[TASK] Visual cleanup

Some minor corrections in the TYPO3 Backend,
so the buttons and search fields look correct,
and the file browser in the Element Browser does not
look "old-school" anymore.

Resolves: #71423
Releases: master
Change-Id: I48a7d9c70129a35af94441d638fc50d4434357ad
Reviewed-on: https://review.typo3.org/44622


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>