We have a few tables using them (e.g. https://developer-new.mozilla.org/en-US/docs/CSS/CSS3 ) They look completely borked right now. Github PR done.
Another page that shows the problem: https://developer-new.mozilla.org/en-US/docs/CSS/display (I add it so that I don't forget to fix it once possible ;-) )
The PR has been pushed to developer-new and both pages are looking ok now. I think we can mark this bug as fixed.