I author in Typora and if it was compliant I would see the highlighting live. It also makes the non-hugo rendering less and less human readable in other contexts.
However, the goldmark demo does render the <mark> tag - is that goldmark doing that rendering?
Can I just style the HTML element <mark> in my hugo theme?
FYI the MARK tag does not show up in rendered markdown when the element is not recognized.
Can I create a shortcode with the standard code so I get both renderings - like this? {{<MARK>}}Testing in Production Like environments to find missing configuration information{{</MARK>}}