In Mac-FF 41 (and 40) the Umlaut-dos of the letter Ä are rendered too close to the rest of the letter, as it shows in the picture below. In other Browsers however (Chrome, Safari) the type renders correctly.
The problem only occurs when I apply css "text-transform: uppercase;" to a small letter "ä". It looks fine when I use the actual uppercase letter "Ä".
The webfont I would like to use is "MuseoSans" – however the same problem occurs when I use a similar webfont "Equip-Light".
I did try playing with font-size and line-height – but the problem remains the same. Also with other Umlaut-letters "Ü" and "Ö" it seems to be ok, probably at least because the letters have a different 'architecture' of the letter.
Most of the answers I found at least close to the topic are related to UTF8-issues – but that's not the problem here. I hope that anybody here might have a suggestion what is causing this problem – and how I can solve it. Any pointers appreciated.