Halo Prism — Référence de design web et prompt

Build a single standalone index.html (no build step, no local assets, no video, no images) containing ONE full-viewport dark hero section for a fictional product called "halo" — "The P3 palette kit, crafted for screens." All visuals are generated in code: a real-time 3D glass prism (three.js) that refracts a white light beam into a soft rainbow, steered by the mouse. Recreate everything below exactly.

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1. HEAD, FONTS, TOKENS
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- <title>halo — The P3 palette kit</title>, meta description "halo is the P3 palette kit, crafted for screens.", meta theme-color #151517, viewport "width=device-width, initial-scale=1, viewport-fit=cover".
- Google Fonts (preconnect to fonts.googleapis.com and fonts.gstatic.com):
  https://fonts.googleapis.com/css2?family=Geist:wght@300..600&family=Newsreader:opsz,wght@6..72,300..500&display=swap
- CSS custom properties on :root:
  --bg:#151517; --bg-2:#1b1b1e; --ink:#ededed; --muted:#a1a1a1; --dim:#6e6e73;
  --line:rgba(255,255,255,.12); --chip:rgba(255,255,255,.04);
  --gutter:clamp(16px,2.6vw,28px);