As someone who really enjoys working with CSS, but also working with colleagues who struggle with it, I strongly recommend Kevin Powell’s YouTube channel.

He has touched on exact feature a few times, here’s a video he uploaded a week ago that shows one useful feature that registered properties enables: https://youtu.be/U8NykwZNbGs

There’s also this article that breaks down registered properties with an easy-to-follow example: https://moderncss.dev/providing-type-definitions-for-css-wit...