you could use the table view instead of the card view. (the icon is beside the quick filter button) That reduces back to the original lists, but I an not aware of any individualization settings for the fonts or positioning in the card view.

Thanks for your reply.

I am using table view already.

I just fixed a whole bunch of problems with Supanova after having them for many months by creating a new profile and adding my 7 email account and local archive folders. Now I am finally starting to enjoy Supanova. I do think there seems to be quite a bit of wasted space. The search bar for one which many have complained about which could go to the right of the main menu,

https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2024-04-13-19-26-30-7a408b.png

Change the font of the Subject in the Header Pane with css:

https://support.mozilla.org/en-US/questions/1434228#answer-1624920

Other parts of the pane:

https://support.mozilla.org/en-US/questions/1434228#answer-1624985

See also the Compact Headers add-on.