Enable and use the Dark Theme in Firefox

The Developer edition of the Mozilla Firefox browser comes with a different, dark theme. Here is a trick which will allow you to use this dark theme for Firefox stable builds. After you follow the instructions in this article, you will be able to get the dark theme in Firefox 35 and above.

Previously, this trick only worked in the Nightly version of the Firefox browser, but yesterday Mozilla released Firefox 35, which also supports this theme. You might need to update your older Firefox version to version 35 before you follow the instructions below.
Here is where you can get it.

  1. Open a new tab and enter the following text in the address bar:

    Confirm that you will be careful if a warning message appears for you.

  2. Enter the following text in the filter box:

    You will see the parameter browser.devedition.theme.enabled. Set it to true.

  3. Press F12 to open Developer tools:
  4. Click the Options icon (the gray gear icon on the right) and pick the Dark theme:

That's it. Enjoy the dark theme in your Firefox.

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Author: Sergey Tkachenko

Sergey Tkachenko is a software developer who started Winaero back in 2011. On this blog, Sergey is writing about everything connected to Microsoft, Windows and popular software. Follow him on Telegram, Twitter, and YouTube.

4 thoughts on “Enable and use the Dark Theme in Firefox”

      1. Oh, yeah, it does. It was interesting to try this out but it doesn‘t look very modern. At least, this happens when you‘re used to brighter themes.

  1. yes, it also works on my 32 bit version of firefox 39. however in the latest beta of the 64 bit version (firefox 40 beta, windows 10) there is no entry “browser.devedition.theme.enabled”. it doesn’t exist hence cannot be changed. what can i do?

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