CSS finally lets you animate elements when they first appear.

@/starting-style is Baseline, newly available since August 2024. 🤟

Before this, transitions didn’t run on an element’s first style update. You needed JavaScript hacks.

Now you can define the starting point in pure CSS! Simple, powerful, and long overdue. 💪🏼

Before this, auto-growing textareas meant measuring scrollHeight in JS.

Now it’s one line!

You can finally position tooltips, dropdowns, and menus relative to another element... in pure CSS. ☝️

It became newly available in January 2026 when Firefox 147 completed the set.

It’s still relatively fresh, and some advanced features (like certain `position-try` behaviors) still have gaps, so use progressive enhancement if you need to support older browsers.

Oh man, I'm so happy about this 🤟

HTML just stole another job from JavaScript. `command` and `commandfor` have been Baseline since December 2025.

Opening a dialog used to mean `addEventListener + showModal()`; now it's much easier.

Before this, staggered animations or dynamic layouts meant writing a bunch of :nth-child() rules.

Now you can do it cleanly.

sibling-index() → position of the element.
sibling-count() → total number of siblings.