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Firefox for Web Developers
@firefoxwebdevs
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Official Firefox account for people who build on the web. Learn about the things we're working on to grow and improve the web platform.
We're experimenting with a way to visualize session history in Firefox DevTools, and we'd love your feedback!
Here's the background, and how to try it: https://blog.farre.se/posts/2026/06/01/session-history-diagrams/
See our announcement post for more detail, demos, and docs https://hacks.mozilla.org/2026/05/web-serial-support-in-firefox/
Announcing Web Serial Support in Firefox – Mozilla Hacks - the Web developer blog
Support for Web Serial in Firefox 151 for Desktop Firefox can now connect directly to microcontrollers, development boards, 3D printers, power meters, and other serial-connected hardware from the web. Starting ...
The Web Serial API landed in Firefox 151, allowing you to connect directly to microcontrollers, dev boards, 3D printers, power meters, and other serial-connected hardware from the web. Here's how it works:
Thanks to everyone who responded! These three have been tricky to prioritise:
line-clamp - somewhat already supported, but the standard version has some nice new features.
Animating display:none - falling back to no animation in Firefox is non-breaking.
margin-trim - a nice feature, but ok to work around the lack of it in many situations.
But yes, I agree with the results here. This feedback has been passed onto the teams.
Which of the following CSS features would you prefer Firefox to support first?
(note that we already support the quirky -webkit-line-clamp)
line-clamp
margin-trim
animating/transitioning display:none
Poll ended at .
Web Serial landed in Firefox 151! Here's how it works, and what you can do with it: https://hacks.mozilla.org/2026/05/web-serial-support-in-firefox/
Announcing Web Serial Support in Firefox – Mozilla Hacks - the Web developer blog
Support for Web Serial in Firefox 151 for Desktop Firefox can now connect directly to microcontrollers, development boards, 3D printers, power meters, and other serial-connected hardware from the web. Starting ...
And here's the full documentation on MDN https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Containment/Container_size_and_style_queries#container_style_queries
CSS style() queries landed in Firefox 151 making them newly available across engines. Here's how they work:
Firefox 151 is out now, and brings with it some tasty new web platform features:
🎉 Container style() queries
🎉 Web Serial API
🎉 Document Picture-in-Picture API
🎉 keyboardLock on requestFullscreen
…and more!
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/151
