Layout of theme- and plugin-pages broken in smaller windows

[Heiko_Mamerow]

What were you trying to do?
Read a plugin- or theme-page in a small (less then 975px) browser window.

What happened / what did you see?
The 3column layout is broken: The 2nd (main-content) and 3th (sidebar) column are the under the 1st column (menu):

What browser are you using?
Chromium, Chrome, Firefox (current versions)

PS: Maybe its time for media queries here? ;-)

[ocean90]

Duplicate of #270.