A dark veil: black-on-black volumetric drape of domain-warped ridged fbm where only the fold crests catch a whisper of light and a deep violet undertone breathes at a tenth of a hertz — luminance hard-capped so overlay text always wins. Original OGL fragment shader, time-dithered, offscreen-paused, reduced-motion-safe.
pnpm dlx shadcn@latest add "https://crucibleui.com/r/umbra.json"