Info popup css problem

Hello!
What a wonderful plugin! Everything works perfectly, except for one little thing…
…The tip of the info popup bubble have fallen off and are stuck a bit below where it is supposed to be.
It looks like this (in Firefox 40.0, OS X):
https://dl.dropboxusercontent.com/u/15071513/maptip.jpg (screen capture)
http://uppsalamagicandcomedy.se/scener/ (live example).

I obviously have some kind of CSS conflict going on, but I can’t for my life figure out what might be the cause, even less how to fix it.

Any advise would be greatly appreciated!
-Tom

https://ww.wp.xz.cn/plugins/pronamic-google-maps/