- Add proper container styling (mx-auto, px-4, py-12) to main content wrappers matching single.html pattern
- Replace gray color hardcodes with theme-aware CSS variables:
- bg-gray-50/gray-900 → bg-bg/50 with hover:bg-bg/70 for article cards
- text-gray-600/gray-400 → text-text-dim for text
- border-gray-300/gray-700 → border-border for borders
- bg-gray-200/gray-800 → bg-border/20 for tags
- Fixes color inconsistency in both light and dark modes
- Ensures 404 latest articles and Repository tags use theme colors instead of fixed gray
