Al the font, etc-changing tips and tricks in the other threads methods are not systemic, in that each only changes one but not all the locations where fonts need to be sized. OR, the Px method changes everything all at once, but doesn't change their relative sizes when they are already differently-sized. We need to be able to independently define and (if necessary) change: 1. Folder pane font size 2. Inbox (and other folder) font size 3. Message font size That this functionality is not available attests to the programmer-orientation of T'bird developers and many (but not most) users. Calling on your average user to build and place CSS files is (to be kind) an example of techno-arrogance. I agree with the many voices on this forum that propose the T'bird developers address this user-interface bollocks once and for all with a "View" menu-item drop-down (or some similar architecture) and give us a T'bird that doesn't hurt our eyes. Similarly, why not let us adjust the spacing between lines in the inbox and other folders? And going to Dark Mode in the MacOS now makes all the text in the tag colors illegible? What about that? Let me propose that the T'bird developers and the generous contributors re-focus (at least for a while) on usability matters rather than on functionality matters. Most of the more-obscure functions are not used by even many users, not even close to most. If T'bird is REALLY the best e-mail client (I think it is, which is why I am using it), it should be that in every respect. Thank you. Alexander