Update copy of Cantarell served as web font
Damned Lies is still using an ancient, very buggy version of Cantarell as its web font. Please update it to the most recent version, which solves many long-standing issues with diacritics and character coverage.
(Note: Google Fonts also contains the ancient version: just like you did with GNOME’s last Bugzilla reskinning, you’ve got to self-host the files.)