- Add CSS Colors, Typography, Advanced Selectors, and Grid modules
- Remove deprecated HTML Marquee module from all languages
- Remove redundant div & span lesson from HTML Block & Inline
- Move SVG module from HTML to CSS section
- Enhance first lessons with comprehensive explanations:
- Flexbox: historical context, axes concept
- Colors: named colors, background-color explained
- Grid: comparison to Flexbox, key properties
- Swap header logo highlight (CRISPIES instead of CODE)
- Use English fallbacks for new modules in non-EN languages
- Fix test to include 'playground' mode
New path: 19 modules (~78 lessons) vs previous 16 modules (62 lessons)
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