H1/H2/H3 Subtitles

I want to be able to add a subtitle or description to an H tag that’s still visible when it’s collapsed.

Currently, if I have a list of H1 items that are collapsed with content underneath, the page is real bland and clunky looking, and because everything under it disappears when I collapse it, there’s no place to add additional information explaining what’s in that section:

This is something closer to what I’d like to be able to do:

This seems like a small thing, but it would make a huge difference in SOP documents (i.e., this step is for this scenario, only look at this in this circumstance).