Must be a svg display bug .(i didn't look at the code ). Does the firebug inspector show some details ?
In console, I don't have errors for this.
In that new browser for Windows 10( i don't know it's name) it shows fine. EDIT: Microsoft edge
In internet explorer it looks like this:
EDIT 2
In Ubuntu with firefox, chromium and opera it looks ok.
EDIT 3.
I think this is happening on all windows 10 with this version of firefox.