How Do We Highlight Text In Markdown?

If you run the code snippets on this answer on stackoverflow you will see 2 different ways of highlighting text with markdown

https://stackoverflow.com/a/36039773/1000011

<mark>Marked text</mark>

<span style="background-color: #FFFF00">Marked text</span>

Neither works in IDEA.

How do we highlight text with markdown in IDEA?