How to Enable the Dark Mode in Mozilla Firefox Settings UI

Dark modes are the new big thing in terms of software user interface, and pretty much every developer out there considers adding one to their apps.

Large companies like Google and Microsoft made a huge progress in this regard, so Windows 10, for example, comes with its very own dark mode to make the OS overall easier on the eye during the night.

Mozilla is one of the companies that are still working on refining the dark theme in their software, and Firefox is set to improve even more in the upcoming updates.

The most recent changes that the company made to the Nightly build shows that Mozilla is currently in the process of implementing a dark visual style for the about: pages, which, in essence, means that Firefox is set to get a dark mode in settings as well.

As with everything that’s being developed by Mozilla, the feature is currently part of Firefox Nightly, as all improvements are being tested here before they are released to everyone as part of the stable browser.

Firefox Nightly isn’t recommended as a daily driver, but instead can help you figure out where Firefox is going and to help you try out certain new features in advance.

Enabling the dark settings flag in Firefox

If you want to try out the dark settings screen in Firefox, here’s what you need to know.

First and foremost, it looks like this feature currently works on Windows 10 exclusively, albeit there’s no doubt that Mozilla would bring it to all supported desktop platforms sooner or later.

But on Windows 10, the dark mode comes with a neat implementation. The browser can adapt to your OS visual settings, so when switching to a dark theme in Windows 10, Firefox can enable the same look in settings as well.

However, this behavior requires the dark settings interface to be enabled. As mentioned, this option only exists in the Nightly build, so it you need to activate it manually, but in the stable version of Firefox more straightforward options could be offered too.

To try out this new interface, you first have to update to the latest Firefox version. The version that I’m running for this tutorial is 68.0a1 (2019-04-14), so anything newer than this should be alright.

Launch the browser and head over to the flags screen to configure additional advanced options. To do this, type:


Advance to the next step when asked if you understand the risks of changing the settings here and then search for a flag that is called:

By default, this flag is set to false, you need to change it to true by clicking the Toggle button. A browser reboot is then required.

The dark mode in Firefox settings

If the dark mode is enabled on Windows 10, Firefox should then use a dark theme for the settings screen when reloading the browser.

On the other hand, if you want to use the Firefox Settings screen without a dark mode in Windows 10, you can do so by adding a new flag called:


To do this, copy the flag name, paste in the search box in Firefox about:config screen > Add > True. If everything works correctly, after a browser reboot, the dark theme in the settings UI should be enabled regardless of the visual mode that is running on Windows 10.

At this point, there are no specifics as to when Mozilla plans to bring this improvement to all users in a stable version of Firefox. The update, however, first needs to make it from the Nightly build of Firefox to all the other channels before hitting the stable ring.


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