in the interest of people understanding what is and is not within CSS's domain, these effects aren't pure CSS. The information about where your cursor is, as well as how rotated the cards should be, is all computed in JavaScript and made available to the CSS via custom properties. A lot of this is genuinely very cool CSS! You can do all the 3D transformations and lighting effects in CSS. But the interactivity is pure JS.
I could probably make this bounce back and forth using The One Animation On Cohost, except to get that working smoothly I'd need to animate the custom properties rather than their derived values and Cohost filters custom properties. Oh well!
