BrianGilbert

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * This style will hide the tab bar. For MacOS Big Sur
 *
 * Contributor(s): Isaac-Newt, Ivan0xFF, millerdev, AMomchilov
 */

olmstadfm

Tree style tab custom CSS with auto-hide

1. Install Tree Style Tabs Firefox extensions.
2. Install userChrome.css (see file content below below)
   • Linux
     • cd to ~/.mozilla/firefox/[your profile id].default/
     • create folder chrome if it doesn’t exist
     • put userChrome.css in it
   • Windows
     • press Win+R