FYI in an actual editor the syntax highlighting works. In the (new) website it's using a different highlighter which has issues. Will be fixed soon!
If I may ask, what made you settle on the double dash to disambiguate content from tags? Like is it some sort of nod to SGML from way back when? It seems like an odd choice to me at first glance, but I bet it was thought about long and hard so I’d love to hear some background about what alternatives you considered.