Install xul-ext-classic-theme-restorer by entering the following commands in the terminal:
sudo apt update sudo apt install xul-ext-classic-theme-restorer
Description:
customize the new Firefox interface
Classic Theme Restorer allows restoration of squared tabs, tabs-not-on-top, the app menu, the add-on bar, small button view and more. . Such elements were removed in Mozilla's Australis redesign of Firefox.
Homepage: https://addons.mozilla.org/firefox/addon/classicthemerestorer/
Version: 1.5.9-1
Section: universe/web