You had MarginTop
instead of marginTop
http://jsfiddle.net/kX7b6/1/
It is also very buggy if you leave mid animation, here is update:
http://jsfiddle.net/kX7b6/3/
Note I changed it to mouseenter
and mouseleave
because I don’t think the intention was to cancel the animation when you hover over the red or green area.