css works on preview, but not on the site

Please select Full HTML in place of Basic HTML in editor Text format. also clear the admin cache for viewing.

Might help to add this suggestion in the README of the module with a brief explanation.

I'm having the same issue. Not sure what selecting "Full HTML in place of Basic HTML" means but the editor is in text format and I've cleared all caches through admin/config/development/performance as well. Using D10 with base theme. Preview works, but the saved changes never seem to take effect on the site itself.