- NightModeProvider context (localStorage persisted) in contexts/NightMode.tsx
- Full-screen fixed red overlay (rgba 160,0,0 @ 55%, mix-blend-mode: multiply) fades in over the entire UI; multiply blend keeps dark backgrounds black while turning all white/bright content deep red
- Desktop: toggle button at the bottom of the sidebar, glows red when active
- Mobile: floating red circle button fixed just above the bottom nav bar
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
