Velvet Grain

Written for the variant you picked above: Oxblood

Write a WebGL1 full-screen fragment shader background (no libraries): a slow whorl of colour on near-black under heavy film grain. Centre polar coordinates a little left of the middle (the pointer nudges the centre). Bands wind around it: sin(7.5r − θ + w − 0.1t), where w is soft fBm (± 1.6) so the whorl is never a perfect spiral, plus a gentler diagonal sine; band = smoothstep(0.05, 1, 0.75·a + 0.3·b), faded out right at the centre and slightly towards the far edges. Mix the ground towards the dye colour by the band, and vignette the corners. Then the grain: per-pixel hash noise re-seeded every frame, added as luminance (amount × (0.35 + band)) and as colour in the dye's hue inside the bands, so the colour itself looks grainy. Render at full resolution so the grain stays sharp. Render through a small WebGL1 harness: a full-screen triangle, the device pixel ratio capped at 2 and scaled down (and about 30fps) on touch, paused offscreen and in hidden tabs, one still frame under reduced motion, the pointer eased in with a slow lerp and released when it leaves, and a CSS gradient fallback without WebGL. Add a little per-pixel noise so the gradients never band. An optional fade prop softens the bottom edge into the ground colour: a gradient to the ground plus a backdrop blur masked to grow towards the edge. Children sit above the canvas. Selected variant — Oxblood (oxblood): Dark red on near-black: bg #070405, dye #7a1515, grain 0.14. This selection takes precedence over references to other themes or options in the general brief. Implement this selected appearance; do not add a variant picker or alternative appearances unless requested. Implementation requirements: Use React and TypeScript. Keep the component self-contained, with uniquely scoped CSS and no animation libraries. Include required imports, styles and font setup in the result. Interaction: Move the pointer to shift the whorl. Motion: The whorl turns slowly and the grain crawls every frame. Reduced motion draws one still, grainy frame. Accessibility: Decorative and hidden from assistive tech. Very dark overall, so white text reads well anywhere. Responsive behavior: Fills its container at any aspect ratio; device pixel ratio capped at 2. The optional fade softens the bottom edge into the ground colour. Touch: No pointer response on touch; the whorl keeps turning. Preserve keyboard access, visible focus and reduced-motion behavior. Keep fictional demo data and simulated service calls in a separate usage example; expose callbacks for real actions and recover from rejected requests. Keep usage-example links inside the demo: use local buttons or prevent navigation. Demonstration links must not navigate to Vitrine routes or open other pages; preserve real URL support in the reusable component itself. Verify the result at narrow and wide viewport sizes, with keyboard input and reduced motion enabled.

Notes

Interaction

Move the pointer to shift the whorl.

Motion

The whorl turns slowly and the grain crawls every frame. Reduced motion draws one still, grainy frame.

Accessibility

Decorative and hidden from assistive tech. Very dark overall, so white text reads well anywhere.

Responsive

Fills its container at any aspect ratio; device pixel ratio capped at 2. The optional fade softens the bottom edge into the ground colour.

On touch

No pointer response on touch; the whorl keeps turning.