MathJax-src VS MathJax

I am using MathJax from Emacs org-mode and it is grabbing MJ 3 from https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js In Emacs I supposedly have configuration options to get, for example, the LaTeX Euler font -- or a few others. But it doesn't seem to work. I inspect my web page output and I see a CSS class MJX-TEX, and it's CSS breakdown is .MJX-TEX { font-family: MJXZERO, MJXTEX; } Good. I think I can simply go into my own CSS and change something with the font family. But I wouldn't know what to. I found this code where it seems to have a long list of "font families" but I have no idea what they are or how to change the above CSS font-family tag. I read that 3 doesn't allow changing fonts. Is that still true? Any knowledge on how to handle/change fonts appreciated.

One thing that the article gets wrong is accusing mathjax of being abandoned. Development has moved to a new repo for the next version.

https://github.com/mathjax/MathJax-src/graphs/contributors

Obsidian uses MathJax for their LaTeX integration, so it will auto center without using any of the formatting syntax. You only need to put in your equations and it will format automatically.

MathJax - Mathematical Notations expressed using Tex or MathML

Developer tools point to MathJax https://www.mathjax.org/. If you disable javascript you can see some LaTex.

It is something we could add, but it is not planned in the near future. We also have requests for adding math notation (like https://www.mathjax.org/), and that could be a more general solution.

I don't know what Obsidian is, but if it's requiring old TeX math mode toggles (the double dollar sign), then it might not actually be using LaTeX underneath. Many tools that provide LaTeX-style syntax for equations are actually using something like MathJaX, BlahTex, or some custom system by which to translate LaTeX-like syntax into their own equation rendering. This often means you only get a pre-defined subset of what's possible with LaTeX (and the results are never quite faithful to how LaTeX would typeset them).

This will depend heavily on where you're asking the question, e.g. stackexchange has built in mathjax to render it. I'm going to assume you're intending to ask here (because that would make sense), in which case check out the bottom of the sidebar.

From the screenshot, Obsidian looks like a typical Markdown editor that supports some LaTeX math syntax, probably rendered with something like Mathjax. On the other hand, Xournalapp seems to actually use LaTeX, even allowing you to use LaTeX packages like graphicx, tikz, etc.