CSS: Flex Box not printing all pages on Firefox

Question

I have a page with a structure similar to this:

Answer 1

Having looked into this for a bit now, I'm still not sure what about Firefox causes printing flex containers to be cut off. I found some extremely old bug reports on Bugzilla (eg. https://bugzilla.mozilla.org/show_bug.cgi?id=258397), but they had something to do with overflow properties on the body tag. Unfortunately, trying to adjust the overflow of body for this does nothing.

I even went to Bootstrap 4's page which uses layouts based on flexbox. Sure enough, attempting to print it on Firefox results in the same issue.

Finally, even display: inline-block has the same effect.

It seems to me that forcing display: block on print is what will ensure Firefox paginates correctly. Ideally, the layout you use for printing will be as simple as possible so that this doesn't become too much of a hindrance. Still, it's very surprising, at least to me.

Perhaps someone with more knowledge can chip in and inform whether this is a legitimate Firefox bug or just a part of their design philosophy.