The CSS settings of a template can be modified with a user.css, 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

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