Page layout: when window is small, let the right column appear on the top

[Zack-83]

Rationale / Begründung

When viewing RDMO on a narrow browser windows, all the menues (Options, Export...) roll to the bottom.

Affected

Mostly managers, but also users

Minimal functionality

It would be more practical to have the menues on the top, especially in the "manager" view, since selection of content items goes before their preview.

Nice-to-have functionality

Some details may possibly printed smaller, or hidden via an accordeon.