Firefox Theming

Source of truth

Firefox ships CSS inside omni.ja (a zip file). Always extract and read source files before writing or auditing userChrome rules.

Extract source

OMNI=$(ls /nix/store/*firefox-unwrapped*/lib/firefox/browser/omni.ja 2>/dev/null | head -1)
OMNI_TK=$(ls /nix/store/*firefox-unwrapped*/lib/firefox/omni.ja 2>/dev/null | head -1)
DEST=/tmp/ff-omni

mkdir -p "$DEST" && cd "$DEST"

# CSS
unzip -o "$OMNI" "chrome/browser/skin/classic/browser/*.css" "chrome/browser/skin/classic/browser/**/*.css" 2>/dev/null
unzip -o "$OMNI_TK" "chrome/toolkit/skin/classic/global/*.css" "chrome/toolkit/skin/classic/global/**/*.css" 2>/dev/null