In the commit 5a56f9699c (3.) the min-height was applied to all wiki
elements. This resulted in huge blank spaces when viewing the wiki.
This fixes this by only applying the min-height to the preview when
editing.
Refs: https://codeberg.org/forgejo/forgejo/pulls/2080
(cherry picked from commit 8f0baefe5d)
Co-authored-by: Fl1tzi <git@fl1tzi.com>
92711b001e