Firefox Nightly
@firefoxnightly.bsky.social
Latest Firefox for Desktop development, live from Bugzilla! https://firefox.com/nightly
The CSS attr() function now supports values of any type, letting authors use attribute values in any property as opposed to just strings in the content property for the old attr() function. bugzilla.mozilla.org/2038940
2038940 - Enable new CSS attr() on Release
RESOLVED (descalante) in Core - CSS Parsing and Computation. Last updated 2026-08-04.
bugzilla.mozilla.org
PDFs can now be scaled up to fill a larger sheet of paper when printing. bugzilla.mozilla.org/1856162
1856162 - Firefox doesn't offer a way to scale up small PDFs to fill a larger sheet of paper
RESOLVED (emcdonough) in Core - Print Preview. Last updated 2026-08-04.
bugzilla.mozilla.org
Fixed Firefox preventing Linux systems from sleeping or suspending after a long browsing session. bugzilla.mozilla.org/2057365
2057365 - Firefox prevent Linux from sleep/suspend
RESOLVED (thinker.li) in Core - Widget: Gtk. Last updated 2026-08-01.
bugzilla.mozilla.org
Firefox now supports the progress() CSS function. This is a math function that can be used in calculations to compute the position of a value relative to a start and an end. bugzilla.mozilla.org/2047345
2047345 - Set layout.css.progress-function.enabled for all users
RESOLVED (sajidanwar94) in Core - CSS Parsing and Computation. Last updated 2026-08-01.
bugzilla.mozilla.org
Starting with Firefox 154, Firefox Nightly now supports QUIC version 2 (RFC 9369) for HTTP/3 connections. Firefox offers both QUIC v1 and v2 using compatible version negotiation (RFC 9368). bugzilla.mozilla.org/2040450
2040450 - Enable QUIC version negotiation
RESOLVED (mail) in Core - Networking. Last updated 2026-07-21.
bugzilla.mozilla.org
Firefox 154 arrives pretty soon and I genuinely can't contain my excitement 😇 text-box-trim was the first "big" feature I wanted to contribute but it felt like it was a bit beyond my reach. So I started on some other layout work, and took a detour to work on sibling-index() and sibling-count() ...
Firefox Nightly@firefoxnightly.bsky.social · 3w agoFirefox now supports the text-box-trim and text-box-edge CSS properties, and the associated text-box shorthand. These properties allow you to control the leading space above and below text, enabling simpler and consistent vertical spacing and alignment. bugzilla.mozilla.org/show_bug.cgi...
Starting with Firefox 154, Firefox Nightly now supports the alpha() CSS function. This is a relative color function that can be used to modify just the alpha component of a given color. bugzilla.mozilla.org/2047437
2047437 - Implement alpha() function behind pref
RESOLVED (sajidanwar94) in Core - CSS Parsing and Computation. Last updated 2026-07-26.
bugzilla.mozilla.org
You can now backup your profile locally on macOS devices and restore that profile between windows, macOS and linux. bugzilla.mozilla.org/2033325
2033325 - Firefox keeps requesting Documents folder permission without explaining why
RESOLVED (hsohaney) in Firefox - Profile Backup. Last updated 2026-07-21.
bugzilla.mozilla.org
Community Roundup: Project Nova, Tab Groups & more – about:community blog.mozilla.org/community/20...
Community Roundup: Project Nova, Tab Groups & more – about:community
Firefox keeps evolving, and the community continues to play a big part in shaping what's next. In this edition, you can get an early look at Project Nova through our ...
blog.mozilla.org
[Nightly Blog] Try the New Firefox Design in Nightly blog.nightly.mozilla.org/2026/07/27/n...
Try the New Firefox Design in Nightly – Firefox Nightly News
This past May, we shared our vision for the future of Firefox. Starting today, you can try out the next design evolution of Firefox in Nightly. It's still Firefox, now ...
blog.nightly.mozilla.org
Performing a hard reload on a page (holding Shift while clicking the Refresh button) now also clears and updates its cached favicons. bugzilla.mozilla.org/show_bug.cgi...
418144 - Favicons are not affected by a hard refresh
RESOLVED (mak) in Toolkit - Places. Last updated 2026-07-17.
bugzilla.mozilla.org
Firefox now gives Windows users the ability to change their default browser icon in Settings (except for MSIX installs). Support for MSIX installs, macOS and Linux is coming soon. bugzilla.mozilla.org/show_bug.cgi...
2053546 - Move browserIcon.ftl strings into preferences.ftl and enable browser.shell.customIcon.enabled by default to ride the trains
RESOLVED (mconley) in Firefox - Settings UI. Last updated 2026-07-16.
bugzilla.mozilla.org
Starting with Firefox 154, We’re testing a simpler tab context menu in Firefox Labs. Turn it on in Settings > Firefox Labs > Streamline tab menu and tell us what you think on Mozilla Connect. connect.mozilla.org/t5/discussio...
Firefox now supports the text-box-trim and text-box-edge CSS properties, and the associated text-box shorthand. These properties allow you to control the leading space above and below text, enabling simpler and consistent vertical spacing and alignment. bugzilla.mozilla.org/show_bug.cgi...
2050141 - [text-box-trim] Set layout.css.text-box.enabled for all users
RESOLVED (sajidanwar94) in Core - Layout: Block and Inline. Last updated 2026-07-15.
bugzilla.mozilla.org
HDR video in Firefox for Windows tech retrospective – Mozilla Gfx Team Blog mozillagfx.wordpress.com/2026/07/14/h...
HDR video in Firefox for Windows tech retrospective
HDR video is coming to Firefox for Windows users (and has been available for some time on macOS). This blog post explains how we developed the feature and gives a retrospective on the technic…
mozillagfx.wordpress.com
Firefox Security & Privacy Newsletter 2026 Q2 | Attack & Defense attackanddefense.dev/2026/07/12/f...
Firefox Security & Privacy Newsletter 2026 Q2
Welcome to the Q2 2026 edition of the Firefox Security & Privacy Newsletter.
attackanddefense.dev
[Web Platform] Firefox now supports new Iterator.prototype.chunks and Iterator.prototype.windows methods that allow consuming an iterator as either overlapping or non-overlapping subsequences of configurable size. bugzilla.mozilla.org/2047997
iterator.prototype.windows
The address bar now includes a "Manage AI" quick action that opens the AI section of Settings. bugzilla.mozilla.org/2038834
2038834 - Quick Action for turning off AI Mode
VERIFIED (dharvey) in Firefox - Address Bar. Last updated 2026-07-06.
bugzilla.mozilla.org
[Community newsletter] A new Firefox look, hidden features, and more – about:community blog.mozilla.org/community/20...
A new Firefox look, hidden features, and more – about:community
Hi Mozillians, welcome to another Mozilla community roundup! This month, we’re taking a look at what’s next for Firefox. From an upcoming visual refresh and a peek behind the new ...
blog.mozilla.org
Firefox's Local Network Access protections now extends to WebSocket connections. Websites that try to open a WebSocket to a device on your local network will now ask for your permission first. bugzilla.mozilla.org/show_bug.cgi...
2042339 - [LNA] Enable LNA Restrictions for Websockets
RESOLVED (smayya) in Core - DOM: Networking. Last updated 2026-07-02.
bugzilla.mozilla.org
Added support for the No-Vary-Search HTTP response header for the HTTP disk cache. developer.mozilla.org/docs/Web/HTT... bugzilla.mozilla.org/2038013
No-Vary-Search header - HTTP | MDN
The HTTP No-Vary-Search response header specifies a set of rules that define how a URL's query parameters will affect cache matching. These rules dictate whether the same URL with different URL parame...
developer.mozilla.org
Community power in action! 💪 Mozilla volunteer Valery Ledovskoy has released a new Russian dictionary extension. The goal: a modern, MPL-licensed Hunspell dictionary to replace Firefox's aging default. 🧩 Try it: addons.mozilla.org/en-US/firefo... 📝 Feedback: habr.com/ru/articles/...
Russian Spelling Dictionary – Get this Dictionary for 🦊 Firefox (en-US)
Download Russian Spelling Dictionary for Firefox. Modern Russian spell-checking dictionary for Firefox and Thunderbird.
addons.mozilla.org
[Nightly Blog] Eyedropper Quick Action, geckodriver 0.37, and Tighter File Permissions – These Weeks in Firefox: Issue 205 blog.nightly.mozilla.org/2026/06/22/e...
Eyedropper Quick Action, geckodriver 0.37, and Tighter File Permissions – These Weeks in Firefox: Issue 205 – Firefox Nightly News
Highlights Dao added a new Eyedropper quick action! Check it out by typing “color” or “eyedropper” in the URL bar (Bug 1803575) on Nightly. Henrik Skupin ...
blog.nightly.mozilla.org
This is your periodic reminder that you can follow the general Mozilla news, team work and individual contributors work on Planet Mozilla (which has a RSS feed you can subscribe to). We have 1 to 2 blog posts per day for you. 🌍️ planet.mozilla.org
Planet Mozilla
Follow the pulse of the Mozilla project. Aggregated updates from the developers, designers, and volunteers building a better internet.
planet.mozilla.org
What's new in Firefox this June, and what's next on the Firefox roadmap blog.mozilla.org/en/firefox/f...
What's new in Firefox this June, and what's next on the Firefox roadmap | The Mozilla Blog
Firefox has been busy introducing updates across productivity, privacy and AI. From Project Nova and browser-wide AI controls to expanded privacy protectio
blog.mozilla.org
[Nightly Blog] Giving You More Control – These Weeks in Firefox: Issue 204 blog.nightly.mozilla.org/2026/06/15/g...
Giving You More Control – These Weeks in Firefox: Issue 204 – Firefox Nightly News
Highlights Maxx Crawford added a pref to hide the New Tab logo so users can opt out of branding without altering page layout or resorting to CSS overrides. Harshit ...
blog.nightly.mozilla.org
[Nightly Blog] More Kit, More Control – These Weeks in Firefox: Issue 203 blog.nightly.mozilla.org/2026/06/03/m...
More Kit, More Control – These Weeks in Firefox: Issue 203 – Firefox Nightly News
Highlights James enabled adaptive autofill in Nightly for testing, which we believe should provide better results in the URL bar when doing autocomplete! Jack updated the illustrations shown on ...
blog.nightly.mozilla.org
The location permission icon in the address bar now turns red while a website is actively accessing your location, making it easier to notice when your location is being shared. bugzilla.mozilla.org/2038194
Quickly pick and copy a color from any page by typing "pick color", "color picker", or "eyedropper" in the address bar and selecting the "Pick a color" quick action.
Firefox now verifies and displays Qualified Website Authentication Certificates (QWACs) in accordance with eIDAS regulations. bugzilla.mozilla.org/2043399
2043399 - enable QWACs by default on desktop
RESOLVED (dkeeler) in Core - Security: PSM. Last updated 2026-06-01.
bugzilla.mozilla.org