Nice Christmas gift: MathJax in Markdown on Codeberg.
https://codeberg.org/harald/Codeschnipselnotizen/src/branch/main/MathJaxTryout.md
**Except:** when I look at the page's HTML code, there is no MathJax. There is katex, which seems to do something similar. 🙂
Anyway, as long as a (La)TeX manual or the amsldoc https://texdoc.org/serve/amsldoc/0 suffices to get the math typed, all is fine :-)
(I am sure that not long ago I saw an open issue discussing MathJax in Markdown. Can't find it anymore.)