This is the achievements drop-down on Ask Ubuntu:
It doesn't look very good. The same happens on Meta SE - so it's a new and old top-bar issue.
Mac OS 10.12.6, Chrome 60.0.3112.113. Also happens in Safari 11.0 and Chrome incognito mode with no extensions, so is not a user-script issue. Zoom at 100%.
Does not happen with Chrome on Windows 10.