The works fine in Chrome, but on Safari, if you go to me demo site http://wordpress4.stevenkuppers.com, and roll over the LINK button in the first Revolutions Slide, you will see that the hover state creates a residual artifact when you roll off the button. I did some testing and this only happens when the button created is about the size you see in my Demo. If you create the button larger than what is shown in my Demo, the buttons works fine. Screenshot attached.
Seems like a little bug and looking forward for a fix.