It is very easy to use for making themes. It has a color palette which lets you use colors that are already used, and there is an advanced mode to color specific parts of the browser, complete with a manual explaining where each color goes.

However, it has issues:

1. As of the latest Firefox update, there are some advanced colors that don't work anymore, such as the tab background separator, pop up highlight and the new tab text.

2. There are also new attributes in the new Firefox version that can't be edited yet, like the border around the text in the ≡ menu which appears when using up/down arrows.

3. There is currently no way to navigate to saved ♡ themes.

There is also room for improvement:

1. An option to upload a theme file (.xpi) to edit

2. An option to edit the Firefox default themes

All in all, good app.
Hopefully the developers update it soon.

this is like the best firefox extention. i mean, gosh i love it

oh yeah it has some issue that can be really infuriating like, just because you clicked "save" doesn't mean your theme is really saved. not sure if it's because i configured my firefox in a way it will reset and clear many things each time i close it. anyway, lesson learned, and my workaround for this is to bookmark the page/link/theme, instead of clicking that save button

I really like the idea of this addon to make Firefox more beautiful.

Once I had a nice theme with red and yellow-colors in the presets, but I cannot seem to be able to get it back.

I exported the theme.zip and the theme.xpi, I even tried to add it to the Firefox Marketplace (because Firefox Color suggests to do so, but it was rejected).

When I look inside the theme.xpi I can understand, because it only contains a manifest.json with just some colors defined. I guess that is enough for Firefox Color, but it would be nice if this would write a complete theme.xpi that I can easily distribute to others.

Now I also created a theme with a custom background, but I could not share this by using the Share-button (because it uses a custom background). I would expect that the custom background can be saved as a base64-image and then will be able to share it.

When that would mean that it does not fit in a regular URL than Mozilla can save the theme somewhere online, make it publicly available and just enable sharing the short url with other people.

By using that the complete theme can be downloaded by other users, so they can install it into their Firefox. Then people can easily design themes for their community, just like they can now do using the Firefox light themes (using custom toolbar backgrounds).

IMHO, this extension could have so much more possibilities in the near future.

Super dodatek można robić fajne rzeczy.

A complete waste of time trying to bring back the system theme that Firefox screwed up.
If you want to to something useful allow us to configure the _existing_ theme then not a useless preset

Only wanted to change active tab colour in dark theme (actually "System theme, following operating system" which is set to dark mode).
Couldn't figure out what was meant by various items I can change.
It changed more than it indicated.
Neither Undo nor Revert actually work.
Opened issue in GitHub.
Disabled add-on until it can do this 1 simple and commonly wanted tweak.
Investigating userchrome.css

Great addition! But there is also a minus - there is no translation 😢

All I wanted to do was change the color of the active tab so I can see it more easily. The second I clicked on that one new color, it changed EVERYTHING, and it looked horrible. I can't remove this add-on fast enough.