This function is part of the CSS Functions and Values Level 5 specification, along with sibling-count(), which gives you the total number of siblings. Both functions are still experimental, so check caniuse before using them in your project. Currently, Chrome, Edge, and Safari have the most support, but other browsers might not fully support them yet.

tons of pseudo elements and classes, states, animations... I'm not trying to be professional, it's just a personal microblog that I've been experimenting with everything I've been learning hehe
the site doesn't look like it has a lot of content but there's quite a few hidden stuff (although none so cryptic)
After I finish updating my friends' links I'm going to make a loop (not marquee) changing the display of divs... anyway, been having quite some fun writing CSS rules https://pxhc.neocities.org/

Here's some rad CSS that just hit baseline between October 2025 - April 2026.

CSS now does what Floating UI, GSAP ScrollTrigger, Framer Motion, and react-select used to require JavaScript for. Here is exactly how much that saves, why these libraries were painful beyond their size, and what the platform still hasn't figured out.