Can't support mathematical formula

Steps to reproduce the problem (provide example Markdown if applicable):

$x+y=z$ or  $$x+y=z$$

Expected behavior:

such as <span class="katex-display"></span>

Actual behavior:

<p>$$x+y=z$$</p>

(Also see what the reference implementation does: https://spec.commonmark.org/dingus/)

The markdown to html should render like the picture below.

Many thanks

This is not a bug. Maths rendering is not part of CommonMark. So it's an additional extension that would be needed (depending on how it's done).

Note that if you're rendering it as HTML and can add some JS, you can already do it, see #194 (comment)

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