[TASK] Restructured HTML and added basic css to opendocs

I moved the inline css to opendocs.css introducing a new class name.
Resolves: #62945
Releases: master
Change-Id: I5d008a3ed2d079f86abe3e97656fbe7389dffc71
Reviewed-on: http://review.typo3.org/34158
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Felix Kopp <felix-source@phorax.com>
Tested-by: Felix Kopp <felix-source@phorax.com>