Idea: Use MathJax for expressions

[effigies]

Your idea

There are a few places where we write out mathematical expressions like B<sub>0</sub> to get $B_0$, rather than using the common TeX formatting $B_0$. The MathJax (https://mrkeo.github.io/reference/mathjax/) extension should make it possible to switch to something more readable, but we need to verify that it works for the PDF build as well.