saguaros oh, it's my yet in production site, on local machine, so I can't share a link. At the moment I'm corrected problem in my own template CSS, but strange that problem started just from recent two T4 versions (2.1.5 & 2.1.6). I guess it's linked with such T4 updates like "Logo size properties (width and height) update for better Google speed index" as written in T4 Framework Changelog. If you share which changes were done from 2.1.4 to 2.1.5 to make this "Logo size properties (width and height) update" probably I'll discover the certain reason.
Also have to note - I use only current Joomla (at the moment 4.1.2) and no other plugins except T4.
Thank you for for great product! I guess, with help and testing from community it'll be absolute awesome!