Looks good enough to my eyes. It's Microsoft Word, after all. Inconsistent behaviour is basically baked into MS Word.
Interesting issue, though. Another weird one in my list. What happens though, if you export both versions in both browsers to PDF? Are they rendered consistently or does the issue persist?
The fix should be easy as well: Use Word on Chromium or use the desktop app. If you're looking for more sophisticated layouts, I can only recommend either learning a desktop publishing software or trying out LaTeX