The CSS settings of a template can be modified with a user.cs, changing the appearance.
The user.css must be in the directory /media/templates/site/[yourtemplate]/css (Joomla 4.1).
The following submenus are based on the standard Cassiopeia template. 
Each submenu loads the corresponding user.css of a Cassiopeia modul position and the css code in the content area

Copyright © 2021 J4 How To - Modified Design by D. Nederveld. All Rights Reserved.
Joomla! is Free Software released under the GNU Generel Public License. 
The content is released under the "Friendly License".  The content can be copied and changed as often as you like. A link to the original URL is welcome.