I've been working on reproducing one of my favorite card games in JavaScript and I'm having some problems getting the 3d rotations to work the way I'd like.   I'm using TweenLite to flip the cards' divs with rotationX and rotationY, but I can't figure out how to tell when I need to swap out the front and back of the card. Is there a way to detect which side of the card is visible?   I've seen it done with CSS like this: http://davidwalsh.name/css-flip, but 'backface-visibility: hidden' doesn