I am using Tumbleweed and have had Firefox 37 installed from the standard repo. I also tried to install Firefox 38 from the Mozilla:Factory repo.
There seems to be a large problem with Mathjax. It doesn’t display anything (essentially blank) in html-css mode and only some random lines in mathml mode.
The same versions of firefox on Windows 7 work fine.
I tried the 13.2 KDE-Live version in a virtual machine and both with firefox 33 and an updated firefox 37 everything works fine.
I tried deleting my firefox profile on my machine but the problem persists.
I tried creating a new user on my system but the problem still exists.
I cannot find anything on the net that references such a problem except for:
http://meta.math.stackexchange.com/questions/20213/broken-mathjax-on-firefox
but it seems to be a different problem since I on a 13.2 kde-live version and on windows everything runs fine. On the other hand if on my system I change the user-agent headers (as seems to be the problem in the above post) the rendering problem remains.