Not sure you're aware of this... most markdown engines allow you to also use a very constrained set of HTML tags inline.
e.g.:
``` ## <p style="margin-left=4em;font-family: 'Courier,mono"> Life is death's way of giving what it kills time to grow in. —w.s. burroughs. </p> ```
Necessarily, inline HTML tags, attributes and CSS is carefully sanitized by engines that support this. And, unfortunately the extent of sanitization, and actual supported tags vary from engine to engine. But it's there, and it is widely supported, and relatively predictable for basic HTML formatting. And mostly manages to excise ever-evolving ways to inject javascript into standard CSS.
HNs markdown engine doesn't support inline HTML; but Github's markdown engine does.