demos: Fix margins and position
demos: Fix margins and position

Fixes some visual glitches when transitioning
from >960 to <960 page width.

Change-Id: Ib25a93f75bca19734d169c2a5b06df6f6448e8f1

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui