[BUGFIX] Layout of page tree filter function broken

Small CSS fix to overwrite general margin
of paragraph tags in page tree indicator bar.

Resolves: #55536
Releases: 6.2
Change-Id: I9a4766a7fbc22f6ab2506f8a12463f5695813205
Reviewed-on: https://review.typo3.org/27231
Reviewed-by: Stefan Froemken
Tested-by: Stefan Froemken
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind