Instead of a separate back button, the Previous button is repurposed
as "Back" in playground mode - same position (left), same style.
Only the Next button is hidden in playground mode.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
- Add back button to game-controls (shown only in playground mode)
- Replace dice img with inline SVG using currentColor for consistent styling
- Add SVG sizing rule to .btn-icon
- Add "back" translation to all 6 languages
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Progress System:
- Replace percentage-based progress with milestone markers (1, 5, 10, 20, 30, 50, 75, 100)
- Add visual milestone indicators with reached/current/next states
- Add celebration animation when milestones are reached
- Update progress bar to show progress toward next milestone
- Add progressTextMilestone i18n key for all 6 languages
New Lessons Activated:
- HTML Dialog (native modal dialogs)
- HTML Progress & Meter (indicator elements)
- HTML Fieldset (form grouping)
- HTML Datalist (autocomplete inputs)
This adds 10 new lessons across all 6 languages, bringing total from ~66 to ~76.
