Synthora Hero — Référence de design web et prompt

# Prompt: Synthora AI hero

Build a single-file, one-screen **landing hero for an AI solutions company**, **Synthora**. Use plain HTML, CSS and vanilla JS, with no framework and no build step. The look is a black page with a futuristic rounded display font, a centred headline, and a blazing molten-orange solar ring rising from the bottom edge.

## Media

- **Glow plate:** `https://d2ol7oe51mr4n9.cloudfront.net/user_38xzZboKViGWJOttwIXH07lWA1P/7e2a7695-c32b-4179-9c90-cae865819272.jpg` (1663×940). A pure-black field with a burning ring arching up from the bottom centre: a white-gold edge, fiery orange plasma with crackling filaments, a dark interior, drifting embers and thin vertical orange light streaks. The top half is pure black.
- **Motion:** a muted 4s loop of the same ring, laid over the plate with identical sizing: `https://d2ol7oe51mr4n9.cloudfront.net/user_38xzZboKViGWJOttwIXH07lWA1P/6ad9485f-ab40-444b-bd3c-40dcb9bd0e2f.mp4`.
  - The flares lick around the ring, embers rise, and the camera pushes in slowly.
  - The last second crossfades into the first, so it never plays in reverse.
  - Fade it in (0.8s) once its first frame is ready.
- **Rule:** nothing in the glow is drawn or animated in code.