[TASK] CSS: Button style :active and :hover

Brings visual illusion for :active / click state.
Bugfixes :hover on <button>

Resolves: #56480
Releases: 6.2
Change-Id: I08d38c50d23f5fbcf591dbd54edca34944568591
Reviewed-on: https://review.typo3.org/27983
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer