Post

@webdevs.firefox.com

Firefox 149 is out now, and adds bunch of new web platform features, like 🎉 The CloseWatcher API 🎉 popover=hint (although I'm concerned about the spec'd behaviour) 🎉 hasUAVisualTransition on PopStateEvent 🎉 font-family: math 🎉 The CSP reporting API And more! developer.mozilla.org/en-US/docs/M...

developer.mozilla.orgFirefox 149 release notes for developers (Stable) - Mozilla | MDNThis article provides information about the changes in Firefox 149 that affect developers. Firefox 149 was released on March 24, 2026.

24/3/26, 2:47 pm14 reposts68 likes

Cyd Stumpel

@cydstumpel.nl

25 Mar

What happened to the line height of the headings there?!

Mastro.{js,ts}

@mastrojs.bsky.social

25 Mar

ha, other MDN pages are fine 🧐

Claas Augner

@claasaug.bsky.social

25 Mar

Are you referring to the page title, or the section headings? (Screenshots appreciated.)

Cyd Stumpel

@cydstumpel.nl

25 Mar

All large headings look a off to me on mobile. The h3 (“WebDriver conformance[…]”) looks alright but still a bit to widely spaced imho

Claas Augner

@claasaug.bsky.social

25 Mar

Thanks for clarifying. Would this look better (`line-height: 1.5` instead of `line-height: 1.75`):

Firefox for Web Developers

@webdevs.firefox.com

25 Mar

Ooooo, I'm sure we can fix that… Thanks for raising it!

Noa 🪻

@noahbogart.com

24 Mar

thank you for the concern, little fox, i appreciate your tireless work.

Firefox for Web Developers

@webdevs.firefox.com

24 Mar

In terms of popover=hint, I dug into it when scripting a video, and… I can't make sense of the behaviour at all. Here's my investigation so far if you want to follow along: github.com/whatwg/html/... & github.com/whatwg/html/...

github.compopover=hint inconsistent behavior nested vs unnested · Issue #12304 · whatwg/htmlWhat is the issue with the HTML Standard? https://random-stuff.jakearchibald.com/popover-hint/ nested-hint.mp4 (includes audio) At the top level, a popover=hint, when opened, will not close a sibli...