API docs runs out of the frame

[bsipocz]

If the generated API reference summary is too long it runs past the sidebar an thus looks weird.

[bsipocz]

Collapsing the sidebar js and extending it again fixes the problem for the given page for that given time.

[astrofrog]

Related: astropy/astropy#689 (I don't think we ever did the proper fix)

[kakirastern]

Hi, just wondering if a sticky navigation bar would do the trick? This is like the stickysidebar HTML theme option for the "classic" theme as described in http://www.sphinx-doc.org/en/stable/theming.html? Might produce a different effect but a viable solution.