Very cool anyway. Because you are just using CSS instead of the DOM trickery of MathJax I should still be able to use it for my purposes.

Even though we're using CSS as much as possible, we do need the character metrics in order to do positioning properly. (For example, $x^2$ and $F^2$ differ in the vertical position of the 2.) You'll need to update these metrics to use it with a different font -- see

https://github.com/Khan/KaTeX/blob/master/src/fontMetrics.js

and the "make metrics" Makefile rule. We haven't added the ability to swap font metrics at runtime or to easily build a version with different metrics but I'm not opposed to the idea.