Accessible mathjax

[tonyfast]

currently, mathjax equations are ignored from automated tests #80 . there should be ways to tune mathjax to improve accessibility.

• https://docs.mathjax.org/en/latest/basic/accessibility.html
• https://github.com/mathjax/MathJax-a11y
• https://github.com/search?q=repo%3Amathjax%2FMathJax+accessibility&type=issues