Complete matrix rain background effect implementation

- Add canvas-based matrix rain animation with ASCII + katakana characters
- Implement per-column animation with varied drop speeds (2-4 frame throttle)
- Theme-aware colors: purple and green accents with live switching
- Homepage: 28% opacity (dark) / 35% opacity (light) for prominent hero effect
- Inner pages: 13% opacity (dark) / 18% opacity (light) for subtle side gutters
- Respect prefers-reduced-motion system setting
- Add opaque background to content grids to block rain under text
- Add .content-grid class to differentiate single pages from list pages
- Add solid background to article list item cards
- Update article list item with bg-bg class for readability
- Z-index stack: canvas (z-1), content grid (z-9), main content (z-10)

Files modified:
- matrix-rain.js: new IIFE animation script with MutationObserver for theme switching
- baseof.html: add canvas element and script tag with guard
- main.css: add canvas positioning, opacity rules, content grid background
- _default/single.html: add max-w-7xl and .content-grid class
- articles/single.html: add max-w-7xl and .content-grid class
- is/list.html: add max-w-7xl and .content-grid class
- article-list-item.html: add bg-bg class for solid background

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions