This bug has been acknowledged by Mozilla. The fix is to add transform: rotateX(0deg) to the front and back objects. Adding backface-visiblity:hidden on the container, as suggested by @yalia, makes the back unresponsive in Chrome, hence that fix should be avoided. Here’s a fiddle with the fix.
Sadly, you really can’t transition gradients for now. So, the only workable workaround is using an extra element with needed gradient and transition it’s opacity: a.button { position: relative; z-index: 9; display: inline-block; padding: 0 10px; background: -webkit-gradient(linear, 0 0, 0 100%, from(green), to(#a5c956)); background: -webkit-linear-gradient(top, green, #a5c956); background: -moz-linear-gradient(top, green, #a5c956); background: -o-linear-gradient(top, green, … Read more