Dynamic Firefox Theme

A minimal dark Firefox theme that dynamically colors the interface using the system's accent color (works on Windows, Linux and probably MacOS) while maintaining the browser's default layout and behavior.

Installation

1. Go to about:config and set toolkit.legacyUserProfileCustomizations.stylesheets to true
2. Find your profile folder via about:profiles
3. Create a chrome folder in your profile directory
4. Save userChrome.css & userContent.css in the chrome folder
5. Restart Firefox

Simpler version

Windows

cd $env:APPDATA\Mozilla\Firefox\profiles\*.default-release

mkdir *.default-release\chrome

cd chrome

wget https://raw.githubusercontent.com/zachvlat/Dynamic-Color-Firefox-Theme/refs/heads/main/chrome/userChrome.css -O userChrome.css

wget https://raw.githubusercontent.com/zachvlat/Dynamic-Color-Firefox-Theme/refs/heads/main/chrome/userContent.css -O userContent

Linux (Flatpak)

cd ./var/org.mozilla.firefox/config/mozilla/profiles

for /d %i in (*release*) do mkdir "%i\chrome"

for /d %i in (*release*) do wget -O "%i\chrome\userChrome.css" https://raw.githubusercontent.com/zachvlat/Dynamic-Color-Firefox-Theme/refs/heads/main/chrome/userChrome.css

for /d %i in (*release*) do wget -O "%i\chrome\userContent.css" https://raw.githubusercontent.com/zachvlat/Dynamic-Color-Firefox-Theme/refs/heads/main/chrome/userContent.css

for /d %i in (*release*) do wget -O "%i\user.js" https://raw.githubusercontent.com/zachvlat/firefox/refs/heads/main/user.js

Examples

Thanks

Special thanks to MrOtherGuy's Firefox CSS Hacks which is a great material for creating themes on Firefox.