[KeplerBoy]

Okay, so it's not LaTeX, just math typesetting that looks like LaTeX and takes LaTeX input.

I'm more interested in solutions that work with the broader LaTeX ecosystem (like SiUnitX or amsmath).

[abdullahkhalids]

Mathjax does support a whole bunch of common latex math related packages [1]. SiUnitX is notably missing from the inbuilt extensions, but a port to version 2 is available [2]. Should be updated to version 3.

[1] https://docs.mathjax.org/en/latest/input/tex/extensions/inde...

[2] https://github.com/mathjax/MathJax-third-party-extensions

[Wdorf]

Thank you, I wasn't aware of these extensions.

[fweimer]

Ahh. I was confused for a moment why \def wasn't working.