firefox-custom-ui

install userChrome overrides

• clone or download the files in this github repo into the firefox user PROFILE_FOLDER
• find PROFILE_FOLDER on about:support page
• make sure to clone the repo to .../PROFILE_FOLDER/chrome not .../PROFILE_FOLDER/firefox-custom-ui

install core config override (optional)

Needed for new UI element CSS overrides (i.e. sidebar) that use web components and shadow dom (lit), which makes CSS overrides impossible from the userChrome.css. It replaces the corresponding core css files completely with custom ones.

• Install custom config: ./install-config.sh (paths might need to be adjusted, depending on the firefox installation)
• Clear startup cache: on about:support page, click "clear the startup-cache" button (so firefox loads the config override)