What should happen with text-box-trim and margin-trim when it comes to negative values? Do negatives 'trim'?

CSS issue: https://github.com/w3c/csswg-drafts/issues/14328

CSS text-box is newly baseline, and it's solves a common text layout issue. Here's how it works:

Full docs on MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/text-box

Firefox 154 landed today, and brings with it some great web platform features:

🎉 CSS text-box
🎉 CSS sibling-index() and sibling-count()
🎉 JS Iterator methods like chunks, window, includes, & join
🎉 HTTP No-Vary-Search

…And more! https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/154

We have an open position for a student worker on the Firefox Networking team in Germany. We work on the full stack, from high level HTTP all the way down to TCP/UDP. Some C++, some Rust. If that interests you, here are the details: https://www.mozilla.org/en-US/careers/position/gh/8068406/

JS promise integration for WebAssembly landed in Firefox 153, making it easier to work with asynchronous calls from Wasm. Here's how it works:

More docs: https://developer.mozilla.org/en-US/docs/WebAssembly/Reference/JavaScript_interface/Suspending

Full documentation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import/with

JS text imports landed in Firefox 153, making it the first browser to support this feature. Here's how it works:

I made an accessibility error when coding up some tooltips. Here's where I went wrong, and how you can avoid making the same mistake:

https://jakearchibald.com/2026/my-tooltip-a11y-mistake/

I made an accessibility error in one of my recent videos, and I want you to learn from my mistake:

Here's Scott's demos https://scottaohara.github.io/a11y_tooltips/, and my fixed toolbar demo https://random-stuff.jakearchibald.com/popover-hint-tooltip/

A little dive into web standards… Why changes were made to popover="hint", and why diversity in browser engines is important:

So @tink just let me know that aria-labelledby would be a better option than aria-describedby in this case. TIL!

@firefoxwebdevs the PR for hint merged in WebKit last Friday https://github.com/WebKit/WebKit/pull/62557

popover="hint" landed in Firefox 153. Here's how it differs from regular popovers:

Full documentation on the popover API: https://developer.mozilla.org/en-US/docs/Web/API/Popover_API/Using

JS declarations in conditionals is being discussed at TC39 again. The tricky detail is, how should the "else" block be handled? I think Rust has the right answer here:

https://mastodon.social/@firefoxwebdevs/115722856715320931

RE: https://mastodon.social/@FirefoxOfficial/116958818480299400

The official Firefox account is back on fedi!

(I mean, this one is official too, but… you know what I mean)