Firefox Community Forum

Dear Mozilla Support Team,

I am writing to report an issue I have consistently encountered while using the Firefox browser. Whenever I log into my Mozilla account, the custom theme I have selected for Firefox is reset to the default theme. This necessitates manually re-selecting my preferred theme each time I log in.

This issue is a minor inconvenience, but it disrupts my user experience. I would appreciate it if you could investigate this behavior. I am using the latest version of Firefox on Windows 11 Pro.

Thank you for your time and attention to this matter. I look forward to a resolution.

Sincerely,

Clóvis Lauriano laurianoperez@yahoo.com.br

I’m at my wits’ end with this. Firefox keeps forcing a system-synced theme at launch, and it flat-out refuses to respect the settings I’ve configured — both in about:config and via a custom user.js file.

Here’s what I’ve tried:

• Set layout.css.prefers-color-scheme.content-override to 0 in about:config → it reverts back to 2 after every restart.

• Created a user.js with user_pref("layout.css.prefers-color-scheme.content-override", 0); → completely ignored.

• Disabled all sync options, including themes.

• Verified that no active studies are interfering.

• Double-checked that I’m not syncing across devices.

• Tried applying a specific theme and setting it manually — still overridden at launch.

No matter what I do, Firefox insists on syncing the theme to the system’s dark/light setting. I want my browser theme independent from the OS — period.

Is there a deeper setting I’m missing? A hidden override? Some service that’s reapplying the system setting post-launch? This feels like Firefox is actively fighting me — and it's infuriating.

Would appreciate any insight or workaround. I just want full manual control over my theme. Why is that so hard?

Hi there,

I'm experiencing a theming issue when using Firefox (flatpak) on Hyprland with a pure black (#000000) theme applied via a theme extension. When the Firefox window is out of focus, everything looks fine — the background is truly black as expected. However, when the focus is on the window, the blacks turn washed out grey, losing the #000000 appearance. This doesn't seem to happen in other apps and I don't seem to have any filter for the focused windows (except for borders), so it seems related to how focused windows are handled in Hyprland or how Firefox draws its content under Wayland - have you heard about this issue and could you help me diagnose it + find a solution? Is there a setting I could tweak either in Hyprland, Firefox, or GTK/Qt config to prevent this color shift on focus? Thanks in advance!

Every single time I close my Firefox and open the browser again, it reverts back to a previous theme that I already deleted. When I open the Add-ons manager, it shows that the theme I want is enabled but the wrong theme is the one active. I have to click the "disable/enable" button to toggle it on and off to re-enable the theme I want. I've looked this issue up but haven't found any answers. I appreciate any help!

I am unable to remove add on themes. The remove button is not provided. Only manage which enables the theme. I do not want these themes and want them removed now. mac ios

you are repeating old mistakes. You have become worse than Microsoft. Firefox is not remembering open tabs again. I have supported your Firefox until now but enough is enough.

I have literally over 200 tabs open at a time and recover them every time I reboot Firefox, but they are very disorganized. Is there a good way to organize them, for example, group related tabs together?

I've noticed recently after system reboots that Firefox forgets the "Open previous windows and tabs" setting and restarts with only a blank tab. I've confirmed that this setting is ticked prior to the reboot. I know I can restore the session under History but why isn't Firefox remembering this setting and re-opening the windows & tabs like previously?

Running Firefox 135.0.1 and Mac Sequoia 15.3 (but has been happening in recent previous versions of both).

Hello,

I Created a few weeks ago a custom theme for my own personal use (Not uploaded to WEB). I exported it from Firefox myself and fully tested that it could be loaded as is custom when I create something. Unfortunately I had a system crash and have had to reinstall software & apps including FireFox. I am using exactly the same version of firefox as before and all the same identical plug-ins. I know on some ocassions issues can be caused with different versions of the same software. There for I have made completly sure that I have installed all same versions as before.

I always get error when trying to load my theme. I know the file is not corrupted as I mentioned I had tested it.

The error that is displayed is as follow.

about:addons This add-on could not be installed because it appears to be corrupt.

As I mentioned above I know the file is not corrupt. Can someone please help as I would like to do this locally not via the WEB or Firefox addon's site.

I'm attempting to try out the new experimental Mica theme for Firefox, but I can't seem to get it working

I have enabled the following in about:config widget.windows.mica = true browser.theme.native-theme = true browser.tabs.allow_transparent_browser

I've tried setting both automatic browser theme and dark theme, neither works. The browser toolbar looks as in attached image.

I recently updated to Firefox 135.0 on MacBook Pro, Catalina, OS 10.15.7 In the past, with multiple Firefox windows open & multiple tabs open in each, when restarting, "reopen pages on startup" selected, system loaded & ready to go, I'd find all windows, tabs & history available upon launching Firefox. Since update to 135.0, shut down & restart, launch Firefox and I find a single blank new window, no multiple windows, no tabs, no history. I've tried to find [Settings] to make everything come back - no joy, to no avail. Suggestions? Help? Thanks, JS

Good Day,

I am leaving Brave as my default browser for Firefox.... Brave is good, just would prefer Firefox. I used to love it.

The problem is...I have a theme on Brave and Chrome that I love dearly. Is there a way to bring that theme to Firefox? I tried using Firefox Color, but it looked awful.

PS: I am the tech Village Idiot so please talk to me in that vein ;)

Thank you and Warmest Regards, Alisa (Stormwolfe)