Last modified: 2014-10-05 07:46:53 UTC
Greg also reproduced this. He sees a superscript, but I have an additional issue, that the beta is roughly the same horizontal position.
Created attachment 13057 [details] Screenshot of beta with overline This is from a few hours ago on enwiki. It is reproducible (try a fresh account on enwiki), almost 100% of the time (one load seemed not to do it).
Firefox-specific rendering bug.
Filed as https://bugzilla.mozilla.org/show_bug.cgi?id=1009874
Seems to be already reported as https://bugzilla.mozilla.org/show_bug.cgi?id=727125
Upstream bug has been marked as fixed since 2014-06-19 15:05:07 (for FF33 - currently in Aurora, which seems to be fixed to me), marking this as fixed as well.
*** Bug 71651 has been marked as a duplicate of this bug. ***