Install clearlooks-phenix-theme by entering the following commands in the terminal:
sudo apt update sudo apt install clearlooks-phenix-theme
Description:
GTK3 port of Clearlooks theme
Clearlooks-Phénix is a GTK3 theme which is a port of Clearlooks, the default theme for GNOME 2. Files for GTK3 is a Clearlooks theme ported to GTK3 CSS language. Files for GTK2 come from the unmodified Clearlooks theme.
Homepage: http://www.jpfleury.net/en/software/clearlooks-phenix.php
Version: 7.0.1-1
Section: universe/gnome