It's a pretty darn good tool for people like me who don't know how to create/edit style sheets. The big problem is something I have seen in past on other style tools on other platforms. It would be so much more helpful if you provided a simple numbered MARKUP diagram that shows exactly where within the browser tabs and toolbars each of the adjustable color elements exist. Only about 5 or 6 adjustment tools are super-obvious about where this color will get applied, such as "Active Tab" background color, or color of Icons. But far too many of the elements are very non-obvious to end users who didn't write the Firefox Color tool. YES it's great that some (but only very few) UI elements actually "light up" in the simplified preview element as you make a change. Either do it for all the elements or its huge disservice. ... I should really subtract a 2nd star for the non-obvious way to RE-APPLY your theme when buggy things happen that suddenly strip out the entire theme reverting to default. You show how to SAVE, how to favorite, how to share, but missing a simple actuator to "Re-apply theme".

Provides almost every basic theme-color setting needed.
The one standout thing missing is a setting for "ntp_card_background" - the New Tab (StartPage) card/button background color. Add that and its practically complete.

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A new update seems to have fixed the issue. Working with no problem now!

It's always been a very good plugin, and now I'm concerned about its recent malfunctions. Every time I launch Firefox, I have to turn this plugin off and back on in order to actually make it work. Please fix?

this causes the bookmarks to be extremely slow in edit adding due to the popup loading the style newly each time it seems.

Good

For those who are having issues on 132 with the theme not loading on startup, go to the about:config page and leave ""extensions.activeThemeID" blank.

Edit: It keeps reverting, changing it to "firefox-color@mozilla.org" has not made it revert yet.

new update fixed it!

This add-om longer works as of newest versions of Firefox. I hope it will soon be updated so that it can work again since I have used this add-on for years without any issues. Since the last update it no longer functions until manually enabled, some parts still don't function after manually enabling. Dependencies and deprecations are likely to blame.

Es funktioniert hervorragend, aber nur, wenn das standard "Hell" oder "Dunkel" Theme in den Einstellungen ausgewählt ist. Das standardmäßig aktivierte Theme, dass sich an den Systemstandard anpasst funktioniert leider nicht mit diesem Add-On.

Used to work great; in Firefox 132 it often doesn't work when the browser starts and backgrounds all revert to white. Worked great in at least Firefox 109 and earlier. It also no longer affects top menu bar menu backgrounds and right-click menu backgrounds. This is one of the reasons I don't normally update the browser... because it breaks extensions and it's a nightmare and takes hours of time to try to troubleshoot, often with no resolution. Very frustrating.