The site toolbar looks broken in Chrome. How can I fix it?

Since earlier this month, the main toolbar of the site (with links to Questions, Tags, Users, Badges, Unanswered and Ask Question) has changed, distinctly for the worse:

The font looks blocky and ugly, the shaded rectangle is shifted down so that it overlaps with the question titles. This looks amateurish and mostly just wrong.

This issue is present in Chrome but (apparently) not in other browsers. Is this by design, or is it a bug? If so, how can I fix it?

about:flags

It may be necessary to close and reopen Chrome, or to visit chrome://restart on a new tab, to make this work.