Is there a good base theme for D10 with everything done in CSS instead of Javascript? The theme does not have to be perfect, it just has to present everything in a good readable format in environments where Javascript is blocked.
I worked with some in D7 but they are not upgraded for D10. The closest for D8 is missing important highlighting which makes, in some cases, core text not display and in others, buttons appear as unhighlighted text. They appear to be to hard to both fix the css and convert to D10.
Javascript is okay for making things look better but should not be required to read the content. Javascript is okay for Admin editing as the admin can control things but should not be needed by visitors to read content or use the drop down menus or search or post comments.
Comments
This is not an answer but
This is not an answer but even core theme, Olivero, uses javascript for responsive menu.
I'm using Olivero and the responsive menu has some issue so I customized the css a lot that took a lot of time.
Customizing incomplete components takes time rather than making from the scratch. SoI think selecting Stark and add CSS responsive menu would be your option if you are used to Drupal.