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@FirefoxWebDevs

Firefox for Web Developers

@FirefoxWebDevs
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.
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hacks.mozilla.org
Joined June 2009
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  • Pinned
    @FirefoxWebDevs
    Firefox for Web Developers
    @FirefoxWebDevs
    2h
    Major versions of Firefox now land every two weeks, so Firefox 155 dropped today with web platform features including: 🎉 Fully typed CSS attr() 🎉 CSS progress() 🎉 Promise.allKeyed() and allSettledKeyed() 🎉 Lots of new WebTransport stuff …And more!
    The MDN logo
    developer.mozilla.org
    Firefox 155 release notes for developers (Stable) - Mozilla | MDN
    This article provides information about the changes in Firefox 155 that affect developers. Firefox 155 was released on September 1, 2026.
    3
  • @FirefoxWebDevs
    Firefox for Web Developers
    @FirefoxWebDevs
    Aug 25
    CSS sibling-count() and sibling-index() are newly available across engines! Here's how they work:
    00:00
    2
  • @FirefoxWebDevs
    Firefox for Web Developers
    @FirefoxWebDevs
    Aug 24
    JPEG XL is slated to ship in Firefox 157 next month! Here's how we're shipping it safely…
    Intent to Ship: JPEG XL – Mozilla Hacks - the Web developer blog
    From hacks.mozilla.org
    3
  • @FirefoxWebDevs
    Firefox for Web Developers
    @FirefoxWebDevs
    Aug 24
    Intent to ship: JPEG XL! This will be on-by-default in Firefox 157, which should become the main release version at the end of September. This includes key JPEG XL features like progressive rendering. groups.google.com/a/mozilla.org/…
    8
  • @FirefoxWebDevs
    Firefox for Web Developers
    @FirefoxWebDevs
    Aug 20
    What should happen with text-box-trim and margin-trim when it comes to negative values? Do negatives 'trim'?
    00:00
    3