Firefox Gnome Theme

Description

This is a bunch of CSS code to make Firefox 57+ look closer to GNOME's default theme. It styles the UI and, if you pick the dark variant, interal Firefox' pages like about: and view-source:. Both light and dark variants are supported.

Installation

Extensions can no longer style UI elements, but we can still use good old userChrome.css and userContent.css files. Just drop this repo to your chrome directory:

1. Go to your Firefox profile's directory.

2. Clone this repo to the chrome directory:

   git clone 'https://github.com/kurogetsusai/firefox-gnome-theme.git' chrome
   

3. The GTK theme variant must match the variant you picked for this Firefox theme, which means you must either enable (for the dark variant) or disable (for the light one) global dark theme in GNOME Tweak Tools, or alternativelly, you can run Firefox with a specific variant without changing the global theme by supplying the GTK_THEME variable like this:

   # for the dark theme
   GTK_THEME=Adwaita:dark firefox
   
   # for the light one
   GTK_THEME=Adwaita:light firefox
   

If you choose the light variant, you must also enable it in your userChrome.css file and disable the dark one. Just uncomment the @import "ui/theme-light.css"; file and comment the @import "ui/theme-dark.css"; one, so it looks like this:

/* Dark theme */
/*@import "ui/theme-dark.css"; /**/
/* Light theme */
@import "ui/theme-light.css"; /**/

The userContent.css file makes all the Firefox' internal pages dark, so if you don't want them dark, just remove that file.

You might want to adjust your default link colors so they are more visible on dark background, either drop the code below into your (firefox profile)/user.js file or change them manually in about:config.

user_pref("browser.active_color", "#cc1a1a");
user_pref("browser.anchor_color", "#0a8dff");
user_pref("browser.visited_color", "#0871cc");
user_pref("browser.display.background_color", "#2e3436");
user_pref("browser.display.foreground_color", "#ccc");

You can't get rid of the title bar for now (except for Fedora I think, where you can enable CSD in about:config), but you will be able to do it when they add client-side decoration support. For now you can use a GNOME extension like No Title Bar to hide it.

Broken stuff

Icons might appear black where they should be white on some systems. I have no idea why, but you can adjust them in the ui/theme.css file, look for filter: invert.

I haven't finished styling the new... new tab page. I just replaced it with a blank page, because I don't like all that clutter anyway, but feel free to finish it yourself (my attempts are in the userContent.css file, look for about:newtab).

Probably more things are broken, it looks okay for me, feel free to report issues here on GitHub and share your ideas if you know how to fix them.

Development

If you wanna mess around the styles and change something, you might find these things useful.

To use the Inspector to debug the UI, open the developer tools (F12) on any page, go to options, check both of those:

• Enable browser chrome and add-on debugging toolboxes
• Enable remote debugging

Now you can close those tools and press Ctrl+Alt+Shift+I to Inspect the browser UI.

Also you can inspect any GTK3 application, for example type this into a terminal and it will run Epiphany with the GTK Inspector, so you can check the CSS styles of its elements too.

GTK_DEBUG=interactive epiphany

Feel free to use any parts of my code to develop your own themes, I don't force any specific license on your code.