I am running the latest version of Mozilla firefox and there seems to be some problem: The math font appears dark. It's been happening for the past two days. Before it was working fine. Below is the image:
Any idea of how this can be resolved?
When MathJax fonts are defined to be a color, but are displayed in black, this almost certainly means you are receiving image fonts (rather than web-fonts).
As a first resort you should clear the browser cache and try again. After that, some things to check are:
Are you behind a proxy that rejects OTF web-fonts?
Have you installed STIX or MathJax fonts locally (but incorrectly)?
Do you have a slow internet connection? This could cause the loading of web-fonts to timeout.