https://github.com/mbnuqw/sidebery
brew reinstall librewolf --no-quarantine
about:config
toolkit.legacyUserProfileCustomizations.stylesheets true
Menu > Help > Troubleshooting Information > Profile Directory
mkdir /Users/nicolasdanelon/Library/Application\ Support/librewolf/Profiles/88888888.default-default/chrome
userChrome.css
#TabsToolbar {
display: none;
}