail</code></pre>
+				</div>
+			</div>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>Text Formatting</h2>
+				<p>Emphasize text with <code>**bold**</code> or <code>*italic*</code>. Combine them with <code>***bold italic***</code>. Use backticks for <code>\`inline code\`</code> to highlight commands or code snippets in your text.</p>
+				<p>
+					<a href="#markdown-basics/2" class="topic-link">Practice formatting →</a>
+				</p>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code>This is **bold** text.
+This is *italic* text.
+This is \`inline code\`.</code></pre>
+				</div>
+			</div>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>Lists</h2>
+				<p>Create bullet lists with <code>-</code>, <code>*</code>, or <code>+</code>. Numbered lists use <code>1.</code>, <code>2.</code>, etc. Indent items with spaces to create nested lists for complex outlines.</p>
+				<p>
+					<a href="#markdown-basics/4" class="topic-link">Practice lists →</a>
+				</p>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code>- First item
+- Second item
+  - Nested item
+
+1. Step one
+2. Step two
+3. Step three</code></pre>
+				</div>
+			</div>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>Links & Images</h2>
+				<p>Create links with <code>[text](url)</code> syntax. Images use the same format with an exclamation mark: <code>![alt text](image-url)</code>. The alt text describes the image for accessibility.</p>
+				<p>
+					<a href="#markdown-basics/6" class="topic-link">Practice links →</a>
+				</p>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code>[Visit Google](https://google.com)
+
+![Logo](https://example.com/logo.png)</code></pre>
+				</div>
+			</div>
+		</div>
+	`,
+	javascript: `
+		<div class="section-overview">
+			<p><strong>JavaScript</strong> is the programming language of the web. It adds interactivity to HTML pages—responding to clicks, updating content dynamically, validating forms, and much more. Every modern browser includes a JavaScript engine, making it the most widely deployed programming language in the world.</p>
+			<p>These beginner lessons cover the fundamentals: declaring variables, selecting and modifying DOM elements, and handling user events. Each concept builds on the previous one, giving you the tools to make any web page interactive.</p>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>Variables & Data Types</h2>
+				<p>JavaScript uses <code>const</code> for values that won't change and <code>let</code> for values that will. Template literals with backticks make it easy to embed expressions in strings using <code>\${...}</code> syntax.</p>
+				<p>Arrays store ordered collections in square brackets. Objects store key-value pairs in curly braces. These are the building blocks of every JavaScript program.</p>
+				<a href="#js-variables/0" class="topic-link">Learn JS Variables</a>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code>const name = "Alice";
+let count = 0;
+count = count + 1;
+
+const msg = \`Hello, \${name}!\`;
+const colors = ["red", "green"];</code></pre>
+				</div>
+			</div>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>DOM Manipulation</h2>
+				<p>The DOM (Document Object Model) is how JavaScript sees your HTML. Use <code>document.querySelector()</code> to find elements by CSS selector, then modify them with properties like <code>textContent</code>, <code>style</code>, and <code>classList</code>.</p>
+				<a href="#js-dom/0" class="topic-link">Practice DOM Methods</a>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code>const title = document.querySelector('h1');
+title.textContent = "New Title";
+title.style.color = "coral";
+title.classList.add("active");</code></pre>
+				</div>
+			</div>
+		</div>
+
+		<div class="topic-row">
+			<div class="topic-text">
+				<h2>Event Handling</h2>
+				<p>Events let your code respond to user actions. Use <code>addEventListener()</code> to run a function when something happens—a click, a keystroke, or an input change. The callback receives an event object with details about what happened.</p>
+				<a href="#js-events/0" class="topic-link">Handle Events</a>
+			</div>
+			<div class="topic-code">
+				<div class="code-block">
+					<pre><code>const btn = document.querySelector('.btn');
+
+btn.addEventListener('click', () => {
+  alert('Clicked!');
+});</code></pre>
+				</div>
+			</div>
+		</div>
 	`
 };

@@ -1825,6 +2072,105 @@ const referenceContent = {
 		</section>

 		<p class="ref-see-also">Learn: <a href="#html">HTML Section</a> | Style with: <a href="#reference/css">CSS Properties</a></p>
+	`,
+
+	markdown: `
+		<h1>Markdown Syntax Reference</h1>
+		<p class="ref-intro">A quick guide to Markdown syntax for formatting text documents. Markdown is used in GitHub, documentation, and note-taking apps.</p>
+
+		<section class="ref-section">
+			<h2>Text Formatting</h2>
+			<table class="ref-table">
+				<thead><tr><th>Syntax</th><th>Result</th><th>Notes</th></tr></thead>
+				<tbody>
+					<tr><td><code>**bold**</code></td><td><strong>bold</strong></td><td>Or use __bold__</td></tr>
+					<tr><td><code>*italic*</code></td><td><em>italic</em></td><td>Or use _italic_</td></tr>
+					<tr><td><code>***bold italic***</code></td><td><strong><em>bold italic</em></strong></td><td>Combine both</td></tr>
+					<tr><td><code>~~strikethrough~~</code></td><td><s>strikethrough</s></td><td>GFM extension</td></tr>
+					<tr><td><code>\`inline code\`</code></td><td><code>inline code</code></td><td>Monospace font</td></tr>
+				</tbody>
+			</table>
+		</section>
+
+		<section class="ref-section">
+			<h2>Headings</h2>
+			<table class="ref-table">
+				<thead><tr><th>Syntax</th><th>Level</th><th>Usage</th></tr></thead>
+				<tbody>
+					<tr><td><code># Heading 1</code></td><td>h1</td><td>Document title</td></tr>
+					<tr><td><code>## Heading 2</code></td><td>h2</td><td>Main sections</td></tr>
+					<tr><td><code>### Heading 3</code></td><td>h3</td><td>Subsections</td></tr>
+					<tr><td><code>#### Heading 4</code></td><td>h4</td><td>Minor sections</td></tr>
+					<tr><td><code>##### Heading 5</code></td><td>h5</td><td>Rarely used</td></tr>
+					<tr><td><code>###### Heading 6</code></td><td>h6</td><td>Smallest heading</td></tr>
+				</tbody>
+			</table>
+		</section>
+
+		<section class="ref-section">
+			<h2>Lists</h2>
+			<table class="ref-table">
+				<thead><tr><th>Syntax</th><th>Type</th><th>Notes</th></tr></thead>
+				<tbody>
+					<tr><td><code>- Item</code></td><td>Unordered</td><td>Or use * or +</td></tr>
+					<tr><td><code>1. Item</code></td><td>Ordered</td><td>Numbers auto-increment</td></tr>
+					<tr><td><code>  - Nested</code></td><td>Nested list</td><td>2-space indent</td></tr>
+					<tr><td><code>- [x] Task</code></td><td>Task list</td><td>GFM extension</td></tr>
+					<tr><td><code>- [ ] Task</code></td><td>Unchecked task</td><td>Interactive checkboxes</td></tr>
+				</tbody>
+			</table>
+		</section>
+
+		<section class="ref-section">
+			<h2>Links & Images</h2>
+			<table class="ref-table">
+				<thead><tr><th>Syntax</th><th>Purpose</th><th>Example</th></tr></thead>
+				<tbody>
+					<tr><td><code>[text](url)</code></td><td>Inline link</td><td>[Google](https://google.com)</td></tr>
+					<tr><td><code>[text](url "title")</code></td><td>Link with tooltip</td><td>Hover text</td></tr>
+					<tr><td><code>![alt](url)</code></td><td>Image</td><td>Alt text for accessibility</td></tr>
+					<tr><td><code>&lt;url&gt;</code></td><td>Auto-link</td><td>URLs become clickable</td></tr>
+					<tr><td><code>[ref]: url</code></td><td>Reference link</td><td>Define at doc bottom</td></tr>
+				</tbody>
+			</table>
+		</section>
+
+		<section class="ref-section">
+			<h2>Code Blocks</h2>
+			<table class="ref-table">
+				<thead><tr><th>Syntax</th><th>Purpose</th><th>Notes</th></tr></thead>
+				<tbody>
+					<tr><td><code>\`\`\`</code></td><td>Fenced code</td><td>3 backticks or tildes</td></tr>
+					<tr><td><code>\`\`\`js</code></td><td>Syntax highlight</td><td>Add language identifier</td></tr>
+					<tr><td><code>    code</code></td><td>Indented code</td><td>4-space indent</td></tr>
+				</tbody>
+			</table>
+		</section>
+
+		<section class="ref-section">
+			<h2>Block Elements</h2>
+			<table class="ref-table">
+				<thead><tr><th>Syntax</th><th>Element</th><th>Notes</th></tr></thead>
+				<tbody>
+					<tr><td><code>> Quote</code></td><td>Blockquote</td><td>Nest with >></td></tr>
+					<tr><td><code>---</code></td><td>Horizontal rule</td><td>Or *** or ___</td></tr>
+					<tr><td><code>| A | B |</code></td><td>Table</td><td>GFM extension</td></tr>
+				</tbody>
+			</table>
+		</section>
+
+		<section class="ref-section">
+			<h2>Tables (GFM)</h2>
+			<div class="ref-example">
+				<pre><code>| Header 1 | Header 2 |
+|----------|----------|
+| Cell 1   | Cell 2   |
+| Cell 3   | Cell 4   |</code></pre>
+			</div>
+			<p>Use colons for alignment: <code>:---</code> (left), <code>:---:</code> (center), <code>---:</code> (right)</p>
+		</section>
+
+		<p class="ref-see-also">Learn: <a href="#markdown">Markdown Section</a> | Also try: <a href="#html">HTML Elements</a></p>
 	`
 };

@@ -1852,7 +2198,7 @@ function stripHtml(html) {
 * Update page meta tags based on current route for SEO
 */
 function updatePageMeta(route) {
-	const defaultTitle = "Code Crispies - Learn HTML & CSS Interactively | Free Coding Practice";
+	const defaultTitle = "CODE CRISPIES - Learn HTML & CSS Interactively | Free Coding Practice";
 	const defaultDesc =
 		"Master HTML, CSS, and Tailwind through hands-on coding exercises. Free, open-source learning platform with instant feedback. No account required.";

@@ -1870,9 +2216,9 @@ function updatePageMeta(route) {
 			break;

 		case RouteType.SECTION: {
-			const sectionNames = { css: "CSS", html: "HTML", tailwind: "Tailwind CSS" };
+			const sectionNames = { css: "CSS", html: "HTML", tailwind: "Tailwind CSS", markdown: "Markdown" };
 			const sectionName = sectionNames[route.sectionId] || route.sectionId;
-			title = `${sectionName} Lessons - Code Crispies | Learn ${sectionName}`;
+			title = `${sectionName} Lessons - CODE CRISPIES | Learn ${sectionName}`;
 			description = `Learn ${sectionName} through interactive coding exercises. Hands-on practice with instant feedback.`;
 			break;
 		}
@@ -1881,7 +2227,7 @@ function updatePageMeta(route) {
 			const module = lessonEngine.modules.find((m) => m.id === route.moduleId);
 			const lesson = module?.lessons[route.lessonIndex];
 			if (module && lesson) {
-				title = `${lesson.title} - ${module.title} | Code Crispies`;
+				title = `${lesson.title} - ${module.title} | CODE CRISPIES`;
 				const lessonDesc = stripHtml(lesson.description || lesson.task);
 				description = lessonDesc.length > 155 ? lessonDesc.slice(0, 152) + "..." : lessonDesc || defaultDesc;
 			}
@@ -1894,10 +2240,11 @@ function updatePageMeta(route) {
 				selectors: "CSS Selectors",
 				flexbox: "Flexbox",
 				grid: "CSS Grid",
-				html: "HTML Elements"
+				html: "HTML Elements",
+				markdown: "Markdown Syntax"
 			};
 			const refName = refNames[route.refId] || "Reference";
-			title = `${refName} Reference - Code Crispies`;
+			title = `${refName} Reference - CODE CRISPIES`;
 			description = `Quick reference guide for ${refName}. Syntax, examples, and common patterns for web development.`;
 			break;
 		}
@@ -1913,13 +2260,13 @@ function updatePageMeta(route) {
 	// Update Open Graph tags
 	const ogTitle = document.querySelector('meta[property="og:title"]');
 	const ogDesc = document.querySelector('meta[property="og:description"]');
-	if (ogTitle) ogTitle.setAttribute("content", title.replace(" | Code Crispies", "").replace(" - Code Crispies", ""));
+	if (ogTitle) ogTitle.setAttribute("content", title.replace(" | CODE CRISPIES", "").replace(" - CODE CRISPIES", ""));
 	if (ogDesc) ogDesc.setAttribute("content", description);

 	// Update Twitter tags
 	const twitterTitle = document.querySelector('meta[name="twitter:title"]');
 	const twitterDesc = document.querySelector('meta[name="twitter:description"]');
-	if (twitterTitle) twitterTitle.setAttribute("content", title.replace(" | Code Crispies", "").replace(" - Code Crispies", ""));
+	if (twitterTitle) twitterTitle.setAttribute("content", title.replace(" | CODE CRISPIES", "").replace(" - CODE CRISPIES", ""));
 	if (twitterDesc) twitterDesc.setAttribute("content", description);
 }

@@ -1994,6 +2341,11 @@ function updateSectionColor(sectionId) {
 	} else {
 		document.body.removeAttribute("data-section");
 	}
+
+	// Update code editor theme for section
+	if (codeEditor) {
+		codeEditor.setSection(sectionId);
+	}
 }

 /**
@@ -2002,7 +2354,6 @@ function updateSectionColor(sectionId) {
 function showLandingPage() {
 	hideAllPages();
 	elements.landingPage?.classList.remove("hidden");
-	window.scrollTo(0, 0);

 	// Reset section color on landing page
 	updateSectionColor(null);
@@ -2012,16 +2363,17 @@ function showLandingPage() {

 	// Render footer lesson links
 	renderFooterLessonLinks();
+
+	// Scroll to top after content is rendered
+	requestAnimationFrame(() => window.scrollTo(0, 0));
 }

 /**
 * Render module links in the landing page footer, grouped by section
 */
 function renderFooterLessonLinks() {
-	if (!elements.footerLessonLinks) return;
-
 	const modules = lessonEngine.modules || [];
-	const sectionGroups = { css: [], html: [] };
+	const sectionGroups = { css: [], html: [], javascript: [] };

 	modules.forEach((module) => {
 		if (module.excludeFromProgress) return;
@@ -2042,14 +2394,23 @@ function renderFooterLessonLinks() {
 		html += "</div>";
 	});

-	elements.footerLessonLinks.innerHTML = html;
+	// Update all footer lesson links
+	if (elements.footerLessonLinks) {
+		elements.footerLessonLinks.innerHTML = html;
+	}
+	if (elements.refFooterLessonLinks) {
+		elements.refFooterLessonLinks.innerHTML = html;
+	}
+	if (elements.sectionFooterLessonLinks) {
+		elements.sectionFooterLessonLinks.innerHTML = html;
+	}
 }

 /**
 * Update progress indicators on landing page
 */
 function updateLandingProgress() {
-	["css", "html", "tailwind"].forEach((sectionId) => {
+	["css", "html", "markdown", "javascript"].forEach((sectionId) => { // tailwind temporarily disabled
 		const progressEl = document.getElementById(`${sectionId}-progress`);
 		if (progressEl) {
 			const sectionModules = getModulesBySection(lessonEngine.modules, sectionId);
@@ -2077,7 +2438,6 @@ function updateLandingProgress() {
 function showSectionPage(sectionId) {
 	hideAllPages();
 	elements.sectionPage?.classList.remove("hidden");
-	window.scrollTo(0, 0);

 	// Update section color
 	updateSectionColor(sectionId);
@@ -2120,6 +2480,9 @@ function showSectionPage(sectionId) {
 	const percent = total > 0 ? Math.round((completed / total) * 100) : 0;
 	if (elements.sectionProgressFill) elements.sectionProgressFill.style.width = `${percent}%`;
 	if (elements.sectionProgressText) elements.sectionProgressText.textContent = `${completed} of ${total} lessons complete`;
+
+	// Scroll to top after content is rendered
+	requestAnimationFrame(() => window.scrollTo(0, 0));
 }

 /**
@@ -2128,13 +2491,12 @@ function showSectionPage(sectionId) {
 function showReferencePage(refId) {
 	hideAllPages();
 	elements.referencePage?.classList.remove("hidden");
-	window.scrollTo(0, 0);

 	// Default to CSS if no refId
 	const activeRef = refId || "css";

 	// Map reference to section for color coding
-	const refToSection = { css: "css", selectors: "css", flexbox: "css", grid: "css", html: "html" };
+	const refToSection = { css: "css", selectors: "css", flexbox: "css", grid: "css", html: "html", markdown: "markdown" };
 	updateSectionColor(refToSection[activeRef] || "css");

 	// Track reference page view
@@ -2156,6 +2518,9 @@ function showReferencePage(refId) {
 	} else if (elements.referenceBody) {
 		elements.referenceBody.innerHTML = `<p>Reference for "${activeRef}" coming soon...</p>`;
 	}
+
+	// Scroll to top after content is rendered
+	requestAnimationFrame(() => window.scrollTo(0, 0));
 }

 /**
@@ -2337,6 +2702,11 @@ function init() {
 	// Initialize i18n before anything else
 	initI18n();

+	// Set dynamic year in footer
+	document.querySelectorAll(".current-year").forEach((el) => {
+		el.textContent = new Date().getFullYear();
+	});
+
 	loadUserSettings();

 	// Restore cached lesson content immediately to avoid "Loading..." flash
@@ -2348,22 +2718,34 @@ function init() {
 	// Set timeout to show fallback if loading takes too long
 	loadingTimeout = setTimeout(showLoadingFallback, 3000);

-	// Load modules after editor is ready
-	initializeModules();
+	// Handle OAuth callback FIRST (tokens are in URL hash, must run before router)
+	handleOAuthCallback().then(() => {
+		// Load modules (this also calls handleRoute inside)
+		initializeModules();

-	// Initialize URL router for shareable links
-	initRouter();
+		// Initialize URL router for browser back/forward
+		initRouter();
+
+		// Initialize authentication
+		initAuth(lessonEngine);
+	});

 	// Sidebar controls
 	elements.menuBtn.addEventListener("click", openSidebar);
 	elements.closeSidebar.addEventListener("click", closeSidebar);
 	elements.sidebarBackdrop.addEventListener("click", closeSidebar);

+	// Sidebar nav links (mobile) - close sidebar on click
+	document.querySelectorAll(".sidebar-nav-link").forEach((link) => {
+		link.addEventListener("click", closeSidebar);
+	});
+
 	// Logo click - navigate to home landing
 	elements.logoLink.addEventListener("click", (e) => {
 		e.preventDefault();
 		navigateTo("");
 		showLandingPage();
+		track("logo_click");
 	});

 	// Language select
@@ -2416,10 +2798,42 @@ function init() {
 	});
 	elements.copyUrlBtn.addEventListener("click", copyShareUrl);

+	// Legal dialogs (Privacy & Imprint)
+	const privacyDialog = document.getElementById("privacy-dialog");
+	const imprintDialog = document.getElementById("imprint-dialog");
+
+	document.querySelectorAll(".privacy-link").forEach((btn) => {
+		btn.addEventListener("click", () => {
+			privacyDialog?.showModal();
+			track("privacy_open");
+		});
+	});
+	document.querySelectorAll(".imprint-link").forEach((btn) => {
+		btn.addEventListener("click", () => {
+			imprintDialog?.showModal();
+			track("imprint_open");
+		});
+	});
+
+	document.querySelector(".privacy-dialog-close")?.addEventListener("click", () => {
+		privacyDialog?.close();
+	});
+	document.querySelector(".imprint-dialog-close")?.addEventListener("click", () => {
+		imprintDialog?.close();
+	});
+
+	privacyDialog?.addEventListener("click", (e) => {
+		if (e.target === privacyDialog) privacyDialog.close();
+	});
+	imprintDialog?.addEventListener("click", (e) => {
+		if (e.target === imprintDialog) imprintDialog.close();
+	});
+
 	// Settings
 	elements.disableFeedbackToggle.addEventListener("change", (e) => {
 		state.userSettings.disableFeedbackErrors = !e.target.checked;
 		saveUserSettings();
+		track("setting_change", { setting: "feedback_errors", enabled: e.target.checked });
 	});

 	// Click on editor content to focus CodeMirror
@@ -2427,6 +2841,46 @@ function init() {
 		if (codeEditor) codeEditor.focus();
 	});

+	// Track clicks on "Coming Soon" disabled topic links
+	document.addEventListener("click", (e) => {
+		const disabledLink = e.target.closest(".topic-link-disabled");
+		if (disabledLink) {
+			const topicText = disabledLink.textContent.replace("Coming Soon", "").trim();
+			track("coming_soon_click", { topic: topicText });
+		}
+	});
+
+	// Track external link clicks
+	document.addEventListener("click", (e) => {
+		const link = e.target.closest('a[target="_blank"]');
+		if (link) {
+			track("external_link", { url: link.href, text: link.textContent.trim() });
+		}
+	});
+
+	// Track header nav link clicks (CSS, HTML, Tailwind)
+	document.querySelectorAll(".nav-link[data-section]").forEach((link) => {
+		link.addEventListener("click", () => {
+			track("header_nav_click", { section: link.dataset.section });
+		});
+	});
+
+	// Track footer link clicks
+	document.addEventListener("click", (e) => {
+		const footerLink = e.target.closest(".landing-footer a, .section-footer a, .reference-footer a");
+		if (footerLink && !footerLink.target) {
+			track("footer_link", { href: footerLink.getAttribute("href"), text: footerLink.textContent.trim() });
+		}
+	});
+
+	// Track practice/reference cross-links
+	document.addEventListener("click", (e) => {
+		const refLink = e.target.closest(".ref-see-also a");
+		if (refLink) {
+			track("practice_link", { href: refLink.getAttribute("href"), text: refLink.textContent.trim() });
+		}
+	});
+
 	// Keyboard shortcuts
 	document.addEventListener("keydown", (e) => {
 		// Ctrl+Enter to run code
@@ -2454,6 +2908,27 @@ function init() {
 			track("support_click", { location: "landing" });
 		}
 	});
+
+	// Newsletter form submission
+	const newsletterForm = document.getElementById("newsletter-form");
+	const newsletterThanks = document.getElementById("newsletter-thanks");
+	newsletterForm?.addEventListener("submit", async (e) => {
+		e.preventDefault();
+		const emailInput = document.getElementById("newsletter-email");
+		const email = emailInput?.value;
+		if (email) {
+			// Import newsletter helper dynamically to avoid loading Supabase if not needed
+			try {
+				const { newsletter } = await import("./supabase.js");
+				await newsletter.subscribe(email);
+			} catch (err) {
+				console.error("Newsletter subscription error:", err);
+			}
+			track("newsletter_signup", { email: email });
+			newsletterForm.classList.add("hidden");
+			newsletterThanks?.classList.remove("hidden");
+		}
+	});
 }

 // Start the application
--- a/src/auth.js
+++ b/src/auth.js
@@ -0,0 +1,526 @@
+import { t, applyTranslations } from "./i18n.js";
+
+// Analytics tracking helper
+function track(eventName, eventData = {}) {
+  if (typeof umami !== "undefined" && umami.track) {
+    umami.track(eventName, eventData);
+  }
+}
+
+let currentUser = null;
+let oauthHandled = false;
+let lessonEngineRef = null;
+let authModule = null;
+let progressModule = null;
+let supabaseAvailable = false;
+
+/**
+ * Check for OAuth callback tokens in URL hash BEFORE router runs.
+ * Call this before initializing the router.
+ * @returns {Promise<boolean>} true if OAuth callback was detected and handled
+ */
+export async function handleOAuthCallback() {
+  const hash = window.location.hash;
+
+  // Check if hash contains OAuth tokens (access_token, error, etc.)
+  if (!hash.includes("access_token") && !hash.includes("error_description") && !hash.includes("refresh_token")) {
+    return false;
+  }
+
+  try {
+    const supabaseModule = await import("./supabase.js");
+    if (!supabaseModule.isConfigured) {
+      return false;
+    }
+
+    // Parse tokens from hash
+    const params = new URLSearchParams(hash.substring(1));
+    const accessToken = params.get("access_token");
+    const refreshToken = params.get("refresh_token");
+
+    if (accessToken && refreshToken) {
+      // Explicitly set the session with tokens from URL
+      const { data, error } = await supabaseModule.auth.setSession({
+        access_token: accessToken,
+        refresh_token: refreshToken
+      });
+
+      if (!error && data?.session) {
+        oauthHandled = true;
+        const provider = data.session.user?.app_metadata?.provider || "oauth";
+        track("auth_login", { method: provider });
+      }
+    }
+
+    // Restore the original route (saved before OAuth redirect)
+    const savedRoute = localStorage.getItem("codeCrispies.oauthReturnRoute");
+    if (savedRoute) {
+      localStorage.removeItem("codeCrispies.oauthReturnRoute");
+      window.history.replaceState(null, "", window.location.pathname + savedRoute);
+    } else {
+      // No saved route - just clear the hash
+      window.history.replaceState(null, "", window.location.pathname);
+    }
+
+    return true;
+  } catch (e) {
+    console.error("[Auth] OAuth callback handling failed:", e.message);
+    return false;
+  }
+}
+
+/**
+ * Initialize the auth system
+ * @param {Object} engine - The LessonEngine instance
+ */
+export async function initAuth(engine) {
+  lessonEngineRef = engine;
+
+  // Try to load Supabase - if not configured, auth is disabled
+  try {
+    const supabaseModule = await import("./supabase.js");
+
+    // Check if Supabase is configured via environment variables
+    if (!supabaseModule.isConfigured) {
+      console.log("Supabase not configured - auth disabled");
+      hideAuthUI();
+      return;
+    }
+
+    authModule = supabaseModule.auth;
+    progressModule = supabaseModule.progressDB;
+    supabaseAvailable = true;
+  } catch (e) {
+    console.log("Supabase not available - auth disabled:", e.message);
+    hideAuthUI();
+    return;
+  }
+
+  // Listen for auth changes
+  authModule.onAuthStateChange((event, session) => {
+    if (event === "SIGNED_IN" && session?.user) {
+      handleLogin(session.user);
+    } else if (event === "SIGNED_OUT") {
+      handleLogout();
+    }
+  });
+
+  // Check initial session
+  try {
+    const { data } = await authModule.getSession();
+    if (data?.session?.user) handleLogin(data.session.user);
+  } catch (e) {
+    // Session check failed - continue without auth
+  }
+
+  // Attach form handlers
+  setupAuthForms();
+}
+
+function hideAuthUI() {
+  document.getElementById("auth-trigger-header")?.classList.add("hidden");
+  document.querySelector(".sidebar-auth-box")?.classList.add("hidden");
+}
+
+async function handleLogin(user) {
+  currentUser = user;
+  updateAuthUI(user);
+
+  if (!progressModule) return;
+
+  // Load cloud progress
+  const { data } = await progressModule.load(user.id);
+
+  if (data) {
+    // Merge with localStorage (cloud wins for conflicts)
+    mergeProgress(data);
+  } else {
+    // First login: upload localStorage to cloud
+    await syncToCloud();
+  }
+}
+
+function handleLogout() {
+  currentUser = null;
+  updateAuthUI(null);
+  // Keep localStorage progress, just disconnect from cloud
+}
+
+function updateAuthUI(user) {
+  // Header elements
+  const authTriggerHeader = document.getElementById("auth-trigger-header");
+  const userEmailHeader = document.getElementById("user-email-header");
+
+  // Sidebar elements
+  const authTriggerSidebar = document.getElementById("auth-trigger-sidebar");
+  const authTriggerMobile = document.getElementById("auth-trigger-mobile");
+  const userMenuSidebar = document.getElementById("user-menu-sidebar");
+  const userEmailSidebar = document.getElementById("user-email-sidebar");
+  const sidebarHint = document.querySelector(".sidebar-auth-hint");
+
+  if (user) {
+    authTriggerHeader?.classList.add("hidden");
+    userEmailHeader?.classList.remove("hidden");
+    authTriggerSidebar?.classList.add("hidden");
+    authTriggerMobile?.classList.add("hidden");
+    userMenuSidebar?.classList.remove("hidden");
+    sidebarHint?.classList.add("hidden");
+    if (userEmailHeader) userEmailHeader.textContent = user.email;
+    if (userEmailSidebar) userEmailSidebar.textContent = user.email;
+  } else {
+    authTriggerHeader?.classList.remove("hidden");
+    userEmailHeader?.classList.add("hidden");
+    authTriggerSidebar?.classList.remove("hidden");
+    authTriggerMobile?.classList.remove("hidden");
+    userMenuSidebar?.classList.add("hidden");
+    sidebarHint?.classList.remove("hidden");
+  }
+}
+
+export async function syncToCloud() {
+  if (!currentUser || !progressModule) return;
+
+  const progress = JSON.parse(
+    localStorage.getItem("codeCrispies.progress") || "{}"
+  );
+  const userCodeEntries = JSON.parse(
+    localStorage.getItem("codeCrispies.userCode") || "[]"
+  );
+  const userCode = Object.fromEntries(userCodeEntries);
+  const settings = JSON.parse(
+    localStorage.getItem("codeCrispies.settings") || "{}"
+  );
+  const language = localStorage.getItem("codeCrispies.language") || "en";
+
+  await progressModule.save(currentUser.id, progress, userCode, settings, language);
+}
+
+function mergeProgress(cloudData) {
+  // Update localStorage with cloud data
+  localStorage.setItem(
+    "codeCrispies.progress",
+    JSON.stringify(cloudData.progress)
+  );
+  localStorage.setItem(
+    "codeCrispies.userCode",
+    JSON.stringify(Object.entries(cloudData.user_code))
+  );
+  localStorage.setItem(
+    "codeCrispies.settings",
+    JSON.stringify(cloudData.settings)
+  );
+  localStorage.setItem("codeCrispies.language", cloudData.language);
+
+  // Reload engine state
+  if (lessonEngineRef) {
+    lessonEngineRef.loadUserProgress();
+    lessonEngineRef.loadUserCodeFromStorage();
+  }
+}
+
+export function isLoggedIn() {
+  return supabaseAvailable && currentUser !== null;
+}
+
+export function getCurrentUser() {
+  return currentUser;
+}
+
+// Debounce utility
+function debounce(fn, delay) {
+  let timeoutId;
+  return (...args) => {
+    clearTimeout(timeoutId);
+    timeoutId = setTimeout(() => fn(...args), delay);
+  };
+}
+
+// Export debounced sync for use by LessonEngine
+export const debouncedSyncToCloud = debounce(() => syncToCloud(), 2000);
+
+function setupAuthForms() {
+  const authDialog = document.getElementById("auth-dialog");
+  const loginForm = document.getElementById("login-form");
+  const signupForm = document.getElementById("signup-form");
+  const resetForm = document.getElementById("reset-form");
+
+  // Form submissions
+  loginForm?.addEventListener("submit", handleLoginSubmit);
+  signupForm?.addEventListener("submit", handleSignupSubmit);
+  resetForm?.addEventListener("submit", handleResetSubmit);
+
+  // Form switchers
+  document
+    .getElementById("show-signup")
+    ?.addEventListener("click", () => switchForm("signup"));
+  document
+    .getElementById("show-login")
+    ?.addEventListener("click", () => switchForm("login"));
+  document
+    .getElementById("show-reset")
+    ?.addEventListener("click", () => switchForm("reset"));
+
+  // Dialog triggers (header, sidebar, and mobile)
+  document
+    .getElementById("auth-trigger-header")
+    ?.addEventListener("click", () => {
+      authDialog?.showModal();
+    });
+  document
+    .getElementById("auth-trigger-sidebar")
+    ?.addEventListener("click", () => {
+      authDialog?.showModal();
+    });
+  document
+    .getElementById("auth-trigger-mobile")
+    ?.addEventListener("click", () => {
+      authDialog?.showModal();
+    });
+
+  // Logout button (sidebar only)
+  document
+    .getElementById("logout-btn-sidebar")
+    ?.addEventListener("click", async () => {
+      await authModule?.signOut();
+      track("auth_logout");
+    });
+
+  // Delete account button and dialog
+  const deleteDialog = document.getElementById("delete-account-dialog");
+
+  document
+    .getElementById("delete-account-btn")
+    ?.addEventListener("click", () => {
+      deleteDialog?.showModal();
+    });
+
+  document
+    .getElementById("cancel-delete")
+    ?.addEventListener("click", () => {
+      deleteDialog?.close();
+    });
+
+  document
+    .getElementById("delete-dialog-close")
+    ?.addEventListener("click", () => {
+      deleteDialog?.close();
+    });
+
+  deleteDialog?.addEventListener("click", (e) => {
+    if (e.target === deleteDialog) deleteDialog.close();
+  });
+
+  document
+    .getElementById("confirm-delete")
+    ?.addEventListener("click", async () => {
+      const errorEl = document.getElementById("delete-account-error");
+      const confirmBtn = document.getElementById("confirm-delete");
+
+      confirmBtn.disabled = true;
+
+      const { error } = await authModule.deleteAccount();
+
+      if (error) {
+        errorEl.textContent = error.message;
+        errorEl.classList.remove("hidden");
+        confirmBtn.disabled = false;
+      } else {
+        errorEl.classList.add("hidden");
+        deleteDialog.close();
+        track("auth_delete_account");
+        // Sign out and clear local state
+        await authModule.signOut();
+      }
+    });
+
+  // OAuth buttons - save current route before redirect
+  document.getElementById("google-login")?.addEventListener("click", async () => {
+    // Save current route to restore after OAuth
+    const currentHash = window.location.hash;
+    if (currentHash && !currentHash.includes("access_token")) {
+      localStorage.setItem("codeCrispies.oauthReturnRoute", currentHash);
+    }
+    const { error } = await authModule?.signInWithGoogle() ?? { error: null };
+    if (error) {
+      showOAuthError(error.message);
+    }
+  });
+
+  document.getElementById("github-login")?.addEventListener("click", async () => {
+    // Save current route to restore after OAuth
+    const currentHash = window.location.hash;
+    if (currentHash && !currentHash.includes("access_token")) {
+      localStorage.setItem("codeCrispies.oauthReturnRoute", currentHash);
+    }
+    const { error } = await authModule?.signInWithGitHub() ?? { error: null };
+    if (error) {
+      showOAuthError(error.message);
+    }
+  });
+
+  // Close dialog on backdrop click
+  authDialog?.addEventListener("click", (e) => {
+    if (e.target === authDialog) authDialog.close();
+  });
+
+  // Close button
+  authDialog?.querySelector(".close-dialog")?.addEventListener("click", () => {
+    authDialog.close();
+  });
+}
+
+async function handleLoginSubmit(e) {
+  e.preventDefault();
+  const email = document.getElementById("login-email").value;
+  const password = document.getElementById("login-password").value;
+  const errorEl = document.getElementById("login-error");
+  const submitBtn = e.target.querySelector('button[type="submit"]');
+
+  // Disable button while processing
+  submitBtn.disabled = true;
+
+  const { error } = await authModule.signIn(email, password);
+
+  submitBtn.disabled = false;
+
+  if (error) {
+    errorEl.textContent = error.message;
+    errorEl.classList.remove("hidden");
+  } else {
+    errorEl.classList.add("hidden");
+    document.getElementById("auth-dialog").close();
+    track("auth_login", { method: "email" });
+  }
+}
+
+async function handleSignupSubmit(e) {
+  e.preventDefault();
+  const email = document.getElementById("signup-email").value;
+  const password = document.getElementById("signup-password").value;
+  const confirm = document.getElementById("signup-confirm").value;
+  const errorEl = document.getElementById("signup-error");
+  const submitBtn = e.target.querySelector('button[type="submit"]');
+
+  if (password !== confirm) {
+    errorEl.textContent = t("authPasswordMismatch") || "Passwords do not match";
+    errorEl.classList.remove("hidden");
+    return;
+  }
+
+  // Disable button while processing
+  submitBtn.disabled = true;
+
+  const { error } = await authModule.signUp(email, password);
+
+  submitBtn.disabled = false;
+
+  if (error) {
+    errorEl.textContent = error.message;
+    errorEl.classList.remove("hidden");
+    document.getElementById("signup-success")?.classList.add("hidden");
+  } else {
+    errorEl.classList.add("hidden");
+    // Show success message
+    const successEl = document.getElementById("signup-success");
+    successEl?.classList.remove("hidden");
+    // Hide the form fields and button
+    e.target.querySelectorAll(".form-field, button[type='submit']").forEach(el => {
+      el.classList.add("hidden");
+    });
+    track("auth_signup", { method: "email" });
+  }
+}
+
+async function handleResetSubmit(e) {
+  e.preventDefault();
+  const email = document.getElementById("reset-email").value;
+  const errorEl = document.getElementById("reset-error");
+  const successEl = document.getElementById("reset-success");
+  const submitBtn = e.target.querySelector('button[type="submit"]');
+
+  // Disable button while processing
+  submitBtn.disabled = true;
+
+  const { error } = await authModule.resetPassword(email);
+
+  submitBtn.disabled = false;
+
+  if (error) {
+    errorEl.textContent = error.message;
+    errorEl.classList.remove("hidden");
+    successEl.classList.add("hidden");
+  } else {
+    errorEl.classList.add("hidden");
+    successEl.classList.remove("hidden");
+  }
+}
+
+function showOAuthError(message) {
+  // Show error in the currently visible form's error element
+  const loginError = document.getElementById("login-error");
+  const signupError = document.getElementById("signup-error");
+
+  // Use whichever form is visible
+  const errorEl = !document.getElementById("login-form")?.classList.contains("hidden")
+    ? loginError
+    : signupError;
+
+  if (errorEl) {
+    errorEl.textContent = message;
+    errorEl.classList.remove("hidden");
+  }
+}
+
+function switchForm(formName) {
+  const loginForm = document.getElementById("login-form");
+  const signupForm = document.getElementById("signup-form");
+  const resetForm = document.getElementById("reset-form");
+  const showSignup = document.getElementById("show-signup");
+  const showLogin = document.getElementById("show-login");
+  const showReset = document.getElementById("show-reset");
+  const titleEl = document.getElementById("auth-dialog-title");
+  const socialSection = document.querySelector(".auth-social");
+
+  // Hide all forms
+  loginForm?.classList.add("hidden");
+  signupForm?.classList.add("hidden");
+  resetForm?.classList.add("hidden");
+
+  // Show the selected form
+  if (formName === "login") {
+    loginForm?.classList.remove("hidden");
+    showSignup?.classList.remove("hidden");
+    showLogin?.classList.add("hidden");
+    showReset?.classList.remove("hidden");
+    socialSection?.classList.remove("hidden");
+    if (titleEl) titleEl.setAttribute("data-i18n", "authLogin");
+  } else if (formName === "signup") {
+    signupForm?.classList.remove("hidden");
+    // Reset signup form to initial state (in case it was showing success)
+    signupForm?.querySelectorAll(".form-field, button[type='submit']").forEach(el => {
+      el.classList.remove("hidden");
+    });
+    signupForm?.reset();
+    showSignup?.classList.add("hidden");
+    showLogin?.classList.remove("hidden");
+    showReset?.classList.add("hidden");
+    socialSection?.classList.remove("hidden");
+    if (titleEl) titleEl.setAttribute("data-i18n", "authSignUp");
+  } else if (formName === "reset") {
+    resetForm?.classList.remove("hidden");
+    showSignup?.classList.add("hidden");
+    showLogin?.classList.remove("hidden");
+    showReset?.classList.add("hidden");
+    socialSection?.classList.add("hidden");
+    if (titleEl) titleEl.setAttribute("data-i18n", "authResetPassword");
+  }
+
+  // Clear error messages
+  document.getElementById("login-error")?.classList.add("hidden");
+  document.getElementById("signup-error")?.classList.add("hidden");
+  document.getElementById("reset-error")?.classList.add("hidden");
+  document.getElementById("reset-success")?.classList.add("hidden");
+
+  // Apply translations to updated elements
+  applyTranslations();
+}
--- a/src/config/lessons.js
+++ b/src/config/lessons.js
@@ -16,11 +16,24 @@ import htmlElementsEN from "../../lessons/20-html-elements.json";
 import htmlFormsBasicEN from "../../lessons/21-html-forms-basic.json";
 import htmlFormsValidationEN from "../../lessons/22-html-forms-validation.json";
 import htmlDetailsSummaryEN from "../../lessons/23-html-details-summary.json";
+import htmlProgressMeterEN from "../../lessons/24-html-progress-meter.json";
+import htmlDatalistEN from "../../lessons/25-html-datalist.json";
+import htmlDialogEN from "../../lessons/27-html-dialog.json";
+import htmlFieldsetEN from "../../lessons/28-html-forms-fieldset.json";
 import htmlFigureEN from "../../lessons/29-html-figure.json";
 import htmlTablesEN from "../../lessons/30-html-tables.json";
 import htmlSvgEN from "../../lessons/32-html-svg.json";
+import htmlSemanticEN from "../../lessons/33-html-semantic.json";
 import flexboxEN from "../../lessons/flexbox.json";
 import gridEN from "../../lessons/grid.json";
+import gradientsEN from "../../lessons/09-gradients.json";
+import filtersEN from "../../lessons/11-filters.json";
+import positioningEN from "../../lessons/12-positioning.json";
+import pseudoElementsEN from "../../lessons/13-pseudo-elements.json";
+import markdownBasicsEN from "../../lessons/40-markdown-basics.json";
+import jsVariablesEN from "../../lessons/50-js-variables.json";
+import jsDomEN from "../../lessons/51-js-dom.json";
+import jsEventsEN from "../../lessons/52-js-events.json";
 import playgroundEN from "../../lessons/98-playground.json";
 import goodbyeEN from "../../lessons/99-goodbye.json";

@@ -35,6 +48,10 @@ import htmlElementsDE from "../../lessons/de/20-html-elements.json";
 import htmlFormsBasicDE from "../../lessons/de/21-html-forms-basic.json";
 import htmlFormsValidationDE from "../../lessons/de/22-html-forms-validation.json";
 import htmlDetailsSummaryDE from "../../lessons/de/23-html-details-summary.json";
+import htmlProgressMeterDE from "../../lessons/de/24-html-progress-meter.json";
+import htmlDatalistDE from "../../lessons/de/25-html-datalist.json";
+import htmlDialogDE from "../../lessons/de/27-html-dialog.json";
+import htmlFieldsetDE from "../../lessons/de/28-html-forms-fieldset.json";
 import htmlTablesDE from "../../lessons/de/30-html-tables.json";
 import htmlSvgDE from "../../lessons/de/32-html-svg.json";
 import flexboxDE from "../../lessons/de/flexbox.json";
@@ -50,6 +67,10 @@ import htmlElementsPL from "../../lessons/pl/20-html-elements.json";
 import htmlFormsBasicPL from "../../lessons/pl/21-html-forms-basic.json";
 import htmlFormsValidationPL from "../../lessons/pl/22-html-forms-validation.json";
 import htmlDetailsSummaryPL from "../../lessons/pl/23-html-details-summary.json";
+import htmlProgressMeterPL from "../../lessons/pl/24-html-progress-meter.json";
+import htmlDatalistPL from "../../lessons/pl/25-html-datalist.json";
+import htmlDialogPL from "../../lessons/pl/27-html-dialog.json";
+import htmlFieldsetPL from "../../lessons/pl/28-html-forms-fieldset.json";
 import htmlTablesPL from "../../lessons/pl/30-html-tables.json";
 import htmlSvgPL from "../../lessons/pl/32-html-svg.json";
 import flexboxPL from "../../lessons/pl/flexbox.json";
@@ -65,6 +86,10 @@ import htmlElementsES from "../../lessons/es/20-html-elements.json";
 import htmlFormsBasicES from "../../lessons/es/21-html-forms-basic.json";
 import htmlFormsValidationES from "../../lessons/es/22-html-forms-validation.json";
 import htmlDetailsSummaryES from "../../lessons/es/23-html-details-summary.json";
+import htmlProgressMeterES from "../../lessons/es/24-html-progress-meter.json";
+import htmlDatalistES from "../../lessons/es/25-html-datalist.json";
+import htmlDialogES from "../../lessons/es/27-html-dialog.json";
+import htmlFieldsetES from "../../lessons/es/28-html-forms-fieldset.json";
 import htmlTablesES from "../../lessons/es/30-html-tables.json";
 import htmlSvgES from "../../lessons/es/32-html-svg.json";
 import flexboxES from "../../lessons/es/flexbox.json";
@@ -80,6 +105,10 @@ import htmlElementsAR from "../../lessons/ar/20-html-elements.json";
 import htmlFormsBasicAR from "../../lessons/ar/21-html-forms-basic.json";
 import htmlFormsValidationAR from "../../lessons/ar/22-html-forms-validation.json";
 import htmlDetailsSummaryAR from "../../lessons/ar/23-html-details-summary.json";
+import htmlProgressMeterAR from "../../lessons/ar/24-html-progress-meter.json";
+import htmlDatalistAR from "../../lessons/ar/25-html-datalist.json";
+import htmlDialogAR from "../../lessons/ar/27-html-dialog.json";
+import htmlFieldsetAR from "../../lessons/ar/28-html-forms-fieldset.json";
 import htmlTablesAR from "../../lessons/ar/30-html-tables.json";
 import htmlSvgAR from "../../lessons/ar/32-html-svg.json";
 import flexboxAR from "../../lessons/ar/flexbox.json";
@@ -95,6 +124,10 @@ import htmlElementsUK from "../../lessons/uk/20-html-elements.json";
 import htmlFormsBasicUK from "../../lessons/uk/21-html-forms-basic.json";
 import htmlFormsValidationUK from "../../lessons/uk/22-html-forms-validation.json";
 import htmlDetailsSummaryUK from "../../lessons/uk/23-html-details-summary.json";
+import htmlProgressMeterUK from "../../lessons/uk/24-html-progress-meter.json";
+import htmlDatalistUK from "../../lessons/uk/25-html-datalist.json";
+import htmlDialogUK from "../../lessons/uk/27-html-dialog.json";
+import htmlFieldsetUK from "../../lessons/uk/28-html-forms-fieldset.json";
 import htmlTablesUK from "../../lessons/uk/30-html-tables.json";
 import htmlSvgUK from "../../lessons/uk/32-html-svg.json";
 import flexboxUK from "../../lessons/uk/flexbox.json";
@@ -106,24 +139,39 @@ const moduleStoreEN = [
 	// CSS Visual (immediate impact)
 	basicSelectorsEN,
 	colorsEN,
+	gradientsEN,
 	typographyEN,
 	boxModelEN,
 	// CSS Layout
 	flexboxEN,
 	gridEN,
+	positioningEN,
 	unitsVariablesEN,
 	responsiveEN,
 	// CSS Polish
 	transitionsAnimationsEN,
+	filtersEN,
+	pseudoElementsEN,
 	// HTML Structure
 	htmlElementsEN,
+	htmlSemanticEN,
 	htmlFigureEN,
 	htmlSvgEN,
 	// HTML Interactive
 	htmlDetailsSummaryEN,
+	htmlDialogEN,
+	htmlProgressMeterEN,
 	htmlFormsBasicEN,
 	htmlFormsValidationEN,
+	htmlFieldsetEN,
+	htmlDatalistEN,
 	htmlTablesEN,
+	// Markdown
+	markdownBasicsEN,
+	// JavaScript
+	jsVariablesEN,
+	jsDomEN,
+	jsEventsEN,
 	// Outro
 	goodbyeEN,
 	playgroundEN
@@ -136,24 +184,39 @@ const moduleStoreDE = [
 	// CSS Visual (immediate impact)
 	basicSelectorsDE,
 	colorsEN, // Using EN fallback until translated
+	gradientsEN, // Using EN fallback until translated
 	typographyEN, // Using EN fallback until translated
 	boxModelDE,
 	// CSS Layout
 	flexboxDE,
 	gridEN, // Using EN fallback until translated
+	positioningEN, // Using EN fallback until translated
 	unitsVariablesDE,
 	responsiveDE,
 	// CSS Polish
 	transitionsAnimationsDE,
+	filtersEN, // Using EN fallback until translated
+	pseudoElementsEN, // Using EN fallback until translated
 	// HTML Structure
 	htmlElementsDE,
+	htmlSemanticEN, // Using EN fallback until translated
 	htmlFigureEN, // Using EN fallback until translated
 	htmlSvgDE,
 	// HTML Interactive
 	htmlDetailsSummaryDE,
+	htmlDialogDE,
+	htmlProgressMeterDE,
 	htmlFormsBasicDE,
 	htmlFormsValidationDE,
+	htmlFieldsetDE,
+	htmlDatalistDE,
 	htmlTablesDE,
+	// Markdown
+	markdownBasicsEN, // Using EN fallback until translated
+	// JavaScript
+	jsVariablesEN, // Using EN fallback until translated
+	jsDomEN, // Using EN fallback until translated
+	jsEventsEN, // Using EN fallback until translated
 	// Outro
 	goodbyeEN,
 	playgroundEN
@@ -166,24 +229,39 @@ const moduleStorePL = [
 	// CSS Visual (immediate impact)
 	basicSelectorsPL,
 	colorsEN, // Using EN fallback until translated
+	gradientsEN, // Using EN fallback until translated
 	typographyEN, // Using EN fallback until translated
 	boxModelPL,
 	// CSS Layout
 	flexboxPL,
 	gridEN, // Using EN fallback until translated
+	positioningEN, // Using EN fallback until translated
 	unitsVariablesPL,
 	responsivePL,
 	// CSS Polish
 	transitionsAnimationsPL,
+	filtersEN, // Using EN fallback until translated
+	pseudoElementsEN, // Using EN fallback until translated
 	// HTML Structure
 	htmlElementsPL,
+	htmlSemanticEN, // Using EN fallback until translated
 	htmlFigureEN, // Using EN fallback until translated
 	htmlSvgPL,
 	// HTML Interactive
 	htmlDetailsSummaryPL,
+	htmlDialogPL,
+	htmlProgressMeterPL,
 	htmlFormsBasicPL,
 	htmlFormsValidationPL,
+	htmlFieldsetPL,
+	htmlDatalistPL,
 	htmlTablesPL,
+	// Markdown
+	markdownBasicsEN, // Using EN fallback until translated
+	// JavaScript
+	jsVariablesEN, // Using EN fallback until translated
+	jsDomEN, // Using EN fallback until translated
+	jsEventsEN, // Using EN fallback until translated
 	// Outro
 	goodbyeEN,
 	playgroundEN
@@ -196,24 +274,39 @@ const moduleStoreES = [
 	// CSS Visual (immediate impact)
 	basicSelectorsES,
 	colorsEN, // Using EN fallback until translated
+	gradientsEN, // Using EN fallback until translated
 	typographyEN, // Using EN fallback until translated
 	boxModelES,
 	// CSS Layout
 	flexboxES,
 	gridEN, // Using EN fallback until translated
+	positioningEN, // Using EN fallback until translated
 	unitsVariablesES,
 	responsiveES,
 	// CSS Polish
 	transitionsAnimationsES,
+	filtersEN, // Using EN fallback until translated
+	pseudoElementsEN, // Using EN fallback until translated
 	// HTML Structure
 	htmlElementsES,
+	htmlSemanticEN, // Using EN fallback until translated
 	htmlFigureEN, // Using EN fallback until translated
 	htmlSvgES,
 	// HTML Interactive
 	htmlDetailsSummaryES,
+	htmlDialogES,
+	htmlProgressMeterES,
 	htmlFormsBasicES,
 	htmlFormsValidationES,
+	htmlFieldsetES,
+	htmlDatalistES,
 	htmlTablesES,
+	// Markdown
+	markdownBasicsEN, // Using EN fallback until translated
+	// JavaScript
+	jsVariablesEN, // Using EN fallback until translated
+	jsDomEN, // Using EN fallback until translated
+	jsEventsEN, // Using EN fallback until translated
 	// Outro
 	goodbyeEN,
 	playgroundEN
@@ -226,24 +319,39 @@ const moduleStoreAR = [
 	// CSS Visual (immediate impact)
 	basicSelectorsAR,
 	colorsEN, // Using EN fallback until translated
+	gradientsEN, // Using EN fallback until translated
 	typographyEN, // Using EN fallback until translated
 	boxModelAR,
 	// CSS Layout
 	flexboxAR,
 	gridEN, // Using EN fallback until translated
+	positioningEN, // Using EN fallback until translated
 	unitsVariablesAR,
 	responsiveAR,
 	// CSS Polish
 	transitionsAnimationsAR,
+	filtersEN, // Using EN fallback until translated
+	pseudoElementsEN, // Using EN fallback until translated
 	// HTML Structure
 	htmlElementsAR,
+	htmlSemanticEN, // Using EN fallback until translated
 	htmlFigureEN, // Using EN fallback until translated
 	htmlSvgAR,
 	// HTML Interactive
 	htmlDetailsSummaryAR,
+	htmlDialogAR,
+	htmlProgressMeterAR,
 	htmlFormsBasicAR,
 	htmlFormsValidationAR,
+	htmlFieldsetAR,
+	htmlDatalistAR,
 	htmlTablesAR,
+	// Markdown
+	markdownBasicsEN, // Using EN fallback until translated
+	// JavaScript
+	jsVariablesEN, // Using EN fallback until translated
+	jsDomEN, // Using EN fallback until translated
+	jsEventsEN, // Using EN fallback until translated
 	// Outro
 	goodbyeEN,
 	playgroundEN
@@ -256,24 +364,39 @@ const moduleStoreUK = [
 	// CSS Visual (immediate impact)
 	basicSelectorsUK,
 	colorsEN, // Using EN fallback until translated
+	gradientsEN, // Using EN fallback until translated
 	typographyEN, // Using EN fallback until translated
 	boxModelUK,
 	// CSS Layout
 	flexboxUK,
 	gridEN, // Using EN fallback until translated
+	positioningEN, // Using EN fallback until translated
 	unitsVariablesUK,
 	responsiveUK,
 	// CSS Polish
 	transitionsAnimationsUK,
+	filtersEN, // Using EN fallback until translated
+	pseudoElementsEN, // Using EN fallback until translated
 	// HTML Structure
 	htmlElementsUK,
+	htmlSemanticEN, // Using EN fallback until translated
 	htmlFigureEN, // Using EN fallback until translated
 	htmlSvgUK,
 	// HTML Interactive
 	htmlDetailsSummaryUK,
+	htmlDialogUK,
+	htmlProgressMeterUK,
 	htmlFormsBasicUK,
 	htmlFormsValidationUK,
+	htmlFieldsetUK,
+	htmlDatalistUK,
 	htmlTablesUK,
+	// Markdown
+	markdownBasicsEN, // Using EN fallback until translated
+	// JavaScript
+	jsVariablesEN, // Using EN fallback until translated
+	jsDomEN, // Using EN fallback until translated
+	jsEventsEN, // Using EN fallback until translated
 	// Outro
 	goodbyeEN,
 	playgroundEN
--- a/src/config/playground-templates.js
+++ b/src/config/playground-templates.js
--- a/src/config/sections.js
+++ b/src/config/sections.js
@@ -15,7 +15,7 @@ export const sections = {
 		id: "html",
 		title: "HTML",
 		description: "Semantic markup and native elements",
-		color: "#d4637b",
+		color: "#c75b7a",
 		order: 2
 	},
 	tailwind: {
@@ -24,6 +24,20 @@ export const sections = {
 		description: "Utility-first CSS framework",
 		color: "#26a69a",
 		order: 3
+	},
+	markdown: {
+		id: "markdown",
+		title: "Markdown",
+		description: "Lightweight markup language for formatting text",
+		color: "#5b8dd9",
+		order: 4
+	},
+	javascript: {
+		id: "javascript",
+		title: "JavaScript",
+		description: "Interactive scripting for web pages",
+		color: "#f0db4f",
+		order: 5
 	}
 };

@@ -57,6 +71,8 @@ export function getModuleSection(module) {
 	const mode = module.mode || "css";
 	if (mode === "html") return "html";
 	if (mode === "tailwind") return "tailwind";
+	if (mode === "markdown") return "markdown";
+	if (mode === "javascript") return "javascript";
 	return "css";
 }

--- a/src/helpers/renderer.js
+++ b/src/helpers/renderer.js
@@ -2,6 +2,50 @@
 * Renderer - Handles UI updates for the CSS learning platform
 */
 import { t } from "../i18n.js";
+import { getModuleSection, getSection, getSectionList } from "../config/sections.js";
+
+/**
+ * Compute lesson difficulty based on lesson structure
+ * - Easy: selector is provided in codePrefix (student only writes properties)
+ * - Medium: student writes a simple selector (single element/class)
+ * - Hard: student writes compound selectors (descendant, chained classes, type+class)
+ * @param {Object} lesson - The lesson object
+ * @returns {"easy"|"medium"|"hard"} The computed difficulty
+ */
+export function computeLessonDifficulty(lesson) {
+	const codePrefix = lesson.codePrefix || "";
+	const solution = lesson.solution || "";
+
+	// If codePrefix contains an opening brace, selector is provided → Easy
+	if (codePrefix.includes("{")) {
+		return "easy";
+	}
+
+	// No codePrefix with selector - check the solution complexity
+	// Hard: descendant selectors (space before {), chained classes (.a.b), type+class (a.class)
+	const selectorMatch = solution.match(/^([^{]+)\{/);
+	if (selectorMatch) {
+		const selector = selectorMatch[1].trim();
+
+		// Descendant selector: has space (e.g., ".nav a", ".card p")
+		if (/\S\s+\S/.test(selector)) {
+			return "hard";
+		}
+
+		// Chained classes: multiple dots without space (e.g., ".btn.primary")
+		if ((selector.match(/\./g) || []).length > 1) {
+			return "hard";
+		}
+
+		// Type + class: element followed by dot (e.g., "a.btn", "div.card")
+		if (/^[a-z]+\.[a-z]/i.test(selector)) {
+			return "hard";
+		}
+	}
+
+	// Simple selector → Medium
+	return "medium";
+}

 // Feedback elements cache
 let feedbackElement = null;
@@ -29,8 +73,24 @@ export function renderModuleList(container, modules, onSelectModule, onSelectLes
 		}
 	}

+	// Group modules by section for headers
+	let currentSectionId = null;
+
 	// Create list items for each module
 	modules.forEach((module) => {
+		// Insert section header when section changes
+		const sectionId = getModuleSection(module);
+		if (sectionId !== currentSectionId && !module.excludeFromProgress) {
+			currentSectionId = sectionId;
+			const section = getSection(sectionId);
+			if (section) {
+				const header = document.createElement("h3");
+				header.className = "sidebar-section-header";
+				header.textContent = section.title;
+				header.style.borderLeftColor = section.color;
+				container.appendChild(header);
+			}
+		}
 		// Create module container
 		// Use native <details>/<summary> for expand/collapse
 		const moduleContainer = document.createElement("details");
@@ -138,6 +198,42 @@ export function renderLesson(titleEl, descriptionEl, taskEl, previewEl, prefixEl
 	// The LessonEngine will handle this when it's first set
 }

+/**
+ * Render the difficulty badge (right-aligned in title row)
+ * @param {HTMLElement} container - The container element (lesson-title-row)
+ * @param {Object} lesson - The lesson object
+ */
+export function renderDifficultyBadge(container, lesson) {
+	// Remove existing difficulty wrapper if any
+	const existingWrapper = container.querySelector(".difficulty-wrapper");
+	if (existingWrapper) {
+		existingWrapper.remove();
+	}
+
+	// Compute difficulty
+	const difficulty = computeLessonDifficulty(lesson);
+
+	// Create wrapper for right-alignment
+	const wrapper = document.createElement("span");
+	wrapper.className = "difficulty-wrapper";
+
+	// Create badge element with three bars
+	const badge = document.createElement("span");
+	badge.className = `difficulty-badge difficulty-${difficulty}`;
+	badge.setAttribute("aria-label", t(`difficulty_${difficulty}_label`));
+	badge.setAttribute("title", t(`difficulty_${difficulty}`));
+
+	// Add three bars
+	for (let i = 0; i < 3; i++) {
+		const bar = document.createElement("span");
+		bar.className = "bar";
+		badge.appendChild(bar);
+	}
+
+	wrapper.appendChild(badge);
+	container.appendChild(wrapper);
+}
+
 /**
 * Update the level indicator
 * @param {HTMLElement} element - The level indicator element
--- a/src/helpers/router.js
+++ b/src/helpers/router.js
@@ -8,6 +8,7 @@
 * - #css           -> CSS section landing
 * - #html          -> HTML section landing
 * - #tailwind      -> Tailwind section landing
+ * - #markdown      -> Markdown section landing
 * - #reference/css -> CSS cheatsheet
 * - #module/index  -> Lesson (e.g., #flexbox/2)
 */
@@ -26,7 +27,7 @@ export const RouteType = {
 /**
 * Valid section IDs
 */
-const SECTIONS = ["css", "html", "tailwind"];
+const SECTIONS = ["css", "html", "markdown", "javascript"]; // tailwind temporarily disabled

 /**
 * Valid language codes for URL-based switching
--- a/src/helpers/validator.js
+++ b/src/helpers/validator.js
@@ -10,6 +10,8 @@ export function validateUserCode(userCode, lesson) {
 			return validateHtmlCode(userCode, lesson);
 		case "tailwind":
 			return validateTailwindClasses(userCode, lesson);
+		case "javascript":
+			return validateJavaScriptCode(userCode, lesson);
 		case "css":
 		default:
 			return validateCssCode(userCode, lesson);
@@ -204,6 +206,80 @@ function validateHtmlCode(userHtml, lesson) {
 	return result;
 }

+/**
+ * Validate user JavaScript code against the lesson requirements
+ * @param {string} userCode - User submitted JavaScript code
+ * @param {Object} lesson - The current lesson object
+ * @returns {Object} Validation result with isValid and message properties
+ */
+function validateJavaScriptCode(userCode, lesson) {
+	if (!lesson || !lesson.validations) {
+		return { isValid: true, message: "No validations specified for this lesson." };
+	}
+
+	const validations = lesson.validations;
+
+	let result = {
+		isValid: true,
+		validCases: 0,
+		totalCases: validations.length,
+		message: "Your CODE looks CRISPY!"
+	};
+
+	for (const validation of validations) {
+		const { type, value, message, options } = validation;
+		let validationPassed = false;
+
+		switch (type) {
+			case "contains":
+				validationPassed = containsValidation(userCode, value, options);
+				if (!validationPassed) {
+					result = {
+						...result,
+						isValid: false,
+						message: message || `Your code should include "${value}".`
+					};
+				}
+				break;
+
+			case "not_contains":
+				validationPassed = !containsValidation(userCode, value, options);
+				if (!validationPassed) {
+					result = {
+						...result,
+						isValid: false,
+						message: message || `Your code should not include "${value}".`
+					};
+				}
+				break;
+
+			case "regex":
+				validationPassed = regexValidation(userCode, value, options);
+				if (!validationPassed) {
+					result = {
+						...result,
+						isValid: false,
+						message: message || "Your code does not match the expected pattern."
+					};
+				}
+				break;
+
+			default:
+				console.warn(`Unknown JavaScript validation type: ${type}`);
+				validationPassed = true;
+		}
+
+		if (validationPassed) {
+			result.validCases++;
+		} else {
+			return result;
+		}
+	}
+
+	result.validCases = validations.length;
+	return result;
+}
+
 function validateTailwindClasses(userClasses, lesson) {
 	if (!lesson || !lesson.validations) {
 		return { isValid: true, message: "No validations specified for this lesson." };
--- a/src/i18n.js
+++ b/src/i18n.js
--- a/src/impl/CodeEditor.js
+++ b/src/impl/CodeEditor.js
@@ -1,18 +1,20 @@
 /**
 * CodeEditor - CodeMirror 6 wrapper with Emmet support
 */
-import { EditorState, Prec } from "@codemirror/state";
-import { EditorView, keymap, placeholder } from "@codemirror/view";
+import { EditorState, EditorSelection, Prec, StateField, Compartment } from "@codemirror/state";
+import { EditorView, keymap, placeholder, Decoration } from "@codemirror/view";
 import { defaultKeymap, historyKeymap, indentMore, indentLess, undo, redo } from "@codemirror/commands";
 import { history } from "@codemirror/commands";
 import { html } from "@codemirror/lang-html";
 import { css } from "@codemirror/lang-css";
+import { markdown } from "@codemirror/lang-markdown";
+import { javascript } from "@codemirror/lang-javascript";
 import { autocompletion } from "@codemirror/autocomplete";
 import { abbreviationTracker, expandAbbreviation } from "@emmetio/codemirror6-plugin";
 import { HighlightStyle, syntaxHighlighting } from "@codemirror/language";
 import { tags } from "@lezer/highlight";

-// Custom theme with purple accent colors (matching app completed state)
+// Custom theme with pink accent colors (matching app completed state)
 const crispyTheme = EditorView.theme(
 	{
 		"&": {
@@ -20,10 +22,10 @@ const crispyTheme = EditorView.theme(
 			color: "#c8c8d0"
 		},
 		".cm-content": {
-			caretColor: "#9b6dd4"
+			caretColor: "#d46d9b"
 		},
 		".cm-cursor, .cm-dropCursor": {
-			borderLeftColor: "#9b6dd4"
+			borderLeftColor: "#d46d9b"
 		},
 		"&.cm-focused > .cm-scroller > .cm-selectionLayer .cm-selectionBackground, .cm-selectionBackground, .cm-content ::selection": {
 			backgroundColor: "#3e3e4a"
@@ -34,10 +36,10 @@ const crispyTheme = EditorView.theme(
 		},
 		".cm-searchMatch": {
 			backgroundColor: "#3e3e4a",
-			outline: "1px solid #9b6dd4"
+			outline: "1px solid #d46d9b"
 		},
 		".cm-searchMatch.cm-searchMatch-selected": {
-			backgroundColor: "rgba(155, 109, 212, 0.3)"
+			backgroundColor: "rgba(212, 109, 155, 0.3)"
 		},
 		".cm-activeLine": {
 			backgroundColor: "#2e2e3a"
@@ -60,15 +62,15 @@ const crispyTheme = EditorView.theme(
 	{ dark: true }
 );

-// Syntax highlighting with purple accent
-const crispyHighlight = HighlightStyle.define([
-	{ tag: tags.keyword, color: "#c9a6eb" },
+// Default syntax highlighting (blue accent)
+const defaultHighlight = HighlightStyle.define([
+	{ tag: tags.keyword, color: "#eba6c9" },
 	{ tag: tags.operator, color: "#cdd6f4" },
 	{ tag: tags.variableName, color: "#89b4fa" },
 	{ tag: tags.propertyName, color: "#89b4fa" },
 	{ tag: tags.attributeName, color: "#89b4fa" },
 	{ tag: tags.className, color: "#89b4fa" },
-	{ tag: tags.tagName, color: "#c9a6eb" },
+	{ tag: tags.tagName, color: "#eba6c9" },
 	{ tag: tags.string, color: "#a6e3a1" },
 	{ tag: tags.number, color: "#fab387" },
 	{ tag: tags.bool, color: "#fab387" },
@@ -78,13 +80,47 @@ const crispyHighlight = HighlightStyle.define([
 	{ tag: tags.punctuation, color: "#cdd6f4" },
 	{ tag: tags.definition(tags.variableName), color: "#89b4fa" },
 	{ tag: tags.function(tags.variableName), color: "#89b4fa" },
-	{ tag: tags.atom, color: "#c9a6eb" },
+	{ tag: tags.atom, color: "#eba6c9" },
 	{ tag: tags.unit, color: "#a6e3a1" },
 	{ tag: tags.color, color: "#f9e2af" }
 ]);

-// Combined theme export
-export const crispyEditorTheme = [crispyTheme, syntaxHighlighting(crispyHighlight)];
+// CSS section highlighting (pink selectors)
+const cssHighlight = HighlightStyle.define([
+	{ tag: tags.keyword, color: "#eba6c9" },
+	{ tag: tags.operator, color: "#cdd6f4" },
+	{ tag: tags.variableName, color: "#eba6c9" },
+	{ tag: tags.propertyName, color: "#89b4fa" },
+	{ tag: tags.attributeName, color: "#89b4fa" },
+	{ tag: tags.className, color: "#eba6c9" },
+	{ tag: tags.tagName, color: "#eba6c9" },
+	{ tag: tags.string, color: "#a6e3a1" },
+	{ tag: tags.number, color: "#fab387" },
+	{ tag: tags.bool, color: "#fab387" },
+	{ tag: tags.null, color: "#fab387" },
+	{ tag: tags.comment, color: "#6c7086", fontStyle: "italic" },
+	{ tag: tags.bracket, color: "#cdd6f4" },
+	{ tag: tags.punctuation, color: "#cdd6f4" },
+	{ tag: tags.definition(tags.variableName), color: "#eba6c9" },
+	{ tag: tags.function(tags.variableName), color: "#89b4fa" },
+	{ tag: tags.atom, color: "#eba6c9" },
+	{ tag: tags.unit, color: "#a6e3a1" },
+	{ tag: tags.color, color: "#f9e2af" }
+]);
+
+// Get highlight style based on section
+function getHighlightForSection(section) {
+	if (section === "css") return cssHighlight;
+	return defaultHighlight;
+}
+
+// Get theme with section-specific highlighting
+export function getEditorTheme(section) {
+	return [crispyTheme, syntaxHighlighting(getHighlightForSection(section))];
+}
+
+// Default combined theme export (for backwards compatibility)
+export const crispyEditorTheme = [crispyTheme, syntaxHighlighting(defaultHighlight)];

 // Custom overrides for editor styling
 const editorTheme = EditorView.theme(
@@ -110,26 +146,149 @@ export class CodeEditor {
 		this.options = options;
 		this.view = null;
 		this.mode = options.mode || "css";
+		this.section = options.section || null;
 		this.onChange = options.onChange || (() => {});
+		// Read-only zones support
+		this.prefixLength = 0;
+		this.suffixLength = 0;
+		this.currentPrefix = "";
+		this.currentSuffix = "";
+		this.readOnlyCompartment = new Compartment();
 	}

 	/**
-	 * Initialize the editor
+	 * Initialize the editor (backwards compatible wrapper)
 	 */
 	init(initialValue = "") {
+		return this.initWithContext("", initialValue, "");
+	}
+
+	/**
+	 * Initialize the editor with read-only prefix/suffix zones
+	 * @param {string} prefix - Read-only prefix text (e.g., ".card {\n  ")
+	 * @param {string} initialValue - Editable user code
+	 * @param {string} suffix - Read-only suffix text (e.g., "\n}")
+	 */
+	initWithContext(prefix = "", initialValue = "", suffix = "") {
 		// Clear container
 		this.container.innerHTML = "";

+		// Store prefix/suffix for re-initialization (e.g., when mode changes)
+		this.currentPrefix = prefix;
+		this.currentSuffix = suffix;
+		this.prefixLength = prefix.length;
+		this.suffixLength = suffix.length;
+
+		const fullDoc = prefix + initialValue + suffix;
+
 		// Get language extension based on mode
-		const langExtension = this.mode === "html" ? html() : css();
+		const langExtension =
+			this.mode === "html" ? html() : this.mode === "javascript" ? javascript() : this.mode === "markdown" ? markdown() : css();
+
+		// Create read-only zones decorations
+		const readOnlyMark = Decoration.mark({ class: "cm-readonly-zone" });
+
+		// StateField to track and provide decorations for read-only zones
+		const readOnlyDecorations = StateField.define({
+			create: (state) => {
+				const decorations = [];
+				if (this.prefixLength > 0) {
+					decorations.push(readOnlyMark.range(0, this.prefixLength));
+				}
+				if (this.suffixLength > 0) {
+					const suffixStart = state.doc.length - this.suffixLength;
+					decorations.push(readOnlyMark.range(suffixStart, state.doc.length));
+				}
+				return Decoration.set(decorations);
+			},
+			update: (decorations, tr) => {
+				if (!tr.docChanged) return decorations;
+				// Recalculate decorations after document changes
+				const newDecorations = [];
+				if (this.prefixLength > 0) {
+					newDecorations.push(readOnlyMark.range(0, this.prefixLength));
+				}
+				if (this.suffixLength > 0) {
+					const suffixStart = tr.state.doc.length - this.suffixLength;
+					newDecorations.push(readOnlyMark.range(suffixStart, tr.state.doc.length));
+				}
+				return Decoration.set(newDecorations);
+			},
+			provide: (f) => EditorView.decorations.from(f)
+		});
+
+		// Change filter to prevent edits in read-only zones
+		const readOnlyFilter = EditorState.changeFilter.of((tr) => {
+			// If no prefix/suffix, allow all changes
+			if (this.prefixLength === 0 && this.suffixLength === 0) {
+				return true;
+			}
+
+			const prefixEnd = this.prefixLength;
+			const suffixStart = tr.startState.doc.length - this.suffixLength;
+
+			// Check all change ranges - allow only changes within [prefixEnd, suffixStart]
+			let blocked = false;
+			tr.changes.iterChangedRanges((fromA, toA) => {
+				// Block if change starts in prefix zone
+				if (fromA < prefixEnd) {
+					blocked = true;
+				}
+				// Block if change extends into suffix zone
+				if (toA > suffixStart) {
+					blocked = true;
+				}
+			});
+
+			return !blocked;
+		});
+
+		// Transaction filter to constrain cursor/selection to editable area
+		const cursorFilter = EditorState.transactionFilter.of((tr) => {
+			// If no prefix/suffix, no constraints needed
+			if (this.prefixLength === 0 && this.suffixLength === 0) {
+				return tr;
+			}
+
+			const prefixEnd = this.prefixLength;
+			const suffixStart = tr.newDoc.length - this.suffixLength;
+
+			// Check if selection needs adjustment
+			const selection = tr.newSelection;
+			let needsAdjustment = false;
+
+			for (const range of selection.ranges) {
+				if (range.from < prefixEnd || range.to > suffixStart) {
+					needsAdjustment = true;
+					break;
+				}
+			}
+
+			if (!needsAdjustment) {
+				return tr;
+			}
+
+			// Clamp selection to editable area
+			const newRanges = selection.ranges.map((range) => {
+				const from = Math.max(prefixEnd, Math.min(suffixStart, range.from));
+				const to = Math.max(prefixEnd, Math.min(suffixStart, range.to));
+				return EditorSelection.range(from, to);
+			});
+
+			return [tr, { selection: EditorSelection.create(newRanges, selection.mainIndex) }];
+		});

 		// Build extensions array
 		const extensions = [
 			langExtension,
-			crispyEditorTheme,
+			getEditorTheme(this.section),
 			editorTheme,
 			// History for undo/redo
 			history(),
+			// Read-only zones (decorations, change filter, and cursor constraint)
+			readOnlyDecorations,
+			readOnlyFilter,
+			cursorFilter,
 			// Emmet abbreviation tracking
 			abbreviationTracker(),
 			// High priority keymap for Emmet
@@ -149,20 +308,21 @@ export class CodeEditor {
 			}),
 			EditorView.updateListener.of((update) => {
 				if (update.docChanged) {
-					this.onChange(this.getValue());
+					// Report only the editable portion to the onChange handler
+					this.onChange(this.getEditableValue());
 				}
 			}),
 			EditorView.lineWrapping
 		];

-		// Add placeholder if provided
-		if (this.options.placeholder) {
+		// Add placeholder if provided (only makes sense when no prefix/suffix)
+		if (this.options.placeholder && this.prefixLength === 0 && this.suffixLength === 0) {
 			extensions.push(placeholder(this.options.placeholder));
 		}

 		// Create editor state
 		const state = EditorState.create({
-			doc: initialValue,
+			doc: fullDoc,
 			extensions
 		});

@@ -172,26 +332,47 @@ export class CodeEditor {
 			parent: this.container
 		});

+		// Position cursor at start of editable area
+		if (this.prefixLength > 0) {
+			this.view.dispatch({
+				selection: { anchor: this.prefixLength }
+			});
+		}
+
 		return this;
 	}

 	/**
-	 * Get current editor value
+	 * Get current full editor value (including prefix/suffix)
 	 */
 	getValue() {
 		return this.view ? this.view.state.doc.toString() : "";
 	}

 	/**
-	 * Set editor value (preserves history)
+	 * Get only the editable portion (excluding prefix/suffix)
+	 */
+	getEditableValue() {
+		if (!this.view) return "";
+		const fullText = this.view.state.doc.toString();
+		const editableEnd = fullText.length - this.suffixLength;
+		return fullText.slice(this.prefixLength, editableEnd);
+	}
+
+	/**
+	 * Set editor value in the editable zone only (preserves history)
 	 */
 	setValue(value) {
 		if (!this.view) return;

+		// Only replace the editable portion
+		const editableStart = this.prefixLength;
+		const editableEnd = this.view.state.doc.length - this.suffixLength;
+
 		this.view.dispatch({
 			changes: {
-				from: 0,
-				to: this.view.state.doc.length,
+				from: editableStart,
+				to: editableEnd,
 				insert: value
 			}
 		});
@@ -199,9 +380,12 @@ export class CodeEditor {

 	/**
 	 * Set editor value and clear history (for lesson switching)
+	 * @param {string} value - The editable user code (not including prefix/suffix)
+	 * @param {string} prefix - Optional read-only prefix
+	 * @param {string} suffix - Optional read-only suffix
 	 */
-	setValueAndClearHistory(value) {
-		this.init(value);
+	setValueAndClearHistory(value, prefix = "", suffix = "") {
+		this.initWithContext(prefix, value, suffix);
 	}

 	/**
@@ -211,8 +395,19 @@ export class CodeEditor {
 		if (this.mode === mode) return;

 		this.mode = mode;
-		const currentValue = this.getValue();
-		this.init(currentValue);
+		const editableValue = this.getEditableValue();
+		this.initWithContext(this.currentPrefix, editableValue, this.currentSuffix);
+	}
+
+	/**
+	 * Set section for theme (css, html, tailwind)
+	 */
+	setSection(section) {
+		if (this.section === section) return;
+
+		this.section = section;
+		const editableValue = this.getEditableValue();
+		this.initWithContext(this.currentPrefix, editableValue, this.currentSuffix);
 	}

 	/**
--- a/src/impl/LessonEngine.js
+++ b/src/impl/LessonEngine.js
@@ -3,6 +3,21 @@
 * Single source of truth for lesson state and progress
 */
 import { validateUserCode } from "../helpers/validator.js";
+import { marked } from "marked";
+
+// Auth sync - lazy loaded to avoid circular dependencies
+let authModule = null;
+async function getAuthModule() {
+	if (!authModule) {
+		try {
+			authModule = await import("../auth.js");
+		} catch (e) {
+			// Auth module not available, skip cloud sync
+			return null;
+		}
+	}
+	return authModule;
+}

 export class LessonEngine {
 	constructor() {
@@ -201,18 +216,18 @@ export class LessonEngine {
 		iframe.style.height = "100%";
 		iframe.style.border = "none";
 		iframe.title = "Preview";
+		iframe.setAttribute("sandbox", "allow-scripts");

 		const container = document.getElementById(previewContainer || "preview-area");
 		container.innerHTML = "";
 		container.appendChild(iframe);

-		const iframeDoc = iframe.contentDocument || iframe.contentWindow.document;
-		iframeDoc.open();
+		let html;

 		if (mode === "html" || mode === "playground") {
 			// For HTML/playground mode, user code IS the HTML content (may include <style> blocks)
 			const userHtml = this.userCode || "";
-			iframeDoc.write(`
+			html = `
      <!DOCTYPE html>
      <html>
        <head>
@@ -224,11 +239,11 @@ export class LessonEngine {
          ${userHtml}
        </body>
      </html>
-    `);
+    `;
 		} else if (mode === "tailwind") {
 			// For Tailwind mode, user code goes directly in HTML classes
 			const htmlWithClasses = this.injectTailwindClasses(previewHTML, this.userCode);
-			iframeDoc.write(`
+			html = `
      <!DOCTYPE html>
      <html>
        <head>
@@ -241,11 +256,67 @@ export class LessonEngine {
          ${htmlWithClasses}
        </body>
      </html>
-    `);
+    `;
+		} else if (mode === "javascript") {
+			// For JavaScript mode, user code runs as a script against previewHTML
+			const { codePrefix, codeSuffix } = this.currentLesson;
+			const fullScript = `${codePrefix || ""}${this.userCode || ""}${codeSuffix || ""}`;
+			html = `
+      <!DOCTYPE html>
+      <html>
+        <head>
+          <style>html, body { min-height: 100%; margin: 0; }</style>
+          <style>${previewBaseCSS || ""}</style>
+          <style>${sandboxCSS || ""}</style>
+        </head>
+        <body>
+          ${previewHTML || ""}
+          <script>
+          try {
+            ${fullScript}
+          } catch (e) {
+            document.body.innerHTML += '<pre style="color:red">' + e.message + '</pre>';
+          }
+          </script>
+        </body>
+      </html>
+    `;
+		} else if (mode === "markdown") {
+			// For Markdown mode, parse user code to HTML
+			const renderedHtml = marked.parse(this.userCode || "");
+			html = `
+      <!DOCTYPE html>
+      <html>
+        <head>
+          <style>html, body { min-height: 100%; margin: 0; }</style>
+          <style>${previewBaseCSS || ""}</style>
+          <style>
+            body { font-family: system-ui, sans-serif; line-height: 1.6; padding: 1rem; }
+            h1, h2, h3, h4, h5, h6 { margin: 1em 0 0.5em; line-height: 1.3; }
+            h1 { font-size: 2em; border-bottom: 1px solid #eee; padding-bottom: 0.3em; }
+            h2 { font-size: 1.5em; border-bottom: 1px solid #eee; padding-bottom: 0.3em; }
+            p { margin: 0.5em 0; }
+            ul, ol { margin: 0.5em 0; padding-left: 2em; }
+            li { margin: 0.25em 0; }
+            code { background: #f4f4f4; padding: 2px 6px; border-radius: 3px; font-family: monospace; }
+            pre { background: #f4f4f4; padding: 1em; overflow-x: auto; border-radius: 4px; }
+            pre code { background: none; padding: 0; }
+            blockquote { margin: 0.5em 0; padding-left: 1em; border-left: 4px solid #ddd; color: #666; }
+            a { color: #0366d6; }
+            hr { border: none; border-top: 1px solid #eee; margin: 1em 0; }
+            img { max-width: 100%; }
+          </style>
+          <style>${sandboxCSS || ""}</style>
+        </head>
+        <body>
+          ${renderedHtml}
+        </body>
+      </html>
+    `;
 		} else {
 			// Original CSS mode
 			const userCssWithWrapper = this.getCompleteCss();
-			iframeDoc.write(`
+			html = `
      <!DOCTYPE html>
      <html>
        <head>
@@ -258,10 +329,10 @@ export class LessonEngine {
          ${previewHTML}
        </body>
      </html>
-    `);
+    `;
 		}

-		iframeDoc.close();
+		iframe.srcdoc = html;
 	}

 	injectTailwindClasses(html, userClasses) {
@@ -294,6 +365,7 @@ export class LessonEngine {
 		iframe.style.height = "100%";
 		iframe.style.border = "none";
 		iframe.title = "Expected Result";
+		iframe.setAttribute("sandbox", "allow-scripts");

 		const container = document.getElementById("preview-expected");
 		if (!container) return;
@@ -301,12 +373,11 @@ export class LessonEngine {
 		container.innerHTML = "";
 		container.appendChild(iframe);

-		const iframeDoc = iframe.contentDocument || iframe.contentWindow.document;
-		iframeDoc.open();
+		let html;

 		if (mode === "html" || mode === "playground") {
 			// For HTML/playground mode, solution code IS the HTML content
-			iframeDoc.write(`
+			html = `
      <!DOCTYPE html>
      <html>
        <head>
@@ -318,11 +389,11 @@ export class LessonEngine {
          ${solutionCode}
        </body>
      </html>
-    `);
+    `;
 		} else if (mode === "tailwind") {
 			// For Tailwind mode, inject solution classes into HTML
 			const htmlWithClasses = this.injectTailwindClasses(previewHTML, solutionCode);
-			iframeDoc.write(`
+			html = `
      <!DOCTYPE html>
      <html>
        <head>
@@ -335,12 +406,68 @@ export class LessonEngine {
          ${htmlWithClasses}
        </body>
      </html>
-    `);
+    `;
+		} else if (mode === "javascript") {
+			// For JavaScript mode, solution code runs as a script against previewHTML
+			const { codePrefix, codeSuffix } = this.currentLesson;
+			const fullScript = `${codePrefix || ""}${solutionCode}${codeSuffix || ""}`;
+			html = `
+      <!DOCTYPE html>
+      <html>
+        <head>
+          <style>html, body { min-height: 100%; margin: 0; }</style>
+          <style>${previewBaseCSS || ""}</style>
+          <style>${sandboxCSS || ""}</style>
+        </head>
+        <body>
+          ${previewHTML || ""}
+          <script>
+          try {
+            ${fullScript}
+          } catch (e) {
+            document.body.innerHTML += '<pre style="color:red">' + e.message + '</pre>';
+          }
+          </script>
+        </body>
+      </html>
+    `;
+		} else if (mode === "markdown") {
+			// For Markdown mode, parse solution to HTML
+			const renderedHtml = marked.parse(solutionCode || "");
+			html = `
+      <!DOCTYPE html>
+      <html>
+        <head>
+          <style>html, body { min-height: 100%; margin: 0; }</style>
+          <style>${previewBaseCSS || ""}</style>
+          <style>
+            body { font-family: system-ui, sans-serif; line-height: 1.6; padding: 1rem; }
+            h1, h2, h3, h4, h5, h6 { margin: 1em 0 0.5em; line-height: 1.3; }
+            h1 { font-size: 2em; border-bottom: 1px solid #eee; padding-bottom: 0.3em; }
+            h2 { font-size: 1.5em; border-bottom: 1px solid #eee; padding-bottom: 0.3em; }
+            p { margin: 0.5em 0; }
+            ul, ol { margin: 0.5em 0; padding-left: 2em; }
+            li { margin: 0.25em 0; }
+            code { background: #f4f4f4; padding: 2px 6px; border-radius: 3px; font-family: monospace; }
+            pre { background: #f4f4f4; padding: 1em; overflow-x: auto; border-radius: 4px; }
+            pre code { background: none; padding: 0; }
+            blockquote { margin: 0.5em 0; padding-left: 1em; border-left: 4px solid #ddd; color: #666; }
+            a { color: #0366d6; }
+            hr { border: none; border-top: 1px solid #eee; margin: 1em 0; }
+            img { max-width: 100%; }
+          </style>
+          <style>${sandboxCSS || ""}</style>
+        </head>
+        <body>
+          ${renderedHtml}
+        </body>
+      </html>
+    `;
 		} else {
 			// CSS mode - wrap solution with prefix/suffix
 			const { codePrefix, codeSuffix } = this.currentLesson;
 			const solutionCss = `${codePrefix || ""}${solutionCode}${codeSuffix || ""}`;
-			iframeDoc.write(`
+			html = `
      <!DOCTYPE html>
      <html>
        <head>
@@ -353,10 +480,10 @@ export class LessonEngine {
          ${previewHTML}
        </body>
      </html>
-    `);
+    `;
 		}

-		iframeDoc.close();
+		iframe.srcdoc = html;
 	}

 	/**
@@ -458,10 +585,11 @@ export class LessonEngine {
 	}

 	/**
-	 * Get overall progress statistics
-	 * @returns {Object} Progress statistics
+	 * Get overall progress statistics with milestone data
+	 * @returns {Object} Progress statistics including milestone progress
 	 */
 	getProgressStats() {
+		const MILESTONES = [1, 5, 10, 20, 30, 50, 75, 100];
 		let totalLessons = 0;
 		let totalCompleted = 0;

@@ -476,15 +604,30 @@ export class LessonEngine {
 			}
 		});

+		// Calculate milestone progress
+		const milestonesReached = MILESTONES.filter((m) => totalCompleted >= m);
+		const currentMilestone = milestonesReached[milestonesReached.length - 1] || 0;
+		const nextMilestone = MILESTONES.find((m) => m > totalCompleted) || 100;
+		const progressToNext =
+			nextMilestone > currentMilestone
+				? Math.round(((totalCompleted - currentMilestone) / (nextMilestone - currentMilestone)) * 100)
+				: 100;
+
 		return {
 			totalLessons,
 			totalCompleted,
-			percentComplete: totalLessons > 0 ? Math.round((totalCompleted / totalLessons) * 100) : 0
+			percentComplete: totalLessons > 0 ? Math.round((totalCompleted / totalLessons) * 100) : 0,
+			// Milestone data
+			milestones: MILESTONES,
+			milestonesReached,
+			currentMilestone,
+			nextMilestone,
+			progressToNext
 		};
 	}

 	/**
-	 * Save progress to localStorage
+	 * Save progress to localStorage and optionally sync to cloud
 	 */
 	saveUserProgress() {
 		try {
@@ -494,11 +637,24 @@ export class LessonEngine {
 				timestamp: new Date().toISOString()
 			};
 			localStorage.setItem("codeCrispies.progress", JSON.stringify(progressData));
+
+			// Trigger cloud sync if logged in (debounced)
+			this.triggerCloudSync();
 		} catch (e) {
 			console.error("Error saving progress:", e);
 		}
 	}

+	/**
+	 * Trigger cloud sync if user is logged in (debounced)
+	 */
+	async triggerCloudSync() {
+		const auth = await getAuthModule();
+		if (auth?.isLoggedIn()) {
+			auth.debouncedSyncToCloud();
+		}
+	}
+
 	/**
 	 * Load progress from localStorage
 	 */
@@ -521,11 +677,14 @@ export class LessonEngine {
 	}

 	/**
-	 * Save user code to localStorage
+	 * Save user code to localStorage and optionally sync to cloud
 	 */
 	saveUserCodeToStorage() {
 		try {
 			localStorage.setItem("codeCrispies.userCode", JSON.stringify(Array.from(this.userCodeMap.entries())));
+
+			// Trigger cloud sync if logged in (debounced)
+			this.triggerCloudSync();
 		} catch (e) {
 			console.error("Error saving user code:", e);
 		}
--- a/src/index.html
+++ b/src/index.html
@@ -4,9 +4,10 @@
 		<meta charset="UTF-8" />
 		<link rel="icon" href="./favicon.ico" type="image/x-icon" />
 		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
+		<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline' https://librete.ch https://liberapay.com; style-src 'self' 'unsafe-inline'; connect-src 'self' https://*.supabase.co wss://*.supabase.co; img-src 'self' https://liberapay.com data:; font-src 'self'; frame-src 'self' blob:" />

 		<!-- Primary Meta Tags -->
-		<title>Code Crispies - Learn HTML & CSS Interactively | Free Coding Practice</title>
+		<title>CODE CRISPIES - Learn HTML & CSS Interactively | Free Coding Practice</title>
 		<meta
 			name="description"
 			content="Master HTML, CSS, and Tailwind through hands-on coding exercises. Free, open-source learning platform with instant feedback. No account required."
@@ -19,14 +20,14 @@
 		<!-- Open Graph / Facebook -->
 		<meta property="og:type" content="website" />
 		<meta property="og:url" content="https://codecrispi.es/" />
-		<meta property="og:title" content="Code Crispies - Learn HTML & CSS Interactively" />
+		<meta property="og:title" content="CODE CRISPIES - Learn HTML & CSS Interactively" />
 		<meta property="og:description" content="Master HTML, CSS, and Tailwind through hands-on coding exercises. Free and open source." />
 		<meta property="og:image" content="https://codecrispi.es/og-image.png" />
-		<meta property="og:site_name" content="Code Crispies" />
+		<meta property="og:site_name" content="CODE CRISPIES" />

 		<!-- Twitter -->
 		<meta name="twitter:card" content="summary_large_image" />
-		<meta name="twitter:title" content="Code Crispies - Learn HTML & CSS Interactively" />
+		<meta name="twitter:title" content="CODE CRISPIES - Learn HTML & CSS Interactively" />
 		<meta name="twitter:description" content="Master HTML, CSS, and Tailwind through hands-on coding exercises." />
 		<meta name="twitter:image" content="https://codecrispi.es/og-image.png" />

@@ -35,7 +36,7 @@
 			{
 				"@context": "https://schema.org",
 				"@type": "WebApplication",
-				"name": "Code Crispies",
+				"name": "CODE CRISPIES",
 				"description": "Interactive platform for learning HTML, CSS, and Tailwind through hands-on coding exercises",
 				"url": "https://codecrispi.es/",
 				"applicationCategory": "EducationalApplication",
@@ -74,9 +75,13 @@
 					<nav class="main-nav" id="main-nav" aria-label="Main sections">
 						<a href="#css" class="nav-link" data-section="css">CSS</a>
 						<a href="#html" class="nav-link" data-section="html">HTML</a>
-						<a href="#tailwind" class="nav-link" data-section="tailwind">Tailwind</a>
+						<!-- <a href="#tailwind" class="nav-link" data-section="tailwind">Tailwind</a> -->
+						<a href="#markdown" class="nav-link" data-section="markdown">Markdown</a>
+						<a href="#javascript" class="nav-link" data-section="javascript">JavaScript</a>
 						<a href="#reference/css" class="nav-link nav-link-ref" data-section="reference">Reference</a>
 					</nav>
+					<button id="auth-trigger-header" class="btn btn-outline btn-sm" data-i18n="authLogin">Log In</button>
+					<span id="user-email-header" class="user-email hidden"></span>
 					<button id="help-btn" class="help-toggle" data-i18n-aria-label="help" aria-label="Help">?</button>
 				</div>
 			</header>
@@ -100,7 +105,7 @@
 					</section>

 					<section class="why-it-works">
-						<h2 data-i18n="landingWhyTitle">Why Code Crispies Works</h2>
+						<h2 data-i18n="landingWhyTitle">Why CODE CRISPIES Works</h2>
 						<div class="benefits-grid">
 							<article class="benefit-card">
 								<svg class="benefit-icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
@@ -139,7 +144,7 @@
 								</svg>
 								<h3 data-i18n="landingBenefit4Title">Free & Open Source</h3>
 								<p data-i18n="landingBenefit4Text">
-									No account, no paywall, no tracking. Your progress stays in your browser. The code is open for everyone.
+									No paywall, no tracking. Optional account for cloud sync across devices. The code is open for everyone.
 								</p>
 							</article>
 						</div>
@@ -160,18 +165,71 @@
 								<p data-i18n="landingHtmlDesc">Semantic markup and native elements</p>
 								<span class="section-card-progress" id="html-progress"></span>
 							</a>
+							<!-- Tailwind temporarily disabled
 							<a href="#tailwind" class="section-card" data-section="tailwind">
 								<div class="section-card-icon" style="background: #26a69a">TW</div>
 								<h3>Tailwind CSS</h3>
 								<p data-i18n="landingTailwindDesc">Utility-first CSS framework</p>
 								<span class="section-card-progress" id="tailwind-progress"></span>
 							</a>
+							-->
+							<a href="#markdown" class="section-card" data-section="markdown">
+								<div class="section-card-icon" style="background: #5b8dd9">MD</div>
+								<h3>Markdown</h3>
+								<p data-i18n="landingMarkdownDesc">Lightweight markup for formatting text</p>
+								<span class="section-card-progress" id="markdown-progress"></span>
+							</a>
+							<a href="#javascript" class="section-card" data-section="javascript">
+								<div class="section-card-icon" style="background: #f0db4f; color: #333">JS</div>
+								<h3>JavaScript</h3>
+								<p data-i18n="landingJsDesc">Interactive scripting for web pages</p>
+								<span class="section-card-progress" id="javascript-progress"></span>
+							</a>
+						</div>
+						<p class="device-notice" data-i18n-html="deviceNotice">
+							<strong>Best on desktop or tablet (landscape).</strong> Mobile works, but larger screens make coding easier.
+						</p>
+					</section>
+
+					<section class="coming-soon">
+						<h2 data-i18n="landingComingSoonTitle">Coming Soon</h2>
+						<div class="coming-soon-grid">
+							<article class="coming-soon-card">
+								<span class="coming-soon-icon">
+									<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><circle cx="12" cy="8" r="6"/><path d="M15.477 12.89 17 22l-5-3-5 3 1.523-9.11"/></svg>
+								</span>
+								<h3 data-i18n="comingSoonAchievementsTitle">Achievements</h3>
+								<p data-i18n="comingSoonAchievementsText">Earn badges as you master new skills. Track your learning milestones.</p>
+							</article>
+							<article class="coming-soon-card">
+								<span class="coming-soon-icon">
+									<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><rect x="3" y="3" width="7" height="7"/><rect x="14" y="3" width="7" height="7"/><rect x="14" y="14" width="7" height="7"/><rect x="3" y="14" width="7" height="7"/></svg>
+								</span>
+								<h3 data-i18n="comingSoonFrameworksTitle">Frameworks</h3>
+								<p data-i18n="comingSoonFrameworksText">React, Vue, and Svelte basics. Build real components step by step.</p>
+							</article>
+							<article class="coming-soon-card">
+								<span class="coming-soon-icon">
+									<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M12 2l3.09 6.26L22 9.27l-5 4.87 1.18 6.88L12 17.77l-6.18 3.25L7 14.14 2 9.27l6.91-1.01L12 2z"/></svg>
+								</span>
+								<h3 data-i18n="comingSoonChallengesTitle">Code Challenges</h3>
+								<p data-i18n="comingSoonChallengesText">Test your skills with timed puzzles. Compete on leaderboards and earn ranks.</p>
+							</article>
+						</div>
+						<div class="newsletter-signup">
+							<p data-i18n="newsletterText">Want to know when new features launch?</p>
+							<form id="newsletter-form" class="newsletter-form">
+								<input type="email" id="newsletter-email" required data-i18n-placeholder="newsletterPlaceholder" placeholder="your@email.com">
+								<button type="submit" class="btn btn-outline" data-i18n="newsletterButton">Notify Me</button>
+							</form>
+							<p class="newsletter-disclaimer" data-i18n="newsletterDisclaimer">Max once a week. Unsubscribe anytime via mail@codecrispi.es</p>
+							<p id="newsletter-thanks" class="newsletter-thanks hidden" data-i18n="newsletterThanks">Thanks! We'll keep you posted.</p>
 						</div>
 					</section>

 					<section class="landing-cta">
 						<h2 data-i18n="landingCtaTitle">Start Learning Today</h2>
-						<a href="#welcome/0" class="cta-button" data-i18n="landingCtaButton">Begin Your Journey</a>
+						<a href="#welcome/0" class="cta-button" data-i18n="landingCtaButton">Let's get crispy!</a>
 						<p class="cta-sub" data-i18n="landingCtaSub">Free and open source. No account required. Progress saved locally.</p>
 					</section>

@@ -198,13 +256,18 @@
 							</section>
 							<section class="footer-section footer-support">
 								<h4 data-i18n="footerSupport">Support</h4>
-								<p data-i18n="footerSupportText">Help keep Code Crispies free and open source.</p>
+								<p data-i18n="footerSupportText">Help keep CODE CRISPIES free and open source.</p>
 								<script src="https://liberapay.com/libretech/widgets/button.js"></script>
 								<noscript><a href="https://liberapay.com/libretech/donate"><img alt="Donate using Liberapay" src="https://liberapay.com/assets/widgets/donate.svg"></a></noscript>
 							</section>
 						</div>
 						<div class="footer-bottom">
-							<p>&copy; 2025 <a href="https://librete.ch">LibreTECH</a>. <span data-i18n="footerLicense">Open source under MIT License.</span></p>
+							<p>&copy; <span class="current-year"></span> <a href="https://librete.ch">LibreTECH</a>. <span data-i18n="footerLicense">Open source under MIT License.</span></p>
+							<p class="footer-legal">
+								<button type="button" class="btn-text privacy-link" data-i18n="footerPrivacy">Privacy Policy</button>
+								<span class="footer-separator">·</span>
+								<button type="button" class="btn-text imprint-link" data-i18n="footerImprint">Imprint</button>
+							</p>
 						</div>
 					</footer>
 				</div>
@@ -227,6 +290,43 @@
 					<!-- Educational content with integrated module links -->
 					<div class="section-intro" id="section-intro"></div>
 				</article>
+				<footer class="section-footer landing-footer">
+					<div class="footer-grid">
+						<section class="footer-section footer-modules">
+							<div id="section-footer-lesson-links" class="footer-links"></div>
+						</section>
+						<section class="footer-section">
+							<h4 data-i18n="footerResources">Resources</h4>
+							<ul class="footer-links">
+								<li><a href="#reference/css">CSS Reference</a></li>
+								<li><a href="#reference/html">HTML Reference</a></li>
+								<li><a href="#playground/0" data-i18n="footerPlayground">Playground</a></li>
+							</ul>
+						</section>
+						<section class="footer-section">
+							<h4 data-i18n="footerAbout">About</h4>
+							<ul class="footer-links">
+								<li><a href="https://librete.ch" target="_blank">LibreTECH</a></li>
+								<li><a href="https://git.librete.ch/libretech/code-crispies" target="_blank">Source Code</a></li>
+								<li><a href="https://github.com/nextlevelshit/code-crispies" target="_blank">GitHub</a></li>
+							</ul>
+						</section>
+						<section class="footer-section footer-support">
+							<h4 data-i18n="footerSupport">Support</h4>
+							<p data-i18n="footerSupportText">Help keep CODE CRISPIES free and open source.</p>
+							<script src="https://liberapay.com/libretech/widgets/button.js"></script>
+							<noscript><a href="https://liberapay.com/libretech/donate"><img alt="Donate using Liberapay" src="https://liberapay.com/assets/widgets/donate.svg"></a></noscript>
+						</section>
+					</div>
+					<div class="footer-bottom">
+						<p>&copy; <span class="current-year"></span> <a href="https://librete.ch">LibreTECH</a>. <span data-i18n="footerLicense">Open source under MIT License.</span></p>
+						<p class="footer-legal">
+							<button type="button" class="btn-text privacy-link" data-i18n="footerPrivacy">Privacy Policy</button>
+							<span class="footer-separator">·</span>
+							<button type="button" class="btn-text imprint-link" data-i18n="footerImprint">Imprint</button>
+						</p>
+					</div>
+				</footer>
 			</div>

 			<!-- Reference/Cheatsheet Pages -->
@@ -238,13 +338,48 @@
 						<a href="#reference/flexbox" class="ref-nav-link" data-ref="flexbox">Flexbox</a>
 						<a href="#reference/grid" class="ref-nav-link" data-ref="grid">Grid</a>
 						<a href="#reference/html" class="ref-nav-link" data-ref="html">HTML Elements</a>
+						<a href="#reference/markdown" class="ref-nav-link" data-ref="markdown">Markdown</a>
 					</nav>
 					<div class="reference-body" id="reference-body">
 						<!-- Reference content injected by JS -->
 					</div>
 				</article>
-				<footer class="reference-footer">
-					<p>&copy; 2025 <a href="https://librete.ch">LibreTECH</a>. <span data-i18n="footerLicense">Released into public domain.</span></p>
+				<footer class="reference-footer landing-footer">
+					<div class="footer-grid">
+						<section class="footer-section footer-modules">
+							<div id="ref-footer-lesson-links" class="footer-links"></div>
+						</section>
+						<section class="footer-section">
+							<h4 data-i18n="footerResources">Resources</h4>
+							<ul class="footer-links">
+								<li><a href="#reference/css">CSS Reference</a></li>
+								<li><a href="#reference/html">HTML Reference</a></li>
+								<li><a href="#playground/0" data-i18n="footerPlayground">Playground</a></li>
+							</ul>
+						</section>
+						<section class="footer-section">
+							<h4 data-i18n="footerAbout">About</h4>
+							<ul class="footer-links">
+								<li><a href="https://librete.ch" target="_blank">LibreTECH</a></li>
+								<li><a href="https://git.librete.ch/libretech/code-crispies" target="_blank">Source Code</a></li>
+								<li><a href="https://github.com/nextlevelshit/code-crispies" target="_blank">GitHub</a></li>
+							</ul>
+						</section>
+						<section class="footer-section footer-support">
+							<h4 data-i18n="footerSupport">Support</h4>
+							<p data-i18n="footerSupportText">Help keep CODE CRISPIES free and open source.</p>
+							<script src="https://liberapay.com/libretech/widgets/button.js"></script>
+							<noscript><a href="https://liberapay.com/libretech/donate"><img alt="Donate using Liberapay" src="https://liberapay.com/assets/widgets/donate.svg"></a></noscript>
+						</section>
+					</div>
+					<div class="footer-bottom">
+						<p>&copy; <span class="current-year"></span> <a href="https://librete.ch">LibreTECH</a>. <span data-i18n="footerLicense">Open source under MIT License.</span></p>
+						<p class="footer-legal">
+							<button type="button" class="btn-text privacy-link" data-i18n="footerPrivacy">Privacy Policy</button>
+							<span class="footer-separator">·</span>
+							<button type="button" class="btn-text imprint-link" data-i18n="footerImprint">Imprint</button>
+						</p>
+					</div>
 				</footer>
 			</div>

@@ -281,6 +416,7 @@
 								<label for="code-input" class="editor-label" data-i18n="editorLabel">CSS Editor</label>
 								<div class="editor-actions">
 									<div class="editor-tools">
+										<button id="random-template-btn" class="btn btn-icon hidden" title="Load random template"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><rect x="2" y="2" width="20" height="20" rx="3" ry="3"/><circle cx="7" cy="7" r="1.5" fill="currentColor" stroke="none"/><circle cx="12" cy="12" r="1.5" fill="currentColor" stroke="none"/><circle cx="17" cy="17" r="1.5" fill="currentColor" stroke="none"/><circle cx="17" cy="7" r="1.5" fill="currentColor" stroke="none"/><circle cx="7" cy="17" r="1.5" fill="currentColor" stroke="none"/></svg></button>
 										<button id="undo-btn" class="btn btn-icon" data-i18n-title="undoTitle" title="Undo (Ctrl+Z)">↶</button>
 										<button id="redo-btn" class="btn btn-icon" data-i18n-title="redoTitle" title="Redo (Ctrl+Shift+Z)">↷</button>
 										<button
@@ -291,7 +427,6 @@
 										>
 											⟲
 										</button>
-										<button id="random-template-btn" class="btn btn-icon hidden" title="Load random template"><img src="./dice.svg" alt="" /></button>
 									</div>
 									<button id="run-btn" class="btn btn-run"><img src="./gear.svg" alt="" /><span data-i18n="run">Run</span></button>
 								</div>
@@ -339,40 +474,76 @@
 					<button id="close-sidebar" class="close-btn" data-i18n-aria-label="closeMenu" aria-label="Close menu">&times;</button>
 				</div>

+				<nav class="sidebar-section sidebar-nav-mobile" aria-label="Learning paths">
+					<a href="#css" class="sidebar-nav-link" data-section="css">CSS</a>
+					<a href="#html" class="sidebar-nav-link" data-section="html">HTML</a>
+					<!-- <a href="#tailwind" class="sidebar-nav-link" data-section="tailwind">Tailwind</a> -->
+					<a href="#javascript" class="sidebar-nav-link" data-section="javascript">JavaScript</a>
+					<button id="auth-trigger-mobile" class="sidebar-nav-link sidebar-auth-link" data-i18n="authLogin">Log In</button>
+				</nav>
+
 				<div class="sidebar-section">
 					<h4 data-i18n="progress">Progress</h4>
-					<div class="progress-display" id="progress-display">
-						<div class="progress-bar">
-							<div class="progress-fill" id="progress-fill"></div>
+					<div class="progress-display milestone-progress" id="progress-display">
+						<div class="milestones" id="milestones">
+							<span class="milestone" data-value="1">1</span>
+							<span class="milestone" data-value="5">5</span>
+							<span class="milestone" data-value="10">10</span>
+							<span class="milestone" data-value="20">20</span>
+							<span class="milestone" data-value="30">30</span>
+							<span class="milestone" data-value="50">50</span>
+							<span class="milestone" data-value="75">75</span>
+							<span class="milestone" data-value="100">100</span>
 						</div>
-						<span class="progress-text" id="progress-text">0% Complete</span>
+						<div class="progress-bar-row">
+							<div class="progress-bar">
+								<div class="progress-fill" id="progress-fill"></div>
+							</div>
+							<span class="progress-current" id="progress-current">0/1</span>
+						</div>
+						<span class="progress-total" id="progress-total">0 of 100 lessons</span>
 					</div>
 				</div>

 				<nav class="sidebar-section" aria-label="Lesson navigation">
 					<h4 id="lessons-heading" data-i18n="lessons">Lessons</h4>
 					<div class="module-list" id="module-list" role="tree" aria-labelledby="lessons-heading"></div>
+
+					<div class="sidebar-auth-box">
+						<h4 data-i18n="authAccount">Account</h4>
+						<button id="auth-trigger-sidebar" class="btn btn-outline btn-full" data-i18n="authLogin">Log In</button>
+						<div id="user-menu-sidebar" class="user-menu-sidebar hidden">
+							<span id="user-email-sidebar" class="user-email"></span>
+							<button id="logout-btn-sidebar" class="btn btn-outline btn-full" data-i18n="authLogout">Log Out</button>
+							<button id="delete-account-btn" class="btn btn-text btn-danger btn-full" data-i18n="authDeleteAccount">Delete Account</button>
+						</div>
+						<p class="sidebar-auth-hint" data-i18n="authSyncHint">Log in to sync progress across devices</p>
+					</div>
 				</nav>

 				<div class="sidebar-section">
 					<h4 data-i18n="settings">Settings</h4>
-					<label class="setting-row">
-						<span class="setting-label" data-i18n="language">Language</span>
-						<select id="lang-select" class="lang-select">
-							<option value="en">English</option>
-							<option value="de">Deutsch</option>
-							<option value="pl">Polski</option>
-							<option value="es">Español</option>
-							<option value="ar">العربية</option>
-							<option value="uk">Українська</option>
-						</select>
-					</label>
-					<label class="toggle-switch">
-						<input type="checkbox" id="disable-feedback-toggle" checked />
-						<span class="toggle-slider"></span>
-						<span class="toggle-label" data-i18n="showHints">Show Hints</span>
-					</label>
-					<button id="reset-btn" class="btn btn-text" data-i18n="resetAllProgress">Reset All Progress</button>
+					<div class="settings-card">
+						<label class="settings-row">
+							<span class="settings-label" data-i18n="language">Language</span>
+							<select id="lang-select" class="lang-select">
+								<option value="en">English</option>
+								<option value="de">Deutsch</option>
+								<option value="pl">Polski</option>
+								<option value="es">Español</option>
+								<option value="ar">العربية</option>
+								<option value="uk">Українська</option>
+							</select>
+						</label>
+						<label class="settings-row">
+							<span class="settings-label" data-i18n="showHints">Show Hints</span>
+							<input type="checkbox" id="disable-feedback-toggle" class="settings-toggle" checked />
+						</label>
+						<div class="settings-row">
+							<span class="settings-label" data-i18n="resetAllProgress">Reset All Progress</span>
+							<button id="reset-btn" class="btn btn-sm btn-ghost" data-i18n="reset">Reset</button>
+						</div>
+					</div>
 				</div>

 				<footer class="app-footer">
@@ -389,9 +560,9 @@
 					<button id="help-dialog-close" class="dialog-close" aria-label="Close">&times;</button>
 				</div>
 				<div class="dialog-content">
-					<h4 data-i18n="aboutTitle">About Code Crispies</h4>
+					<h4 data-i18n="aboutTitle">About CODE CRISPIES</h4>
 					<p data-i18n="aboutText">
-						Code Crispies is a free, open-source platform for learning web development through hands-on exercises. No account required -
+						CODE CRISPIES is a free, open-source platform for learning web development through hands-on exercises. No account required -
 						just start coding!
 					</p>

@@ -455,7 +626,7 @@
 					</div>

 					<h4 data-i18n="contactTitle">Contact & Links</h4>
-					<p data-i18n-html="contactText">Code Crispies is developed by <a href="https://librete.ch" target="_blank">LibreTECH</a></p>
+					<p data-i18n-html="contactText">CODE CRISPIES is developed by <a href="https://librete.ch" target="_blank">LibreTECH</a></p>
 					<ul>
 						<li><a href="https://git.librete.ch/libretech/code-crispies" target="_blank">Gitea</a> – Self-hosted source repository</li>
 						<li><a href="https://github.com/nextlevelshit/code-crispies" target="_blank">GitHub</a> – Public mirror</li>
@@ -463,7 +634,7 @@
 					</ul>

 					<h4 data-i18n="supportTitle">Support the Project</h4>
-					<p data-i18n="supportText">Help keep Code Crispies free and open source.</p>
+					<p data-i18n="supportText">Help keep CODE CRISPIES free and open source.</p>
 					<div class="help-support" onclick="typeof umami !== 'undefined' && umami.track('support_click', {location: 'help'})">
 						<script src="https://liberapay.com/libretech/widgets/button.js"></script>
 						<noscript><a href="https://liberapay.com/libretech/donate"><img alt="Donate using Liberapay" src="https://liberapay.com/assets/widgets/donate.svg"></a></noscript>
@@ -506,6 +677,22 @@
 				</div>
 			</dialog>

+			<!-- Delete Account Confirmation Dialog -->
+			<dialog id="delete-account-dialog" class="dialog">
+				<div class="dialog-header">
+					<h3 data-i18n="authDeleteDialogTitle">Delete Account</h3>
+					<button id="delete-dialog-close" class="dialog-close" aria-label="Close">&times;</button>
+				</div>
+				<div class="dialog-content">
+					<p data-i18n="authDeleteDialogText">Are you sure you want to delete your account? All your cloud progress will be permanently deleted. This cannot be undone.</p>
+					<p id="delete-account-error" class="auth-error hidden"></p>
+					<div class="dialog-actions">
+						<button id="cancel-delete" class="btn" data-i18n="cancel">Cancel</button>
+						<button id="confirm-delete" class="btn btn-danger" data-i18n="authDeleteConfirm">Delete Account</button>
+					</div>
+				</div>
+			</dialog>
+
 			<!-- Share Dialog -->
 			<dialog id="share-dialog" class="dialog">
 				<div class="dialog-header">
@@ -521,6 +708,136 @@
 					<p id="copy-feedback" class="copy-feedback" data-i18n="urlCopied" hidden>URL copied to clipboard!</p>
 				</div>
 			</dialog>
+
+			<!-- Privacy Policy Dialog -->
+			<dialog id="privacy-dialog" class="dialog legal-dialog">
+				<div class="dialog-header">
+					<h3 data-i18n="privacyTitle">Privacy Policy</h3>
+					<button class="dialog-close privacy-dialog-close" aria-label="Close">&times;</button>
+				</div>
+				<div class="dialog-content legal-content">
+					<p data-i18n="privacyIntro">CODE CRISPIES respects your privacy. This policy explains what data we collect and how we use it.</p>
+
+					<h4 data-i18n="privacyLocalTitle">Local Storage</h4>
+					<p data-i18n="privacyLocalText">Your learning progress, code, and settings are stored locally in your browser. This data never leaves your device unless you create an account.</p>
+
+					<h4 data-i18n="privacyAccountTitle">Account Data (Optional)</h4>
+					<p data-i18n="privacyAccountText">If you create an account, we store your email address and encrypted password to enable cloud sync. Your progress data is synced to our servers (Supabase) so you can access it across devices.</p>
+
+					<h4 data-i18n="privacyNewsletterTitle">Newsletter (Optional)</h4>
+					<p data-i18n="privacyNewsletterText">If you subscribe to our newsletter, we store your email address to send updates about new features. You can unsubscribe anytime.</p>
+
+					<h4 data-i18n="privacyNoTrackingTitle">No Tracking</h4>
+					<p data-i18n="privacyNoTrackingText">We do not use cookies for tracking, analytics, or advertising. We do not share your data with third parties.</p>
+
+					<h4 data-i18n="privacyRightsTitle">Your Rights (GDPR)</h4>
+					<p data-i18n="privacyRightsText">You can delete your account and all associated data at any time from the sidebar menu. For questions or data requests, contact us at mail@codecrispi.es</p>
+
+					<p class="legal-updated" data-i18n="privacyUpdated">Last updated: January 2025</p>
+				</div>
+			</dialog>
+
+			<!-- Imprint Dialog -->
+			<dialog id="imprint-dialog" class="dialog legal-dialog">
+				<div class="dialog-header">
+					<h3 data-i18n="imprintTitle">Imprint</h3>
+					<button class="dialog-close imprint-dialog-close" aria-label="Close">&times;</button>
+				</div>
+				<div class="dialog-content legal-content">
+					<h4 data-i18n="imprintResponsibleTitle">Responsible for content</h4>
+					<p>
+						Michael Czechowski<br>
+						Schnellweg 3<br>
+						70199 Stuttgart<br>
+						Germany
+					</p>
+
+					<h4 data-i18n="imprintContactTitle">Contact</h4>
+					<p>
+						Email: mail@codecrispi.es<br>
+						Website: <a href="https://librete.ch" target="_blank">librete.ch</a>
+					</p>
+
+					<h4 data-i18n="imprintDisclaimerTitle">Disclaimer</h4>
+					<p data-i18n="imprintDisclaimerText">CODE CRISPIES is provided "as is" without warranty. We are not liable for any damages arising from the use of this service. External links are provided for convenience; we are not responsible for their content.</p>
+				</div>
+			</dialog>
+
+			<!-- Auth Dialog -->
+			<dialog id="auth-dialog" class="dialog auth-dialog">
+				<div class="dialog-header">
+					<h2 id="auth-dialog-title" data-i18n="authLogin">Log In</h2>
+					<button class="dialog-close close-dialog" aria-label="Close">&times;</button>
+				</div>
+				<div class="dialog-content">
+					<!-- Login Form -->
+					<form id="login-form" class="auth-form">
+						<div class="form-field">
+							<label for="login-email" data-i18n="authEmail">Email</label>
+							<input type="email" id="login-email" required autocomplete="email">
+						</div>
+						<div class="form-field">
+							<label for="login-password" data-i18n="authPassword">Password</label>
+							<input type="password" id="login-password" required minlength="6" autocomplete="current-password">
+						</div>
+						<p id="login-error" class="auth-error hidden"></p>
+						<button type="submit" class="btn btn-primary btn-full" data-i18n="authLogin">Log In</button>
+					</form>
+
+					<!-- Signup Form (hidden by default) -->
+					<form id="signup-form" class="auth-form hidden">
+						<div class="form-field">
+							<label for="signup-email" data-i18n="authEmail">Email</label>
+							<input type="email" id="signup-email" required autocomplete="email">
+						</div>
+						<div class="form-field">
+							<label for="signup-password" data-i18n="authPassword">Password</label>
+							<input type="password" id="signup-password" required minlength="6" autocomplete="new-password">
+						</div>
+						<div class="form-field">
+							<label for="signup-confirm" data-i18n="authConfirmPassword">Confirm Password</label>
+							<input type="password" id="signup-confirm" required minlength="6" autocomplete="new-password">
+						</div>
+						<p id="signup-error" class="auth-error hidden"></p>
+						<p id="signup-success" class="auth-success hidden" data-i18n="authSignupSuccess">Account created! Check your email to confirm.</p>
+						<button type="submit" class="btn btn-primary btn-full" data-i18n="authSignUp">Sign Up</button>
+					</form>
+
+					<!-- Password Reset Form (hidden by default) -->
+					<form id="reset-form" class="auth-form hidden">
+						<p class="auth-instructions" data-i18n="authResetInstructions">Enter your email to receive a password reset link.</p>
+						<div class="form-field">
+							<label for="reset-email" data-i18n="authEmail">Email</label>
+							<input type="email" id="reset-email" required autocomplete="email">
+						</div>
+						<p id="reset-error" class="auth-error hidden"></p>
+						<p id="reset-success" class="auth-success hidden" data-i18n="authResetSent">Check your email for the reset link.</p>
+						<button type="submit" class="btn btn-primary btn-full" data-i18n="authSendReset">Send Reset Link</button>
+					</form>
+
+					<!-- Social Login Buttons -->
+					<div class="auth-social">
+						<div class="auth-divider"><span data-i18n="authOrContinueWith">or continue with</span></div>
+						<div class="auth-social-buttons">
+							<button type="button" id="google-login" class="btn btn-social">
+								<svg class="social-icon" viewBox="0 0 24 24"><path d="M22.56 12.25c0-.78-.07-1.53-.2-2.25H12v4.26h5.92c-.26 1.37-1.04 2.53-2.21 3.31v2.77h3.57c2.08-1.92 3.28-4.74 3.28-8.09z" fill="#4285F4"/><path d="M12 23c2.97 0 5.46-.98 7.28-2.66l-3.57-2.77c-.98.66-2.23 1.06-3.71 1.06-2.86 0-5.29-1.93-6.16-4.53H2.18v2.84C3.99 20.53 7.7 23 12 23z" fill="#34A853"/><path d="M5.84 14.09c-.22-.66-.35-1.36-.35-2.09s.13-1.43.35-2.09V7.07H2.18C1.43 8.55 1 10.22 1 12s.43 3.45 1.18 4.93l2.85-2.22.81-.62z" fill="#FBBC05"/><path d="M12 5.38c1.62 0 3.06.56 4.21 1.64l3.15-3.15C17.45 2.09 14.97 1 12 1 7.7 1 3.99 3.47 2.18 7.07l3.66 2.84c.87-2.6 3.3-4.53 6.16-4.53z" fill="#EA4335"/></svg>
+								Google
+							</button>
+							<button type="button" id="github-login" class="btn btn-social">
+								<svg class="social-icon" viewBox="0 0 24 24"><path d="M12 0C5.37 0 0 5.37 0 12c0 5.31 3.435 9.795 8.205 11.385.6.105.825-.255.825-.57 0-.285-.015-1.23-.015-2.235-3.015.555-3.795-.735-4.035-1.41-.135-.345-.72-1.41-1.23-1.695-.42-.225-1.02-.78-.015-.795.945-.015 1.62.87 1.845 1.23 1.08 1.815 2.805 1.305 3.495.99.105-.78.42-1.305.765-1.605-2.67-.3-5.46-1.335-5.46-5.925 0-1.305.465-2.385 1.23-3.225-.12-.3-.54-1.53.12-3.18 0 0 1.005-.315 3.3 1.23.96-.27 1.98-.405 3-.405s2.04.135 3 .405c2.295-1.56 3.3-1.23 3.3-1.23.66 1.65.24 2.88.12 3.18.765.84 1.23 1.905 1.23 3.225 0 4.605-2.805 5.625-5.475 5.925.435.375.81 1.095.81 2.22 0 1.605-.015 2.895-.015 3.3 0 .315.225.69.825.57A12.02 12.02 0 0024 12c0-6.63-5.37-12-12-12z" fill="currentColor"/></svg>
+								GitHub
+							</button>
+						</div>
+					</div>
+
+					<!-- Form switcher links -->
+					<div class="auth-links">
+						<button type="button" id="show-signup" class="btn-text" data-i18n="authNoAccount">Don't have an account? Sign up</button>
+						<button type="button" id="show-login" class="btn-text hidden" data-i18n="authHaveAccount">Already have an account? Log in</button>
+						<button type="button" id="show-reset" class="btn-text" data-i18n="authForgotPassword">Forgot password?</button>
+					</div>
+				</div>
+			</dialog>
 		</div>

 		<script type="module" src="app.js"></script>
--- a/src/main.css
+++ b/src/main.css
--- a/src/supabase.js
+++ b/src/supabase.js
@@ -0,0 +1,106 @@
+import { createClient } from "@supabase/supabase-js";
+
+const supabaseUrl = import.meta.env.VITE_SUPABASE_URL;
+const supabaseAnonKey = import.meta.env.VITE_SUPABASE_ANON_KEY;
+
+// Check if Supabase is configured
+export const isConfigured = Boolean(supabaseUrl && supabaseAnonKey);
+
+// Only create client if configured
+const supabase = isConfigured
+  ? createClient(supabaseUrl, supabaseAnonKey)
+  : null;
+
+// Auth helpers - all return null/rejected promise if not configured
+export const auth = {
+  signUp: (email, password) =>
+    supabase?.auth.signUp({ email, password }) ??
+    Promise.resolve({ data: null, error: { message: "Not configured" } }),
+
+  signIn: (email, password) =>
+    supabase?.auth.signInWithPassword({ email, password }) ??
+    Promise.resolve({ data: null, error: { message: "Not configured" } }),
+
+  signOut: () =>
+    supabase?.auth.signOut() ??
+    Promise.resolve({ error: null }),
+
+  resetPassword: (email) =>
+    supabase?.auth.resetPasswordForEmail(email) ??
+    Promise.resolve({ data: null, error: { message: "Not configured" } }),
+
+  signInWithGoogle: () =>
+    supabase?.auth.signInWithOAuth({ provider: "google" }) ??
+    Promise.resolve({ data: null, error: { message: "Not configured" } }),
+
+  signInWithGitHub: () =>
+    supabase?.auth.signInWithOAuth({ provider: "github" }) ??
+    Promise.resolve({ data: null, error: { message: "Not configured" } }),
+
+  getUser: () =>
+    supabase?.auth.getUser() ??
+    Promise.resolve({ data: { user: null }, error: null }),
+
+  getSession: () =>
+    supabase?.auth.getSession() ??
+    Promise.resolve({ data: { session: null }, error: null }),
+
+  setSession: ({ access_token, refresh_token }) =>
+    supabase?.auth.setSession({ access_token, refresh_token }) ??
+    Promise.resolve({ data: { session: null }, error: { message: "Not configured" } }),
+
+  onAuthStateChange: (callback) =>
+    supabase?.auth.onAuthStateChange(callback) ?? { data: { subscription: { unsubscribe: () => {} } } },
+
+  deleteAccount: async () => {
+    if (!supabase) return { error: { message: "Not configured" } };
+    const { error } = await supabase.rpc("delete_own_account");
+    return { error };
+  },
+};
+
+// Progress sync helpers
+export const progressDB = {
+  async load(userId) {
+    if (!supabase) return { data: null, error: { message: "Not configured" } };
+    const { data, error } = await supabase
+      .from("user_progress")
+      .select("*")
+      .eq("user_id", userId)
+      .single();
+    return { data, error };
+  },
+
+  async save(userId, progress, userCode, settings, language) {
+    if (!supabase) return { error: { message: "Not configured" } };
+    const { error } = await supabase.from("user_progress").upsert(
+      {
+        user_id: userId,
+        progress,
+        user_code: userCode,
+        settings,
+        language,
+      },
+      { onConflict: "user_id" }
+    );
+    return { error };
+  },
+};
+
+// Newsletter subscription helper
+export const newsletter = {
+  async subscribe(email) {
+    if (!supabase) return { error: { message: "Not configured" } };
+    // Use insert with ignoreDuplicates since RLS only allows INSERT
+    const { error } = await supabase.from("newsletter_subscribers").insert(
+      {
+        email: email.toLowerCase().trim(),
+        subscribed_at: new Date().toISOString(),
+      },
+      { onConflict: "email", ignoreDuplicates: true }
+    );
+    // Ignore duplicate email errors (already subscribed)
+    if (error?.code === "23505") return { error: null };
+    return { error };
+  },
+};
--- a/supabase-setup.sql
+++ b/supabase-setup.sql
@@ -0,0 +1,58 @@
+-- CODE CRISPIES - Supabase Database Setup
+-- Run this in Supabase Dashboard → SQL Editor → New Query
+
+-- Drop existing objects first
+  DROP FUNCTION IF EXISTS delete_own_account();
+  DROP TABLE IF EXISTS user_progress;
+  DROP TABLE IF EXISTS newsletter_subscribers;
+
+-- User progress table
+CREATE TABLE user_progress (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  user_id UUID REFERENCES auth.users(id) ON DELETE CASCADE,
+  progress JSONB NOT NULL DEFAULT '{}',
+  user_code JSONB NOT NULL DEFAULT '{}',
+  settings JSONB NOT NULL DEFAULT '{}',
+  language TEXT DEFAULT 'en',
+  updated_at TIMESTAMPTZ DEFAULT NOW(),
+  created_at TIMESTAMPTZ DEFAULT NOW(),
+  UNIQUE(user_id)
+);
+
+-- Newsletter subscribers table
+CREATE TABLE newsletter_subscribers (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  email TEXT UNIQUE NOT NULL,
+  subscribed_at TIMESTAMPTZ DEFAULT NOW()
+);
+
+-- Row Level Security
+ALTER TABLE user_progress ENABLE ROW LEVEL SECURITY;
+ALTER TABLE newsletter_subscribers ENABLE ROW LEVEL SECURITY;
+
+-- Users can only access their own progress
+CREATE POLICY "Users can CRUD own progress"
+  ON user_progress FOR ALL
+  USING (auth.uid() = user_id)
+  WITH CHECK (auth.uid() = user_id);
+
+-- Anyone can subscribe to newsletter (public insert)
+CREATE POLICY "Anyone can subscribe to newsletter"
+  ON newsletter_subscribers FOR INSERT
+  WITH CHECK (true);
+
+-- Function to delete own account (called via RPC)
+CREATE OR REPLACE FUNCTION delete_own_account()
+RETURNS void
+LANGUAGE plpgsql
+SECURITY DEFINER
+SET search_path = public
+AS $$
+BEGIN
+  -- Delete user's progress (CASCADE should handle this, but be explicit)
+  DELETE FROM user_progress WHERE user_id = auth.uid();
+
+  -- Delete the user from auth.users
+  DELETE FROM auth.users WHERE id = auth.uid();
+END;
+$$;
--- a/tests/unit/lessons.test.js
+++ b/tests/unit/lessons.test.js
@@ -19,6 +19,10 @@ describe("Lessons Config Module", () => {
 			expect(moduleIds).toContain("css-basic-selectors");
 			expect(moduleIds).toContain("box-model");
 			expect(moduleIds).toContain("flexbox");
+			// JavaScript modules
+			expect(moduleIds).toContain("js-variables");
+			expect(moduleIds).toContain("js-dom");
+			expect(moduleIds).toContain("js-events");
 		});

 		test("should have mode set on each lesson", async () => {
@@ -27,7 +31,7 @@ describe("Lessons Config Module", () => {
 			modules.forEach((module) => {
 				module.lessons.forEach((lesson) => {
 					expect(lesson.mode).toBeDefined();
-					expect(["html", "css", "tailwind", "playground"]).toContain(lesson.mode);
+					expect(["html", "css", "tailwind", "markdown", "javascript", "playground"]).toContain(lesson.mode);
 				});
 			});
 		});
--- a/tests/unit/renderer-extended.test.js
+++ b/tests/unit/renderer-extended.test.js
@@ -0,0 +1,538 @@
+import { describe, test, expect, vi, beforeEach, afterEach } from "vitest";
+import {
+	renderModuleList,
+	renderLesson,
+	renderLevelIndicator,
+	renderDifficultyBadge,
+	showFeedback,
+	clearFeedback,
+	updateActiveLessonInSidebar,
+	computeLessonDifficulty
+} from "../../src/helpers/renderer.js";
+
+// Mock i18n
+vi.mock("../../src/i18n.js", () => ({
+	t: (key, params = {}) => {
+		const translations = {
+			lessonLabel: "Lesson",
+			untitledLesson: "Untitled Lesson",
+			lessonFallback: `Lesson ${params.index || ""}`,
+			difficulty_easy_label: "Easy difficulty",
+			difficulty_medium_label: "Medium difficulty",
+			difficulty_hard_label: "Hard difficulty",
+			difficulty_easy: "Easy",
+			difficulty_medium: "Medium",
+			difficulty_hard: "Hard"
+		};
+		return translations[key] || key;
+	}
+}));
+
+describe("Renderer Extended Coverage", () => {
+	beforeEach(() => {
+		document.body.innerHTML = `
+			<div id="module-list"></div>
+			<div class="lesson-title-row">
+				<h2 id="title"></h2>
+			</div>
+			<div id="description"></div>
+			<div id="task"></div>
+			<div id="preview"></div>
+			<div id="prefix"></div>
+			<textarea id="input"></textarea>
+			<div id="suffix"></div>
+			<div id="level-indicator"></div>
+			<div class="editor-content"></div>
+			<input type="checkbox" id="disable-feedback-toggle" checked>
+		`;
+		localStorage.clear();
+	});
+
+	describe("renderModuleList - progress tracking", () => {
+		test("renderModuleList_CorruptedProgress_HandlesGracefully", () => {
+			const errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+			localStorage.setItem("codeCrispies.progress", "not-valid-json{{{");
+
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [{ title: "L1" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			expect(errorSpy).toHaveBeenCalledWith(expect.stringContaining("Error parsing progress"), expect.anything());
+			// Should still render modules despite parse error
+			expect(container.querySelectorAll(".module-header").length).toBe(1);
+			errorSpy.mockRestore();
+		});
+
+		test("renderModuleList_CompletedModule_AddedCompletedClass", () => {
+			localStorage.setItem(
+				"codeCrispies.progress",
+				JSON.stringify({
+					mod1: { completed: [0, 1], current: 1 }
+				})
+			);
+
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [{ title: "L1" }, { title: "L2" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const header = container.querySelector(".module-header");
+			expect(header.classList.contains("completed")).toBe(true);
+		});
+
+		test("renderModuleList_PartiallyCompleted_NoCompletedClass", () => {
+			localStorage.setItem(
+				"codeCrispies.progress",
+				JSON.stringify({
+					mod1: { completed: [0], current: 1 }
+				})
+			);
+
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [{ title: "L1" }, { title: "L2" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const header = container.querySelector(".module-header");
+			expect(header.classList.contains("completed")).toBe(false);
+		});
+
+		test("renderModuleList_CompletedLesson_HasCompletedClass", () => {
+			localStorage.setItem(
+				"codeCrispies.progress",
+				JSON.stringify({
+					mod1: { completed: [0], current: 1 }
+				})
+			);
+
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [{ title: "L1" }, { title: "L2" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const lessonItems = container.querySelectorAll(".lesson-list-item");
+			expect(lessonItems[0].classList.contains("completed")).toBe(true);
+			expect(lessonItems[1].classList.contains("completed")).toBe(false);
+		});
+
+		test("renderModuleList_CurrentLesson_HasCurrentClass", () => {
+			localStorage.setItem(
+				"codeCrispies.progress",
+				JSON.stringify({
+					mod1: { completed: [0], current: 1 }
+				})
+			);
+
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [{ title: "L1" }, { title: "L2" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const lessonItems = container.querySelectorAll(".lesson-list-item");
+			expect(lessonItems[1].classList.contains("current")).toBe(true);
+			expect(lessonItems[0].classList.contains("current")).toBe(false);
+		});
+	});
+
+	describe("renderModuleList - welcome/playground always expanded", () => {
+		test("renderModuleList_WelcomeModule_AlwaysExpanded", () => {
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "welcome", title: "Welcome", lessons: [{ title: "Intro" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const details = container.querySelector("details.module-container");
+			expect(details.open).toBe(true);
+		});
+
+		test("renderModuleList_PlaygroundModule_AlwaysExpanded", () => {
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "playground", title: "Playground", lessons: [{ title: "Play" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const details = container.querySelector("details.module-container");
+			expect(details.open).toBe(true);
+		});
+
+		test("renderModuleList_RegularModule_CollapsedByDefault", () => {
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "flexbox", title: "Flexbox", lessons: [{ title: "L1" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const details = container.querySelector("details.module-container");
+			expect(details.open).toBe(false);
+		});
+	});
+
+	describe("renderModuleList - lesson fallback title", () => {
+		test("renderModuleList_NoLessonTitle_UsesFallback", () => {
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [{}] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const lessonItem = container.querySelector(".lesson-list-item");
+			expect(lessonItem.textContent).toContain("Lesson");
+		});
+	});
+
+	describe("renderModuleList - click behavior", () => {
+		test("renderModuleList_LessonClick_RemovesActiveFromOthers", () => {
+			const container = document.getElementById("module-list");
+			const modules = [
+				{
+					id: "mod1",
+					title: "Module 1",
+					lessons: [{ title: "L1" }, { title: "L2" }]
+				}
+			];
+			const onSelectLesson = vi.fn();
+
+			renderModuleList(container, modules, vi.fn(), onSelectLesson);
+
+			const lessonItems = container.querySelectorAll(".lesson-list-item");
+
+			// Click first lesson
+			lessonItems[0].click();
+			expect(lessonItems[0].classList.contains("active")).toBe(true);
+			expect(onSelectLesson).toHaveBeenCalledWith("mod1", 0);
+
+			// Click second lesson
+			lessonItems[1].click();
+			expect(lessonItems[0].classList.contains("active")).toBe(false);
+			expect(lessonItems[1].classList.contains("active")).toBe(true);
+			expect(onSelectLesson).toHaveBeenCalledWith("mod1", 1);
+		});
+	});
+
+	describe("renderModuleList - module dataset", () => {
+		test("renderModuleList_DataAttributes_SetCorrectly", () => {
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "flex-mod", title: "Flex Module", lessons: [{ title: "L1" }] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			const details = container.querySelector("details.module-container");
+			expect(details.dataset.moduleId).toBe("flex-mod");
+
+			const header = container.querySelector(".module-header");
+			expect(header.dataset.moduleId).toBe("flex-mod");
+
+			const lesson = container.querySelector(".lesson-list-item");
+			expect(lesson.dataset.moduleId).toBe("flex-mod");
+			expect(lesson.dataset.lessonIndex).toBe("0");
+		});
+	});
+
+	describe("renderModuleList - empty lessons", () => {
+		test("renderModuleList_EmptyLessonsArray_RendersModuleOnly", () => {
+			const container = document.getElementById("module-list");
+			const modules = [{ id: "mod1", title: "Module 1", lessons: [] }];
+
+			renderModuleList(container, modules, vi.fn(), vi.fn());
+
+			expect(container.querySelectorAll(".module-header").length).toBe(1);
+			expect(container.querySelectorAll(".lesson-list-item").length).toBe(0);
+		});
+	});
+
+	describe("renderDifficultyBadge", () => {
+		test("renderDifficultyBadge_EasyLesson_CreatesEasyBadge", () => {
+			const container = document.querySelector(".lesson-title-row");
+			const lesson = { codePrefix: ".box {\n  ", solution: "color: red;" };
+
+			renderDifficultyBadge(container, lesson);
+
+			const badge = container.querySelector(".difficulty-badge");
+			expect(badge).not.toBeNull();
+			expect(badge.classList.contains("difficulty-easy")).toBe(true);
+			expect(badge.querySelectorAll(".bar").length).toBe(3);
+		});
+
+		test("renderDifficultyBadge_MediumLesson_CreatesMediumBadge", () => {
+			const container = document.querySelector(".lesson-title-row");
+			const lesson = { codePrefix: "", solution: "p {\n  color: red;\n}" };
+
+			renderDifficultyBadge(container, lesson);
+
+			const badge = container.querySelector(".difficulty-badge");
+			expect(badge.classList.contains("difficulty-medium")).toBe(true);
+		});
+
+		test("renderDifficultyBadge_HardLesson_CreatesHardBadge", () => {
+			const container = document.querySelector(".lesson-title-row");
+			const lesson = { codePrefix: "", solution: ".nav a {\n  color: white;\n}" };
+
+			renderDifficultyBadge(container, lesson);
+
+			const badge = container.querySelector(".difficulty-badge");
+			expect(badge.classList.contains("difficulty-hard")).toBe(true);
+		});
+
+		test("renderDifficultyBadge_CalledTwice_RemovesPreviousBadge", () => {
+			const container = document.querySelector(".lesson-title-row");
+			const lesson1 = { codePrefix: ".box {\n  ", solution: "color: red;" };
+			const lesson2 = { codePrefix: "", solution: ".nav a {\n  color: white;\n}" };
+
+			renderDifficultyBadge(container, lesson1);
+			expect(container.querySelectorAll(".difficulty-wrapper").length).toBe(1);
+
+			renderDifficultyBadge(container, lesson2);
+			expect(container.querySelectorAll(".difficulty-wrapper").length).toBe(1);
+
+			const badge = container.querySelector(".difficulty-badge");
+			expect(badge.classList.contains("difficulty-hard")).toBe(true);
+		});
+
+		test("renderDifficultyBadge_HasAriaLabel", () => {
+			const container = document.querySelector(".lesson-title-row");
+			const lesson = { codePrefix: ".box {", solution: "color: red;" };
+
+			renderDifficultyBadge(container, lesson);
+
+			const badge = container.querySelector(".difficulty-badge");
+			expect(badge.getAttribute("aria-label")).toBeTruthy();
+			expect(badge.getAttribute("title")).toBeTruthy();
+		});
+	});
+
+	describe("showFeedback", () => {
+		test("showFeedback_Success_CreatesSuccessElement", () => {
+			showFeedback(true, "Great job!");
+
+			const feedback = document.querySelector(".feedback-success");
+			expect(feedback).not.toBeNull();
+			expect(feedback.innerHTML).toBe("Great job!");
+		});
+
+		test("showFeedback_Success_InsertedAfterEditorContent", () => {
+			showFeedback(true, "Good!");
+
+			const editorContent = document.querySelector(".editor-content");
+			const feedback = editorContent.nextSibling;
+			expect(feedback).not.toBeNull();
+			expect(feedback.classList.contains("feedback-success")).toBe(true);
+		});
+
+		test("showFeedback_Error_ToggleChecked_ShowsError", () => {
+			const toggle = document.getElementById("disable-feedback-toggle");
+			toggle.checked = true;
+
+			showFeedback(false, "Try again");
+
+			const feedback = document.querySelector(".feedback-error");
+			expect(feedback).not.toBeNull();
+			expect(feedback.innerHTML).toBe("Try again");
+		});
+
+		test("showFeedback_Error_ToggleUnchecked_HidesError", () => {
+			const toggle = document.getElementById("disable-feedback-toggle");
+			toggle.checked = false;
+
+			showFeedback(false, "Try again");
+
+			const feedback = document.querySelector(".feedback-error");
+			expect(feedback).toBeNull();
+		});
+
+		test("showFeedback_Error_AutoClearsAfterTimeout", () => {
+			vi.useFakeTimers();
+			const toggle = document.getElementById("disable-feedback-toggle");
+			toggle.checked = true;
+
+			showFeedback(false, "Error!");
+
+			expect(document.querySelector(".feedback-error")).not.toBeNull();
+
+			vi.advanceTimersByTime(3000);
+
+			expect(document.querySelector(".feedback-error")).toBeNull();
+			vi.useRealTimers();
+		});
+
+		test("showFeedback_Success_DoesNotAutoCleanup", () => {
+			vi.useFakeTimers();
+
+			showFeedback(true, "Good!");
+
+			vi.advanceTimersByTime(5000);
+
+			expect(document.querySelector(".feedback-success")).not.toBeNull();
+			vi.useRealTimers();
+		});
+
+		test("showFeedback_CalledTwice_ClearsPrevious", () => {
+			showFeedback(true, "First");
+			showFeedback(true, "Second");
+
+			const feedbacks = document.querySelectorAll(".feedback-success");
+			expect(feedbacks.length).toBe(1);
+			expect(feedbacks[0].innerHTML).toBe("Second");
+		});
+	});
+
+	describe("clearFeedback", () => {
+		test("clearFeedback_NoExistingFeedback_DoesNotThrow", () => {
+			expect(() => clearFeedback()).not.toThrow();
+		});
+
+		test("clearFeedback_ExistingFeedback_RemovesIt", () => {
+			showFeedback(true, "Test");
+			expect(document.querySelector(".feedback-success")).not.toBeNull();
+
+			clearFeedback();
+			expect(document.querySelector(".feedback-success")).toBeNull();
+		});
+
+		test("clearFeedback_CalledMultipleTimes_Safe", () => {
+			showFeedback(true, "Test");
+			clearFeedback();
+			clearFeedback();
+			clearFeedback();
+			expect(document.querySelector(".feedback-success")).toBeNull();
+		});
+
+		test("clearFeedback_ClearsTimeout", () => {
+			vi.useFakeTimers();
+			const toggle = document.getElementById("disable-feedback-toggle");
+			toggle.checked = true;
+
+			showFeedback(false, "Error");
+			clearFeedback();
+
+			// Advance past the timeout - should not throw
+			vi.advanceTimersByTime(5000);
+
+			vi.useRealTimers();
+		});
+	});
+
+	describe("updateActiveLessonInSidebar", () => {
+		beforeEach(() => {
+			document.body.innerHTML = `
+				<details class="module-container" data-module-id="mod1">
+					<summary class="module-header">Module 1</summary>
+					<div class="lessons-container">
+						<button class="lesson-list-item active" data-module-id="mod1" data-lesson-index="0">L1</button>
+						<button class="lesson-list-item" data-module-id="mod1" data-lesson-index="1">L2</button>
+					</div>
+				</details>
+				<details class="module-container" data-module-id="mod2">
+					<summary class="module-header">Module 2</summary>
+					<div class="lessons-container">
+						<button class="lesson-list-item" data-module-id="mod2" data-lesson-index="0">L1</button>
+					</div>
+				</details>
+			`;
+			// Mock scrollIntoView on all lesson items (not available in jsdom)
+			document.querySelectorAll(".lesson-list-item").forEach((el) => {
+				el.scrollIntoView = vi.fn();
+			});
+		});
+
+		test("updateActiveLessonInSidebar_ValidLesson_ActivatesCorrectItem", () => {
+			updateActiveLessonInSidebar("mod1", 1);
+
+			const items = document.querySelectorAll(".lesson-list-item");
+			expect(items[0].classList.contains("active")).toBe(false);
+			expect(items[1].classList.contains("active")).toBe(true);
+		});
+
+		test("updateActiveLessonInSidebar_DifferentModule_ExpandsParent", () => {
+			const details = document.querySelector('details[data-module-id="mod2"]');
+			expect(details.open).toBe(false);
+
+			updateActiveLessonInSidebar("mod2", 0);
+
+			expect(details.open).toBe(true);
+			const mod2Lesson = document.querySelector('.lesson-list-item[data-module-id="mod2"]');
+			expect(mod2Lesson.classList.contains("active")).toBe(true);
+		});
+
+		test("updateActiveLessonInSidebar_RemovesPreviousActive", () => {
+			const firstItem = document.querySelector('.lesson-list-item[data-module-id="mod1"][data-lesson-index="0"]');
+			expect(firstItem.classList.contains("active")).toBe(true);
+
+			updateActiveLessonInSidebar("mod2", 0);
+
+			expect(firstItem.classList.contains("active")).toBe(false);
+		});
+
+		test("updateActiveLessonInSidebar_NonExistentItem_DoesNotThrow", () => {
+			expect(() => {
+				updateActiveLessonInSidebar("nonexistent", 99);
+			}).not.toThrow();
+
+			// All active classes should still be removed
+			const activeItems = document.querySelectorAll(".lesson-list-item.active");
+			expect(activeItems.length).toBe(0);
+		});
+
+		test("updateActiveLessonInSidebar_ScrollsToLesson", () => {
+			const targetItem = document.querySelector('.lesson-list-item[data-module-id="mod1"][data-lesson-index="1"]');
+
+			updateActiveLessonInSidebar("mod1", 1);
+
+			expect(targetItem.scrollIntoView).toHaveBeenCalledWith({ behavior: "smooth", block: "nearest" });
+		});
+	});
+
+	describe("computeLessonDifficulty - additional edge cases", () => {
+		test("computeLessonDifficulty_NoSolution_ReturnsMedium", () => {
+			expect(computeLessonDifficulty({ codePrefix: "" })).toBe("medium");
+		});
+
+		test("computeLessonDifficulty_SolutionNoBrace_ReturnsMedium", () => {
+			expect(
+				computeLessonDifficulty({
+					codePrefix: "",
+					solution: "color: red;"
+				})
+			).toBe("medium");
+		});
+
+		test("computeLessonDifficulty_CodePrefixWithBrace_IgnoresSolution", () => {
+			expect(
+				computeLessonDifficulty({
+					codePrefix: ".nav a {",
+					solution: ".nav a {\n  color: white;\n}"
+				})
+			).toBe("easy");
+		});
+
+		test("computeLessonDifficulty_NullCodePrefix_ReturnsMedium", () => {
+			expect(computeLessonDifficulty({ codePrefix: null, solution: null })).toBe("medium");
+		});
+	});
+
+	describe("renderLesson - edge cases", () => {
+		test("renderLesson_NullInputEl_DoesNotThrow", () => {
+			const titleEl = document.getElementById("title");
+			const descriptionEl = document.getElementById("description");
+			const taskEl = document.getElementById("task");
+			const previewEl = document.getElementById("preview");
+			const prefixEl = document.getElementById("prefix");
+			const suffixEl = document.getElementById("suffix");
+			const lesson = { title: "Test", description: "Desc", task: "Task" };
+
+			expect(() => {
+				renderLesson(titleEl, descriptionEl, taskEl, previewEl, prefixEl, null, suffixEl, lesson);
+			}).not.toThrow();
+		});
+	});
+
+	describe("renderLevelIndicator - formatting", () => {
+		test("renderLevelIndicator_ContainsLabelSpan", () => {
+			const element = document.getElementById("level-indicator");
+			renderLevelIndicator(element, 5, 12);
+
+			const label = element.querySelector(".level-label");
+			expect(label).not.toBeNull();
+			expect(label.textContent).toBe("Lesson");
+			expect(element.textContent).toContain("5 / 12");
+		});
+	});
+});
--- a/tests/unit/renderer.test.js
+++ b/tests/unit/renderer.test.js
@@ -1,5 +1,5 @@
 import { describe, test, expect, vi, beforeEach } from "vitest";
-import { renderModuleList, renderLesson, renderLevelIndicator, showFeedback, clearFeedback } from "../../src/helpers/renderer.js";
+import { renderModuleList, renderLesson, renderLevelIndicator, showFeedback, clearFeedback, computeLessonDifficulty } from "../../src/helpers/renderer.js";

 describe("Renderer Module", () => {
 	beforeEach(() => {
@@ -176,4 +176,68 @@ describe("Renderer Module", () => {
 			clearFeedback();
 		});
 	});
+
+	describe("computeLessonDifficulty", () => {
+		test("should return 'easy' when codePrefix contains selector", () => {
+			expect(computeLessonDifficulty({
+				codePrefix: ".text {\n  ",
+				solution: "color: coral;"
+			})).toBe("easy");
+
+			expect(computeLessonDifficulty({
+				codePrefix: "h1, h2, h3 {\n  ",
+				solution: "color: steelblue;"
+			})).toBe("easy");
+		});
+
+		test("should return 'medium' for simple type selector", () => {
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: "p {\n  color: steelblue;\n}"
+			})).toBe("medium");
+
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: "a {\n  color: coral;\n}"
+			})).toBe("medium");
+		});
+
+		test("should return 'medium' for simple class selector", () => {
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: ".badge {\n  background: tomato;\n}"
+			})).toBe("medium");
+		});
+
+		test("should return 'hard' for descendant selectors", () => {
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: ".nav a {\n  color: white;\n}"
+			})).toBe("hard");
+
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: ".card p {\n  font-size: 0.9rem;\n}"
+			})).toBe("hard");
+		});
+
+		test("should return 'hard' for chained class selectors", () => {
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: ".btn.primary {\n  background: steelblue;\n}"
+			})).toBe("hard");
+		});
+
+		test("should return 'hard' for type+class selectors", () => {
+			expect(computeLessonDifficulty({
+				codePrefix: "",
+				solution: "a.btn {\n  text-decoration: none;\n}"
+			})).toBe("hard");
+		});
+
+		test("should handle missing fields gracefully", () => {
+			expect(computeLessonDifficulty({})).toBe("medium");
+			expect(computeLessonDifficulty({ codePrefix: null })).toBe("medium");
+		});
+	});
 });
--- a/tests/unit/router.test.js
+++ b/tests/unit/router.test.js
@@ -0,0 +1,234 @@
+import { describe, test, expect, vi, beforeEach, afterEach } from "vitest";
+import { parseHash, updateHash, navigateTo, replaceHash, replaceTo, getShareableUrl, getSectionIds, RouteType } from "../../src/helpers/router.js";
+
+describe("Router", () => {
+	let pushStateSpy;
+	let replaceStateSpy;
+
+	beforeEach(() => {
+		// Reset hash
+		window.location.hash = "";
+		pushStateSpy = vi.spyOn(history, "pushState").mockImplementation(() => {});
+		replaceStateSpy = vi.spyOn(history, "replaceState").mockImplementation(() => {});
+	});
+
+	afterEach(() => {
+		pushStateSpy.mockRestore();
+		replaceStateSpy.mockRestore();
+	});
+
+	describe("RouteType", () => {
+		test("RouteType_Constants_CorrectValues", () => {
+			expect(RouteType.HOME).toBe("home");
+			expect(RouteType.SECTION).toBe("section");
+			expect(RouteType.REFERENCE).toBe("reference");
+			expect(RouteType.LESSON).toBe("lesson");
+			expect(RouteType.LANGUAGE).toBe("language");
+		});
+	});
+
+	describe("parseHash", () => {
+		test("parseHash_EmptyHash_ReturnsHome", () => {
+			window.location.hash = "";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.HOME });
+		});
+
+		test("parseHash_HashOnly_ReturnsHome", () => {
+			window.location.hash = "#";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.HOME });
+		});
+
+		test.each([
+			["de", "de"],
+			["pl", "pl"],
+			["ar", "ar"],
+			["es", "es"],
+			["en", "en"],
+			["uk", "uk"]
+		])("parseHash_LanguageCode_%s_ReturnsLanguageRoute", (code, expectedLang) => {
+			window.location.hash = `#${code}`;
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.LANGUAGE, lang: expectedLang });
+		});
+
+		test.each([
+			["css", "css"],
+			["html", "html"],
+			["markdown", "markdown"],
+			["javascript", "javascript"]
+		])("parseHash_SectionId_%s_ReturnsSectionRoute", (sectionId, expectedId) => {
+			window.location.hash = `#${sectionId}`;
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.SECTION, sectionId: expectedId });
+		});
+
+		test("parseHash_ReferenceWithoutSubpage_ReturnsReferenceRouteNullRefId", () => {
+			window.location.hash = "#reference";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.REFERENCE, refId: null });
+		});
+
+		test("parseHash_ReferenceWithSubpage_ReturnsReferenceRouteWithRefId", () => {
+			window.location.hash = "#reference/css";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.REFERENCE, refId: "css" });
+		});
+
+		test("parseHash_ReferenceWithFlexboxSubpage_ReturnsCorrectRefId", () => {
+			window.location.hash = "#reference/flexbox";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.REFERENCE, refId: "flexbox" });
+		});
+
+		test("parseHash_SingleUnknownSegment_ReturnsLessonWithIndex0", () => {
+			window.location.hash = "#flexbox";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.LESSON, moduleId: "flexbox", lessonIndex: 0 });
+		});
+
+		test("parseHash_ModuleWithLessonIndex_ReturnsLessonRoute", () => {
+			window.location.hash = "#flexbox/2";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.LESSON, moduleId: "flexbox", lessonIndex: 2 });
+		});
+
+		test("parseHash_ModuleWithIndex0_ReturnsLessonRoute", () => {
+			window.location.hash = "#box-model/0";
+			const result = parseHash();
+			expect(result).toEqual({ type: RouteType.LESSON, moduleId: "box-model", lessonIndex: 0 });
+		});
+
+		test("parseHash_NegativeLessonIndex_ReturnsNull", () => {
+			window.location.hash = "#module/-1";
+			const result = parseHash();
+			expect(result).toBeNull();
+		});
+
+		test("parseHash_NonNumericLessonIndex_ReturnsNull", () => {
+			window.location.hash = "#module/abc";
+			const result = parseHash();
+			expect(result).toBeNull();
+		});
+
+		test("parseHash_ThreeOrMoreSegments_ReturnsNull", () => {
+			window.location.hash = "#a/b/c";
+			const result = parseHash();
+			expect(result).toBeNull();
+		});
+
+		test("parseHash_EmptyModuleIdWithIndex_ReturnsNull", () => {
+			// #/0 → parts = ["", "0"], moduleId is empty string (falsy)
+			window.location.hash = "#/0";
+			const result = parseHash();
+			expect(result).toBeNull();
+		});
+	});
+
+	describe("updateHash", () => {
+		test("updateHash_NewHash_CallsPushState", () => {
+			window.location.hash = "";
+			updateHash("flexbox", 2);
+			expect(pushStateSpy).toHaveBeenCalledWith(null, "", "#flexbox/2");
+		});
+
+		test("updateHash_SameHash_DoesNotCallPushState", () => {
+			window.location.hash = "#flexbox/2";
+			updateHash("flexbox", 2);
+			expect(pushStateSpy).not.toHaveBeenCalled();
+		});
+
+		test("updateHash_DifferentModule_CallsPushState", () => {
+			window.location.hash = "#flexbox/0";
+			updateHash("box-model", 0);
+			expect(pushStateSpy).toHaveBeenCalledWith(null, "", "#box-model/0");
+		});
+	});
+
+	describe("navigateTo", () => {
+		test("navigateTo_SectionRoute_CallsPushState", () => {
+			window.location.hash = "";
+			navigateTo("css");
+			expect(pushStateSpy).toHaveBeenCalledWith(null, "", "#css");
+		});
+
+		test("navigateTo_EmptyRoute_NavigatesToHash", () => {
+			window.location.hash = "#something";
+			navigateTo("");
+			expect(pushStateSpy).toHaveBeenCalledWith(null, "", "#");
+		});
+
+		test("navigateTo_SameHash_DoesNotCallPushState", () => {
+			window.location.hash = "#css";
+			navigateTo("css");
+			expect(pushStateSpy).not.toHaveBeenCalled();
+		});
+	});
+
+	describe("replaceHash", () => {
+		test("replaceHash_ValidArgs_CallsReplaceState", () => {
+			replaceHash("flexbox", 3);
+			expect(replaceStateSpy).toHaveBeenCalledWith(null, "", "#flexbox/3");
+		});
+
+		test("replaceHash_Index0_FormatsCorrectly", () => {
+			replaceHash("box-model", 0);
+			expect(replaceStateSpy).toHaveBeenCalledWith(null, "", "#box-model/0");
+		});
+	});
+
+	describe("replaceTo", () => {
+		test("replaceTo_Route_CallsReplaceState", () => {
+			replaceTo("css");
+			expect(replaceStateSpy).toHaveBeenCalledWith(null, "", "#css");
+		});
+
+		test("replaceTo_EmptyRoute_ReplacesToHash", () => {
+			replaceTo("");
+			expect(replaceStateSpy).toHaveBeenCalledWith(null, "", "#");
+		});
+
+		test("replaceTo_ReferenceRoute_FormatsCorrectly", () => {
+			replaceTo("reference/flexbox");
+			expect(replaceStateSpy).toHaveBeenCalledWith(null, "", "#reference/flexbox");
+		});
+	});
+
+	describe("getShareableUrl", () => {
+		test("getShareableUrl_ValidArgs_ReturnsFullUrl", () => {
+			const url = getShareableUrl("flexbox", 2);
+			expect(url).toContain("#flexbox/2");
+			expect(url).toMatch(/^https?:\/\/.+#flexbox\/2$/);
+		});
+
+		test("getShareableUrl_Index0_IncludesIndex", () => {
+			const url = getShareableUrl("box-model", 0);
+			expect(url).toContain("#box-model/0");
+		});
+	});
+
+	describe("getSectionIds", () => {
+		test("getSectionIds_ReturnsCopy_NotOriginalArray", () => {
+			const ids1 = getSectionIds();
+			const ids2 = getSectionIds();
+			expect(ids1).toEqual(ids2);
+			expect(ids1).not.toBe(ids2); // Different references
+		});
+
+		test("getSectionIds_ContainsExpectedSections", () => {
+			const ids = getSectionIds();
+			expect(ids).toContain("css");
+			expect(ids).toContain("html");
+			expect(ids).toContain("markdown");
+			expect(ids).toContain("javascript");
+		});
+
+		test("getSectionIds_MutatingCopy_DoesNotAffectOriginal", () => {
+			const ids = getSectionIds();
+			ids.push("custom");
+			const freshIds = getSectionIds();
+			expect(freshIds).not.toContain("custom");
+		});
+	});
+});
--- a/tests/unit/sections.test.js
+++ b/tests/unit/sections.test.js
@@ -0,0 +1,176 @@
+import { describe, test, expect } from "vitest";
+import { sections, getSection, getSectionList, getModuleSection, getModulesBySection } from "../../src/config/sections.js";
+
+describe("Sections Config", () => {
+	describe("sections constant", () => {
+		test("sections_AllDefined_HasFiveSections", () => {
+			expect(Object.keys(sections)).toHaveLength(5);
+			expect(sections).toHaveProperty("css");
+			expect(sections).toHaveProperty("html");
+			expect(sections).toHaveProperty("tailwind");
+			expect(sections).toHaveProperty("markdown");
+			expect(sections).toHaveProperty("javascript");
+		});
+
+		test("sections_EachSection_HasRequiredFields", () => {
+			for (const [key, section] of Object.entries(sections)) {
+				expect(section.id).toBe(key);
+				expect(section.title).toBeTruthy();
+				expect(section.description).toBeTruthy();
+				expect(section.color).toMatch(/^#[0-9a-f]{6}$/);
+				expect(typeof section.order).toBe("number");
+			}
+		});
+	});
+
+	describe("getSection", () => {
+		test.each([
+			["css", "CSS"],
+			["html", "HTML"],
+			["tailwind", "Tailwind CSS"],
+			["markdown", "Markdown"],
+			["javascript", "JavaScript"]
+		])("getSection_%s_ReturnsCorrectSection", (id, expectedTitle) => {
+			const section = getSection(id);
+			expect(section).not.toBeNull();
+			expect(section.id).toBe(id);
+			expect(section.title).toBe(expectedTitle);
+		});
+
+		test("getSection_NonExistentId_ReturnsNull", () => {
+			expect(getSection("nonexistent")).toBeNull();
+		});
+
+		test("getSection_Undefined_ReturnsNull", () => {
+			expect(getSection(undefined)).toBeNull();
+		});
+
+		test("getSection_EmptyString_ReturnsNull", () => {
+			expect(getSection("")).toBeNull();
+		});
+	});
+
+	describe("getSectionList", () => {
+		test("getSectionList_Default_ReturnsSortedByOrder", () => {
+			const list = getSectionList();
+			expect(list).toHaveLength(5);
+
+			// Verify sorted by order
+			for (let i = 1; i < list.length; i++) {
+				expect(list[i].order).toBeGreaterThan(list[i - 1].order);
+			}
+		});
+
+		test("getSectionList_Default_CSSIsFirst", () => {
+			const list = getSectionList();
+			expect(list[0].id).toBe("css");
+		});
+
+		test("getSectionList_Default_JavaScriptIsLast", () => {
+			const list = getSectionList();
+			expect(list[list.length - 1].id).toBe("javascript");
+		});
+
+		test("getSectionList_Default_ContainsAllSections", () => {
+			const list = getSectionList();
+			const ids = list.map((s) => s.id);
+			expect(ids).toContain("css");
+			expect(ids).toContain("html");
+			expect(ids).toContain("tailwind");
+			expect(ids).toContain("markdown");
+			expect(ids).toContain("javascript");
+		});
+	});
+
+	describe("getModuleSection", () => {
+		test("getModuleSection_ExplicitSection_UsesExplicitValue", () => {
+			const module = { mode: "css", section: "html" };
+			expect(getModuleSection(module)).toBe("html");
+		});
+
+		test.each([
+			["css", "css"],
+			["html", "html"],
+			["tailwind", "tailwind"],
+			["markdown", "markdown"],
+			["javascript", "javascript"]
+		])("getModuleSection_Mode%s_InfersCorrectSection", (mode, expectedSection) => {
+			const module = { mode };
+			expect(getModuleSection(module)).toBe(expectedSection);
+		});
+
+		test("getModuleSection_NoMode_DefaultsToCss", () => {
+			expect(getModuleSection({})).toBe("css");
+		});
+
+		test("getModuleSection_UndefinedMode_DefaultsToCss", () => {
+			expect(getModuleSection({ mode: undefined })).toBe("css");
+		});
+
+		test("getModuleSection_UnknownMode_DefaultsToCss", () => {
+			expect(getModuleSection({ mode: "unknown-mode" })).toBe("css");
+		});
+
+		test("getModuleSection_ExplicitSectionOverridesMode_UsesSection", () => {
+			const module = { mode: "html", section: "tailwind" };
+			expect(getModuleSection(module)).toBe("tailwind");
+		});
+	});
+
+	describe("getModulesBySection", () => {
+		const testModules = [
+			{ id: "css-basics", mode: "css" },
+			{ id: "flexbox", mode: "css" },
+			{ id: "html-elements", mode: "html" },
+			{ id: "tailwind-intro", mode: "tailwind" },
+			{ id: "markdown-basics", mode: "markdown" },
+			{ id: "welcome", mode: "css", excludeFromProgress: true },
+			{ id: "playground", mode: "css", excludeFromProgress: true }
+		];
+
+		test("getModulesBySection_Css_ReturnsCssModules", () => {
+			const result = getModulesBySection(testModules, "css");
+			expect(result).toHaveLength(2);
+			expect(result.map((m) => m.id)).toEqual(["css-basics", "flexbox"]);
+		});
+
+		test("getModulesBySection_Html_ReturnsHtmlModules", () => {
+			const result = getModulesBySection(testModules, "html");
+			expect(result).toHaveLength(1);
+			expect(result[0].id).toBe("html-elements");
+		});
+
+		test("getModulesBySection_Tailwind_ReturnsTailwindModules", () => {
+			const result = getModulesBySection(testModules, "tailwind");
+			expect(result).toHaveLength(1);
+			expect(result[0].id).toBe("tailwind-intro");
+		});
+
+		test("getModulesBySection_ExcludesFromProgress_FiltersOut", () => {
+			const result = getModulesBySection(testModules, "css");
+			const ids = result.map((m) => m.id);
+			expect(ids).not.toContain("welcome");
+			expect(ids).not.toContain("playground");
+		});
+
+		test("getModulesBySection_EmptyModules_ReturnsEmptyArray", () => {
+			const result = getModulesBySection([], "css");
+			expect(result).toEqual([]);
+		});
+
+		test("getModulesBySection_NonExistentSection_ReturnsEmptyArray", () => {
+			const result = getModulesBySection(testModules, "nonexistent");
+			expect(result).toEqual([]);
+		});
+
+		test("getModulesBySection_ExplicitSectionOverride_IncludesModule", () => {
+			const modules = [
+				{ id: "special", mode: "css", section: "html" },
+				{ id: "normal-html", mode: "html" }
+			];
+			const result = getModulesBySection(modules, "html");
+			expect(result).toHaveLength(2);
+			expect(result.map((m) => m.id)).toContain("special");
+		});
+	});
+});
--- a/tests/unit/validator-extended.test.js
+++ b/tests/unit/validator-extended.test.js
@@ -0,0 +1,735 @@
+import { describe, test, expect, vi, beforeEach } from "vitest";
+import { validateUserCode, validateCssCode } from "../../src/helpers/validator.js";
+
+describe("Validator Extended Coverage", () => {
+	describe("validateUserCode mode dispatch", () => {
+		test("validateUserCode_NoMode_DefaultsToCss", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [{ type: "contains", value: "color: red" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("validateUserCode_CssMode_UsesCssValidator", () => {
+			const result = validateUserCode("display: flex;", {
+				mode: "css",
+				validations: [{ type: "contains", value: "display: flex" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("validateUserCode_TailwindMode_UsesTailwindValidator", () => {
+			const result = validateUserCode("flex items-center", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("validateUserCode_HtmlMode_UsesHtmlValidator", () => {
+			const result = validateUserCode("<div>Hello</div>", {
+				mode: "html",
+				validations: [{ type: "element_exists", value: "div" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("validateUserCode_UnknownMode_DefaultsToCss", () => {
+			const result = validateUserCode("color: red;", {
+				mode: "javascript",
+				validations: [{ type: "contains", value: "color: red" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("validateUserCode_NullLesson_Throws", () => {
+			expect(() => validateUserCode("anything", null)).toThrow();
+		});
+
+		test("validateUserCode_UndefinedLesson_Throws", () => {
+			expect(() => validateUserCode("anything", undefined)).toThrow();
+		});
+	});
+
+	describe("Tailwind validation", () => {
+		test("tailwind_ContainsClass_Pass", () => {
+			const result = validateUserCode("flex items-center justify-between", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex" }]
+			});
+			expect(result.isValid).toBe(true);
+			expect(result.validCases).toBe(1);
+		});
+
+		test("tailwind_ContainsClass_Fail_ReturnsMessage", () => {
+			const result = validateUserCode("items-center", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex", message: "Add flex class" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Add flex class");
+		});
+
+		test("tailwind_ContainsClass_Fail_DefaultMessage", () => {
+			const result = validateUserCode("items-center", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("flex");
+		});
+
+		test("tailwind_ContainsClass_PartialMatch_Fails", () => {
+			// "flex-1" contains "flex" as substring but split should not match
+			const result = validateUserCode("flex-1 items-center", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex" }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("tailwind_ContainsPattern_Pass", () => {
+			const result = validateUserCode("text-lg font-bold", {
+				mode: "tailwind",
+				validations: [{ type: "contains_pattern", value: "text-\\w+" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("tailwind_ContainsPattern_Fail_ReturnsMessage", () => {
+			const result = validateUserCode("font-bold", {
+				mode: "tailwind",
+				validations: [{ type: "contains_pattern", value: "text-\\w+", message: "Add text size" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Add text size");
+		});
+
+		test("tailwind_ContainsPattern_Fail_DefaultMessage", () => {
+			const result = validateUserCode("font-bold", {
+				mode: "tailwind",
+				validations: [{ type: "contains_pattern", value: "text-\\w+" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("pattern");
+		});
+
+		test("tailwind_DefaultType_FallsBackToContains", () => {
+			const result = validateUserCode("flex items-center", {
+				mode: "tailwind",
+				validations: [{ type: "contains", value: "items-center" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("tailwind_NoValidations_ReturnsValid", () => {
+			const result = validateUserCode("flex", { mode: "tailwind" });
+			expect(result.isValid).toBe(true);
+			expect(result.message).toContain("No validations specified");
+		});
+
+		test("tailwind_NullLesson_ReturnsValid", () => {
+			const result = validateUserCode("flex", { mode: "tailwind", validations: null });
+			// validateTailwindClasses checks !lesson.validations
+			expect(result.isValid).toBe(true);
+		});
+
+		test("tailwind_MultipleValidations_AllPass", () => {
+			const result = validateUserCode("flex items-center gap-4", {
+				mode: "tailwind",
+				validations: [
+					{ type: "contains_class", value: "flex" },
+					{ type: "contains_class", value: "items-center" },
+					{ type: "contains_class", value: "gap-4" }
+				]
+			});
+			expect(result.isValid).toBe(true);
+			expect(result.validCases).toBe(3);
+		});
+
+		test("tailwind_MultipleValidations_EarlyReturn", () => {
+			const result = validateUserCode("flex", {
+				mode: "tailwind",
+				validations: [
+					{ type: "contains_class", value: "flex" },
+					{ type: "contains_class", value: "items-center", message: "Missing items-center" },
+					{ type: "contains_class", value: "gap-4" }
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Missing items-center");
+			expect(result.validCases).toBe(1);
+		});
+
+		test("tailwind_WhitespaceHandling_LeadingTrailing", () => {
+			const result = validateUserCode("  flex  items-center  ", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("tailwind_EmptyUserClasses_Fails", () => {
+			const result = validateUserCode("", {
+				mode: "tailwind",
+				validations: [{ type: "contains_class", value: "flex" }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+	});
+
+	describe("HTML validation - sibling type", () => {
+		test("sibling_ValidOrder_Passes", () => {
+			const result = validateUserCode("<h1>Title</h1><p>Content</p>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("sibling_NonAdjacentButAfter_Passes", () => {
+			const result = validateUserCode("<h1>Title</h1><span>Middle</span><p>Content</p>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("sibling_WrongOrder_Fails", () => {
+			const result = validateUserCode("<p>Content</p><h1>Title</h1>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" } }]
+			});
+			// h1 is after p, so p is not a sibling after h1 - but wait, h1 exists and p is before h1...
+			// Actually h1 exists. nextElementSibling of h1 is nothing. So it fails.
+			expect(result.isValid).toBe(false);
+		});
+
+		test("sibling_FirstNotFound_Fails", () => {
+			const result = validateUserCode("<p>Content</p>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" }, message: "h1 not found" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("h1 not found");
+		});
+
+		test("sibling_ThenNotFound_Fails", () => {
+			const result = validateUserCode("<h1>Title</h1><span>Only span</span>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("sibling_DefaultMessage_ContainsBothSelectors", () => {
+			const result = validateUserCode("<div>Only div</div>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" } }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("p");
+			expect(result.message).toContain("h1");
+		});
+
+		test("sibling_NoFollowingSiblings_Fails", () => {
+			const result = validateUserCode("<div><h1>Title</h1></div>", {
+				mode: "html",
+				validations: [{ type: "sibling", value: { first: "h1", then: "p" } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+	});
+
+	describe("HTML validation - not_contains type", () => {
+		test("htmlNotContains_AbsentText_Passes", () => {
+			const result = validateUserCode("<p>Hello</p>", {
+				mode: "html",
+				validations: [{ type: "not_contains", value: "class=" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("htmlNotContains_PresentText_Fails", () => {
+			const result = validateUserCode('<p class="red">Hello</p>', {
+				mode: "html",
+				validations: [{ type: "not_contains", value: "class=", message: "Remove classes" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Remove classes");
+		});
+
+		test("htmlNotContains_DefaultMessage", () => {
+			const result = validateUserCode('<p class="red">Hello</p>', {
+				mode: "html",
+				validations: [{ type: "not_contains", value: "class=" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("should not include");
+		});
+	});
+
+	describe("HTML validation - regex type", () => {
+		test("htmlRegex_MatchingPattern_Passes", () => {
+			const result = validateUserCode('<img src="photo.jpg" alt="A photo">', {
+				mode: "html",
+				validations: [{ type: "regex", value: 'alt="[^"]+"' }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("htmlRegex_NonMatchingPattern_Fails", () => {
+			const result = validateUserCode('<img src="photo.jpg">', {
+				mode: "html",
+				validations: [{ type: "regex", value: 'alt="[^"]+"', message: "Add alt text" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Add alt text");
+		});
+
+		test("htmlRegex_DefaultMessage", () => {
+			const result = validateUserCode("<p>Hello</p>", {
+				mode: "html",
+				validations: [{ type: "regex", value: "<h1>" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("pattern");
+		});
+	});
+
+	describe("HTML validation - unknown type", () => {
+		test("htmlUnknownType_SkipsAndPasses", () => {
+			const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+			const result = validateUserCode("<p>Hello</p>", {
+				mode: "html",
+				validations: [{ type: "unknown_type", value: "anything" }]
+			});
+			expect(result.isValid).toBe(true);
+			expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining("Unknown HTML validation type"));
+			warnSpy.mockRestore();
+		});
+	});
+
+	describe("HTML validation - element_count fallback (>0)", () => {
+		test("elementCount_NoCountNoMin_ChecksGreaterThanZero_Pass", () => {
+			const result = validateUserCode("<ul><li>Item</li></ul>", {
+				mode: "html",
+				validations: [{ type: "element_count", value: { selector: "li" } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("elementCount_NoCountNoMin_NoElements_Fails", () => {
+			const result = validateUserCode("<ul></ul>", {
+				mode: "html",
+				validations: [{ type: "element_count", value: { selector: "li" } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+	});
+
+	describe("HTML validation - attribute_value edge cases", () => {
+		test("attributeValue_ElementNotFound_Fails", () => {
+			const result = validateUserCode("<p>Hello</p>", {
+				mode: "html",
+				validations: [{ type: "attribute_value", value: { selector: "input", attr: "type", value: "email" } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("attributeValue_NullValue_ChecksExists", () => {
+			const result = validateUserCode('<input data-test="anything">', {
+				mode: "html",
+				validations: [{ type: "attribute_value", value: { selector: "input", attr: "data-test", value: null } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("attributeValue_NullValue_AttributeMissing_Fails", () => {
+			const result = validateUserCode("<input>", {
+				mode: "html",
+				validations: [{ type: "attribute_value", value: { selector: "input", attr: "data-test", value: null } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+	});
+
+	describe("HTML validation - element_text edge cases", () => {
+		test("elementText_ElementNotFound_Fails", () => {
+			const result = validateUserCode("<p>Hello</p>", {
+				mode: "html",
+				validations: [{ type: "element_text", value: { selector: "button", text: "Submit" } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("elementText_EmptyTextContent_FailsForNonEmptyExpected", () => {
+			const result = validateUserCode("<button></button>", {
+				mode: "html",
+				validations: [{ type: "element_text", value: { selector: "button", text: "Submit" } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("elementText_EmptyExpectedText_MatchesEmptyElement", () => {
+			const result = validateUserCode("<button></button>", {
+				mode: "html",
+				validations: [{ type: "element_text", value: { selector: "button", text: "" } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+	});
+
+	describe("CSS validation - containsValidation wholeWord option", () => {
+		test("contains_WholeWord_ExactMatch_Passes", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [{ type: "contains", value: "red", options: { wholeWord: true } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("contains_WholeWord_PartialMatch_Fails", () => {
+			const result = validateUserCode("color: darkred;", {
+				validations: [{ type: "contains", value: "red", options: { wholeWord: true } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("contains_WholeWord_CaseInsensitive_Passes", () => {
+			const result = validateUserCode("COLOR: RED;", {
+				validations: [{ type: "contains", value: "red", options: { wholeWord: true, caseSensitive: false } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("contains_WholeWord_SpecialChars_Escaped", () => {
+			// \b doesn't match at non-word chars like ".", so use a word value with special chars around it
+			const result = validateUserCode("value: calc(100% - 20px);", {
+				validations: [{ type: "contains", value: "calc", options: { wholeWord: true } }]
+			});
+			expect(result.isValid).toBe(true);
+
+			// "calc" should not match "recalculate"
+			const failResult = validateUserCode("/* recalculate */", {
+				validations: [{ type: "contains", value: "calc", options: { wholeWord: true } }]
+			});
+			expect(failResult.isValid).toBe(false);
+		});
+	});
+
+	describe("CSS validation - regexValidation options", () => {
+		test("regex_CaseInsensitive_Passes", () => {
+			const result = validateUserCode("COLOR: RED;", {
+				validations: [{ type: "regex", value: "color:\\s*red", options: { caseSensitive: false } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("regex_CaseSensitive_Default_FailsOnCaseMismatch", () => {
+			const result = validateUserCode("COLOR: RED;", {
+				validations: [{ type: "regex", value: "color:\\s*red" }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("regex_MultilineFalse_DoesNotMatchAcrossLines", () => {
+			const code = "body {\n  color: red;\n}";
+			// With multiline=false, ^ should not match beginning of each line
+			const result = validateUserCode(code, {
+				validations: [{ type: "regex", value: "^\\s*color", options: { multiline: false } }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("regex_MultilineTrue_Default_MatchesEachLine", () => {
+			const code = "body {\n  color: red;\n}";
+			const result = validateUserCode(code, {
+				validations: [{ type: "regex", value: "^\\s*color", options: { multiline: true } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("regex_InvalidPattern_ReturnsFalse", () => {
+			const errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+			const result = validateUserCode("color: red;", {
+				validations: [{ type: "regex", value: "[invalid(regex" }]
+			});
+			expect(result.isValid).toBe(false);
+			expect(errorSpy).toHaveBeenCalled();
+			errorSpy.mockRestore();
+		});
+
+		test("regex_EmptyPattern_MatchesEverything", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [{ type: "regex", value: "" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+	});
+
+	describe("CSS validation - propertyValueValidation edge cases", () => {
+		test("propertyValue_PropertyNotFound_Fails", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [
+					{
+						type: "property_value",
+						value: { property: "display", expected: "flex" }
+					}
+				]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("propertyValue_ExactMatch_Passes", () => {
+			const result = validateUserCode("display: flex;", {
+				validations: [
+					{
+						type: "property_value",
+						value: { property: "display", expected: "flex" },
+						options: { exact: true }
+					}
+				]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("propertyValue_ExactMatch_CaseMismatch_Fails", () => {
+			const result = validateUserCode("display: FLEX;", {
+				validations: [
+					{
+						type: "property_value",
+						value: { property: "display", expected: "flex" },
+						options: { exact: true }
+					}
+				]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("propertyValue_FlexibleMatch_CaseInsensitive", () => {
+			const result = validateUserCode("display: FLEX;", {
+				validations: [
+					{
+						type: "property_value",
+						value: { property: "display", expected: "flex" }
+					}
+				]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("propertyValue_ShorthandProperty_Passes", () => {
+			const result = validateUserCode("margin: 10px 20px;", {
+				validations: [
+					{
+						type: "property_value",
+						value: { property: "margin", expected: "10px 20px" }
+					}
+				]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("propertyValue_DefaultMessage_IncludesPropertyAndExpected", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [
+					{
+						type: "property_value",
+						value: { property: "display", expected: "flex" }
+					}
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("display");
+			expect(result.message).toContain("flex");
+		});
+	});
+
+	describe("CSS validation - syntaxValidation", () => {
+		test("syntax_ValidCss_Passes", () => {
+			const result = validateUserCode("div { color: red; }", {
+				validations: [{ type: "syntax" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+	});
+
+	describe("CSS validation - custom edge cases", () => {
+		test("custom_NoValidatorFunction_ReturnsEarlyWithOriginalResult", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [{ type: "custom" }]
+			});
+			// When validator is falsy, validationPassed stays false, but result.isValid was never set to false
+			// The function returns early with the unmodified result (isValid: true)
+			expect(result.isValid).toBe(true);
+		});
+
+		test("custom_NonFunctionValidator_ReturnsEarlyWithOriginalResult", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [{ type: "custom", validator: "not-a-function" }]
+			});
+			// Same behavior: validator check fails, validationPassed stays false, returns unmodified result
+			expect(result.isValid).toBe(true);
+		});
+
+		test("custom_ValidatorReturnsNoMessage_UsesMessage", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [
+					{
+						type: "custom",
+						validator: () => ({ isValid: false }),
+						message: "Fallback message"
+					}
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Fallback message");
+		});
+
+		test("custom_ValidatorReturnsNoMessage_NoLessonMessage_DefaultMessage", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [
+					{
+						type: "custom",
+						validator: () => ({ isValid: false })
+					}
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.message).toContain("does not meet the requirements");
+		});
+	});
+
+	describe("CSS validation - unknown type", () => {
+		test("unknownType_WarnsAndContinues", () => {
+			const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+			const result = validateUserCode("color: red;", {
+				validations: [
+					{ type: "invented_type", value: "anything" },
+					{ type: "contains", value: "color: red" }
+				]
+			});
+			expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining("Unknown validation type"));
+			// The unknown type is skipped (continue), then the next validation passes
+			expect(result.isValid).toBe(true);
+			warnSpy.mockRestore();
+		});
+	});
+
+	describe("CSS validation - empty and whitespace input", () => {
+		test("emptyString_ContainsValidation_Fails", () => {
+			const result = validateUserCode("", {
+				validations: [{ type: "contains", value: "color" }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("whitespaceOnly_ContainsValidation_Fails", () => {
+			const result = validateUserCode("   \n\t  ", {
+				validations: [{ type: "contains", value: "color" }]
+			});
+			expect(result.isValid).toBe(false);
+		});
+
+		test("emptyString_NotContains_Passes", () => {
+			const result = validateUserCode("", {
+				validations: [{ type: "not_contains", value: "color" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+	});
+
+	describe("CSS validation - validCases and totalCases tracking", () => {
+		test("allPassingValidations_ValidCasesEqualsTotalCases", () => {
+			const result = validateUserCode("display: flex; color: red;", {
+				validations: [
+					{ type: "contains", value: "display: flex" },
+					{ type: "contains", value: "color: red" }
+				]
+			});
+			expect(result.isValid).toBe(true);
+			expect(result.validCases).toBe(2);
+			expect(result.totalCases).toBe(2);
+		});
+
+		test("firstValidationFails_ValidCasesIs0", () => {
+			const result = validateUserCode("color: red;", {
+				validations: [
+					{ type: "contains", value: "display: flex" },
+					{ type: "contains", value: "color: red" }
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.validCases).toBe(0);
+			expect(result.totalCases).toBe(2);
+		});
+
+		test("secondValidationFails_ValidCasesIs1", () => {
+			const result = validateUserCode("display: flex;", {
+				validations: [
+					{ type: "contains", value: "display: flex" },
+					{ type: "contains", value: "color: red" }
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.validCases).toBe(1);
+			expect(result.totalCases).toBe(2);
+		});
+	});
+
+	describe("CSS validation - special regex metacharacters in contains", () => {
+		test("contains_DotInValue_TreatedAsLiteral", () => {
+			// ".class" should match literally, not any char + "class"
+			const result = validateUserCode(".card { color: red; }", {
+				validations: [{ type: "contains", value: ".card" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+
+		test("contains_BracketsInValue_TreatedAsLiteral", () => {
+			const result = validateUserCode("content: '[test]';", {
+				validations: [{ type: "contains", value: "[test]" }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+	});
+
+	describe("HTML validation - deeply nested parent_child", () => {
+		test("parentChild_DeeplyNested_Passes", () => {
+			const html = "<div><section><article><p>Deep</p></article></section></div>";
+			const result = validateUserCode(html, {
+				mode: "html",
+				validations: [{ type: "parent_child", value: { parent: "div", child: "p" } }]
+			});
+			expect(result.isValid).toBe(true);
+		});
+	});
+
+	describe("HTML validation - validCases tracking", () => {
+		test("htmlAllPass_ValidCasesEqualsTotal", () => {
+			const result = validateUserCode("<h1>Title</h1><p>Content</p>", {
+				mode: "html",
+				validations: [
+					{ type: "element_exists", value: "h1" },
+					{ type: "element_exists", value: "p" }
+				]
+			});
+			expect(result.isValid).toBe(true);
+			expect(result.validCases).toBe(2);
+			expect(result.totalCases).toBe(2);
+		});
+
+		test("htmlPartialPass_EarlyReturn", () => {
+			const result = validateUserCode("<h1>Title</h1>", {
+				mode: "html",
+				validations: [
+					{ type: "element_exists", value: "h1" },
+					{ type: "element_exists", value: "p", message: "Need paragraph" }
+				]
+			});
+			expect(result.isValid).toBe(false);
+			expect(result.validCases).toBe(1);
+			expect(result.message).toBe("Need paragraph");
+		});
+	});
+});
--- a/tests/unit/validator.test.js
+++ b/tests/unit/validator.test.js
@@ -226,6 +226,86 @@ describe("CSS Validator", () => {
 	});
 });

+describe("JavaScript Validator", () => {
+	describe("validateUserCode with mode: javascript", () => {
+		it("should validate contains correctly for JavaScript", () => {
+			const userCode = 'const name = "Alice";';
+			const lesson = {
+				mode: "javascript",
+				validations: [{ type: "contains", value: "const", message: "Use const" }]
+			};
+
+			const result = validateUserCode(userCode, lesson);
+			expect(result.isValid).toBe(true);
+			expect(result.validCases).toBe(1);
+		});
+
+		it("should validate regex correctly for JavaScript", () => {
+			const userCode = 'const name = "Alice";';
+			const lesson = {
+				mode: "javascript",
+				validations: [{ type: "regex", value: 'const\\s+name\\s*=', message: "Declare name" }]
+			};
+
+			const result = validateUserCode(userCode, lesson);
+			expect(result.isValid).toBe(true);
+		});
+
+		it("should validate not_contains correctly for JavaScript", () => {
+			const userCode = 'const name = "Alice";';
+			const lesson = {
+				mode: "javascript",
+				validations: [{ type: "not_contains", value: "var", message: "Do not use var" }]
+			};
+
+			const result = validateUserCode(userCode, lesson);
+			expect(result.isValid).toBe(true);
+
+			const failCode = 'var name = "Alice";';
+			const failResult = validateUserCode(failCode, lesson);
+			expect(failResult.isValid).toBe(false);
+			expect(failResult.message).toBe("Do not use var");
+		});
+
+		it("should return invalid for missing code", () => {
+			const userCode = "";
+			const lesson = {
+				mode: "javascript",
+				validations: [{ type: "contains", value: "const", message: "Use const" }]
+			};
+
+			const result = validateUserCode(userCode, lesson);
+			expect(result.isValid).toBe(false);
+		});
+
+		it("should pass with no validations", () => {
+			const userCode = 'const x = 1;';
+			const lesson = { mode: "javascript" };
+
+			const result = validateUserCode(userCode, lesson);
+			expect(result.isValid).toBe(true);
+			expect(result.message).toContain("No validations specified");
+		});
+
+		it("should handle multiple validations with early return on failure", () => {
+			const userCode = 'const name = "Alice";';
+			const lesson = {
+				mode: "javascript",
+				validations: [
+					{ type: "contains", value: "const", message: "Use const" },
+					{ type: "contains", value: "let", message: "Use let" },
+					{ type: "contains", value: "name", message: "Declare name" }
+				]
+			};
+
+			const result = validateUserCode(userCode, lesson);
+			expect(result.isValid).toBe(false);
+			expect(result.message).toBe("Use let");
+			expect(result.validCases).toBe(1);
+		});
+	});
+});
+
 describe("HTML Validator", () => {
 	describe("validateUserCode with mode: html", () => {
 		it("should validate element_exists correctly", () => {
--- a/vite.config.js
+++ b/vite.config.js
@@ -3,6 +3,7 @@ import { defineConfig } from "vite";
 export default defineConfig((env) => ({
 	base: "/",
 	root: "./src",
+	envDir: "..",
 	publicDir: "../public",
 	build: {
 		outDir: "../dist",
--- a/wave.yaml
+++ b/wave.yaml
@@ -0,0 +1,376 @@
+adapters:
+    claude:
+        binary: claude
+        default_permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+            deny: []
+        mode: headless
+        output_format: json
+        project_files:
+            - CLAUDE.md
+            - .claude/settings.json
+apiVersion: v1
+kind: WaveManifest
+metadata:
+    description: An interactive platform for learning CSS through practical challenges
+    name: code-crispies
+ontology:
+    telos: Interactive self-learning platform for web technologies (CSS, HTML, JavaScript, Markdown)
+personas:
+    auditor:
+        adapter: claude
+        description: Security review and quality assurance
+        model: claude-haiku
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Grep
+                - Glob
+                - Bash
+            deny:
+                - Edit(*)
+                - Bash(rm -rf /*)
+                - Bash(git push*)
+                - Bash(git commit*)
+        system_prompt_file: .wave/personas/auditor.md
+        temperature: 0.1
+    craftsman:
+        adapter: claude
+        description: Code implementation and testing
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+            deny:
+                - Bash(rm -rf /*)
+        system_prompt_file: .wave/personas/craftsman.md
+        temperature: 0.7
+    debugger:
+        adapter: claude
+        description: Systematic debugging and root cause analysis
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Glob
+                - Grep
+                - Bash
+            deny:
+                - Edit(*)
+                - Bash(rm -rf /*)
+                - Bash(git push*)
+                - Bash(git commit*)
+        system_prompt_file: .wave/personas/debugger.md
+        temperature: 0.1
+    gitea-analyst:
+        adapter: claude
+        description: Gitea issue analysis and scanning
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Bash(tea issues view*)
+                - Bash(tea issues list*)
+                - Bash(tea releases list*)
+                - Bash(tea pulls view*)
+                - Bash(tea pulls list*)
+                - Bash(tea --version)
+                - Bash(git log*)
+                - Bash(git status*)
+                - Bash(ls *)
+            deny:
+                - Bash(tea issues edit*)
+                - Bash(tea issues create*)
+                - Bash(tea issues close*)
+                - Bash(gh *)
+                - Bash(glab *)
+                - Edit(*)
+        system_prompt_file: .wave/personas/gitea-analyst.md
+        temperature: 0.1
+    gitea-commenter:
+        adapter: claude
+        description: Posts comments on Gitea issues and pull requests
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Bash(tea issues comment*)
+                - Bash(tea pulls create*)
+                - Bash(tea --version)
+                - Bash(git push*)
+                - Bash(git status*)
+                - Bash(git log*)
+                - Bash(git remote*)
+                - Bash(git diff*)
+            deny:
+                - Bash(tea issues edit*)
+                - Bash(tea issues close*)
+                - Bash(tea pulls merge*)
+                - Bash(tea pulls close*)
+                - Bash(gh *)
+                - Bash(glab *)
+                - Edit(*)
+        system_prompt_file: .wave/personas/gitea-commenter.md
+        temperature: 0.2
+    gitea-enhancer:
+        adapter: claude
+        description: Gitea issue enhancement and improvement
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Bash(tea issues edit*)
+                - Bash(tea issues view*)
+                - Bash(tea --version)
+            deny:
+                - Bash(tea issues create*)
+                - Bash(tea issues close*)
+                - Bash(gh *)
+                - Bash(glab *)
+                - Edit(*)
+        system_prompt_file: .wave/personas/gitea-enhancer.md
+        temperature: 0.2
+    gitea-scoper:
+        adapter: claude
+        description: Gitea epic analysis, decomposition, and sub-issue creation
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Bash(tea issues create*)
+                - Bash(tea issues view*)
+                - Bash(tea issues list*)
+                - Bash(tea --version)
+            deny:
+                - Bash(tea issues edit*)
+                - Bash(tea issues close*)
+                - Bash(gh *)
+                - Bash(glab *)
+                - Edit(*)
+        system_prompt_file: .wave/personas/gitea-scoper.md
+        temperature: 0.1
+    implementer:
+        adapter: claude
+        description: Execution specialist for code changes and structured output
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+                - Glob
+                - Grep
+            deny:
+                - Bash(rm -rf /*)
+                - Bash(sudo *)
+        system_prompt_file: .wave/personas/implementer.md
+        temperature: 0.3
+    navigator:
+        adapter: claude
+        description: Read-only codebase exploration and analysis
+        model: claude-haiku
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Glob
+                - Grep
+                - Bash(git log*)
+                - Bash(git status*)
+            deny:
+                - Edit(*)
+                - Bash(git commit*)
+                - Bash(git push*)
+        system_prompt_file: .wave/personas/navigator.md
+        temperature: 0.1
+    philosopher:
+        adapter: claude
+        description: Architecture design and specification
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+                - Glob
+                - Grep
+            deny: []
+        system_prompt_file: .wave/personas/philosopher.md
+        temperature: 0.3
+    planner:
+        adapter: claude
+        description: Task breakdown and planning
+        model: claude-haiku
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+                - Glob
+                - Grep
+            deny: []
+        system_prompt_file: .wave/personas/planner.md
+        temperature: 0.2
+    provocateur:
+        adapter: claude
+        description: Creative challenger for divergent thinking and complexity hunting
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Glob
+                - Grep
+                - Bash(wc *)
+                - Bash(git log*)
+                - Bash(git diff*)
+                - Bash(find*)
+                - Bash(ls*)
+            deny:
+                - Edit(*)
+                - Bash(git commit*)
+                - Bash(git push*)
+                - Bash(rm*)
+        system_prompt_file: .wave/personas/provocateur.md
+        temperature: 0.8
+    researcher:
+        adapter: claude
+        description: Deep codebase research and analysis
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+                - Glob
+                - Grep
+                - WebSearch
+                - WebFetch
+            deny: []
+        system_prompt_file: .wave/personas/researcher.md
+        temperature: 0.1
+    reviewer:
+        adapter: claude
+        description: Code review and quality checks
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Glob
+                - Grep
+                - Bash
+            deny:
+                - Write(*.go)
+                - Write(*.ts)
+                - Write(*.py)
+                - Write(*.rs)
+                - Edit(*)
+                - Bash(rm *)
+                - Bash(git push*)
+                - Bash(git commit*)
+        system_prompt_file: .wave/personas/reviewer.md
+        temperature: 0.1
+    summarizer:
+        adapter: claude
+        description: Context compaction for relay handoffs
+        model: claude-haiku
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+                - Glob
+                - Grep
+            deny: []
+        system_prompt_file: .wave/personas/summarizer.md
+        temperature: 0
+    supervisor:
+        adapter: claude
+        description: Work supervision and quality evaluation
+        model: claude-opus
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Glob
+                - Grep
+                - Bash
+            deny:
+                - Edit(*)
+                - Bash(git push*)
+                - Bash(git commit*)
+                - Bash(rm*)
+        system_prompt_file: .wave/personas/supervisor.md
+        temperature: 0.2
+    synthesizer:
+        adapter: claude
+        description: Structured synthesis of analysis findings into actionable JSON proposals
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Edit
+                - Bash
+                - Glob
+                - Grep
+            deny: []
+        system_prompt_file: .wave/personas/synthesizer.md
+        temperature: 0.2
+    validator:
+        adapter: claude
+        description: Skeptical analysis and verification of findings against source code
+        permissions:
+            allowed_tools:
+                - Read
+                - Write
+                - Glob
+                - Grep
+                - Bash(wc *)
+                - Bash(git log*)
+                - Bash(git diff*)
+            deny:
+                - Edit(*)
+                - Bash(git commit*)
+                - Bash(git push*)
+                - Bash(rm*)
+        system_prompt_file: .wave/personas/validator.md
+        temperature: 0.1
+project:
+    build_command: npm run build
+    flavour: node
+    format_command: npm run format
+    language: javascript
+    lint_command: ""
+    skill: javascript
+    source_glob: '*.{js,jsx,ts,tsx}'
+    test_command: npm test
+runtime:
+    audit:
+        log_all_file_operations: false
+        log_all_tool_calls: true
+        log_dir: .wave/traces/
+    default_timeout_minutes: 30
+    max_concurrent_workers: 5
+    meta_pipeline:
+        max_depth: 2
+        max_total_steps: 20
+        max_total_tokens: 500000
+        timeout_minutes: 60
+    relay:
+        strategy: summarize_to_checkpoint
+        token_threshold_percent: 80
+    workspace_root: .wave/workspaces