Similary to "css transform, jagged edges in chrome", same occurs with Firefox on 3D transforms, eg: http://jsfiddle.net/78d8K/5/ (<- remember: Firefox)
This time, backface-visibility
doesn't help :(
Any idea?
Edited answer: (after comments)
"Workaround", add a transparent outline attribute:
outline: 1px solid transparent;
Tested on Firefox 10.0.2 Windows 7: http://jsfiddle.net/nKhr8/
Original answer: (background-color dependent)
"Workaround", add a border attribute with the same color of your background (white this case):
border: 1px solid white;
Tested on Firefox 10.0.2 Windows 7: http://jsfiddle.net/LPEfC/