Corona Arcs

Written for the variant you picked above: Crimson

Write a WebGL1 full-screen fragment shader background (no libraries): soft concentric bands of light rising from the bottom-left corner. Place a centre well below and left of the frame (about −0.25, −1.2 in screen heights) and take the distance r to it, scaled for wide screens and roughened slightly by slow noise. An envelope smoothstep(edge + 0.35, edge − 0.6, r) — the edge at about 2 screen heights, breathing ±0.04 — confines the light to the corner. Inside, banding 0.5 + 0.5·cos(π(4.4r − 0.1t)), raised to 1.4, moves the bands slowly outward; intensity = envelope × (0.3 + 0.68 × bands) plus a steady inner glow near the centre. Map intensity through four tones — ground, deep, main, a pale hot core — with smoothsteps, so the bands are soft and blurred, never lines. The pointer moves the centre a little. 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 — Crimson (crimson): Crimson arcs with a peach core: bg #0e0204, deep #5a0b1b, mid #d6324b, hot #ffb4a2. 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 and the arcs' centre drifts with it. Motion: The bands breathe slowly outward. Reduced motion draws one still frame. Accessibility: Decorative and hidden from assistive tech. The top-right is dark and suits white text; keep text off the bright lower-left. 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 bands keep breathing. 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 and the arcs' centre drifts with it.

Motion

The bands breathe slowly outward. Reduced motion draws one still frame.

Accessibility

Decorative and hidden from assistive tech. The top-right is dark and suits white text; keep text off the bright lower-left.

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 bands keep breathing.