Bug: Maths are truncated on mobile

[fuglede]

Wide maths formulas become truncated horizontally when browsing on mobile (screenshot below). Notably, this is not an issue on the old (non-responsive) SciPy site where one could simply scroll horizontally to see the full thing when it doesn't fit on screen.

Something similar could probably work here; just make sure to make it possible to scroll without having to exactly hit the formula, which might not be very high (cf. #51).

[mdhaber]

I noticed this, too. I was able to scroll code horizontally, but not rendered math.

[rgommers]

I think that may be fixed when switching from pngmath to mathjax, which is still to be done