Flexbox and Box Model lessons:
- Use explicit task instructions with selector AND property
- Include selector in codePrefix for better context
- Replace hex colors with named CSS colors (steelblue, coral, etc.)
- Simplify values (2px instead of 0.125rem, 1rem instead of 1.25rem)
- Remove redundant contains validations
- Wrap code examples in <code> tags for proper styling
- Add 5 CSS modules to lessons.js config (EN)
- Create German translations for all 5 CSS modules
- Add CSS modules to lessons.de.js config
- Fix test to use toBeGreaterThanOrEqual for module count
