You can override the GTK theme that Zrythm uses along with much of the color scheme in a special CSS file. It is a good idea to start by copying the theme from your Zrythm installation directory (normally /usr/share/zrythm/themes/zrythm-theme.css on GNU/Linux and share/zrythm/themes/zrythm-theme.css in the installation path on Windows or the Application contents on MacOS.

You should create a file called theme.css under the themes directory in your Zrythm directory. For example, if your Zrythm directory is /home/me/zrythm, you should create a file at /home/me/zrythm/themes/theme.css.


The Zrythm theme inherits from the Matcha GTK theme, so additional CSS rules may need to be overridden.

Color Scheme

Inside the theme file, you will find lots of colors defined using @define-color. You can override these with your own colors and Zrythm will use them where possible.

Other GTK-Specific Rules

You will find lots of information about changing CSS rules for general GTK widgets online.

Here are some links by official GNOME sources: