[Tip] Force Mozilla Firefox to Always Use Dark or Light Theme Mode
Now-a-days all software programs are coming with built-in Dark Theme or Dark Mode (also known as Night Mode) support. When the Dark theme mode is enabled in a program, it converts the UI or interface of the program into dark colors such as Black or dark gray which reduces eye strain and helps using the program for long time specially at night.
Mozilla Firefox browser also comes with native Dark theme mode. Mozilla Firefox respects Windows 10 Dark app mode and if you turn on Dark app mode in Windows 10, Firefox automatically activates and applies its Dark theme mode in its user interface.
[Tip] How to Enable Built-in Dark Theme Mode in Mozilla Firefox
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Now let’s imagine following situations:
1. There might be people who want to use Dark app mode in Windows 10 but don’t want to use Dark mode in Firefox browser. They want to deactivate and disable Firefox dark theme mode. They want to force Firefox to not follow Windows 10 Dark mode status and keep using Firefox in default Light theme mode.
2. Some people may not want to turn on Dark app mode in Windows 10 but they want to use Firefox in Dark theme mode.
3. Sometimes even after turning on Dark app mode in Windows 10, Firefox doesn’t enable Dark theme mode in its UI and users are forced to use Firefox in Light theme mode.
4. Sometimes even after enabling Dark theme mode in Firefox, it still uses Light theme mode in several places such as Options page, new tab page, library, etc. Users may want to apply and enable Dark theme mode everywhere in Firefox UI.
In such situations, a built-in hidden preference/flag comes to rescue which tells Firefox which theme mode should be used: Dark or Light.
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Actually Firefox comes with a built-in preference to manually control Dark theme mode in its UI. You can force Firefox to always use Dark theme mode or always use Light theme mode irrespective to system app mode i.e. Windows 10 app mode.
If you are also facing any of the above mentioned issues and want to fix it. following steps will help you:
1. Open Mozilla Firefox and type about:config in the addressbar and press Enter. It’ll show you a warning message, click on “Accept the Risk and Continue” button. It’ll open Firefox’s hidden secret advanced configuration page i.e. about:config page.
2. Now type ui.systemUsesDarkTheme in Search filter box. The preference doesn’t exist by default and we need to create it manually.
Select Number radio button and click on (+) or Add button.
Firefox will ask to enter a value for the preference. Now do as following:
- If you want to force Firefox to always use Light theme mode, keep the value as 0 and press Enter key.
- If you want to force Firefox to always use Dark theme mode, keep the value as 1 and press Enter key.
That’s it. The changes will apply immediately.
PS: In future, if you want to restore default behavior and undo any changes, again type ui.systemUsesDarkTheme in search filter box on about:config page and click on Delete (recycle bin) icon given next to preference value. It’ll delete the preference.
PS: Google Chrome, Microsoft Edge and Opera users can check out following articles:
[Tip] How to Enable Built-in Dark Theme Mode in Google Chrome
[Tip] Enable Dark Theme in Opera Web Browser
[Tip] Enable / Disable Dark Mode or Theme in Microsoft Edge Browser
I use color.firefox.com to create my own dark theme for Firefox. But, “dark theme” doesn’t mean “dark mode”. One of my favorite Firefox extensions is Dark Reader, which makes it simple and easy to switch back and forth between dark mode. Some pages just don’t work well in dark mode. With a click of the mouse, I can switch Dark Mode off until I leave that page or site.
I have moderate retina damage, so I always use dark mode in Firefox, unless I need to temporarily turn it off. Frankly, I think a dark mode button should have been built into Firefox long ago. They should incorporate Dark Reader into the browser code.
Love your newsletter. Keep up the good work!
I am facing a small problem, when I type or paste any URL in address bar, then only main URL text appearing in white colour, but other text like SUB-URL text appearing in grey colour. But this issue not happen when type or paste non URL text such as word for search. Unfortunately there is no option available to upload screenshot, but I also posted in Microsoft answer page, you can see screenshot in
answers.microsoft.com/en-us/windows/forum/all/text-appearing-in-grey-colour-when-type-or-paste/645ea13a-25be-4768-b0d5-2314c6bfdb05
^^ That’s by design in all browsers. It was done to put focus on the main domain to prevent phishing attacks, etc. Since you are using dark theme mode, you’re noticing it more.
Hi,
I’m so thankful that this site even exists, I’ve used the information that I’ve found on it several times in the past. I tried using this tip to change all of the web pages that I desire to view to a darker color so the bright background color of some pages (mainly actual firefox pages like this one: support.mozilla.org/en-US/products/firefox won’t be such a bright white color that really hurts my eyes. I already have the dark reader add-on installed but it doesn’t have any effect whatsoever on actual firefox pages. Is there a way to make even ‘actual’ firefox pages be a darker color that the normal white color ?
^^ Try following:
https://www.askvg.com/tip-enable-dark-mode-everywhere-in-mozilla-firefox/
https://www.askvg.com/windows-10-tip-enjoy-dark-theme-in-all-websites-and-software-programs/
This worked like a charm for me. Thanks!
I downgraded from 89 to 88 due to changes. I changed it myself and blocked all future updates. I like having my native Windows theme not some plastic shrink wrap with features removed.
Thank you, I’ve spent ages trying not to get FF to default to dark mode. Fixed it now thanks to this
This preference has been removed from version 89 and continuing to use it interferes with the System Theme extension (built-in).
Selecting the “Trash can” and removing the setting will restore the System Theme option.