[FEATURE] Increase Install Tool font-size to 75%

Since the font-size of the backend is bigger, the Install Tools font-
size is now bigger too.

Resolves: #64366
Releases: master, 6.2
Change-Id: If659e61a51a22d9a1ee64ea06c149958e15ef952
Reviewed-on: http://review.typo3.org/36129


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>