Greetings. Today I discovered the world of theming Firefox through something called CSS. I went to the store page, and I wanted to add the Opera GX theme. Therefore, I first enabled the legacy toolkit config in the about:config page. Then, I went to the UserChrome.css file found on github for that theme and copied the raw data. Here is where things get interesting. I went to the about:profiles page and tried to open the root directory of the default profile, and it failed to open. I then tried searching for the directory in the file manager, it does not exist. No, it’s not hidden, it does not exist! The local directory, however, does exist, so I opened it and made the chrome folder and subsequently the userChrome.css file by using the text editor. I then restarted firefox, and…nothing happened. I cleared my browsing data and disabled all my of extensions, still nothing. I then had the idea of creating the root directory myself, so I created the necessary folders in the correct locations according to the about: profiles page, and then I moved the contents of the local directory to the root directory, and then restarted firefox. And…nothing happened. I was scratching my head at the point, so I tried searching the web to see if anyone else had a similar problem to mine, but I didn’t find anything relevant to my problem. Has anyone encountered a similar problem to mine? Is there anything that I’m missing? My OS is Ubuntu 23.04 and I’m using Firefox 115.0.2 (flatpak). I posted my problem on the Firefox CSS community, but the problem with it is that it’s not active, so I hope the mods don’t mind my post here. Any help would be appreciated.
Make sure that
toolkit.legacyUserProfileCustomizations.stylesheetsis enabled in about:config.Thank you guys. Other than giving Firefox permission to access the root folder, it turns out there was more to do in order to get OperaGX theme to work, like enabling a few more config settings, and copying the entire chrome folder and user.js file from the source.
After looking around, you might be facing an issue with Flatpak permissions. Here’s a comment I found on Reddit created by u/avamk where they solved the same issue.
All right, after much trying I installed Flatseal and enabled the Firefox Flatpak’s access to my home folder.
After this, it created the expected profile folder under ~/.mozilla/firefox/. I put my custom userChrome.css into that profile folder, and >enabled it in my about:config under toolkit.legacyUserProfileCustomizations.stylesheets per these instructions.
With all of these, the custom userChrome.css is finally working!
Link to original post: https://libreddit.tiekoetter.com/r/firefox/comments/rq40cj/cant_find_profile_folder_for_firefox_flatpak_on/
No need to give permissions, you can place the files directly into flatpak’s directory. I don’t know the exact path because I use librewolf but it is something like:
~/.var/app/io.gitlab.librewolf-community/.librewolfJust look for folders with firefox/mozzila in its name.
