With Hugo, can we use HTML code in a md file?

With Hugo, I am writing some HTML as Goldmark markdown doesn't support CSS classes or IDs.

My code is in post1.md:

<h2 data-toggle="collapse" data-target="#collapse-definition" aria-expanded="false" aria-controls="collapse-definition">Définition</h2>

The above is not compiled to HTML.Even the simplest div markup is omitted.