Removes the sequential fade-out → wait → fade-in pattern that causes
a visible black flash in dark mode between page transitions. Replaces
with immediate crossfade (new page fades in over old content, no wait).
Changes:
- layout.css: Add page-crossfade-in keyframe (0.18s) + prefers-reduced-motion override
- router.js: Remove outClass/inClass direction logic and oldPage fadeout wait
The new approach:
1. Old page remains visible until new page renders
2. New page fades in (0.18s) with full opacity, overlaying old content
3. No 120ms delay = no visible flash in dark mode
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Ulas Kalayci
9b7909f690