e already wrote up how the cursor-reactive kinetic type on our web hero works — per-letter font-variation-settings weight tracking pointer distance. This one's not really an explainer. It's the same mechanic, minus the fixed word, so you can just type whatever you want and watch it react instead of reading about it happening to someone else's headline.
Move your cursor near it, type your name, type a client's name, type nothing and leave it idle for a few seconds to see the resting sine-wave breathing take over. It's the exact same requestAnimationFrame loop from the real hero — the only thing that changed is the letters come from an input value instead of a hardcoded prop, so the component re-measures whatever's currently rendered on every keystroke.
If you want the mechanics — the smoothstep easing, the idle fallback, why it mutates the DOM directly instead of going through React state — that's the earlier post: "Type that reaches toward your cursor." This one's just for playing with it.