This is a write-up of the animated ring I built for a 404 page. It's a single component that renders an SVG "portal" — a set of concentric rings with drifting particles, a slow wobble, and a parallax response to the cursor. The page is server-rendered, so the component also has to be SSR-safe and reasonably cheap to run. Here's how each part works. Generating the geometry The rings, particles, and orbital markers are generated from their index rather than placed by hand. T...