Firefox Omarchy Mode

Makes Firefox look like it belongs in Omarchy. Tabs, toolbar, address bar, menus and sidebar take the colors of your active Omarchy theme and follow along whenever you switch themes.

• Theme colors from the current theme's colors.toml, in light and dark themes
• Transparent address field when theme colors are enabled, with an opaque background for open suggestions
• Transparent vertical-tabs toggle at rest when theme colors are enabled; hover and click feedback stay visible
• Square corners on tabs, address bar, buttons, menus and panels
• No close button in the tab strip. You close windows with your Hyprland keybinding.
• Flush tabs with no space around them, or compact tabs with 1px

Every feature can be switched off on its own.

How the bar icon works

The icon only shows up while Firefox is not in Omarchy mode:

Icon	Meaning
visible	Omarchy mode is not enabled yet: click it and enable it
visible	Firefox is running with the old look: restart Firefox
hidden	Firefox is in Omarchy mode, and the plugin syncs in the background

Firefox reads its interface stylesheet only at startup. After every theme switch or settings change, the icon comes back until you restart Firefox.

Install

omarchy plugin add https://github.com/workingtitle/firefox-omarchy-mode.git --enable

Then click the Firefox icon in the bar, choose Enable Omarchy mode, and restart Firefox.

Installing the plugin changes nothing in Firefox. Firefox is only modified once you click Enable Omarchy mode.

Settings

The switches are in the panel. They also appear in the widget's bar settings, and the values are stored in ~/.config/omarchy/shell.json.

Setting	Default	Effect
colors	true	Use the Omarchy theme colors in the browser UI
squareCorners	true	Square corners on tabs, address bar, buttons and menus
hideWindowButtons	true	Hide the close (and minimize/maximize) button in the tab strip
tabSpacing	flush	flush: no space around tabs, a little more room inside; compact: 1px above and below; default: Firefox's spacing

What it changes

For every profile listed in Firefox's profiles.ini (native and Flatpak Firefox), the plugin writes three files:

File	Change
chrome/omarchy-mode.css	Generated stylesheet, rewritten on every theme change
chrome/userChrome.css	One @import line at the top; your own rules stay intact
user.js	Enables toolkit.legacyUserProfileCustomizations.stylesheets

Every line the plugin adds carries the marker omarchy-firefox-mode, so it can remove exactly what it added. The plugin never uses the network or root privileges, and it only writes to your Firefox profiles and ~/.local/state/omarchy-firefox-mode/.

Turning it off and uninstalling

While Firefox is in Omarchy mode, the icon is hidden, so turn the mode off from a terminal:

~/.config/omarchy/plugins/io.github.workingtitle.firefox-omarchy-mode/firefox-omarchy-mode disable

Restart Firefox, and it looks like stock Firefox again. disable deletes omarchy-mode.css and removes only the marked lines from userChrome.css and user.js. It deletes each of those files only if nothing else is left in it. Firefox keeps the stylesheet preference in prefs.js. It does nothing without a stylesheet, and you can reset it in about:config.

To uninstall, run disable first, because omarchy plugin remove cannot run any cleanup code:

~/.config/omarchy/plugins/io.github.workingtitle.firefox-omarchy-mode/firefox-omarchy-mode disable
omarchy plugin remove io.github.workingtitle.firefox-omarchy-mode

Command line

The helper script also works on its own. For example, you can call it from an Omarchy hook:

firefox-omarchy-mode status     # JSON status, used by the bar widget
firefox-omarchy-mode enable     # opt in and apply
firefox-omarchy-mode sync       # re-apply if enabled (no-op when nothing changed)
firefox-omarchy-mode disable    # remove everything again

# enable and sync accept:
#   --colors on|off  --corners square|rounded
#   --window-buttons show|hide  --tabs flush|compact|default

Options you pass are remembered for later runs without options. While the bar widget is running, its settings take precedence.

Troubleshooting

• The icon does not go away. Quit Firefox completely, including every window, and start it again. Firefox loads its stylesheet only at startup.
• Firefox looks partly default after a Firefox update. userChrome.css is not an official Firefox API, and Mozilla sometimes renames internal variables. Firefox still works. Update the plugin with omarchy plugin update io.github.workingtitle.firefox-omarchy-mode, or open an issue.
• A profile is not themed. Only profiles listed in profiles.ini are picked up. firefox-omarchy-mode status lists them.
• Overriding a rule. The plugin's rules use !important. To override one in your own userChrome.css, which comes after the @import, mark your rule !important as well.

Requirements

• Omarchy with the Quickshell-based bar
• Firefox 155 or newer (native or Flatpak)
• jq and flock, both part of a standard Omarchy install

License

MIT