a11y werkzeuge-folie überarbeitet: screenreader tabelle, orca/talkback, wcag-formulierungen

a11y folien feinschliff, input-date demo, tag-attribut demo update, synonyme
a11y vertiefung: keyboard-demo, input-devices, mdn-links vereinheitlicht
2026-04-21 23:38:06 +02:00 · 2026-04-21 23:32:30 +02:00 · 2026-04-21 20:58:52 +02:00 · 2026-04-21 19:43:11 +02:00 · 2026-04-21 19:35:19 +02:00 · 2026-04-20 18:26:50 +02:00
225 changed files with 10509 additions and 1808 deletions
@@ -2,6 +2,7 @@
 build/
 *.pdf
 *.html
+!slides/*/assets/demos/**/*.html
 .dev-index/

 # Dependencies
@@ -0,0 +1,197 @@
+# AGENTS.md - Agent Guidelines for HdM Slides
+
+This file contains comprehensive guidelines for agentic coding agents working on the HdM Slides project.
+
+## Project Overview
+
+This project builds presentation decks for Marp, supporting multiple courses:
+- **223015b** - Dateiformate, Schnittstellen, Speichermedien (6 Kapitel)
+- **223015c** - Internettechnologien (3 Kapitel)
+
+## Development Workflow
+
+### Build Commands
+```bash
+# Development
+make dev              # Start single dev server on port 3000
+npm run dev           # Alternative command for development server
+
+# Build
+make build            # Build all courses (HTML + PDF)
+make build-b          # Build 223015b only
+make build-c          # Build 223015c only
+make html             # HTML only builds
+make pdf              # PDF only builds
+
+# Klausur Folien
+make klausur          # Extract klausurfolien for all courses
+make klausur-b        # Extract klausurfolien for 223015b
+make klausur-c        # Extract klausurfolien for 223015c
+
+# Deployment
+make deploy            # Deploy all courses (requires explicit permission)
+make deploy-b         # Deploy 223015b only
+make deploy-c         # Deploy 223015c only
+
+# Utilities
+make qr URL=...       # Generate QR code
+make optimize-images COURSE=223015b  # Resize images
+make clean            # Remove generated files
+```
+
+### Testing
+No specific test framework is used. To validate changes:
+1. Start dev server: `make dev`
+2. Open http://localhost:3000/223015b/ or /223015c/
+3. Verify slides render correctly
+4. Run `make build` to ensure no build errors
+5. Check generated files in `build/` directory
+
+## Code Style Guidelines
+
+### File Structure
+- Slides in `slides/<course>/` following naming pattern `NN-topic.md`
+- Assets in `slides/<course>/assets/`
+- Always reference images as `./assets/filename.png`
+- Scripts in `scripts/`
+- Themes in `themes/`
+- Generated output in `build/` (gitignored)
+
+### Naming Conventions
+- Slide files: `NN-topic.md` (e.g., `01-grundlagen.md`, `02-bilder.md`)
+- Images: `snake_case.jpg` or `kebab-case.jpg`
+- Klausur files: `klausurfolien.md` (auto-generated)
+- Function names in scripts: `snake_case`
+- Variable names in scripts: `snake_case`
+
+### Markdown Style
+- Use ATX-style headers (`# ## ###`)
+- YAML frontmatter for slide metadata at top of each file
+- Never include a final `---` (creates empty slide)
+- Use `<!-- _class: klausur -->` for exam-relevant slides
+- Use relative paths for assets: `./assets/image.png`
+
+### Script Style
+- Use `#!/usr/bin/env bash` shebang
+- Use `set -e` for error handling
+- Use `2>/dev/null || true` for optional operations
+- Define variables in UPPER_CASE at script top
+- Use colors for terminal output: `\033[0;32m` etc.
+
+### Git Workflow
+- Commit messages: ALWAYS lowercase
+- NEVER add co-authoring lines or generated footers
+- Follow semantic naming: "add-...", "fix-...", "update-..."
+- Commit changes to scripts, Makefile, documentation separately from slide content
+
+## Agent Restrictions
+
+### Security
+- NEVER run commands outside `/home/mwc/Coding/hdm` folder
+- NEVER run build/deploy commands without explicit user request
+- NEVER run deploy commands (make deploy, scp, etc.) without explicit permission
+
+### File Protection
+Slide files in `slides/*/*.md` are main content files:
+- **ALLOWED**: Adding slides, adjusting content, fixing typos, enhancing sections
+- **FORBIDDEN** (without permission): Deleting slides, removing sections, bulk deletions
+- Before ANY deletion: ALWAYS ask user for confirmation
+
+### Klausur Handling
+- Klausur files (`klausurfolien.md`) are auto-generated
+- NEVER edit klausurfolien.md files directly
+- To update klausurfolien: edit source slides with `<!-- _class: klausur -->` markers
+- Run `make klausur` to regenerate
+
+## Development Patterns
+
+### Adding New Slides
+1. Create new file following `NN-topic.md` pattern
+2. Copy frontmatter from existing slides in the same course
+3. Update Makefile `_KAPITEL` variable if needed
+4. Test with `make dev`
+
+### Modifying Existing Slides
+1. Edit the appropriate markdown file in `slides/<course>/`
+2. Maintain consistent styling with course theme
+3. Preserve image paths as `./assets/...`
+4. Test changes with dev server
+
+### Working with Assets
+1. Place images in `slides/<course>/assets/`
+2. Use descriptive names: `diagram-network.jpg`, `example-code.png`
+3. Optimize with `make optimize-images COURSE=223015b`
+4. Reference as `./assets/filename.ext`
+
+### Course-Specific Configuration
+Each course has specific settings in Makefile:
+- Course name and title
+- Kapitel list (slide files)
+- Deploy path
+- Theme colors (in generate-index.sh)
+
+## Common Tasks
+
+### Debugging Build Issues
+1. Check Makefile syntax: `make -n build`
+2. Verify Marp CLI installation: `npx @marp-team/marp-cli --version`
+3. Check file permissions: `ls -la slides/`
+4. Validate markdown syntax with dev server
+
+### Updating Course Structure
+1. Update `_KAPITEL` variables in Makefile
+2. Ensure slide files follow naming convention
+3. Update course-specific themes if needed
+4. Test both dev and build processes
+
+### Working with Themes
+- Custom theme in `themes/custom-theme.css`
+- Course themes defined in individual slide frontmatter
+- Use consistent color schemes per course
+- Test theme changes across all slides
+
+## Deployment Process
+
+Deployment to production server requires explicit permission:
+1. Build process: `make build` (HTML + PDF)
+2. Index generation: automatically handled
+3. Deploy to remote server via SCP
+4. Root index deployment
+
+**IMPORTANT**: Never run deployment commands without explicit user permission.
+
+## Tools and Dependencies
+
+### Core Dependencies
+- Marp CLI for slide rendering
+- Bash scripts for automation
+- Make for build orchestration
+- Git for version control
+
+### Optional Tools
+- qrencode for QR generation (via nix)
+- ImageMagick for image optimization
+- Python 3 for simple HTTP server (legacy)
+
+## Testing Strategy
+
+Since there's no formal test suite:
+1. Manual testing with dev server
+2. Build process validation
+3. Slide rendering checks
+4. Asset path verification
+5. Cross-browser compatibility checks (important)
+
+## Troubleshooting
+
+### Common Issues
+- **Port conflicts**: Use `make dev-kill` to clean up processes
+- **Build failures**: Check file permissions and Marp CLI installation
+- **Asset loading**: Verify relative paths and file existence
+- **Deploy issues**: Check SSH keys and remote permissions
+
+### Getting Help
+1. Check this AGENTS.md file first
+2. Review Makefile targets and scripts
+3. Test changes incrementally
+4. Maintain backup of working configurations
@@ -12,6 +12,7 @@ This project builds presentation decks for Marp, supporting multiple courses.
 - Agent NEVER runs commands outside this folder
 - Agent NEVER runs build/deploy commands without explicit user request
 - Agent NEVER runs deploy commands (make deploy, scp, etc.) without explicit user permission
+- Agent NEVER runs `git checkout --` or `git restore` on files with uncommitted work. To undo specific changes, use targeted Edit operations instead.

 ## Critical File Protection

@@ -34,8 +35,9 @@ build/                  # Generated output (gitignored)
 ## Build Commands

 ```bash
-make dev-b          # Dev server 223015b (port 1311)
-make dev-c          # Dev server 223015c (port 1312)
+make dev            # Marp live server all courses (port 1312, HMR)
+make dev-b          # Marp live server 223015b (port 1313, HMR)
+make dev-c          # Marp live server 223015c (port 1314, HMR)
 make build          # Build all courses
 make build-b        # Build 223015b only
 make build-c        # Build 223015c only
@@ -48,10 +50,7 @@ make deploy         # Deploy all (ASK FIRST!)
 ## Nix Flake Commands

 ```bash
-nix develop                           # Dev shell with all tools
-nix run .#qr -- "https://example.com" # Generate QR code
-nix run .#qr-slides -- 223015b        # QR for course
-nix run .#optimize-img -- <path>      # Optimize images
+nix develop                           # Dev shell with all tools (node 22, npm, make)
 ```

 ## Code Style Guidelines
@@ -7,19 +7,13 @@
 COURSES = 223015b 223015c
 SLIDES_DIR = slides

-# Port configuration (index starts at BASE_PORT, courses increment from there)
-BASE_PORT = 1310
-INDEX_PORT = $(BASE_PORT)
-
 # Course-specific settings
 223015b_NAME = Dateiformate, Schnittstellen, Speichermedien
-223015b_PORT = 1311
-223015b_KAPITEL = 00-intro 01-grundlagen-text-audio 02-bild-audio-video 03-speichermedien-schnittstellen 04-distribution-apis-zukunft 05-vertiefung-offene-fragen klausur
+223015b_KAPITEL = 00-intro 01-grundlagen-text-audio 02-bild-audio-video 03-speichermedien-schnittstellen 04-distribution-apis-zukunft 05-vertiefung-offene-fragen klausurfolien klausurfragen
 223015b_DEPLOY_PATH = /home/tengo/html/hdm/223015b

 223015c_NAME = Internettechnologien
-223015c_PORT = 1312
-223015c_KAPITEL = 01-geschichte-grundlagen-html 02-netzwerke-protokolle-css 03-interaktivitaet-javascript klausur
+223015c_KAPITEL = 01-geschichte-grundlagen-html 02-netzwerke-protokolle-css 03-interaktivitaet-javascript klausurfolien klausurfragen
 223015c_DEPLOY_PATH = /home/tengo/html/hdm/223015c

 DEPLOY_HOST = tengo@tuttle.uberspace.de
@@ -33,9 +27,9 @@ help:
 	@echo "  223015c - Internettechnologien"
 	@echo ""
 	@echo "Development:"
-	@echo "  make dev         - Both servers + index (ports 1311, 1312, 1313)"
-	@echo "  make dev-b       - Dev server for 223015b (port 1312)"
-	@echo "  make dev-c       - Dev server for 223015c (port 1313)"
+	@echo "  make dev         - Marp live server all courses (port 1312, HMR)"
+	@echo "  make dev-b       - Marp live server 223015b (port 1313, HMR)"
+	@echo "  make dev-c       - Marp live server 223015c (port 1314, HMR)"
 	@echo ""
 	@echo "Build:"
 	@echo "  make build       - Build all courses"
@@ -43,7 +37,7 @@ help:
 	@echo "  make build-c     - Build 223015c only"
 	@echo "  make pdf         - Export all to PDF"
 	@echo "  make html        - Export all to HTML"
-	@echo "  make klausur     - Extract klausur slides"
+	@echo "  make klausur     - Extract klausurfolien slides"
 	@echo ""
 	@echo "Tools:"
 	@echo "  make qr URL=...  - Generate QR code for URL"
@@ -63,24 +57,20 @@ build/.exists:
 	@mkdir -p build/223015b build/223015c
 	@touch $@

-# Development servers
+# Development server (Marp live server with HMR)
 dev:
 	@./scripts/dev-server.sh

-dev-kill:
-	@-pkill -f "python3 -m http.server" 2>/dev/null || true
-	@-pkill -f "marp-cli.*--server" 2>/dev/null || true
-	@sleep 0.5
-
 dev-b:
-	@echo "Starting 223015b dev server on port $(223015b_PORT)..."
-	@echo "Open: http://localhost:$(223015b_PORT)"
-	PORT=$(223015b_PORT) npx @marp-team/marp-cli --server $(SLIDES_DIR)/223015b/
+	@./scripts/dev-server.sh 223015b 1313

 dev-c:
-	@echo "Starting 223015c dev server on port $(223015c_PORT)..."
-	@echo "Open: http://localhost:$(223015c_PORT)"
-	PORT=$(223015c_PORT) npx @marp-team/marp-cli --server $(SLIDES_DIR)/223015c/
+	@./scripts/dev-server.sh 223015c 1314
+
+dev-kill:
+	@-fuser -k 1312/tcp 2>/dev/null || true
+	@-fuser -k 1313/tcp 2>/dev/null || true
+	@-fuser -k 1314/tcp 2>/dev/null || true

 # Build functions
 define build_course
@@ -158,7 +148,7 @@ klausur-c:
 	@./scripts/extract-klausur.sh 223015c

 klausur: klausur-b klausur-c
-	@echo "Klausur slides extracted for all courses!"
+	@echo "Klausurfolien slides extracted for all courses!"

 # QR Code generation (uses nix-shell)
 qr:
@@ -198,7 +188,8 @@ HDM_DEPLOY_PATH = /home/tengo/html/hdm

 build-index: build/.exists
 	@echo "Building root index..."
-	@echo '<!DOCTYPE html><html lang="de"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width,initial-scale=1"><title>HdM Vorlesungen</title><style>*{box-sizing:border-box;margin:0;padding:0}body{font-family:-apple-system,BlinkMacSystemFont,"SF Pro Display","Segoe UI",Roboto,sans-serif;max-width:720px;margin:0 auto;padding:3rem 1.5rem;background:#fafafa;color:#1d1d1f;line-height:1.5}h1{font-size:2rem;font-weight:600;letter-spacing:-0.02em;margin-bottom:.5rem}.subtitle{color:#86868b;font-size:1rem}.courses{margin-top:2rem;display:flex;flex-direction:column;gap:.75rem}a.course{display:block;background:#fff;border-radius:12px;padding:1.5rem;text-decoration:none;color:inherit;box-shadow:0 1px 3px rgba(0,0,0,0.08);transition:all .2s ease;cursor:pointer}a.course:hover{transform:translateY(-2px);box-shadow:0 4px 12px rgba(0,0,0,0.12)}.course-label{font-size:.7rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em}.course-b .course-label{color:#1e5f8a}.course-c .course-label{color:#d63384}.course-title{font-size:1.15rem;font-weight:500;color:#1d1d1f;margin:.25rem 0}.course-info{font-size:.85rem;color:#86868b}.section-title{font-size:1rem;font-weight:600;color:#86868b;margin-top:2.5rem;margin-bottom:.75rem}.references{display:flex;flex-direction:column;gap:.75rem}footer{margin-top:2.5rem;padding-top:1.5rem;border-top:1px solid #e5e5e7;color:#86868b;font-size:.85rem}footer a{color:#1d1d1f;text-decoration:none}footer a:hover{text-decoration:underline}.qr-section{margin-top:2.5rem;padding:1.5rem;background:#fff;border-radius:12px;box-shadow:0 1px 3px rgba(0,0,0,0.08);text-align:center}.qr-code{width:100%;height:auto}.qr-url{margin-top:.75rem;font-size:.85rem;color:#86868b}</style></head><body><h1>HdM Vorlesungen</h1><p class="subtitle">Wintersemester 2025/26 · Michael Czechowski</p><div class="courses"><a class="course course-b" href="223015b/"><span class="course-label">223015b</span><div class="course-title">Dateiformate, Schnittstellen, Speichermedien & Distributionswege</div><span class="course-info">6 Kapitel · Modul "Technik 1"</span></a><a class="course course-c" href="223015c/"><span class="course-label">223015c</span><div class="course-title">Grundlagen IT- und Internettechnik</div><span class="course-info">3 Kapitel · Modul "Technik 1"</span></a></div><h2 class="section-title">Referenzen</h2><div class="references"><a class="course" href="https://codecrispi.es/"><span class="course-label">Plattform</span><div class="course-title">Code Crispies</div><span class="course-info">Selbstlernplattform</span></a></div><div class="qr-section"><img src="qr-root.svg" alt="QR Code" class="qr-code"><p class="qr-url">https://librete.ch/hdm/</p></div><footer><a href="mailto:mail@librete.ch">Kontakt</a></footer></body></html>' > build/index.html
+	@mkdir -p build
+	@./scripts/generate-root-index.sh

 # Deploy
 define deploy_course
@@ -27,10 +27,12 @@ build/                # Generated output (gitignored)
 ## Development

 ```bash
-# Start dev servers (hot reload)
-make dev              # All courses + index
-make dev-b            # 223015b only (port 1311)
-make dev-c            # 223015c only (port 1312)
+# Start development server (hot reload)
+make dev              # Single server for all courses (port 3000)
+
+# Access individual courses:
+# 223015b: http://localhost:3000/223015b/
+# 223015c: http://localhost:3000/223015c/
 ```

 ## Build
@@ -43,7 +45,7 @@ make html             # HTML only
 make pdf              # PDF only
 ```

-## Klausur Slides
+## Klausur Folien

 Extract exam-relevant slides (marked with `<!-- _class: klausur -->`) into a single file:

@@ -53,7 +55,7 @@ make klausur-b        # 223015b only
 make klausur-c        # 223015c only
 ```

-Output: `slides/<course>/klausur.md`
+Output: `slides/<course>/klausurfolien.md`

 The generated file includes:
 - A title slide per kapitel for orientation
@@ -1,5 +1,5 @@
 {
-  description = "HdM Slides - Marp presentation builder with tools";
+  description = "HdM Slides - Marp presentation builder";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
@@ -9,114 +9,19 @@
  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
-        pkgs = nixpkgs.legacyPackages.${system};
-
-        # QR code generator script
-        qr-gen = pkgs.writeShellScriptBin "qr" ''
-          if [ -z "$1" ]; then
-            echo "Usage: qr <url> [output.png]"
-            echo ""
-            echo "Examples:"
-            echo "  qr https://example.com"
-            echo "  qr https://example.com my-qr.png"
-            echo "  qr 'https://librete.ch/hdm/223015b/' slides-qr.png"
-            exit 1
-          fi
-
-          URL="$1"
-          OUTPUT="''${2:-qr-code.png}"
-
-          ${pkgs.qrencode}/bin/qrencode -o "$OUTPUT" -s 10 -m 2 "$URL"
-          echo "Generated: $OUTPUT"
-        '';
-
-        # QR code for course slides
-        qr-slides = pkgs.writeShellScriptBin "qr-slides" ''
-          COURSE="''${1:-223015b}"
-          OUTPUT="''${2:-build/$COURSE/qr-$COURSE.png}"
-
-          mkdir -p "$(dirname "$OUTPUT")"
-          ${pkgs.qrencode}/bin/qrencode -o "$OUTPUT" -s 10 -m 2 "https://librete.ch/hdm/$COURSE/"
-          echo "Generated QR for $COURSE: $OUTPUT"
-        '';
-
-        # Image optimizer script
-        optimize-img = pkgs.writeShellScriptBin "optimize-img" ''
-          if [ -z "$1" ]; then
-            echo "Usage: optimize-img <image-or-directory> [max-width]"
-            echo ""
-            echo "Resizes images to max width (default: 1920px)"
-            exit 1
-          fi
-
-          TARGET="$1"
-          MAX_WIDTH="''${2:-1920}"
-
-          if [ -d "$TARGET" ]; then
-            for img in "$TARGET"/*.{png,jpg,jpeg,webp} 2>/dev/null; do
-              [ -f "$img" ] || continue
-              echo "Optimizing: $(basename "$img")"
-              ${pkgs.imagemagick}/bin/magick "$img" -resize "''${MAX_WIDTH}x>" -quality 85 "$img"
-            done
-          elif [ -f "$TARGET" ]; then
-            echo "Optimizing: $TARGET"
-            ${pkgs.imagemagick}/bin/magick "$TARGET" -resize "''${MAX_WIDTH}x>" -quality 85 "$TARGET"
-          else
-            echo "Error: $TARGET not found"
-            exit 1
-          fi
-          echo "Done!"
-        '';
-
+        pkgs = import nixpkgs { inherit system; };
      in {
-        # Development shell with all tools
        devShells.default = pkgs.mkShell {
          buildInputs = with pkgs; [
-            nodejs_20
+            nodejs_22
            nodePackages.npm
-            qrencode
-            imagemagick
            gnumake
          ];

          shellHook = ''
-            echo "HdM Slides Development Environment"
-            echo ""
-            echo "Available commands:"
-            echo "  make dev-b     - Start 223015b dev server (port 1312)"
-            echo "  make dev-c     - Start 223015c dev server (port 1313)"
-            echo "  make build     - Build all courses"
-            echo "  qr <url>       - Generate QR code"
-            echo "  qr-slides 223015b - Generate QR for course"
-            echo "  optimize-img <dir> - Optimize images"
-            echo ""
+            echo "HdM Slides - run 'make' for available commands"
          '';
        };
-
-        # Standalone apps
-        packages = {
-          qr = qr-gen;
-          qr-slides = qr-slides;
-          optimize-img = optimize-img;
-          default = qr-gen;
-        };
-
-        # Direct runnable apps
-        apps = {
-          qr = {
-            type = "app";
-            program = "${qr-gen}/bin/qr";
-          };
-          qr-slides = {
-            type = "app";
-            program = "${qr-slides}/bin/qr-slides";
-          };
-          optimize-img = {
-            type = "app";
-            program = "${optimize-img}/bin/optimize-img";
-          };
-          default = self.apps.${system}.qr;
-        };
      }
    );
 }
@@ -3,13 +3,14 @@
  "version": "1.0.0",
  "description": "HdM Stuttgart - Lecture Slides (Marp)",
  "scripts": {
-    "dev:b": "PORT=1312 marp --server --allow-local-files courses/223015b/slides/",
-    "dev:c": "PORT=1313 marp --server --allow-local-files courses/223015c/slides/",
+    "dev": "PORT=3000 marp --server --allow-local-files slides/",
    "build": "make build",
    "build:b": "make build-b",
    "build:c": "make build-c",
    "pdf": "make pdf",
    "html": "make html",
+    "klausur": "make klausur",
+    "deploy": "make deploy",
    "test": "echo \"No tests specified\" && exit 0"
  },
  "keywords": ["marp", "slides", "hdm", "lectures"],
@@ -1,106 +1,44 @@
 #!/usr/bin/env bash
-# Development server script for HdM slides
-# Starts index server + marp servers for each course
+# Development server for HdM slides
+# Usage:
+#   ./dev-server.sh              - Marp live server for all courses (port 1312)
+#   ./dev-server.sh 223015b 1313 - Marp live server for single course
+#   ./dev-server.sh 223015c 1314 - Marp live server for single course

 set -e

 # Configuration
-INDEX_PORT=1310
-COURSE_B_PORT=1311
-COURSE_C_PORT=1312
 SLIDES_DIR="slides"
-DEV_INDEX_DIR=".dev-index"
+COURSE="${1:-}"
+DEV_PORT="${2:-1312}"

 # Colors
-RED='\033[0;31m'
 GREEN='\033[0;32m'
 BLUE='\033[0;34m'
+RED='\033[0;31m'
 NC='\033[0m' # No Color

-# Cleanup function
-cleanup() {
-    echo -e "\n${RED}Shutting down servers...${NC}"
-    kill $PID_INDEX $PID_B $PID_C 2>/dev/null || true
-    exit 0
-}
-
-# Kill existing processes on our ports
-kill_existing() {
-    echo -e "${BLUE}Cleaning up existing processes...${NC}"
-    # Kill marp processes first
-    pkill -9 -f "marp-cli" 2>/dev/null || true
-    pkill -f "python3 -m http.server" 2>/dev/null || true
-    # Kill ports including marp's WebSocket ports (37717-37720 range)
-    fuser -k $INDEX_PORT/tcp $COURSE_B_PORT/tcp $COURSE_C_PORT/tcp 2>/dev/null || true
-    fuser -k 37717/tcp 37718/tcp 37719/tcp 37720/tcp 2>/dev/null || true
-    sleep 2
-}
-
-# Generate dev index
-generate_index() {
-    mkdir -p "$DEV_INDEX_DIR"
-    cat > "$DEV_INDEX_DIR/index.html" << 'EOF'
-<!DOCTYPE html>
-<html lang="de">
-<head>
-  <meta charset="UTF-8">
-  <meta name="viewport" content="width=device-width,initial-scale=1">
-  <title>HdM Slides - Dev</title>
-  <style>
-    *{box-sizing:border-box;margin:0;padding:0}
-    body{font-family:-apple-system,BlinkMacSystemFont,"SF Pro Display","Segoe UI",Roboto,sans-serif;max-width:720px;margin:0 auto;padding:3rem 1.5rem;background:#fafafa;color:#1d1d1f;line-height:1.5}
-    h1{font-size:2rem;font-weight:600;letter-spacing:-0.02em;margin-bottom:.5rem}
-    .subtitle{color:#86868b;font-size:1rem}
-    .courses{margin-top:2rem;display:flex;flex-direction:column;gap:.75rem}
-    a.course{display:block;background:#fff;border-radius:12px;padding:1.5rem;text-decoration:none;color:inherit;box-shadow:0 1px 3px rgba(0,0,0,0.08);transition:all .2s ease;cursor:pointer}
-    a.course:hover{transform:translateY(-2px);box-shadow:0 4px 12px rgba(0,0,0,0.12)}
-    .course-label{font-size:.7rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em}
-    .course-b .course-label{color:#1e5f8a}
-    .course-c .course-label{color:#d63384}
-    .course-title{font-size:1.15rem;font-weight:500;color:#1d1d1f;margin:.25rem 0}
-    .course-info{font-size:.85rem;color:#86868b}
-  </style>
-</head>
-<body>
-  <h1>HdM Slides</h1>
-  <p class="subtitle">Development Server</p>
-  <div class="courses">
-EOF
-    echo "    <a class=\"course course-b\" href=\"http://localhost:$COURSE_B_PORT\"><span class=\"course-label\">223015b</span><div class=\"course-title\">Dateiformate, Schnittstellen, Speichermedien & Distributionswege</div><span class=\"course-info\">Port $COURSE_B_PORT</span></a>" >> "$DEV_INDEX_DIR/index.html"
-    echo "    <a class=\"course course-c\" href=\"http://localhost:$COURSE_C_PORT\"><span class=\"course-label\">223015c</span><div class=\"course-title\">Grundlagen IT- und Internettechnik</div><span class=\"course-info\">Port $COURSE_C_PORT</span></a>" >> "$DEV_INDEX_DIR/index.html"
-    cat >> "$DEV_INDEX_DIR/index.html" << 'EOF'
-  </div>
-</body>
-</html>
-EOF
+# Kill existing process on our port only
+kill_port() {
+    fuser -k "$DEV_PORT/tcp" 2>/dev/null || true
+    sleep 0.5
 }

 # Main
-trap cleanup SIGINT SIGTERM
+trap 'echo -e "\n${RED}Shutting down...${NC}"; kill 0; exit 0' SIGINT SIGTERM

-kill_existing
-generate_index
+kill_port

-echo -e "${GREEN}Starting development servers...${NC}"
-echo ""
-echo -e "  Index:    ${BLUE}http://localhost:$INDEX_PORT${NC}"
-echo -e "  223015b:  ${BLUE}http://localhost:$COURSE_B_PORT${NC}"
-echo -e "  223015c:  ${BLUE}http://localhost:$COURSE_C_PORT${NC}"
-echo ""
-echo -e "Press ${RED}Ctrl+C${NC} to stop all servers"
+if [ -n "$COURSE" ]; then
+    SERVE_DIR="$SLIDES_DIR/$COURSE"
+    echo -e "${GREEN}Marp dev server${NC} · ${BLUE}$COURSE${NC}"
+else
+    SERVE_DIR="$SLIDES_DIR"
+    echo -e "${GREEN}Marp dev server${NC} · ${BLUE}all courses${NC}"
+fi
+
+echo -e "  ${BLUE}http://localhost:$DEV_PORT${NC}"
+echo -e "  ${BLUE}$SERVE_DIR/${NC}"
 echo ""

-# Start servers
-python3 -m http.server $INDEX_PORT --directory "$DEV_INDEX_DIR" &
-PID_INDEX=$!
-
-PORT=$COURSE_B_PORT npx @marp-team/marp-cli --server "$SLIDES_DIR/223015b/" &
-PID_B=$!
-
-sleep 3  # Stagger starts to avoid WebSocket port collision
-
-PORT=$COURSE_C_PORT npx @marp-team/marp-cli --server "$SLIDES_DIR/223015c/" &
-PID_C=$!
-
-# Wait for any process to exit
-wait
+PORT=$DEV_PORT exec npx @marp-team/marp-cli --server "$SERVE_DIR/"
@@ -1,19 +1,19 @@
 #!/usr/bin/env bash
 # Extract klausur-relevant slides from all kapitel
 # Usage: ./extract-klausur.sh <course_id>
-# Output: slides/<course>/klausur.md
+# Output: slides/<course>/klausurfolien.md

 set -e

 COURSE="${1:-223015b}"
 SLIDES_DIR="slides/$COURSE"
-OUTPUT_FILE="$SLIDES_DIR/klausur.md"
+OUTPUT_FILE="$SLIDES_DIR/klausurfolien.md"

-# Find the first kapitel file (01-*.md) to copy styles from
-FIRST_KAPITEL=$(ls "$SLIDES_DIR"/01-*.md 2>/dev/null | head -1)
+# Find the first kapitel file (00-intro.md or 01-*.md) to copy styles from
+FIRST_KAPITEL=$(ls "$SLIDES_DIR"/00-intro.md "$SLIDES_DIR"/01-*.md 2>/dev/null | head -1)

 if [[ -z "$FIRST_KAPITEL" ]]; then
-  echo "Error: No 01-*.md file found in $SLIDES_DIR"
+  echo "Error: No 00-intro.md or 01-*.md file found in $SLIDES_DIR"
  exit 1
 fi

@@ -57,7 +57,7 @@ awk '
 ' "$FIRST_KAPITEL" >> "$OUTPUT_FILE"

 # Process each kapitel file in order - extract klausur slides only
-for md_file in $(ls "$SLIDES_DIR"/[0-9][0-9]-*.md 2>/dev/null | grep -v klausur | sort); do
+for md_file in $(ls "$SLIDES_DIR"/[0-9][0-9]-*.md 2>/dev/null | grep -v klausurfolien | sort); do
  filename=$(basename "$md_file")
  kapitel_num=$(echo "$filename" | grep -oE '^[0-9]+' | sed 's/^0*//')

@@ -42,6 +42,15 @@ TOPIC_MAP["geschichte-grundlagen-html"]="Geschichte, Grundlagen & HTML"
 TOPIC_MAP["netzwerke-protokolle-css"]="Netzwerke, Protokolle & CSS"
 TOPIC_MAP["interaktivitaet-javascript"]="Interaktivität & JavaScript"

+# Configure which topics should appear disabled per course
+# Two modes: fully disabled (non-clickable card) and buttons-disabled (link remains clickable, buttons are disabled)
+declare -A DISABLED_FULL
+declare -A DISABLED_BUTTONS
+# For course B: chapters 3,4,5 should be fully disabled
+DISABLED_FULL["223015b"]="speichermedien-schnittstellen distribution-apis-zukunft vertiefung-offene-fragen"
+# For course C: chapter 3 should keep link clickable but buttons disabled
+DISABLED_BUTTONS["223015c"]="interaktivitaet-javascript"
+
 cat > "$BUILD_DIR/index.html" << HEADER
 <!DOCTYPE html>
 <html lang="de">
@@ -61,6 +70,15 @@ cat > "$BUILD_DIR/index.html" << HEADER
      line-height: 1.5;
    }
    header { margin-bottom: 2rem; }
+    .breadcrumb {
+      margin-bottom: 1rem;
+      font-size: 0.85rem;
+    }
+    .breadcrumb a {
+      color: #86868b;
+      text-decoration: none;
+    }
+    .breadcrumb a:hover { text-decoration: underline; }
    h1 {
      font-size: 1.75rem;
      font-weight: 600;
@@ -68,6 +86,12 @@ cat > "$BUILD_DIR/index.html" << HEADER
      margin-bottom: 0.5rem;
      color: $ACCENT_COLOR;
    }
+    .course-heading {
+      font-size: 1.25rem;
+      font-weight: 500;
+      color: #1d1d1f;
+      margin-bottom: 0.25rem;
+    }
    .subtitle {
      color: #86868b;
      font-size: 0.95rem;
@@ -77,7 +101,8 @@ cat > "$BUILD_DIR/index.html" << HEADER
      font-size: 0.875rem;
      margin-top: 0.25rem;
    }
-    .kapitel {
+    /* Use the .termine wrapper and add a gap between cards */
+    .termine {
      margin-top: 1.5rem;
      display: flex;
      flex-direction: column;
@@ -93,6 +118,7 @@ cat > "$BUILD_DIR/index.html" << HEADER
      grid-template-columns: 1fr auto auto;
      align-items: center;
      gap: 1rem;
+      padding: 0; /* inner padding handled by kapitel-link */
    }
    .kapitel-card:hover {
      transform: translateY(-2px);
@@ -105,6 +131,8 @@ cat > "$BUILD_DIR/index.html" << HEADER
      color: inherit;
      grid-column: 1;
    }
+    /* Disabled look: dim the entire card and prevent pointer events */
+    .kapitel-card.disabled { opacity: 0.6; pointer-events: none; }
    .kapitel-label {
      font-size: 0.7rem;
      font-weight: 600;
@@ -135,11 +163,11 @@ cat > "$BUILD_DIR/index.html" << HEADER
      white-space: nowrap;
      position: relative;
      z-index: 1;
+      margin-right: 0.5rem;
    }
    .btn-slides {
      background: $ACCENT_COLOR;
      color: #fff;
-      margin-right: 0.5rem;
    }
    .btn-slides:hover {
      filter: brightness(1.1);
@@ -147,9 +175,9 @@ cat > "$BUILD_DIR/index.html" << HEADER
    .btn-pdf {
      background: #f5f5f7;
      color: #1d1d1f;
-      margin-right: 1rem;
    }
    .btn-pdf:hover { background: #e8e8ed; }
+    .btn-disabled { opacity: 0.6; pointer-events: none; }
    /* Make entire card clickable via overlay */
    .kapitel-link::after {
      content: '';
@@ -198,9 +226,11 @@ cat > "$BUILD_DIR/index.html" << HEADER
 </head>
 <body>
  <header>
-    <h1>$TITLE</h1>
+    <p class="breadcrumb"><a href="../">← Kursübersicht</a></p>
+    <h1>HdM Vorlesungen</h1>
+    <h2 class="course-heading">$TITLE</h2>
    <p class="subtitle">$SUBTITLE</p>
-    <p class="meta">HdM Stuttgart · Wintersemester 2025/26 · Michael Czechowski</p>
+    <p class="meta">HdM Stuttgart · Sommersemester 2026 · Michael Czechowski</p>
  </header>
  <div class="termine">
 HEADER
@@ -216,7 +246,7 @@ for html in $(ls "$BUILD_DIR"/[0-9][0-9]-*.html 2>/dev/null | sort); do
  # Look up nice topic name or fallback
  topic="${TOPIC_MAP[$topic_raw]}"
  if [[ -z "$topic" ]]; then
-    topic=$(echo "$topic_raw" | sed 's/-/ /g' | sed 's/.*/\u&/')
+    topic=$(echo "$topic_raw" | sed 's/-/ /g' | sed 's/.*/\\u&/')
  fi

  # Handle kapitel number
@@ -228,42 +258,108 @@ for html in $(ls "$BUILD_DIR"/[0-9][0-9]-*.html 2>/dev/null | sort); do

  pdf_filename="${filename%.html}.pdf"

-  # Check if PDF exists
-  pdf_link=""
-  if [[ -f "$BUILD_DIR/$pdf_filename" ]]; then
-    pdf_link="<a href=\"$pdf_filename\" class=\"btn btn-pdf\">PDF</a>"
+  # Determine whether this topic is configured as disabled for this course
+  disabled_full=false
+  disabled_buttons=false
+  for t in ${DISABLED_FULL["$COURSE"]}; do
+    if [[ "$topic_raw" == "$t" ]]; then
+      disabled_full=true
+      break
+    fi
+  done
+  if [[ "$disabled_full" == false ]]; then
+    for t in ${DISABLED_BUTTONS["$COURSE"]}; do
+      if [[ "$topic_raw" == "$t" ]]; then
+        disabled_buttons=true
+        break
+      fi
+    done
+  fi
+
+  # Decide card class
+  card_class="kapitel-card"
+  if [[ "$disabled_full" == true ]] || [[ "$disabled_buttons" == true ]]; then
+    card_class="$card_class disabled"
+  fi
+
+  # Build link/button HTML depending on disabled state
+  if [[ "$disabled_full" == true ]]; then
+    # non-interactive card (visually dimmed and not clickable)
+    link_html="<div class=\"kapitel-link\"><div class=\"kapitel-label\">$kapitel_label</div><div class=\"kapitel-title\">$topic</div></div>"
+    slides_html="<span class=\"btn btn-slides btn-disabled\">Folien</span>"
+    pdf_html=""
+    if [[ -f "$BUILD_DIR/$pdf_filename" ]]; then
+      pdf_html="<span class=\"btn btn-pdf btn-disabled\">PDF</span>"
+    fi
+  elif [[ "$disabled_buttons" == true ]]; then
+    # link stays clickable, but buttons are disabled; card appears dimmed
+    link_html="<a href=\"$filename\" class=\"kapitel-link\"><div class=\"kapitel-label\">$kapitel_label</div><div class=\"kapitel-title\">$topic</div></a>"
+    slides_html="<span class=\"btn btn-slides btn-disabled\">Folien</span>"
+    pdf_html=""
+    if [[ -f "$BUILD_DIR/$pdf_filename" ]]; then
+      pdf_html="<span class=\"btn btn-pdf btn-disabled\">PDF</span>"
+    fi
+  else
+    # normal interactive card
+    pdf_link=""
+    if [[ -f "$BUILD_DIR/$pdf_filename" ]]; then
+      pdf_link="<a href=\"$pdf_filename\" class=\"btn btn-pdf\">PDF</a>"
+    fi
+    link_html="<a href=\"$filename\" class=\"kapitel-link\"><div class=\"kapitel-label\">$kapitel_label</div><div class=\"kapitel-title\">$topic</div></a>"
+    slides_html="<a href=\"$filename\" class=\"btn btn-slides\">Folien</a>"
+    pdf_html="$pdf_link"
  fi

  cat >> "$BUILD_DIR/index.html" << LINK
-    <div class="kapitel-card">
-      <a href="$filename" class="kapitel-link">
-        <div class="kapitel-label">$kapitel_label</div>
-        <div class="kapitel-title">$topic</div>
-      </a>
-      <a href="$filename" class="btn btn-slides">Folien</a>
-      $pdf_link
+    <div class="$card_class">
+      $link_html
+      $slides_html
+      $pdf_html
    </div>
 LINK
+
 done

-# Add klausur entry if it exists
-if [[ -f "$BUILD_DIR/klausur.html" ]]; then
-  pdf_link=""
-  if [[ -f "$BUILD_DIR/klausur.pdf" ]]; then
-    pdf_link="<a href=\"klausur.pdf\" class=\"btn btn-pdf\">PDF</a>"
+# Add klausurfolien entry if it exists (disabled — wird noch überarbeitet)
+if [[ -f "$BUILD_DIR/klausurfolien.html" ]]; then
+  pdf_disabled=""
+  if [[ -f "$BUILD_DIR/klausurfolien.pdf" ]]; then
+    pdf_disabled="<span class=\"btn btn-pdf btn-disabled\">PDF</span>"
  fi
  cat >> "$BUILD_DIR/index.html" << KLAUSUR
-    <div class="kapitel-card" style="border-left: 3px solid $ACCENT_COLOR;">
-      <a href="klausur.html" class="kapitel-link">
+    <div class="kapitel-card disabled" style="border-left: 3px solid $ACCENT_COLOR;">
+      <div class="kapitel-link">
        <div class="kapitel-label">Prüfung</div>
        <div class="kapitel-title">Klausurrelevante Folien</div>
-      </a>
-      <a href="klausur.html" class="btn btn-slides">Folien</a>
-      $pdf_link
+      </div>
+      <span class="btn btn-slides btn-disabled">Folien</span>
+      $pdf_disabled
    </div>
 KLAUSUR
 fi

+# Add klausurfragen entry if it exists (disabled — wird noch überarbeitet)
+if [[ -f "$BUILD_DIR/klausurfragen.html" ]] || [[ -f "$BUILD_DIR/klausurfragen.pdf" ]]; then
+  pdf_disabled=""
+  if [[ -f "$BUILD_DIR/klausurfragen.pdf" ]]; then
+    pdf_disabled="<span class=\"btn btn-pdf btn-disabled\">PDF</span>"
+  fi
+  slides_disabled=""
+  if [[ -f "$BUILD_DIR/klausurfragen.html" ]]; then
+    slides_disabled="<span class=\"btn btn-slides btn-disabled\">Folien</span>"
+  fi
+  cat >> "$BUILD_DIR/index.html" << KLAUSURFRAGEN
+    <div class="kapitel-card disabled" style="border-left: 3px solid $ACCENT_COLOR;">
+      <div class="kapitel-link">
+        <div class="kapitel-label">Prüfung</div>
+        <div class="kapitel-title">Klausurfragen</div>
+      </div>
+      $slides_disabled
+      $pdf_disabled
+    </div>
+KLAUSURFRAGEN
+fi
+
 cat >> "$BUILD_DIR/index.html" << FOOTER
  </div>
  <div class="qr-section">
@@ -272,7 +368,7 @@ cat >> "$BUILD_DIR/index.html" << FOOTER
  </div>
  <footer>
    <a href="mailto:mail@librete.ch">Kontakt</a> ·
-    <a href="../">Alle Kurse</a>
+    <a href="../">Kursübersicht</a>
  </footer>
 </body>
 </html>
@@ -0,0 +1,158 @@
+#!/usr/bin/env bash
+# Generate root index.html for HdM slides overview
+# Usage: ./generate-root-index.sh
+
+BUILD_DIR="${1:-build}"
+
+cat > "$BUILD_DIR/index.html" << 'HEADER'
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>HdM Vorlesungen</title>
+  <style>
+    * { box-sizing: border-box; margin: 0; padding: 0; }
+    body {
+      font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, sans-serif;
+      max-width: 720px;
+      margin: 0 auto;
+      padding: 3rem 1.5rem;
+      background: #fafafa;
+      color: #1d1d1f;
+      line-height: 1.5;
+    }
+    h1 {
+      font-size: 2rem;
+      font-weight: 600;
+      letter-spacing: -0.02em;
+      margin-bottom: 0.5rem;
+    }
+    .subtitle { color: #86868b; font-size: 1rem; }
+    .courses {
+      margin-top: 2rem;
+      display: flex;
+      flex-direction: column;
+      gap: 0.75rem;
+    }
+    .course-card {
+      position: relative;
+      background: #fff;
+      border-radius: 12px;
+      box-shadow: 0 1px 3px rgba(0,0,0,0.08);
+      transition: all 0.2s ease;
+      display: grid;
+      grid-template-columns: 1fr auto auto;
+      align-items: center;
+      gap: 1rem;
+    }
+    .course-card:hover {
+      transform: translateY(-2px);
+      box-shadow: 0 4px 12px rgba(0,0,0,0.12);
+    }
+    .course-link {
+      display: block;
+      padding: 1.25rem 1.5rem;
+      text-decoration: none;
+      color: inherit;
+      grid-column: 1;
+    }
+    .course-link::after {
+      content: '';
+      position: absolute;
+      inset: 0;
+      border-radius: 12px;
+    }
+    .course-label {
+      font-size: 0.7rem;
+      font-weight: 600;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+    }
+    .course-b .course-label { color: #1e5f8a; }
+    .course-c .course-label { color: #d63384; }
+    .course-title {
+      font-size: 1.15rem;
+      font-weight: 500;
+      color: #1d1d1f;
+      margin: 0.25rem 0;
+    }
+    .course-info { font-size: 0.85rem; color: #86868b; }
+    .section-title {
+      font-size: 1rem;
+      font-weight: 600;
+      color: #86868b;
+      margin-top: 2.5rem;
+      margin-bottom: 0.75rem;
+    }
+    .references {
+      display: flex;
+      flex-direction: column;
+      gap: 0.75rem;
+    }
+    footer {
+      margin-top: 2.5rem;
+      padding-top: 1.5rem;
+      border-top: 1px solid #e5e5e7;
+      color: #86868b;
+      font-size: 0.85rem;
+    }
+    footer a { color: #1d1d1f; text-decoration: none; }
+    footer a:hover { text-decoration: underline; }
+    .qr-section {
+      margin-top: 2.5rem;
+      padding: 1.5rem;
+      background: #fff;
+      border-radius: 12px;
+      box-shadow: 0 1px 3px rgba(0,0,0,0.08);
+      text-align: center;
+    }
+    .qr-code { width: 100%; height: auto; }
+    .qr-url { margin-top: 0.75rem; font-size: 0.85rem; color: #86868b; }
+    @media (max-width: 600px) {
+      .course-card { grid-template-columns: 1fr; }
+      .course-link { padding-bottom: 0.75rem; }
+    }
+  </style>
+</head>
+<body>
+  <h1>HdM Vorlesungen</h1>
+  <p class="subtitle">Sommersemester 2026 · Michael Czechowski</p>
+  <div class="courses">
+    <div class="course-card course-b">
+      <a href="223015b/" class="course-link">
+        <span class="course-label">223015b</span>
+        <div class="course-title">Dateiformate, Schnittstellen, Speichermedien &amp; Distributionswege</div>
+        <span class="course-info">6 Kapitel · Modul &quot;Technik 1&quot;</span>
+      </a>
+    </div>
+    <div class="course-card course-c">
+      <a href="223015c/" class="course-link">
+        <span class="course-label">223015c</span>
+        <div class="course-title">Grundlagen IT- und Internettechnik</div>
+        <span class="course-info">3 Kapitel · Modul &quot;Technik 1&quot;</span>
+      </a>
+    </div>
+  </div>
+  <h2 class="section-title">Referenzen</h2>
+  <div class="references">
+    <div class="course-card">
+      <a href="https://codecrispi.es/" class="course-link">
+        <span class="course-label">Plattform</span>
+        <div class="course-title">Code Crispies</div>
+        <span class="course-info">Selbstlernplattform</span>
+      </a>
+    </div>
+  </div>
+  <div class="qr-section">
+    <img src="qr-root.svg" alt="QR Code" class="qr-code">
+    <p class="qr-url">https://librete.ch/hdm/</p>
+  </div>
+  <footer>
+    <a href="mailto:mail@librete.ch">Kontakt</a>
+  </footer>
+</body>
+</html>
+HEADER
+
+echo "Generated $BUILD_DIR/index.html"
@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Dateiformate, Schnittstellen, Speichermedien & Distributionswege (223015b)"
-footer: "Michael Czechowski – HdM Stuttgart – WS 2025/26"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---

@@ -82,173 +82,109 @@ section.aufgabe footer {
 Digital- und Medienwirtschaft
 Hochschule der Medien Stuttgart

-**Wintersemester 2025/26**
+**Sommersemester 2026**

 [https://librete.ch/hdm/223015b/](https://librete.ch/hdm/223015b/)

 ---

+<!-- _header: '' -->
+<!-- _footer: '' -->
+
 ![bg fit](./assets/qrcode-0.svg)

 ---

 <!-- _class: lead -->

-# Willkommen!
+# Herzlich willkommen!
 ## Einführung

 ---

 # Über mich

-**Michael Czechowski**
+**Michael Werner Czechowski**

- Irgendwas mit IT, Cloud und AI
+- Systems and Platform Engineer
 - Schwerpunkte:
  - Web-Technologien, Barriere-Armut, Systemarchitektur, Open Source
 - Hintergrund:
-  - Philosophie (Uni Stuttgart) -> NO degree
-  - Wirtschafts-Informatik (Leibniz-FH) -> B.Sc.
+  - Philosophie (Uni Stuttgart)
+  - Wirtschaftsinformatik (Leibniz-FH Hannover)
 - Kontakt: lb-czechowski@hdm-stuttgart.de

+---
+
+# Warum dieses Modul?
+
+**Digitale Medien sind überall.**
+
+* Warum enthalten Fotos oft Informationen über den Aufnahmeort?
+* Warum lassen sich gelöschte Dateien wiederherstellen?
+* Warum benötigt eine Minute 4K-Video unkomprimiert 45 GB Speicher?
+* Warum zeigt eine "1 TB"-Festplatte nur 931 GB an?
+* Warum ist USB-C nicht gleich USB-C?
+* Ziel: **→ Mitreden können!**
+
 <!--
-Kurze Vorstellung
-Praxisbezug betonen
-Fragen jederzeit willkommen
+1. EXIF (Exchangeable Image File Format)-Metadaten speichern GPS-Koordinaten, Kameramodell und Zeitstempel automatisch. Die meisten wissen nicht, dass diese Daten beim Versenden mitgeschickt werden. → Kapitel 4: Metadaten
+
+2. Beim Löschen wird nur der Verzeichniseintrag im Dateisystem entfernt, nicht die Daten selbst. Die Bits bleiben auf dem Datenträger, bis sie überschrieben werden. → Kapitel 3: Dateisysteme
+
+3. 3840 × 2160 Pixel × 3 Byte (RGB) × 30 Bilder/Sek × 60 Sek = ~45 GB. Codecs wie H.264/H.265 komprimieren um Faktor 100+. → Kapitel 1+2: Kompression
+
+4. Hersteller rechnen dezimal (1 TB = 10¹² Bytes), Betriebssysteme binär (1 TiB = 2⁴⁰ Bytes). Die Differenz beträgt bei Terabyte bereits ~10%. → Kapitel 1: Dateneinheiten
+
+5. USB-C ist nur die Steckerform. Dahinter können USB 2.0 (480 Mbit/s), USB 3.2 (20 Gbit/s) oder Thunderbolt 4 (40 Gbit/s) laufen — gleiches Kabel, völlig unterschiedliche Leistung. → Kapitel 3: Schnittstellen
 -->

 ---

-<!-- _footer: '' -->
-
-![bg fit](./assets/jung-naiv.png)
-
---
-
-# AMA (Ask my anything)
-
-*Nur ein Vorschlag ...*
-
-* Hast du alle Bände von AoT daheim?
-* Hast du eine Studierenden-Kneipe mal geleitet?
-* Hast du wirklich 17 Semester Philosophie ohne Abschluss studiert?
-
---
-
 # Kurze Umfrage

 **Bitte Hand heben:**

-1) Wer hat schon mal ein Video komprimiert/konvertiert?
-2) Wer kennte die 3-2-1 Regel?
-3) Wer weiß, was der Unterschied zwischen JPEG und PNG ist?
-4) Wer hat schon mal mit APIs gearbeitet?
-5) Wer weiß, was UTF-8 bedeutet?
-6) Wer hat schon mal mit einem CLI gearbeitet?
-6) **Wer hat schon mal etwas mit HTML oder CSS gemacht?** (Hex-Farben wie `#FF0000`?)
+* Wer kennt den Unterschied zwischen analog und digital?
+* Wer hat schon mal eine Datei von einem Format in ein anderes konvertiert?
+* Wer hat schon mal Metadaten aus einem Foto entfernt?
+* Wer hat schon mal ein Backup verloren?
+* Wer hat schon mal ein Backup wiederhergestellt?

 <!--
 Niveau der Gruppe einschätzen
 Keine falschen Antworten
 Zeigt, wo wir starten
-HTML/CSS-Frage: Viele kennen Hex-Codes aus Webdesign
 API = Application Programming Interface
 -->

 ---

-# Warum dieses Modul?
-
-**Digitale Medien sind überall** – aber was steckt dahinter?
-
-* Warum ist ein JPEG kleiner als ein PNG?
-* Warum klingt MP3 anders als FLAC?
-* Warum zeigt meine 1 TB Festplatte nur 931 GB?
-* Warum ist USB-C so verwirrend?
-* Wie funktioniert eigentlich Streaming?
-* **→ Die Technik dahinter verstehen!**
-
-<!--
-Praxisnahe Fragen aus dem Alltag
-Nicht nur "was", sondern "warum"
-Verständnis für technische Entscheidungen
-->
-
---
-
-# Das Ziel
-
-**Technische Grundlagen verstehen**, um fundierte Entscheidungen treffen zu können.
-
-Als Digital- und Medienwirtschaftler:innen werdet ihr täglich mit technischen Fragen konfrontiert:
-* Welches Format für welchen Zweck?
-* Welche Schnittstelle für welches Gerät?
-* Wie funktioniert die Distribution digitaler Inhalte?
-* **→ Mitreden können – nicht (zwingend) programmieren!**
-
-<!--
-Nicht: Ihr sollt Programmierer werden
-Sondern: Ihr sollt technische Entscheidungen verstehen
-Praxisbezug: Medienproduktion, Marketing, Projektmanagement
-->
-
---
-
-# Was ihr lernt
-
-**In dieser Veranstaltung erwerbt ihr folgende Kompetenzen:**
-
-* Fundiertes Grundwissen über Daten und Informationen
-* Dateiformate analysieren und verstehen
-* Grundlagen von Kompression (Audio, Bild, Video)
-* Speichermedien unterscheiden
-* Programmier-Schnittstellen kennenlernen
-* APIs und Distributionswege verstehen
-
-<!--
-Fokus auf Verständnis, nicht auf Programmierung
-Hands-On jede Woche: Selbst ausprobieren
-Ziel: Einblick in die Denkweise von Software-Entwicklern
-->
-
---
-
 # Kursübersicht

-**5 Termine:**
+**Kapitel:**

-| # | Datum | Thema |
-|---|-------|-------|
-| 1 | 19.12.2025 | Bits, Bytes, Zeichenkodierung & Audio |
-| 2 | 09.01.2026 | Bild- & Video-Kompression |
-| 3 | 23.01.2026 | Speichermedien & Schnittstellen |
-| 4 | 30.01.2026 | Distribution, APIs & Zukunft |
-| 5 | TBA | Vertiefung & offene Fragen |
+* 1. **Grundlagen**, Text & Audio (Bits, Bytes, Zeichenkodierung, MP3)
+* 2. Bild- & Video-**Kompression** (JPEG, PNG, H.264/H.265)
+* 3. **Speichermedien** & **Schnittstellen** (HDD, SSD, USB, Thunderbolt)
+* 4. **Distribution** und Verteilung (Streaming, REST, Cloud)
+* Vertiefung & offene Fragen

-**Format:** Theorie + Hands-On (30-40 Min pro Termin)
-
-<!--
-Nicht nur theoretische Inhalte
-Praktische Übungen jede Woche
-Medienwissenschaftler:innen, nicht Informatiker:innen
-->

 ---

-# Prüfungsleistung 18.02.
+<!-- _class: klausur -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+<!-- _backgroundColor: #e3f2fd -->
+
+# Prüfungsleistung

 **Nach aktuellem Kenntnisstand:**

-* 90 min (40% Grundlagen, 40% Dateiformate, 20% AV)
-* Schriftliche Klausur
+* 90 min insg. (Technik 1)
+* Schriftliche Klausur (digital)
 * Teils offene Fragen
-* Vermutlich digital
-* Kein Coding!
-* **Prüfungsrelevant:** Alles in den Folien/im Skript
-
-<!--
-Details können sich noch ändern
-Keine Programmieraufgaben
-Verständnisfragen, keine Auswendiglernerei
-->
-
+* Kein Coding/Programmieren
+* **Prüfungsrelevante Folien:**
+  - Gestreift oder Vollton (PDF) markiert
@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Dateiformate, Schnittstellen, Speichermedien & Distributionswege (223015b)"
-footer: "Michael Czechowski – HdM Stuttgart"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---

@@ -68,6 +68,38 @@ section.aufgabe {
 section.aufgabe footer {
  display: none;
 }
+section.erklaerung {
+  font-size: 1.1rem;
+  background: repeating-linear-gradient(
+    135deg,
+    #e3f2fd,
+    #e3f2fd 40px,
+    #fff 40px,
+    #fff 80px
+  ) !important;
+}
+@media print {
+  section.erklaerung {
+    background: #e3f2fd !important;
+  }
+}
+section.erklaerung h1 {
+  font-size: 1.5rem;
+  color: #1e5f8a;
+  margin-bottom: 0.3rem;
+}
+section.erklaerung ul,
+section.erklaerung ol {
+  font-size: 1.0rem;
+  line-height: 1.4;
+}
+section.erklaerung p {
+  font-size: 1.0rem;
+  line-height: 1.4;
+}
+section.erklaerung table {
+  font-size: 0.9rem;
+}
 </style>

 <!-- _class: invert -->
@@ -220,6 +252,26 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# Rastergrafik – Vertiefung
+
+Ein Pixel ist die kleinste adressierbare Einheit. Bei 24-Bit-Farbtiefe speichert jeder Pixel drei 8-Bit-Werte (0–255) für Rot, Grün und Blau. Diese additive Farbmischung erzeugt 256³ = 16,7 Millionen mögliche Farbtöne.
+
+**Speicherberechnung:** `Breite × Höhe × Bytes pro Pixel`
+
+| Auflösung | Farbtiefe | Berechnung | Größe |
+|-----------|-----------|------------|-------|
+| 1920×1080 | 24 Bit (3 B) | 2.073.600 × 3 | 6,2 MB |
+| 4K (3840×2160) | 24 Bit | 8.294.400 × 3 | 24,9 MB |
+| 4K | 32 Bit (4 B) | 8.294.400 × 4 | 33,2 MB |
+
+Der Alpha-Kanal (32 Bit) speichert Transparenz als Wert von 0 (unsichtbar) bis 255 (vollständig sichtbar). PNG nutzt dies für weiche Kanten; JPEG unterstützt keinen Alpha-Kanal.
+
+---
+
 # Das Problem der Skalierung

 **Vergrößern:**
@@ -274,6 +326,30 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# Vektorgrafik – Vertiefung
+
+Vektorgrafiken speichern keine Pixel, sondern mathematische Beschreibungen: Koordinaten, Kurvenparameter (Bézier-Kontrollpunkte), Füllfarben, Strichstärken. Der Renderer berechnet die Pixel erst bei der Ausgabe – daher beliebig skalierbar.
+
+**Bézier-Kurven** (Pierre Bézier, 1962, für Renault-Karosserien entwickelt):
+- Definiert durch Ankerpunkte und Kontrollpunkte
+- Kubische Bézier: 2 Anker + 2 Kontrollpunkte
+- Mathematisch exakt reproduzierbar
+
+| Aspekt | Raster | Vektor |
+|--------|--------|--------|
+| Skalierung 10× | Pixel sichtbar | Perfekt scharf |
+| Foto-Realismus | Gut geeignet | Unpraktikabel |
+| Dateigröße Logo | Wächst mit Auflösung | Konstant (~5 KB) |
+| Editierbarkeit | Destruktiv | Nicht-destruktiv |
+
+**Rasterisierung:** GPU wandelt Vektordaten in Pixel um. Geschieht bei jeder Darstellung neu – deshalb ist ein 4K-Monitor schärfer als ein 1080p-Monitor bei gleichem SVG.
+
+---
+
 # Raster- und Vektorgrafiken

 | | Raster | Vektor |
@@ -338,6 +414,28 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# Psychovisuelle Wahrnehmung – Vertiefung
+
+Die Netzhaut enthält ~120 Mio. Stäbchen (Helligkeitswahrnehmung) aber nur ~6 Mio. Zapfen (Farbwahrnehmung). Dieses 20:1-Verhältnis erklärt, warum JPEG Farbinformationen stärker reduzieren kann als Helligkeitsinformationen.
+
+**Räumliche Frequenz** beschreibt, wie schnell sich die Helligkeit über eine Bildfläche ändert:
+- **Niedrig:** Himmel, Wand – große einheitliche Flächen
+- **Hoch:** Haare, Texturen, Schrift – schnelle Wechsel
+
+Das Auge ist ein Tiefpassfilter: Hohe Frequenzen (feine Details) werden schwächer wahrgenommen. JPEG verwirft daher zuerst die hohen Frequenzen – der Qualitätsverlust bleibt meist unsichtbar.
+
+| Biologisches Limit | Ausnutzung in JPEG |
+|-------------------|-------------------|
+| Farbauflösung ~20× geringer | Chroma Subsampling (4:2:0) |
+| Hohe Frequenzen unscharf | DCT + Quantisierung |
+| Kontrast-Maskierung | Artefakte in Texturen versteckt |
+
+---
+
 <!-- _header: '' -->
 <!-- _footer: '' -->

@@ -442,6 +540,34 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# Farbraumkonversion – Vertiefung
+
+RGB→YCbCr nutzt die Biologie des menschlichen Auges: 120 Mio. Stäbchen (Helligkeit) vs. nur 6 Mio. Zapfen (Farbe) – ein 20:1-Verhältnis. Die Transformation erfolgt über eine lineare Matrix:
+
+```
+Y  =  0.299·R + 0.587·G + 0.114·B
+Cb = −0.169·R − 0.331·G + 0.500·B + 128
+Cr =  0.500·R − 0.419·G − 0.081·B + 128
+```
+
+Die Gewichtung (G dominiert mit 59%) entspricht der spektralen Empfindlichkeit des Auges bei Tageslicht. Y enthält alle Schärfeinformation; Cb/Cr können reduziert werden.
+
+**Chroma Subsampling – Notation J:a:b** (bezogen auf 4×2 Pixel):
+
+| Schema | Farbdaten | Einsatz |
+|--------|-----------|---------|
+| 4:4:4 | 100% | Postproduktion, Grafik |
+| 4:2:2 | 50% | Broadcast, Pro-Video |
+| 4:2:0 | 25% | JPEG, H.264, Streaming |
+
+Bei 4:2:0 teilen sich 4 Pixel einen Farbwert, behalten aber individuelle Helligkeit → 50% Dateneinsparung bei kaum sichtbarem Unterschied.
+
+---
+
 # JPEG Schritt 2: Chroma Subsampling

 **Notation `J:a:b`** (bezogen auf 4×2 Pixel-Block):
@@ -623,12 +749,36 @@ KLAUSURRELEVANT:
 - Präfix-frei: Kein Code ist Anfang eines anderen
 - Häufigstes Zeichen = kürzester Code
 - Auch in ZIP, PNG, MP3 verwendet
+-->

 ---

-->
+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->

+# Huffman-Coding – Vertiefung

+David Huffman entwickelte 1952 als Student am MIT einen optimalen Algorithmus für präfixfreie Codes – ursprünglich als Hausaufgabe, die zur Veröffentlichung führte.
+
+**Algorithmus (Bottom-Up-Baumkonstruktion):**
+1. Alle Symbole nach Häufigkeit sortieren
+2. Die zwei seltensten Symbole zu einem Knoten kombinieren
+3. Wiederholen bis nur noch die Wurzel übrig ist
+4. Codes ablesen: links = 0, rechts = 1
+
+**Präfixfreiheit:** Kein Code ist Anfang eines anderen → sofort dekodierbar ohne Trennzeichen.
+
+| Eigenschaft | Huffman | Arithmetisch |
+|-------------|---------|--------------|
+| Einheit | Ganze Bits | Fraktionale Bits |
+| Optimalität | Optimal für ganze Bits | Näher an Entropie |
+| Geschwindigkeit | Schneller | Langsamer |
+| JPEG-Einsatz | Standard (Baseline) | Optional (selten) |
+
+JPEG verwendet zwei Huffman-Tabellen: eine für DC-Koeffizienten (Durchschnittswerte), eine für AC-Koeffizienten (Frequenzen). Die Tabellen sind im JPEG-Header gespeichert.
+
+---

 <!-- _class: klausur -->
 <!-- _header: '' -->
@@ -772,6 +922,28 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# WebP & AVIF – Vertiefung
+
+**WebP** entstand 2010 aus Googles VP8-Videocodec (On2 Technologies, für $133M gekauft). Statt I-Frames für Video werden sie als Einzelbilder verwendet. WebP nutzt Intra-Frame-Prediction, die benachbarte Blöcke zur Vorhersage verwendet – effizienter als JPEGs blockweise DCT.
+
+**AVIF** basiert auf dem AV1-Videocodec, entwickelt 2015–2018 von der Alliance for Open Media (Google, Apple, Netflix, Amazon, Microsoft, Mozilla). Nach dem Patent-Chaos von H.265/HEVC vereinten sich die Konkurrenten für einen lizenzfreien Standard.
+
+| Aspekt | WebP | AVIF |
+|--------|------|------|
+| Basis-Codec | VP8/VP9 | AV1 |
+| Kompression vs. JPEG | 25–35% besser | 50% besser |
+| HDR/Wide Gamut | Nein | Ja (10/12 Bit) |
+| Encoding-Geschwindigkeit | Schnell | Sehr langsam |
+| Browser-Support 2025 | 97%+ | 93%+ |
+
+**Warum JPEG dominiert:** Kameras, Bildbearbeitungssoftware und Content-Management-Systeme sind auf JPEG optimiert. Der Wechsel erfordert Infrastruktur-Updates über die gesamte Pipeline.
+
+---
+
 # Formatwahl in der Praxis

 | Anwendung | Format |
@@ -890,6 +1062,33 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# Container vs. Codec – Vertiefung
+
+**Container** (Multiplexer-Format) organisiert mehrere Datenströme mit Timing-Informationen. Er enthält keine Kompressionslogik, sondern synchronisiert Video, Audio, Untertitel und Metadaten.
+
+**Codec** (Coder-Decoder) definiert den Kompressionsalgorithmus. Derselbe Container kann verschiedene Codecs enthalten – die Dateiendung verrät den Codec nicht.
+
+| Container | Entwickler | Typische Codecs | Besonderheit |
+|-----------|------------|-----------------|--------------|
+| MP4 | ISO/MPEG | H.264, H.265, AAC | Web-Standard, DRM-fähig |
+| MKV | Matroska | Alle | Beliebig viele Streams, Kapitel |
+| WebM | Google | VP9, AV1, Opus | HTML5-optimiert, lizenzfrei |
+| MOV | Apple | ProRes, H.264 | Professionelle Produktion |
+
+**Metadaten im Container:**
+- Timecodes für Frame-genaue Synchronisation
+- Kapitelmarken, Thumbnails
+- Sprach-Tags für Audio/Untertitel
+- HDR-Metadaten (MaxCLL, MaxFALL)
+
+**Praktisches Problem:** Eine `.mp4`-Datei mit AV1-Codec spielt auf älteren Geräten nicht ab, obwohl sie MP4 „unterstützen" – der Hardware-Decoder fehlt für AV1.
+
+---
+
 # Gängige Container

 | Container | Verwendung |
@@ -1115,6 +1314,32 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# H.264/AVC – Vertiefung
+
+H.264 (2003) ermöglichte erst YouTube (2005), Netflix-Streaming (2007) und Blu-ray. Vor H.264 war MPEG-2 Standard – H.264 erreichte bei gleicher Qualität die halbe Bitrate.
+
+**Technische Innovationen:**
+- **Variable Blockgrößen:** 16×16 bis 4×4 Macroblocks (MPEG-2: nur 16×16)
+- **Intra-Prediction:** Blöcke werden aus Nachbarn vorhergesagt
+- **In-Loop Deblocking:** Filter reduziert Blockartefakte vor der Referenzierung
+- **CABAC:** Arithmetic Coding ersetzt Huffman (10–15% effizienter)
+
+| Profile | Anwendung | Max. Auflösung |
+|---------|-----------|----------------|
+| Baseline | Videotelefonie, ältere Geräte | 480p |
+| Main | Broadcast, Streaming | 1080p |
+| High | Blu-ray, professionell | 4K |
+
+**Hardware-Ubiquität:** Seit 2010 hat jedes Smartphone, jede GPU, jeder Smart-TV einen H.264-Hardware-Decoder. Encoding in Echtzeit braucht keine CPU – das ermöglichte erst mobiles Video-Streaming und Videotelefonie.
+
+**Patent-Pool (MPEG-LA):** ~2.000 Patente von 30+ Unternehmen. Endnutzer-Streaming ist lizenzfrei; Hardware-Hersteller zahlen ~$0,20/Gerät.
+
+---
+
 # Das Patent-Problem

 **H.264 ist nicht frei**
@@ -1221,6 +1446,29 @@ KLAUSURRELEVANT:

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# AV1 – Vertiefung
+
+Die **Alliance for Open Media** (2015) vereinte Konkurrenten nach dem Patent-Chaos von H.265/HEVC. Drei separate Patent-Pools (MPEG-LA, HEVC Advance, Velos Media) machten H.265-Lizenzierung unberechenbar – die Industrie wollte einen garantiert lizenzfreien Standard.
+
+**Gründungsmitglieder:** Google, Mozilla, Cisco, Netflix, Amazon, Microsoft. Apple trat 2018 bei – historisch, da Apple sonst eigene Standards bevorzugt.
+
+| Technische Innovation | Beschreibung |
+|----------------------|--------------|
+| Superblocks | Bis 128×128 Pixel (H.264: max 16×16) |
+| Prediction Modes | 56 Intra-Modi (H.264: 9) |
+| Transform | 10 verschiedene Transformtypen |
+| Film Grain Synthesis | Filmkorn wird als Parameter übertragen |
+
+**Encoding-Performance:** Software-Encoding ist 50–200× langsamer als H.264. Erst Hardware-Encoder (Intel ab Gen 12, NVIDIA RTX 40, Apple M3) machen Echtzeit-Encoding praktikabel.
+
+**Adoption 2025:** YouTube und Netflix nutzen AV1 für 4K/8K-Streams. 2024 gewann AV1 einen Emmy für technische Innovation – offene Standards können Industriestandard werden.
+
+---
+
 <!-- _header: '' -->
 <!-- _footer: 'https://blog.mozilla.org/en/mozilla/av1-video-codec-wins-emmy/' -->

@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Dateiformate, Schnittstellen, Speichermedien & Distributionswege (223015b)"
-footer: "Michael Czechowski – HdM Stuttgart – WS 2025/26"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---

@@ -68,6 +68,38 @@ section.aufgabe {
 section.aufgabe footer {
  display: none;
 }
+section.erklaerung {
+  font-size: 1.1rem;
+  background: repeating-linear-gradient(
+    135deg,
+    #e3f2fd,
+    #e3f2fd 40px,
+    #fff 40px,
+    #fff 80px
+  ) !important;
+}
+@media print {
+  section.erklaerung {
+    background: #e3f2fd !important;
+  }
+}
+section.erklaerung h1 {
+  font-size: 1.5rem;
+  color: #1e5f8a;
+  margin-bottom: 0.3rem;
+}
+section.erklaerung ul,
+section.erklaerung ol {
+  font-size: 1.0rem;
+  line-height: 1.4;
+}
+section.erklaerung p {
+  font-size: 1.0rem;
+  line-height: 1.4;
+}
+section.erklaerung table {
+  font-size: 0.9rem;
+}
 </style>

 <!-- _class: invert -->
@@ -82,7 +114,7 @@ section.aufgabe footer {
 Digital- und Medienwirtschaft
 Hochschule der Medien Stuttgart

-**Wintersemester 2025/26**
+**Sommersemester 2026**

 [https://librete.ch/hdm/223015b/](https://librete.ch/hdm/223015b/)

@@ -235,6 +267,29 @@ Kleine SSD für System + große HDD für Archiv.

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# HDD vs. SSD – Vertiefung
+
+**HDD (Hard Disk Drive):** Magnetplatten rotieren mit 5.400–7.200 RPM; ein Schreib-/Lesekopf schwebt nanometerweit über der Oberfläche. Die Zugriffszeit setzt sich zusammen aus Seek Time (Kopf bewegen) + Rotational Latency (warten auf Sektor).
+
+**SSD (Solid State Drive):** NAND-Flash-Zellen speichern Bits als elektrische Ladung. Kein mechanischer Zugriff → konstant schnelle Latenz. Aber: Zellen haben begrenzte Schreibzyklen (P/E Cycles).
+
+| Aspekt | HDD | SATA SSD | NVMe SSD |
+|--------|-----|----------|----------|
+| Latenz | 5–10 ms | 0,1 ms | 0,02 ms |
+| Seq. Lesen | 150 MB/s | 550 MB/s | 7.000 MB/s |
+| IOPS (4K random) | 100 | 90.000 | 1.000.000 |
+| TBW (1 TB Modell) | ∞ | 600 TBW | 600 TBW |
+
+**Wear Leveling:** SSD-Controller verteilen Schreibvorgänge gleichmäßig, um einzelne Zellen nicht vorzeitig zu erschöpfen. TRIM informiert den Controller über gelöschte Blöcke.
+
+**Praxis:** System-SSD für OS/Anwendungen (Geschwindigkeit), HDD für Medienarchiv (Kapazität/Preis). RAID schützt vor Einzelausfällen bei beiden.
+
+---
+
 <!-- _class: lead -->

 # Dateisysteme
@@ -484,6 +539,30 @@ Warum 1 Offsite?

 ---

+<!-- _class: erklaerung -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+# 3-2-1-Backup-Regel – Vertiefung
+
+Peter Krogh formulierte die Regel 2005 in „The DAM Book" (Digital Asset Management). Sie schützt gegen unterschiedliche Verlustszenarien:
+
+| Bedrohung | Schutz durch | Beispiel |
+|-----------|--------------|----------|
+| Hardware-Defekt | 3 Kopien | SSD stirbt → HDD-Backup vorhanden |
+| Firmware-Bug/Ransomware | 2 Medientypen | Malware infiziert nur ein System |
+| Feuer/Diebstahl/Flut | 1 Offsite | Haus brennt → Cloud-Backup sicher |
+
+**Moderne Erweiterung 3-2-1-1-0:**
+- **+1** Air-Gapped (offline, nicht verbunden)
+- **+0** Verifizierte Backups (regelmäßig Restore testen)
+
+**Ransomware-Problem:** Vernetzte Backups werden oft mitverschlüsselt. Air-Gapped-Medien (externe HDD im Safe, LTO-Band) bleiben sicher, weil sie physisch getrennt sind.
+
+**Realitäts-Check:** Die meisten Datenverluste entstehen durch menschliche Fehler (versehentliches Löschen), nicht Hardware-Ausfälle. Versionierte Backups (Time Machine, Borg) schützen auch davor – die gelöschte Datei existiert noch in älteren Snapshots.
+
+---
+
 # Backup-Arten

 **Vollständig (Full):**
@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Dateiformate, Schnittstellen, Speichermedien & Distributionswege (223015b)"
-footer: "Michael Czechowski – HdM Stuttgart – WS 2025/26"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---

@@ -83,7 +83,7 @@ section.aufgabe footer {
 Digital- und Medienwirtschaft
 Hochschule der Medien Stuttgart

-**Wintersemester 2025/26**
+**Sommersemester 2026**

 [https://librete.ch/hdm/223015b/](https://librete.ch/hdm/223015b/)

@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Dateiformate, Schnittstellen, Speichermedien & Distributionswege (223015b)"
-footer: "Michael Czechowski – HdM Stuttgart – WS 2025/26"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---

@@ -83,7 +83,7 @@ section.aufgabe footer {
 Digital- und Medienwirtschaft
 Hochschule der Medien Stuttgart

-**Wintersemester 2025/26**
+**Sommersemester 2026**

 [https://librete.ch/hdm/223015b/](https://librete.ch/hdm/223015b/)

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+<rect x="2420" y="0" width="10" height="1440" fill="rgb(13,13,13)"/>
+<rect x="2430" y="0" width="10" height="1440" fill="rgb(12,12,12)"/>
+<rect x="2440" y="0" width="10" height="1440" fill="rgb(11,11,11)"/>
+<rect x="2450" y="0" width="10" height="1440" fill="rgb(10,10,10)"/>
+<rect x="2460" y="0" width="10" height="1440" fill="rgb(9,9,9)"/>
+<rect x="2470" y="0" width="10" height="1440" fill="rgb(8,8,8)"/>
+<rect x="2480" y="0" width="10" height="1440" fill="rgb(7,7,7)"/>
+<rect x="2490" y="0" width="10" height="1440" fill="rgb(6,6,6)"/>
+<rect x="2500" y="0" width="10" height="1440" fill="rgb(5,5,5)"/>
+<rect x="2510" y="0" width="10" height="1440" fill="rgb(4,4,4)"/>
+<rect x="2520" y="0" width="10" height="1440" fill="rgb(3,3,3)"/>
+<rect x="2530" y="0" width="10" height="1440" fill="rgb(2,2,2)"/>
+<rect x="2540" y="0" width="10" height="1440" fill="rgb(1,1,1)"/>
+<rect x="2550" y="0" width="10" height="1440" fill="rgb(0,0,0)"/>
+</svg>
@@ -0,0 +1,53 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1920 1080">
+<rect width="1920" height="1080" fill="#ffffff"/>
+<text x="960.0" y="100" text-anchor="middle" font-family="sans-serif" font-size="54" fill="#1a1a2e" font-weight="bold">Zoom: die 16 hellsten Abstufungen</text>
+<rect x="60.00" y="220" width="101.25" height="500" fill="rgb(255,255,255)" stroke="#1a1a2e" stroke-width="3"/>
+<text x="110.62" y="820" text-anchor="middle" font-family="monospace" font-size="42" fill="#1a1a2e" font-weight="bold">255</text>
+<text x="110.62" y="900" text-anchor="middle" font-family="monospace" font-size="36" fill="#4a4a6a">0xFF</text>
+<rect x="173.25" y="220" width="101.25" height="500" fill="rgb(254,254,254)" stroke="#1a1a2e" stroke-width="3"/>
+<text x="223.88" y="820" text-anchor="middle" font-family="monospace" font-size="42" fill="#1a1a2e" font-weight="bold">254</text>
+<text x="223.88" y="900" text-anchor="middle" font-family="monospace" font-size="36" fill="#4a4a6a">0xFE</text>
+<rect x="286.50" y="220" width="101.25" height="500" fill="rgb(253,253,253)" stroke="#1a1a2e" stroke-width="3"/>
+<text x="337.12" y="820" text-anchor="middle" font-family="monospace" font-size="42" fill="#1a1a2e" font-weight="bold">253</text>
+<text x="337.12" y="900" text-anchor="middle" font-family="monospace" font-size="36" fill="#4a4a6a">0xFD</text>
+<rect x="399.75" y="220" width="101.25" height="500" fill="rgb(252,252,252)" stroke="#1a1a2e" stroke-width="3"/>
+<text x="450.38" y="820" text-anchor="middle" font-family="monospace" font-size="42" fill="#1a1a2e" font-weight="bold">252</text>
+<text x="450.38" y="900" text-anchor="middle" font-family="monospace" font-size="36" fill="#4a4a6a">0xFC</text>
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+<text x="1696.12" y="900" text-anchor="middle" font-family="monospace" font-size="36" fill="#4a4a6a">0xF1</text>
+<rect x="1758.75" y="220" width="101.25" height="500" fill="rgb(240,240,240)" stroke="#1a1a2e" stroke-width="3"/>
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+<text x="1809.38" y="900" text-anchor="middle" font-family="monospace" font-size="36" fill="#4a4a6a">0xF0</text>
+<text x="960.0" y="1020" text-anchor="middle" font-family="sans-serif" font-size="28" fill="#4a4a6a" font-style="italic">jede Stufe = Unterschied von 1/255 ≈ 0,4% Helligkeit</text>
+</svg>
@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Dateiformate, Schnittstellen, Speichermedien & Distributionswege (223015b)"
-footer: "Michael Czechowski – HdM Stuttgart"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---
 <style>
@@ -92,6 +92,8 @@ section.aufgabe footer {
 Digital- und Medienwirtschaft
 Hochschule der Medien Stuttgart

+**Sommersemester 2026**
+
 [https://librete.ch/hdm/223015b/](https://librete.ch/hdm/223015b/)

 ---
@@ -110,7 +112,7 @@ Hochschule der Medien Stuttgart
 | **Formate** | ZIP, PNG, FLAC, GIF | JPEG, MP3, H.264/H.265 |

 **Faustregel:**
- Medien für Endnutzer → Lossy oft akzeptabel
+- Medien für EndnutzerInnen → Lossy oft akzeptabel
 - Quellmaterial, Code, Archive → Lossless nötig

 <!--
@@ -208,13 +210,13 @@ VERGLEICH: SSD ~$50/TB, HDD ~$15/TB, LTO ~$5/TB
 ### Distribution: physisch (Kauf, Verleih, Kopie)

 - **Text**
-  - Bücher, Zeitungen, Zeitschriften, Lochkarten
+    - Bücher, Zeitungen, Zeitschriften, Lochkarten
 - **Bild**
-  - Fotografie (Negativ, Dia, Polaroid), Mikrofilm
+    - Fotografie (Negativ, Dia, Polaroid), Mikrofilm
 - **Audio:**
-  - Schallplatte (Vinyl, Schellack), Tonband, Musikkassette
+    - Schallplatte (Vinyl, Schellack), Tonband, Musikkassette
 - **Video:**
-  - Film (35mm, Super 8), VHS, Betamax
+    - Film (35mm, Super 8), VHS, Betamax


 ---
@@ -227,13 +229,13 @@ VERGLEICH: SSD ~$50/TB, HDD ~$15/TB, LTO ~$5/TB
 ### Distribution: Datenträger (CD, USB), Download, Streaming, P2P

 - **Text**
-  - E-Book (PDF, EPUB), Dokumente (TXT, DOCX)
+    - E-Book (PDF, EPUB), Dokumente (TXT, DOCX)
 - **Bild**
-  - Digitalfoto (JPEG, PNG, RAW, WebP, GIF)
+    - Digitalfoto (JPEG, PNG, RAW, WebP, GIF)
 - **Audio**
-  - Audiodatei (MP3, FLAC, WAV, AAC, OGG)
+    - Audiodatei (MP3, FLAC, WAV, AAC, OGG)
 - **Video**
-  - Videodatei (MP4, MKV, AVI, WebM)
+    - Videodatei (MP4, MKV, AVI, WebM)


 ---
@@ -245,13 +247,13 @@ VERGLEICH: SSD ~$50/TB, HDD ~$15/TB, LTO ~$5/TB
 # Digitale Speichermedien

 - **Optische Speicher**
-  - CD, DVD, Blu-ray
+    - CD, DVD, Blu-ray
 - **Magnetische Speicher**
-  - Festplatte (HDD), Magnetband (LTO)
+    - Festplatte (HDD), Magnetband (LTO)
 - **Flash-Speicher**
-  - SSD, USB-Stick, SD-Karte
+    - SSD, USB-Stick, SD-Karte
 - **Cloud-Speicher**
-  - Dropbox, Google Drive, iCloud, AWS S3
+    - Dropbox, Google Drive, iCloud, AWS S3


 ---
@@ -277,14 +279,12 @@ Breite × Höhe × Farbtiefe (in Bytes)
 | 32 | 16,7 Mio. + Alpha | Transparenz |

 <!--
-BERECHNUNG: Breite × Höhe × (Farbtiefe / 8)
-BEISPIEL: 1920×1080 × 24 Bit = 1920×1080×3 = 6.220.800 Bytes ≈ 6,2 MB
-
-Farbtiefe erklärt:
- 1 Bit: 2^1 = 2 Farben
- 8 Bit: 2^8 = 256 Farben
- 24 Bit: 2^24 = 16.777.216 Farben (je 8 Bit für R, G, B)
- 32 Bit: 24 Bit + 8 Bit Alpha-Kanal
+KLAUSURRELEVANT:
+- Formel: Breite × Höhe × (Farbtiefe / 8) = Bytes
+- Beispielrechnung: 1920 × 1080 × 3 = 6.220.800 Bytes ≈ 6,2 MB
+- Farbtiefe: 2^n Farben bei n Bit
+- 24 Bit = 8 Bit pro Kanal (R, G, B)
+- 32 Bit = 24 Bit + 8 Bit Alpha (Transparenz)
 -->


@@ -306,17 +306,15 @@ Farbtiefe erklärt:
 <circle cx="50" cy="50" r="40" fill="#ff0000"/>
 ```

-<small>SVG beschreibt nicht jeden einzelnen Pixel im Raster, sondern deklariert wie Farben und Formen gesetzt werden.</small>
+<small>SVG beschreibt WAS gezeichnet werden soll, nicht WIE jeder Pixel aussieht.</small>

 <!--
-Vektorgrafiken beschreiben WAS gezeichnet werden soll.
-Rastergrafiken beschreiben WIE jeder Pixel aussieht.
-
-Rendering-Pipeline:
-Vektordaten → Rasterisierung → Framebuffer → Display
-
-Beim Skalieren werden einfach die Koordinaten multipliziert.
-Keine Information geht verloren.
+KLAUSURRELEVANT:
+- Vektor = Beschreibung (deklarativ)
+- Raster = Pixel für Pixel (imperativ)
+- Rendering-Pipeline: Vektordaten → Rasterisierung → Display
+- Skalierung = Koordinaten multiplizieren → keine Information geht verloren
+- SVG = Scalable Vector Graphics (Web-Standard)
 -->


@@ -334,18 +332,17 @@ Keine Information geht verloren.
 - Niedrige Frequenzen besser als hohe

 **JPEG nutzt das aus:**
- Farbauflösung reduzieren (aber Helligkeit behalten)
+- Farbauflösung reduzieren (Helligkeit behalten)
 - Glatte Flächen effizient speichern
- Hohe Frequenzen (Details) verwerfen
+- Hohe Frequenzen (feine Details) verwerfen

 <!--
-Das ist die visuelle Entsprechung zur Psychoakustik.
-
-Das Auge hat mehr Rezeptoren für Helligkeit (Stäbchen)
-als für Farbe (Zapfen).
-
-Hohe Frequenzen = schnelle Wechsel = feine Details
-Niedrige Frequenzen = langsame Wechsel = große Flächen
+KLAUSURRELEVANT:
+- Mehr Stäbchen (Helligkeit) als Zapfen (Farbe) im Auge
+- "Frequenz" = räumliche Frequenz = wie schnell ändert sich Helligkeit?
+- Niedrig = langsame Änderung = große gleichmäßige Fläche
+- Hoch = schnelle Änderung = feine Details, Kanten
+- Analogie zur Psychoakustik bei MP3 (letztes Mal)
 -->


@@ -357,24 +354,25 @@ Niedrige Frequenzen = langsame Wechsel = große Flächen

 ![bg right:20%](./assets/Barn-yuv.png)

-# JPEG: Schritt 1 – Farbraumkonversion
+# JPEG Schritt 1: Farbraumkonversion

-**RGB → Y'CbCr** (seltener Y'UV)
+**RGB → Y'CbCr**

- **Y** = Helligkeit (Luminanz) – Was das Auge am besten sieht
+- **Y** = Helligkeit (Luminanz)
 - **Cb** = Blau-Gelb-Anteil (Chrominanz)
 - **Cr** = Rot-Grün-Anteil (Chrominanz)

-**Warum diese Trennung?**
-Y (Helligkeit) behält volle Auflösung.
-Cb/Cr (Farbe) kann reduziert werden – Auge merkt es kaum.
+**Warum?**
+Y (Helligkeit) behält volle Auflösung
+Cb/Cr (Farbe) kann reduziert werden

 <!--
-YCbCr ist wie RGB ein Tripel aus 3 Werten pro Pixel.
-Der Unterschied: Statt Rot-Grün-Blau speichern wir Helligkeit + 2 Farbdifferenzen.
-
-Die Umrechnung ist reversibel (mathematische Transformation).
-Der Clou: Jetzt können wir Helligkeit und Farbe getrennt behandeln.
+KLAUSURRELEVANT:
+- YCbCr = auch 3 Werte pro Pixel, aber anders organisiert
+- Statt R-G-B: Helligkeit + 2 Farbdifferenzen
+- Umrechnung ist reversibel (mathematische Transformation)
+- Vorteil: Helligkeit und Farbe getrennt behandelbar
+- Bild zeigt: Y (oben), Cb (Mitte), Cr (unten)
 -->


@@ -384,14 +382,14 @@ Der Clou: Jetzt können wir Helligkeit und Farbe getrennt behandeln.
 <!-- _footer: "" -->


-# JPEG: Schritt 6 – Huffman-Coding
+# JPEG Schritt 6: Huffman-Coding

 **Verlustfreie Kompression der Restwerte**

-**Idee:** Statt fester 8 Bit pro Wert → variable Bitlänge
-Häufige Werte bekommen kurze Bit-Sequenzen.
+**Idee:** Variable Bitlänge statt fester 8 Bit
+Häufige Werte → kurze Codes

-| Zeichen | Häufigkeit | Code (Bit-Sequenz) |
+| Zeichen | Häufigkeit | Code |
 |---------|------------|------|
 | e | 40% | `0` (1 Bit) |
 | a | 25% | `10` (2 Bit) |
@@ -400,9 +398,74 @@ Häufige Werte bekommen kurze Bit-Sequenzen.
 | u | 5% | `1111` (4 Bit) |

 <!--
-Huffman-Coding ist verlustfrei.
-Der "Code" ist eine Bit-Sequenz, die das Zeichen eindeutig identifiziert.
-Weil "e" am häufigsten vorkommt, bekommt es den kürzesten Code.
+KLAUSURRELEVANT:
+- Huffman = verlustfrei, optimal für bekannte Häufigkeiten
+- Präfix-frei: Kein Code ist Anfang eines anderen
+- Häufigstes Zeichen = kürzester Code
+- Auch in ZIP, PNG, MP3 verwendet
+-->
+
+
+---
+
+<!-- _header: "" -->
+<!-- _footer: "" -->
+
+<!--
+# Huffman-Coding: Beispiel
+
+**Originaltext:** `ABRACADABRA` (11 Zeichen × 8 Bit = 88 Bit)
+
+**Häufigkeitsanalyse:**
+A=5, B=2, R=2, C=1, D=1
+
+**Huffman-Baum → Codes:**
+| Zeichen | Häufigkeit | Code |
+|---------|------------|------|
+| A | 5 | `0` |
+| B | 2 | `10` |
+| R | 2 | `110` |
+| C | 1 | `1110` |
+| D | 1 | `1111` |
+
+**Codiert:** `0 10 110 0 1110 0 1111 0 10 110 0` = **23 Bit**
+**Kompression:** 88 → 23 Bit = **74% gespart**
+
+
+- Beispiel Schritt für Schritt durchrechnen
+- Warum funktioniert's? A kommt 5× vor, bekommt kürzesten Code
+- Präfix-Eigenschaft: Kein Code ist Anfang eines anderen → eindeutig dekodierbar
+- Frage: "Was passiert, wenn alle Zeichen gleich häufig sind?" → Keine Ersparnis
+- In JPEG: Nicht Buchstaben, sondern DCT-Koeffizienten werden so codiert
+-->
+
+
+---
+
+<!-- _header: "" -->
+<!-- _footer: "" -->
+
+
+# WebP & AVIF: Moderne Alternativen
+
+**WebP (Google, 2010):**
+- Lossy und Lossless
+- Transparenz und Animationen
+- 25–35% kleiner als JPEG
+
+**AVIF (2019):**
+- Basiert auf AV1-Video-Codec
+- 50% kleiner als JPEG
+- HDR-Unterstützung, patent-frei
+
+**Browser-Support 2025:** WebP universell, AVIF wächst
+
+<!--
+KLAUSURRELEVANT:
+- WebP: VP8-Kompression (Google Video-Codec)
+- AVIF: Alliance for Open Media (Google, Netflix, Amazon, Apple, Mozilla)
+- Beide besser als JPEG, aber Kompatibilität bleibt Problem
+- JPEG bleibt dominant: alte Kameras, Software, Workflows
 -->


@@ -414,28 +477,22 @@ Weil "e" am häufigsten vorkommt, bekommt es den kürzesten Code.

 # Container und Codec

-**Container = Das Dateiformat (Beispiel: MP4)**
+**Container = Dateiformat (z.B. MP4)**
 Die "Box", die verschiedene Streams zusammenpackt:
 - Video-Stream
 - Audio-Stream(s)
 - Untertitel
 - Metadaten

-**Codec = Der Kompressionsalgorithmus (Beispiel: AV1)**
-Entscheidet, WIE komprimiert wird.
-
+**Codec = Kompressionsalgorithmus (z.B. H.264)**
+Bestimmt, WIE komprimiert wird

 <!--
-Container ≠ Codec
-Das ist ein häufiges Missverständnis.
-
-MP4 ist ein Container, nicht ein Codec.
-Ein MP4 kann H.264, H.265 oder AV1 enthalten.
-
-Übrigens: JPEG ist ein Codec (für Bilder), kein Container.
-Bei Bildern fallen Container und Codec oft zusammen.
-
-Tools wie MediaInfo zeigen beide Informationen.
+KLAUSURRELEVANT:
+- Container ≠ Codec (häufiges Missverständnis!)
+- MP4 kann H.264, H.265 oder AV1 enthalten
+- Gleiche Endung, unterschiedlicher Inhalt
+- Tool-Tipp: MediaInfo zeigt beides an
 -->


@@ -451,19 +508,19 @@ Tools wie MediaInfo zeigen beide Informationen.

 **Warum dominant?**
 - Exzellente Kompression (~100:1 möglich)
- Hardware-Support in jedem Gerät seit ~2010
+- Hardware-Decoder in jedem Gerät seit ~2010
 - YouTube, Netflix, Blu-ray – alles H.264

 **Features:**
 - Variable Block-Größen (16×16 bis 4×4)
- Deblocking-Filter (reduziert Block-Artefakte)
+- Deblocking-Filter (reduziert Artefakte)

 <!--
-H.264 revolutionierte Video-Streaming.
-Ohne H.264 kein Netflix, kein YouTube in HD.
-
-Hardware-Decoder bedeutet: Kein CPU-Aufwand, kein Akku-Drain.
-Selbst billige Smartphones können H.264 abspielen.
+KLAUSURRELEVANT:
+- H.264 revolutionierte Video-Streaming
+- Ohne H.264 kein Netflix, kein YouTube HD
+- Hardware-Decoder = kein CPU-Aufwand, kein Akku-Drain
+- Selbst billigste Smartphones können H.264 abspielen
 -->


@@ -486,17 +543,16 @@ Google, Netflix, Amazon, Microsoft, Apple, Mozilla...
 - 8K, HDR, hohe Frame-Rates

 **Stand 2025:**
-YouTube und Netflix nutzen AV1 für 4K/8K
+YouTube, Netflix nutzen AV1 für 4K/8K
 Hardware-Encoder in aktuellen GPUs

 <!--
-AOM = Alliance for Open Media, gegründet 2015.
-Historisch: Konkurrierende Tech-Giganten vereint.
-
-Das Ziel: Nie wieder Patent-Chaos wie bei H.265.
-
-Problem: Encoding ist sehr langsam (10-100× vs. H.264).
-Hardware-Encoder lösen das zunehmend.
+KLAUSURRELEVANT:
+- AOM gegründet 2015 – historisch: Konkurrenten vereint
+- Ziel: Nie wieder Patent-Chaos wie bei H.265
+- Problem: Encoding sehr langsam (10–100× vs. H.264)
+- Hardware-Encoder lösen das zunehmend
+- AV1 gewann 2024 einen Emmy für technische Innovation
 -->


@@ -0,0 +1,228 @@
+---
+marp: true
+theme: gaia
+paginate: true
+backgroundColor: #fff
+header: "Grundlagen IT- und Internettechnik (223015c)"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
+title: Grundlagen IT- und Internettechnik
+---
+
+<style>
+:root {
+  --color-foreground: #1a1a2e;
+  --color-highlight: #d63384;
+  --color-dimmed: #4a4a6a;
+}
+section.invert {
+  --color-foreground: #fff;
+}
+section {
+  font-size: 1.7rem;
+}
+h1 {
+  color: #a02060;
+}
+section.invert h1 {
+  color: #fff;
+}
+h2 {
+  color: #1f2937;
+}
+pre {
+  background: #0f0f23;
+  color: #d63384;
+  border-radius: 8px;
+  border-left: 3px solid #d63384;
+}
+pre code {
+  background: transparent;
+  color: inherit;
+}
+code {
+  background: #1a1a2e;
+  color: #d63384;
+  padding: 0.15em 0.4em;
+  border-radius: 4px;
+}
+a {
+  color: var(--color-highlight);
+}
+section.klausur {
+  background: repeating-linear-gradient(
+    135deg,
+    #fce4ec,
+    #fce4ec 40px,
+    #fff 40px,
+    #fff 80px
+  ) !important;
+}
+@media print {
+  section.klausur {
+    background: #fce4ec !important;
+  }
+}
+section.aufgabe {
+  background: #fce4ec !important;
+}
+section.aufgabe footer {
+  display: none;
+}
+</style>
+
+<!-- _class: invert -->
+<!-- _header: '' -->
+<!-- _backgroundColor: #000 -->
+
+![bg cover opacity:0.2](./assets/background-termin-1.png)
+
+# Grundlagen IT- und Internettechnik
+
+**223015c** · Modul "Technik 1" · 1. Semester
+Digital- und Medienwirtschaft
+Hochschule der Medien Stuttgart
+
+**Sommersemester 2026**
+
+[https://librete.ch/hdm/223015c/](https://librete.ch/hdm/223015c/)
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/qr/slides-223015c.png)
+
+---
+
+<!-- _class: lead -->
+
+# Herzlich willkommen!
+## Einführung
+
+---
+
+# Über mich
+
+**Michael Werner Czechowski**
+
+- Systems and Platform Engineer
+- Schwerpunkte:
+  - Web-Technologien, Barriere-Armut, Open Source
+- Hintergrund:
+  - Philosophie (Uni Stuttgart)
+  - Wirtschaftsinformatik (Leibniz-FH Hannover)
+- Kontakt: lb-czechowski@hdm-stuttgart.de
+
+---
+
+# Warum dieses Modul?
+
+**Das Internet ist überall** – aber was steckt dahinter?
+
+* Warum sehen Webseiten auf dem Handy anders aus?
+* Wie funktioniert eigentlich das Internet?
+* Wie erkennen Sie, ob eine Werbeagentur gute Arbeit leistet?
+* Was hat ein Unterseekabel mit meiner E-Mail zu tun?
+* **→ Die Technik dahinter verstehen und fundierte Entscheidungen treffen**
+
+---
+
+# Das Ziel
+
+**Technische Grundlagen verstehen**, um fundierte Entscheidungen treffen zu können.
+
+Als Digital- und MedienwirtschaftlerInnen werdet ihr täglich mit technischen Fragen konfrontiert:
+* Wie baue ich eine barrierearme Webseite?
+* Welches Protokoll für welchen Zweck?
+* Wie funktioniert das Web hinter den Kulissen?
+* **→ Mitreden können – und selbst Webseiten bauen!**
+
+---
+
+# Was Sie hier lernen werden
+
+**In dieser Veranstaltung erwerben Sie folgende Kompetenzen:**
+
+* Geschichte des Computers und Internets
+* HTML-Grundlagen und semantisches Markup
+* CSS für Layout und Gestaltung
+* Netzwerke und Protokolle (TCP/IP, DNS, HTTP(S))
+* "Barrierefreiheit" im Web
+* Grundlagen von JavaScript und Interaktivität
+
+---
+
+# Kurze Umfrage
+
+**Bitte Hand heben:**
+* Wer hat schon mal eine Webseite gebaut?
+* Wer weiß, was HTML ist?
+* Wer hat schon mal CSS geschrieben? 
+* Wer kennt den Unterschied zwischen Internet und WWW? 
+* Wer hat schon mal mit JavaScript gearbeitet?
+
+---
+
+# Kursübersicht
+
+**Kapitel:**
+
+1. Geschichte, Grundlagen & **HTML**
+2. Netzwerke, Protokolle, **semantisches HTML** & **CSS**
+3. Interaktivität, Animationen & **JavaScript**
+
+**Ziel:** "Gelernte Hilflosigkeit" ablegen
+
+---
+
+<!-- _class: klausur -->
+<!-- _header: '' -->
+<!-- _footer: '' -->
+<!-- _backgroundColor: #fce4ec -->
+
+# Prüfungsleistung
+
+**Nach aktuellem Kenntnisstand:**
+
+* 90 min insg. (Technik 1)
+* Schriftliche Klausur (digital)
+* Teils offene Fragen
+* So gut wie kein Coding/Programmieren
+* **Prüfungsrelevant:** Folien sind markiert mit anderem Hintergrund
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/klausur-01.png)
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/klausur-02.png)
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/klausur-03.png)
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/splan.png)
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/asta.png)
+
@@ -4,7 +4,7 @@ theme: gaia
 paginate: true
 backgroundColor: #fff
 header: "Grundlagen IT- und Internettechnik (223015c)"
-footer: "Michael Czechowski – HdM Stuttgart – WS 2025/26"
+footer: "Michael Czechowski – HdM Stuttgart – SoSe 2026"
 title: "Kapitel 3: Interaktivität & JavaScript"
 ---

@@ -83,7 +83,7 @@ section.aufgabe footer {
 Digital- und Medienwirtschaft
 Hochschule der Medien Stuttgart

-**Wintersemester 2025/26**
+**Sommersemester 2026**

 [https://librete.ch/hdm/223015c/](https://librete.ch/hdm/223015c/)

@@ -208,6 +208,8 @@ Fehler werden hier auch angezeigt

 # Variablen: Daten speichern

+![bg right:35%](./assets/demos/js-console.png)
+
 ```javascript
 // Modern (empfohlen)
 let age = 25;              // Kann geändert werden
@@ -260,6 +262,8 @@ Template Literals mit Backticks!

 # Arrays: Listen

+![bg right:35%](./assets/demos/js-arrays.png)
+
 ```javascript
 const colors = ["red", "green", "blue"];

@@ -284,6 +288,8 @@ Arrays sind veränderbar auch bei const

 # Objects: Strukturierte Daten

+![bg right:35%](./assets/demos/js-objects.png)
+
 ```javascript
 const person = {
    firstName: "Max",
@@ -342,7 +348,7 @@ true || false  // true (ODER)

 **In der Browser-Konsole:**

-1. Erstelle Variablen für dich:
+1. Erstellen Sie Variablen für sich:
   ```javascript
   const name = "Your Name";
   let age = 20;
@@ -413,6 +419,8 @@ Code-Block in geschweiften Klammern

 # Schleifen: Wiederholen

+![bg right:35%](./assets/demos/js-loops.png)
+
 ```javascript
 // for-Schleife
 for (let i = 0; i < 5; i++) {
@@ -491,15 +499,7 @@ Funktionale Programmierung, Original-Array bleibt unverändert
 - JavaScript kann diesen Baum **lesen und ändern**
 - Jedes HTML-Element = ein "Node"

-```
-document
-└── html
-    ├── head
-    │   └── title
-    └── body
-        ├── h1
-        └── p
-```
+![bg right:45% fit](./assets/demos/dom-tree.png)

 <!--
 DOM = Programmierschnittstelle für HTML
@@ -536,6 +536,8 @@ querySelectorAll = alle Treffer

 # Elemente manipulieren

+![bg right:35%](./assets/demos/js-manipulate.png)
+
 ```javascript
 const element = document.querySelector("#meinElement");

@@ -564,6 +566,8 @@ style = Inline-Styles (camelCase!)

 # Klassen manipulieren

+![bg right:35%](./assets/demos/js-classlist.png)
+
 ```javascript
 const element = document.querySelector(".box");

@@ -592,6 +596,8 @@ toggle schaltet hin und her

 # Elemente erstellen

+![bg right:35%](./assets/demos/js-create.png)
+
 ```javascript
 // Neues Element erstellen
 const neuerAbsatz = document.createElement("p");
@@ -660,6 +666,8 @@ Interaktive Webseiten durch Events

 # Event Listener

+![bg right:35%](./assets/demos/js-event-listener.png)
+
 ```javascript
 const button = document.querySelector("#meinButton");

@@ -737,6 +745,8 @@ target = auslösendes Element

 # Event.preventDefault()

+![bg right:35%](./assets/demos/js-preventdefault.png)
+
 ```javascript
 // Link ohne Navigation
 const link = document.querySelector("a");
@@ -763,6 +773,8 @@ Formular-Validierung ohne Reload

 # Beispiel: Toggle Dark Mode

+![bg right:35%](./assets/demos/js-darkmode.png)
+
 ```javascript
 const toggleButton = document.querySelector("#darkModeToggle");
 const body = document.body;
@@ -851,6 +863,8 @@ HTML (Struktur) + CSS (Design) + JavaScript (Interaktivität)

 # Beispiel: Todo-Liste

+![bg right:35%](./assets/demos/js-todo.png)
+
 ```javascript
 const form = document.querySelector("#todoForm");
 const input = document.querySelector("#todoInput");
@@ -893,6 +907,8 @@ Node.js für Backend

 # Fetch: Daten laden

+![bg right:35%](./assets/demos/js-fetch.png)
+
 ```javascript
 // Mit async/await (modern)
 async function loadData() {
@@ -914,6 +930,8 @@ APIs = Schnittstellen zu Daten, JSON = JavaScript Object Notation

 # LocalStorage: Daten speichern

+![bg right:35%](./assets/demos/js-localstorage.png)
+
 ```javascript
 // Speichern
 localStorage.setItem("name", "Max");
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: __TITLE__</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">__URL__</span>
+    </div>
+    <iframe src="__SRC__"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: a11y-error</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/email-form.html</span>
+    </div>
+    <iframe src="./a11y-error.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Fehlermeldung</title>
+  <style>
+    body { font-family: system-ui, sans-serif; padding: 1.2rem; }
+    label { display: block; margin-bottom: 4px; font-weight: 600; }
+    input {
+      font: inherit;
+      padding: 6px 10px;
+      width: 100%;
+      box-sizing: border-box;
+      border: 2px solid #d63384;
+      border-radius: 4px;
+    }
+    #email-error {
+      color: #d63384;
+      font-size: 0.9em;
+      margin-top: 6px;
+    }
+  </style>
+</head>
+<body>
+  <label for="email">E-Mail-Adresse</label>
+  <input id="email" type="email" aria-describedby="email-error" value="michael@">
+  <p id="email-error" role="alert">
+    Bitte geben Sie eine gültige E-Mail-Adresse ein.
+  </p>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: a11y-focus</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/focus.html</span>
+    </div>
+    <iframe src="./a11y-focus.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Fokus-Indikator</title>
+  <style>
+    body { font-family: system-ui, sans-serif; padding: 1.2rem; }
+    :focus, .is-focused {
+      outline: 2px solid blue;
+      outline-offset: 2px;
+    }
+    button:focus-visible, button.is-focused {
+      box-shadow: 0 0 0 3px rgba(0, 100, 255, 0.5);
+    }
+    button { font: inherit; padding: 6px 14px; margin: 6px 0; display: block; }
+  </style>
+</head>
+<body>
+  <p>Tab-Taste drücken:</p>
+  <button class="is-focused">Erster Button</button>
+  <button>Zweiter Button</button>
+  <button>Dritter Button</button>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: a11y-semantic</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/klick.html</span>
+    </div>
+    <iframe src="./a11y-semantic.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>div vs button</title>
+  <style>
+    body { font-family: system-ui, sans-serif; padding: 1.2rem; }
+    h3 { margin: 0.8rem 0 0.4rem; font-size: 1rem; }
+    .bad { color: #b91c1c; }
+    .good { color: #15803d; }
+    .button {
+      display: inline-block;
+      background: #e5e7eb;
+      border: 1px solid #9ca3af;
+      padding: 6px 14px;
+      cursor: pointer;
+      border-radius: 4px;
+    }
+    button { font: inherit; padding: 6px 14px; }
+  </style>
+</head>
+<body>
+  <h3 class="bad">Schlecht (div)</h3>
+  <div class="button" onclick="alert('!')">Klick mich</div>
+  <p><small>❌ Tab überspringt, kein Enter, kein Screenreader</small></p>
+
+  <h3 class="good">Gut (button)</h3>
+  <button type="button">Klick mich</button>
+  <p><small>✅ Tastatur + Screenreader eingebaut</small></p>
+</body>
+</html>
@@ -0,0 +1,65 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>ARP</title>
+  <style>
+    html, body { margin: 0; padding: 0; background: #fff; font-family: system-ui, sans-serif; }
+    body { padding: 30px; display: inline-block; }
+    .row { display: flex; align-items: center; gap: 16px; margin-bottom: 20px; }
+    .actor {
+      background: #1a1a2e;
+      color: #fff;
+      padding: 10px 16px;
+      border-radius: 6px;
+      font-weight: 700;
+      min-width: 160px;
+      text-align: center;
+      font-size: 0.9rem;
+    }
+    .laptop { background: #1e40af; }
+    .router { background: #c2410c; }
+    .arrow-right, .arrow-left {
+      width: 0; height: 0;
+      border-top: 10px solid transparent;
+      border-bottom: 10px solid transparent;
+    }
+    .arrow-right { border-left: 14px solid #d63384; }
+    .arrow-left { border-right: 14px solid #15803d; }
+    .bubble {
+      padding: 10px 14px;
+      border-radius: 8px;
+      font-size: 0.95rem;
+      max-width: 460px;
+    }
+    .ask { background: #fce7f3; border: 2px solid #d63384; color: #7c2d12; }
+    .reply { background: #dcfce7; border: 2px solid #15803d; color: #14532d; }
+    .meta {
+      font-size: 0.7rem;
+      font-weight: 700;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+      opacity: 0.7;
+      margin-bottom: 3px;
+    }
+  </style>
+</head>
+<body>
+  <div class="row">
+    <div class="actor laptop">Laptop</div>
+    <div class="arrow-right"></div>
+    <div class="bubble ask">
+      <div class="meta">Broadcast</div>
+      "Wer hat die IP 192.168.1.1? Sag mir deine MAC!"
+    </div>
+  </div>
+  <div class="row">
+    <div class="bubble reply">
+      <div class="meta">Antwort</div>
+      "Das bin ich! Meine MAC ist 11:22:33:44:55:66"
+    </div>
+    <div class="arrow-left"></div>
+    <div class="actor router">Router</div>
+  </div>
+</body>
+</html>
@@ -0,0 +1,53 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Box-Modell Diagramm</title>
+  <style>
+    html, body { margin: 0; padding: 0; background: #fff; font-family: system-ui, sans-serif; }
+    body { padding: 40px; display: inline-block; box-sizing: border-box; }
+    .layer {
+      padding-top: 38px;
+      padding-bottom: 30px;
+      padding-left: 30px;
+      padding-right: 30px;
+      position: relative;
+      border-radius: 4px;
+    }
+    .layer::before {
+      position: absolute;
+      top: 8px; left: 14px;
+      font-size: 0.95rem;
+      font-weight: 700;
+      letter-spacing: 0.02em;
+    }
+    .margin { background: #fde68a; }
+    .margin::before { content: "margin"; color: #92400e; }
+    .border { background: #fca5a5; }
+    .border::before { content: "border"; color: #991b1b; }
+    .padding { background: #86efac; }
+    .padding::before { content: "padding"; color: #166534; }
+    .content {
+      background: #93c5fd;
+      width: 260px;
+      height: 110px;
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      color: #1e3a8a;
+      font-weight: 700;
+      font-size: 1.2rem;
+      border-radius: 4px;
+    }
+  </style>
+</head>
+<body>
+  <div class="layer margin">
+    <div class="layer border">
+      <div class="layer padding">
+        <div class="content">content</div>
+      </div>
+    </div>
+  </div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: button</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/button.html</span>
+    </div>
+    <iframe src="./button.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Button</title>
+</head>
+<body>
+  <button>Add to favorites</button>
+</body>
+</html>
@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Client/Server Ports</title>
+  <style>
+    html, body { margin: 0; padding: 0; background: #fff; font-family: system-ui, sans-serif; }
+    body { padding: 30px; display: inline-block; }
+    .endpoint {
+      border: 2px solid #4a4a6a;
+      border-radius: 6px;
+      padding: 18px 24px;
+      margin-bottom: 24px;
+      min-width: 380px;
+      background: #f3f4f6;
+    }
+    .endpoint.client { background: #dbeafe; border-color: #1e40af; }
+    .endpoint.server { background: #fed7aa; border-color: #c2410c; }
+    .role {
+      font-weight: 700;
+      font-size: 1rem;
+      margin-bottom: 6px;
+    }
+    .client .role { color: #1e3a8a; }
+    .server .role { color: #7c2d12; }
+    .addr {
+      font-family: ui-monospace, monospace;
+      font-size: 1.4rem;
+      color: #0f172a;
+    }
+    .port {
+      background: #fde68a;
+      color: #7c2d12;
+      padding: 1px 8px;
+      border-radius: 4px;
+      font-weight: 700;
+    }
+    .label {
+      margin-top: 6px;
+      font-size: 0.85rem;
+      color: #4a4a6a;
+      font-style: italic;
+    }
+  </style>
+</head>
+<body>
+  <div class="endpoint client">
+    <div class="role">Client</div>
+    <div class="addr">141.62.xxx.xxx:<span class="port">52431</span></div>
+    <div class="label">↳ zufälliger Port vom OS</div>
+  </div>
+  <div class="endpoint server">
+    <div class="role">Server</div>
+    <div class="addr">212.132.79.37:<span class="port">443</span></div>
+    <div class="label">↳ HTTPS-Standardport</div>
+  </div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: Kontrast</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/contrast.html</span>
+    </div>
+    <iframe src="./contrast-levels.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,97 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Kontrast-Stufen</title>
+  <style>
+    body { font-family: system-ui, sans-serif; padding: 1.6rem; margin: 0; }
+    .row {
+      background: #fff;
+      padding: 22px 20px;
+      margin-bottom: 14px;
+      border-radius: 6px;
+      border: 1px solid #e5e7eb;
+      display: flex;
+      align-items: center;
+      justify-content: space-between;
+      gap: 14px;
+    }
+    .sample {
+      font-size: 1.5rem;
+      font-weight: 600;
+      flex: 1;
+    }
+    .meta {
+      text-align: right;
+      font-size: 0.85rem;
+      white-space: nowrap;
+    }
+    .ratio {
+      font-family: ui-monospace, monospace;
+      font-weight: 700;
+      font-size: 0.95rem;
+      color: #1a1a2e;
+    }
+    .badge {
+      display: inline-block;
+      padding: 2px 8px;
+      border-radius: 3px;
+      font-size: 0.7rem;
+      font-weight: 700;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+      margin-top: 4px;
+    }
+    .fail { background: #fee2e2; color: #991b1b; }
+    .aa-large { background: #fed7aa; color: #7c2d12; }
+    .aa { background: #dcfce7; color: #166534; }
+    .aaa { background: #bbf7d0; color: #14532d; }
+    .hint {
+      margin-top: 14px;
+      font-size: 0.78rem;
+      color: #6b7280;
+      font-style: italic;
+      text-align: right;
+    }
+    .hint a { color: #d63384; }
+  </style>
+</head>
+<body>
+  <div class="row" style="background: #fff;">
+    <div class="sample" style="color: #aaaaaa;">Barrierefrei lesen</div>
+    <div class="meta">
+      <div class="ratio">2.3:1</div>
+      <span class="badge fail">✗ Fail</span>
+    </div>
+  </div>
+  <div class="row" style="background: #fff;">
+    <div class="sample" style="color: #949494;">Barrierefrei lesen</div>
+    <div class="meta">
+      <div class="ratio">3:1</div>
+      <span class="badge aa-large">AA Large</span>
+    </div>
+  </div>
+  <div class="row" style="background: #fff;">
+    <div class="sample" style="color: #767676;">Barrierefrei lesen</div>
+    <div class="meta">
+      <div class="ratio">4.5:1</div>
+      <span class="badge aa">✓ AA</span>
+    </div>
+  </div>
+  <div class="row" style="background: #fff;">
+    <div class="sample" style="color: #595959;">Barrierefrei lesen</div>
+    <div class="meta">
+      <div class="ratio">7:1</div>
+      <span class="badge aaa">✓ AAA</span>
+    </div>
+  </div>
+  <div class="row" style="background: #fff;">
+    <div class="sample" style="color: #1a1a1a;">Barrierefrei lesen</div>
+    <div class="meta">
+      <div class="ratio">16:1</div>
+      <span class="badge aaa">✓ AAA+</span>
+    </div>
+  </div>
+  <div class="hint">Check: webaim.org/resources/contrastchecker</div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-anatomie</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/anatomie.html</span>
+    </div>
+    <iframe src="./css-anatomie.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>CSS Anatomie</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; }
+    p { color: blue; font-size: 16px; }
+  </style>
+</head>
+<body>
+  <p>Dieser Absatz ist blau und 16 Pixel groß.</p>
+  <p>Alle p-Elemente werden gleich gestylt.</p>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-box-model</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/box-model.html</span>
+    </div>
+    <iframe src="./css-box-model.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Box-Modell</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; background: #fff; }
+    .box { display: inline-block; }
+    .layer {
+      padding-top: 22px;
+      padding-bottom: 18px;
+      padding-left: 18px;
+      padding-right: 18px;
+      position: relative;
+    }
+    .layer::before {
+      position: absolute;
+      top: 4px; left: 8px;
+      font-size: 0.75em;
+      font-weight: 600;
+    }
+    .margin { background: #fde68a; }
+    .margin::before { content: "margin"; color: #92400e; }
+    .border { background: #fca5a5; }
+    .border::before { content: "border"; color: #991b1b; }
+    .padding { background: #86efac; }
+    .padding::before { content: "padding"; color: #166534; }
+    .content {
+      background: #93c5fd;
+      width: 140px;
+      height: 56px;
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      color: #1e3a8a;
+      font-weight: 600;
+    }
+    pre { background: #f3f4f6; padding: 10px; border-radius: 4px; font-size: 0.85em; margin-top: 1rem; font-family: ui-monospace, monospace; }
+  </style>
+</head>
+<body>
+  <div class="box">
+    <div class="layer margin">
+      <div class="layer border">
+        <div class="layer padding">
+          <div class="content">content</div>
+        </div>
+      </div>
+    </div>
+  </div>
+  <pre>.box {
+  width: 140px;
+  padding: 18px;
+  border: 18px solid;
+  margin: 18px;
+}</pre>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-colors</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/colors.html</span>
+    </div>
+    <iframe src="./css-colors.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Farben</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; font-size: 14px; }
+    .swatch { display: flex; align-items: center; margin-bottom: 8px; }
+    .chip { width: 40px; height: 40px; border-radius: 4px; margin-right: 12px; border: 1px solid #e5e7eb; }
+    code { background: #f3f4f6; padding: 2px 6px; border-radius: 3px; font-family: ui-monospace, monospace; font-size: 0.85em; }
+  </style>
+</head>
+<body>
+  <div class="swatch"><div class="chip" style="background: red;"></div><code>color: red;</code></div>
+  <div class="swatch"><div class="chip" style="background: rebeccapurple;"></div><code>color: rebeccapurple;</code></div>
+  <div class="swatch"><div class="chip" style="background: #FF0000;"></div><code>#FF0000</code></div>
+  <div class="swatch"><div class="chip" style="background: rgb(255, 0, 0);"></div><code>rgb(255, 0, 0)</code></div>
+  <div class="swatch"><div class="chip" style="background: rgba(255, 0, 0, 0.5);"></div><code>rgba(255, 0, 0, 0.5)</code></div>
+  <div class="swatch"><div class="chip" style="background: hsl(0, 100%, 50%);"></div><code>hsl(0, 100%, 50%)</code></div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-combinators</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/combinators.html</span>
+    </div>
+    <iframe src="./css-combinators.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Kombinatoren</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; font-size: 14px; }
+    article p { line-height: 1.6; background: #fef3c7; padding: 4px; }
+    nav > a { text-decoration: none; color: #d63384; margin-right: 10px; font-weight: 600; }
+    h2 + p { font-size: 1.2em; color: #065f46; }
+    p.wichtig { color: red; }
+  </style>
+</head>
+<body>
+  <nav>
+    <a href="#">Link</a><a href="#">Link</a>
+  </nav>
+  <article>
+    <h2>Artikel-Überschrift</h2>
+    <p>Direkt nach h2 (größer, grün).</p>
+    <p>Normaler Absatz im article (gelb).</p>
+    <p class="wichtig">Wichtig (rot).</p>
+  </article>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-pseudo-classes</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/pseudo-classes.html</span>
+    </div>
+    <iframe src="./css-pseudo-classes.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Pseudo-Klassen</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; font-size: 14px; }
+    a { color: #2563eb; }
+    a:hover, a.is-hovered { color: red; text-decoration: underline; }
+    a:visited, a.is-visited { color: purple; }
+    input:focus, input.is-focused { border-color: blue; outline: 2px solid blue; }
+    input { padding: 4px 8px; border: 1px solid #9ca3af; border-radius: 3px; }
+    ul { list-style: none; padding: 0; }
+    li { padding: 6px 10px; }
+    li:first-child, li.is-first { font-weight: bold; }
+    li:nth-child(odd), li.is-odd { background: #eee; }
+    h3 { margin: 0.6rem 0 0.3rem; font-size: 0.95rem; }
+  </style>
+</head>
+<body>
+  <h3>:hover / :visited</h3>
+  <a href="#" class="is-hovered">Link mit Hover</a> &middot;
+  <a href="#" class="is-visited">Besuchter Link</a>
+
+  <h3>:focus</h3>
+  <input class="is-focused" value="fokussiert">
+
+  <h3>:first-child, :nth-child(odd)</h3>
+  <ul>
+    <li class="is-first is-odd">Erster (bold, zebra)</li>
+    <li>Zweiter</li>
+    <li class="is-odd">Dritter (zebra)</li>
+    <li>Vierter</li>
+    <li class="is-odd">Fünfter (zebra)</li>
+  </ul>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-pseudo-elements</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/pseudo-elements.html</span>
+    </div>
+    <iframe src="./css-pseudo-elements.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Pseudo-Elemente</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; font-size: 14px; }
+    .required::before {
+      content: "* ";
+      color: red;
+    }
+    p.drop { line-height: 1.5; }
+    p.drop::first-letter {
+      font-size: 3em;
+      font-weight: bold;
+      color: #d63384;
+      float: left;
+      line-height: 0.9;
+      padding-right: 6px;
+      padding-top: 2px;
+    }
+    label { display: block; margin-top: 10px; }
+    input { padding: 4px 8px; border: 1px solid #9ca3af; border-radius: 3px; margin-top: 3px; }
+    h3 { margin: 0.6rem 0 0.3rem; font-size: 0.95rem; }
+  </style>
+</head>
+<body>
+  <h3>::before (Pflichtfeld-Sternchen)</h3>
+  <label class="required">E-Mail-Adresse</label>
+  <input type="email">
+
+  <h3>::first-letter (Initial-Buchstabe)</h3>
+  <p class="drop">Lorem ipsum dolor sit amet. Der erste Buchstabe wird per CSS hervorgehoben – kein extra HTML nötig.</p>
+</body>
+</html>
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Responsive Container</title>
+  <style>
+    body { padding: 0; margin: 0; font-family: system-ui, sans-serif; background: #fff; }
+    .container {
+      padding: 1rem;
+      background: white;
+      color: #111;
+      text-align: left;
+      font-weight: 600;
+      border: 1px solid #d1d5db;
+    }
+    .container::before { content: "< 768px — weiß, padding 1rem"; }
+    @media (min-width: 768px) {
+      .container { padding: 2rem; background: red; color: white; border: none; }
+      .container::before { content: "≥ 768px — rot, padding 2rem"; }
+    }
+    @media (min-width: 1024px) {
+      .container { background: green; }
+      .container::before { content: "≥ 1024px — grün"; }
+    }
+  </style>
+</head>
+<body>
+  <div class="container"></div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-responsive</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/responsive.html</span>
+    </div>
+    <iframe src="./css-responsive.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Responsive Design – 3 Viewports</title>
+  <style>
+    html, body { margin: 0; padding: 0; font-family: system-ui, sans-serif; background: #fff; }
+    body { padding: 1rem; }
+    .viewport {
+      margin-bottom: 12px;
+      border: 1px solid #9ca3af;
+      border-radius: 4px;
+      overflow: hidden;
+    }
+    .bar {
+      background: #e5e7eb;
+      padding: 4px 10px;
+      font-size: 11px;
+      color: #374151;
+      font-family: ui-monospace, monospace;
+      border-bottom: 1px solid #9ca3af;
+    }
+    iframe { display: block; width: 100%; border: 0; }
+    .vp-mobile iframe { width: 360px; }
+    .vp-tablet iframe { width: 800px; }
+    .vp-desktop iframe { width: 1100px; }
+    .vp-mobile { width: 362px; }
+    .scroll { overflow: hidden; }
+  </style>
+</head>
+<body>
+  <div class="viewport vp-mobile">
+    <div class="bar">Mobile @ 360px</div>
+    <div class="scroll"><iframe src="./css-responsive-container.html" height="80"></iframe></div>
+  </div>
+  <div class="viewport vp-tablet">
+    <div class="bar">Tablet @ 800px</div>
+    <div class="scroll" style="overflow-x: auto;"><iframe src="./css-responsive-container.html" height="100"></iframe></div>
+  </div>
+  <div class="viewport vp-desktop">
+    <div class="bar">Desktop @ 1100px</div>
+    <div class="scroll" style="overflow-x: auto;"><iframe src="./css-responsive-container.html" height="100"></iframe></div>
+  </div>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-selector-class</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/selector-class.html</span>
+    </div>
+    <iframe src="./css-selector-class.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Klassen-Selektor</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; }
+    .wichtig { color: red; font-weight: bold; }
+  </style>
+</head>
+<body>
+  <p class="wichtig">Dieser Text ist wichtig.</p>
+  <p>Dieser nicht.</p>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-selector-element</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/selector-element.html</span>
+    </div>
+    <iframe src="./css-selector-element.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Element-Selektor</title>
+  <style>
+    body { padding: 1.2rem; }
+    p { color: gray; font-family: Georgia, serif; }
+    h1, h2, h3 { font-family: sans-serif; }
+  </style>
+</head>
+<body>
+  <h1>Überschrift (sans-serif)</h1>
+  <p>Absatz: grau, Georgia (serif).</p>
+  <h2>Untertitel (sans-serif)</h2>
+  <p>Noch ein grauer Absatz.</p>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-selector-id</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/selector-id.html</span>
+    </div>
+    <iframe src="./css-selector-id.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>ID-Selektor</title>
+  <style>
+    body { padding: 0; margin: 0; font-family: system-ui, sans-serif; }
+    #hauptnavigation {
+      background: #333;
+      padding: 1rem;
+      color: white;
+    }
+    #hauptnavigation a { color: #fff; margin-right: 1rem; }
+  </style>
+</head>
+<body>
+  <nav id="hauptnavigation">
+    <a href="#">Home</a>
+    <a href="#">Kurse</a>
+    <a href="#">Kontakt</a>
+  </nav>
+  <p style="padding: 1rem;">Rest der Seite.</p>
+</body>
+</html>
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+<meta charset="UTF-8">
+<title>Preview: css-specificity</title>
+<style>
+  :root {
+    --hl: #d63384;
+    --dark: #0f0f23;
+    --chrome: #1a1a2e;
+    --muted: #4a4a6a;
+  }
+  html, body { margin: 0; padding: 0; background: var(--dark); font-family: system-ui, -apple-system, sans-serif; }
+  .browser { box-sizing: border-box; width: 100vw; min-height: 100vh; padding: 18px; }
+  .window { background: #fff; border-radius: 10px; box-shadow: 0 12px 32px rgba(0,0,0,.35); overflow: hidden; border: 2px solid var(--hl); }
+  .chrome { background: var(--chrome); border-bottom: 2px solid var(--hl); padding: 10px 14px; display: flex; align-items: center; gap: 7px; }
+  .dot { width: 11px; height: 11px; border-radius: 50%; opacity: 0.9; }
+  .r { background: #ff5f56; } .y { background: #ffbd2e; } .g { background: #27c93f; }
+  .url { flex: 1; margin-left: 12px; background: var(--dark); border: 1px solid var(--hl); border-radius: 6px; padding: 5px 10px; font: 12px/1.3 ui-monospace, "SF Mono", Menlo, monospace; color: var(--hl); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+  iframe { display: block; width: 100%; height: 700px; border: 0; background: #fff; }
+</style>
+</head>
+<body>
+<div class="browser">
+  <div class="window">
+    <div class="chrome">
+      <span class="dot r"></span><span class="dot y"></span><span class="dot g"></span>
+      <span class="url">file:///beispiel/specificity.html</span>
+    </div>
+    <iframe src="./css-specificity.html"></iframe>
+  </div>
+</div>
+</body>
+</html>
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Spezifität</title>
+  <style>
+    body { padding: 1.2rem; font-family: system-ui, sans-serif; }
+    p { color: blue; }          /* 0,0,0,1 */
+    .text { color: green; }     /* 0,0,1,0 */
+    #intro { color: red; }      /* 0,1,0,0 */
+    code { background: #f3f4f6; padding: 1px 5px; border-radius: 3px; font-size: 0.9em; }
+    .row { margin-bottom: 10px; }
+    .label { color: #6b7280; font-size: 0.85em; }
+  </style>
+</head>
+<body>
+  <div class="row">
+    <p>Nur <code>p</code>: <strong>blau</strong></p>
+    <span class="label">0,0,0,1</span>
+  </div>
+  <div class="row">
+    <p class="text">Nur <code>.text</code>: <strong>grün</strong> schlägt p</p>
+    <span class="label">0,0,1,0 &gt; 0,0,0,1</span>
+  </div>
+  <div class="row">
+    <p id="intro" class="text">ID <code>#intro</code>: <strong>rot</strong> schlägt alles</p>
+    <span class="label">0,1,0,0 &gt; 0,0,1,0</span>
+  </div>
+</body>
+</html>
@@ -0,0 +1,65 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <title>Decapsulation Stack</title>
+  <style>
+    html, body { margin: 0; padding: 0; background: #fff; font-family: system-ui, sans-serif; }
+    body { padding: 30px; display: inline-block; }
+    .stack { display: flex; flex-direction: column; gap: 0; }
+    .layer {
+      border: 2px solid;
+      border-radius: 6px;
+      padding: 10px 18px;
+      min-width: 540px;
+      font-size: 0.95rem;
+      margin-bottom: 4px;
+    }
+    .layer-name { font-weight: 700; font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.05em; opacity: 0.8; }
+    .layer-desc { font-family: ui-monospace, monospace; margin-top: 3px; }
+    .check { margin-top: 3px; font-size: 0.85rem; font-style: italic; }
+    .http { background: #e0e7ff; border-color: #4f46e5; color: #3730a3; }
+    .tcp { background: #dbeafe; border-color: #1e40af; color: #1e3a8a; }
+    .ip { background: #dcfce7; border-color: #15803d; color: #14532d; }
+    .eth { background: #fed7aa; border-color: #c2410c; color: #7c2d12; }
+    .bit { background: #e5e7eb; border-color: #4b5563; color: #1f2937; }
+    .arrow {
+      align-self: center;
+      width: 0; height: 0;
+      border-left: 9px solid transparent;
+      border-right: 9px solid transparent;
+      border-top: 12px solid #d63384;
+      margin: 2px 0;
+    }
+  </style>
+</head>
+<body>
+  <div class="stack">
+    <div class="layer bit">
+      <div class="layer-name">Physical</div>
+      <div class="layer-desc">Bits empfangen</div>
+    </div>
+    <div class="arrow"></div>
+    <div class="layer eth">
+      <div class="layer-name">Ethernet-Frame</div>
+      <div class="check">MAC = meine MAC? ✓ auspacken</div>
+    </div>
+    <div class="arrow"></div>
+    <div class="layer ip">
+      <div class="layer-name">IP-Paket</div>
+      <div class="check">Ziel-IP = meine IP? ✓ auspacken</div>
+    </div>
+    <div class="arrow"></div>
+    <div class="layer tcp">
+      <div class="layer-name">TCP-Segment</div>
+      <div class="check">Port 52431 = mein Browser? ✓ auspacken</div>
+    </div>
+    <div class="arrow"></div>
+    <div class="layer http">
+      <div class="layer-name">HTTP-Response</div>
+      <div class="layer-desc">"HTTP/1.1 200 OK ..."</div>
+      <div class="check">→ Browser rendert Seite</div>
+    </div>
+  </div>
+</body>
+</html>
Author	SHA1	Message	Date
libretech	ec800d28ae	a11y werkzeuge-folie überarbeitet: screenreader tabelle, orca/talkback, wcag-formulierungen	2026-04-21 23:38:06 +02:00
libretech	80786cb040	a11y folien feinschliff, input-date demo, tag-attribut demo update, synonyme	2026-04-21 23:32:30 +02:00
libretech	67857b9bfd	a11y vertiefung: keyboard-demo, input-devices, mdn-links vereinheitlicht	2026-04-21 20:58:52 +02:00
libretech	cedda338df	double qr overlay size on wave slide	2026-04-21 19:43:11 +02:00
libretech	bfe7f3576a	add inverted wave qr overlay on tab-order slide	2026-04-21 19:35:19 +02:00
libretech	6b21b45e01	shrink mdn reference urls to compact text links	2026-04-20 18:26:50 +02:00
libretech	aeaeed6867	wave-tab-order as standalone full-bleed slide	2026-04-20 18:24:14 +02:00
libretech	72b7d51af9	add contrast-levels demo, wave-tab-order image, link a11y tools, mark axe as paid/pro	2026-04-20 18:22:42 +02:00
libretech	bd5d7f0028	disable klausurfolien and klausurfragen cards on index (still being reworked)	2026-04-20 13:35:08 +02:00
libretech	b6334035fc	add js basics demos: console, arrays, objects, loops	2026-04-20 13:25:09 +02:00
libretech	7626852ac1	add js demos for chapter 3: manipulate, classlist, create, events, preventdefault, todo, fetch, localstorage	2026-04-20 13:14:56 +02:00
libretech	754ff9436c	add dark mode js demo on chapter 3 slide	2026-04-20 12:54:52 +02:00
libretech	0367f07166	fix broken dns tree and port connector, full-bleed handshake and dns-lookup slides, siezen in all demos, first-letter sizing	2026-04-20 12:06:04 +02:00
libretech	c45ddc779c	replace arp dialog with visual, inline first-hop arrow	2026-04-20 11:52:13 +02:00
libretech	5b7170e5f4	remove stray handshake png from repo root	2026-04-20 11:48:06 +02:00
libretech	cbebc1a6f7	remove klausur class from chapter 2, siezen students, add server-decap demo, hide header/footer on oversized slides	2026-04-20 11:47:55 +02:00
libretech	8ed7796968	replace ascii trees: dns hierarchy, dom structure	2026-04-20 11:38:28 +02:00
libretech	5d4d167cbd	replace ascii: encap layers, timeline, dns lookup sequence, hop chain	2026-04-20 11:34:56 +02:00
libretech	6c8688c9f6	replace ascii arrows: network chain, port highlight, client/server, encap/decap, response hops	2026-04-20 11:27:28 +02:00
libretech	54ba08cdbc	mark css einheiten slide as klausur	2026-04-20 11:11:57 +02:00
libretech	777e0ffddb	replace ascii encapsulation diagrams: tcp, ip, ethernet, router re-hop	2026-04-20 11:10:47 +02:00
libretech	76f7ff3a46	replace ascii osi/tcpip layer diagram with rendered visual	2026-04-20 11:06:16 +02:00
libretech	b3c0994b7e	replace ascii box-model with diagram, expand explanation	2026-04-20 10:59:00 +02:00
libretech	fb361a2854	add css demos for 223015c chapter 2: selectors, specificity, box-model, colors, pseudo, responsive	2026-04-20 10:53:11 +02:00
libretech	a2934f1327	add html/css demos for 223015c chapter 1: html basics, widgets, a11y	2026-04-20 10:44:12 +02:00
libretech	558d0e5ecd	update 223015c chapter 1: wording, formatting, gendering	2026-04-20 10:27:06 +02:00
libretech	6aba40e128	rename materials wtf1-3 to hex1-3 and add hex4, hex5	2026-04-17 12:37:12 +02:00
libretech	f6d9992a2c	add grayscale gradient svg and zoom slide - replace grayscale-gradient.png with svg (256 discrete rects) - add grayscale-zoom.svg: 16 brightest shades with decimal + hex labels - add zoom slide after '256 shades of gray' - minor tweaks: Mbps capitalization, remove redundant '256' prefix in states list	2026-04-17 12:37:09 +02:00
libretech	3e7fdf5dfc	fix order	2026-04-17 03:34:01 +02:00
libretech	85ff73774c	fix questions	2026-04-17 02:57:54 +02:00
libretech	e5e7d80050	update 223015b chapter 1: step-by-step reveals, content tweaks - split 'ein konkretes beispiel' into 5 progressive reveal slides - add lead slide 'das problem der datengröße oder knappen speichers' - add samplerate.webp background to 'zurück zu analog' slides - rework bandbreite slide: klausur class, clearer mbit/s vs mb/s framing - update 'was sind daten': hausarbeit, 3d-rendering examples - add matrix red/blue pill to das bit slide - replace dvd.jpg with kubrick.jpg for video eskaliert slide - minor wording fixes (mögliche zustände, mbps notation)	2026-04-17 01:42:38 +02:00
libretech	8c2f388c7f	update 223015b chapter 1: remove unused slides, fix erklaerung comment, reorder hex slide content - remove placeholder todo slides and compression-types image slide - remove hex-dec-lookup-table slide - remove dateneinheiten-vertiefung erklaerung slide - fix broken erklaerung comment block in kompression-vertiefung - reorder hexadezimal slide: nibble definition before ascii table link	2026-04-17 00:44:29 +02:00
libretech	1bbe41b6fc	update 223015b chapter 1: new assets, slide edits, asset cleanup - add druckwelle.png, samplerate.webp, kubrick.jpg, morpheus.jpg - remove Red-Pill-Blue-Pill-in-Matrix.jpg - update slide content	2026-04-16 22:18:15 +02:00
libretech	fde51856ce	fix 223015b chapter 1: marp fragment pattern for druckwelle + zurück zu analog - split 'schall ist eine druckwelle' into two slides: * fragments then full reveal + vinyl line - split 'zurück zu analog' into two slides: * fragments for dac chain then full reveal + conclusion - apply duplicate-slide reveal pattern consistently	2026-04-16 21:55:00 +02:00
libretech	8935f31091	rework 223015b chapter 1: analog/digital narrative arc replace flat analog-vs-digital slide and sampling overview with four-slide narrative: schallwelle → abtastung → digitales ergebnis → zurück zu analog (dac). builds a causal chain from sound wave through digitization back to playback.	2026-04-16 18:29:41 +02:00
libretech	81156284ac	update 223015b chapter 1: new slides, speaker notes, abbreviation fixes - add download/upload speed slides with ADSL/FTTH context - add quiz slide (250 Mbit/s → MB/min) - add analog vs. digital and sampling slides - add cd-audio vertiefung (erklaerung slide) - expand "was sind daten?" with content - expand speaker notes with sources and terminology (DE/EN) - resolve all abbreviations in speaker notes: FTTH, ITU, NTSC, PAL, NHK, IEC - fix typo: "eie" → "eine" binärdatei - fix spelling: "spektrogram" → "spektrogramm" - update zettabyte example and 181 ZB as projection not fact	2026-04-16 18:10:00 +02:00
libretech	7dd46de5d9	WIP: dateiformate rework	2026-04-16 11:20:08 +02:00
libretech	7d8e9f596c	add diday and palantir slides to 223015c chapter 1	2026-04-10 09:18:58 +02:00
libretech	ef0a55db77	update 223015c chapter 1: new hex table, zahlensysteme slide, fix byte to 42	2026-04-10 09:18:44 +02:00
libretech	ceb5f89320	update 223015b chapter 1: add floridi source to speaker notes, fix artemis slide	2026-04-10 09:18:37 +02:00
libretech	a18afde2db	update 223015b intro: fix umfrage wording, remove suggestive question	2026-04-10 09:18:30 +02:00
libretech	38563e2142	fix growth-of-big-data image: rename to remove spaces, hide footer	2026-04-10 01:29:16 +02:00
libretech	aeb0adada9	update 223015b chapter 1: add images, artemis slide, fix hex table - add cd logo, cd player, dvd, artemis images - add artemis ii slide with apollo comparison and bandwidth calculation - regenerate hex-dec lookup table as 16x16 grid with ascii highlight - move hex-dec table next to hexadezimal slides - fix mp3 bitrate: 320 -> 128 kbps to match stated file size	2026-04-10 01:10:26 +02:00
libretech	e58dacd98c	rework 223015b intro: cleaner structure, new umfrage, consolidate slides - update über mich (full name, proper title) - remove ama/jung-naiv slides - new course-specific umfrage questions with speaker notes - consolidate warum/ziel/kompetenzen into two slides - chapter-based kursübersicht, klausur-styled prüfungsleistung	2026-04-10 01:10:17 +02:00
libretech	edc9225ccf	add assembler and fortran slides to 223015c chapter 1 - assembler (1947): kathleen booth, mnemonics, rollercoaster tycoon - fortran (1957): john backus, lois haibt, formula translator - detailed speaker notes with biographical and technical context	2026-04-09 22:11:11 +02:00
libretech	5b94593d94	update 223015b klausurfolien: endnutzer -> endnutzerInnen	2026-04-09 22:11:04 +02:00
libretech	3bd6d7b459	update 223015b chapter 1: content fixes, expand speaker notes with abbreviations - endnutzer -> endnutzerInnen, fix lossy reversibility wording - add tar to deflate examples, reword shannon-limit - expand kompression-vertiefung speaker notes: lz77/lz78/deflate/tar explained - resolve all abbreviations in speaker notes (cmyk, rgb, css, html, http, smtp, url, cjk, utf-8, si, iec, iot, lto, ssd, hdd, ecc, raid, vhs, fft, jpeg, aac, riaa, foss, iis, rle) - minor slide fixes: hex examples, byte value, wording improvements	2026-04-09 22:10:59 +02:00
libretech	c57db78c52	rework dev server: hmr for all courses, per-course targets, root index - make dev serves all courses on port 1312 with marp live reload - make dev-b/dev-c for single course on 1313/1314 - dev-kill only kills specific ports instead of all marp processes - add generate-root-index.sh for prod build overview page - cleanup function uses exec + trap instead of pid files	2026-04-09 22:10:48 +02:00
libretech	c1277cc737	update 223015c chapter 1: add mosaic browser image, remove duplicate speaker notes	2026-03-27 09:46:56 +01:00
libretech	fd8b107643	add 00-intro for 223015c, update chapter 1 speaker notes and five eyes - new intro deck for 223015c with adapted content, colors, and assets - chapter 1: expanded sputnik/kalter krieg speaker notes, five eyes on unterseekabel slide - bits/bytes table: added factor 8 conversion, removed 1tb slide	2026-03-27 09:41:29 +01:00
libretech	3a2e1a8d15	rework 223015c chapter 1: reorder history, improve slides, fix terminology - kursübersicht: themen -> kapitel, format-zeile entfernt, vor kapitel 1 verschoben - teil 1/2/3 prefixes entfernt, section titles vereinfacht - von-neumann-architektur: konzeptfolie überarbeitet, klausur-titel ergänzt, redundante zeile entfernt - folien-reihenfolge: von-neumann direkt nach eniac, lektionen für heute ans ende - slide 34 (kalter krieg): inhalt erweitert, sputnik-schock speaker notes ergänzt - bits/bytes-tabelle: faktor 8 zwischen bit und byte ergänzt - 1tb-festplatte folie entfernt - unterseekabel: bild hinzugefügt, five eyes ergänzt, text verbessert	2026-03-26 19:02:31 +01:00
libretech	ac89d69365	update claude.md: add git checkout restriction, simplify nix section	2026-03-26 18:17:23 +01:00
libretech	552949811e	rework 223015c chapter 1: improve formatting, speaker notes, remove redundant slides	2026-03-26 18:17:16 +01:00
libretech	030bb322a2	update semester to sommersemester 2026 across all courses	2026-03-26 18:17:09 +01:00
libretech	9631a1c45b	simplify flake.nix: remove redundant scripts and claude-code, bump to node 22	2026-03-26 18:17:01 +01:00
libretech	4245ea2567	add essay questions across all blocks in 223015c - A4: von-neumann komponenten (disabled) - B7a: IP/MAC/Port vergleichen - B13a: TCP vs UDP vergleichen - C9a: status codes 2xx/4xx/5xx erklären - C9b: HTTP-methoden vergleichen (disabled) - D5: encapsulation erklären (disabled) - E3: gesamtablauf DNS/TCP/HTTP - H2a: einschränkungstypen erklären	2026-02-02 21:12:48 +01:00
libretech	51146d3dfc	add more essay questions to 223015b (all disabled) - J25: redundanz vs irrelevanz - K12: rasterisierung vs vektorisierung - L12: warum 8x8 blöcke bei JPEG - N9: container vs codec transfer	2026-02-02 21:10:47 +01:00
libretech	fda4aca4c7	add essay questions across all blocks in 223015b - J23-J24: distribution comparison, analog vs digital - K10-K11: image types, color depth (disabled) - L10-L11: JPEG pipeline, artifacts (L11 disabled) - M7-M8: image format comparison, GIF alternatives (M8 disabled) - N7-N8: frame types, video codec comparison (N8 disabled) - O14-O15: storage tech comparison, backup strategies (O15 disabled)	2026-02-02 20:51:46 +01:00
libretech	aff352fa91	add questions for analog/digital media and storage types in 223015b - J15-J22: analog/digital media, distribution methods, generationsverlust - O9-O13: storage media categories, cloud, LTO - some questions disabled for later use	2026-02-02 20:38:48 +01:00
libretech	ea7e905c61	split klausurfragen into per-course files and add erklaerung slides to 223015c - split slides/klausurfragen.md into course-specific files: - slides/223015b/klausurfragen.md (blocks J-O: dateiformate) - slides/223015c/klausurfragen.md (blocks A-I: it-grundlagen) - add erklaerung slides to 223015c (16 new vertiefung slides) - update erklaerung slides in 223015b with deeper content - update makefile to build klausurfragen per-course - remove global klausurfragen from root index	2026-02-02 19:06:37 +01:00
libretech	512fbd9d3d	add erklaerung slides to 223015b course files - add erklaerung css class and 6 explanation slides to 01-grundlagen-text-audio.md - add erklaerung css class and 9 explanation slides to 02-bild-audio-video.md - add erklaerung css class and 2 explanation slides to 03-speichermedien-schnittstellen.md - regenerate klausurfolien.md with updated content	2026-02-02 14:25:04 +01:00
libretech	f9185d25e0	add functionality to disable topics in course index and improve layout	2026-02-02 02:28:06 +01:00
libretech	4f3b680951	add build and deploy targets for klausurfragen	2026-02-02 01:20:33 +01:00
libretech	a2b1c0484a	update klausurfragen.md to improve visibility and clarify title	2026-02-02 01:13:31 +01:00
libretech	1480d31a54	refactor klausurfragen.md to use gender-neutral language and improve clarity	2026-02-01 22:38:14 +01:00
libretech	514896db33	update flake.nix to allow unfree packages and add claude-code dependency	2026-02-01 22:38:02 +01:00
libretech	b21e2394d5	fix layout and add disabled state for slides	2026-02-01 22:27:26 +01:00
libretech	7da018d92c	add klausurfragen for 223015c	2026-02-01 18:21:01 +01:00
libretech	9e12447528	rebuild dev and build system with single marp server - simplify development: single marp server on port 3000 instead of 3 processes - rename klausur to klausurfolien for better naming - update extract script to use 00-intro.md as template when no 01-*.md exists - update makefile and package.json for new workflow - add comprehensive AGENTS.md guidelines	2026-02-01 18:17:51 +01:00