Use css transition instead of jQuery.animate when available.
.transition() uses the same synthax as the .animate() method:
.transition( properties [, duration] [, easing] [, complete] [, delay] )
properties A map of CSS properties that the animation will move toward.
duration A string or number determining how long the animation will run.
easing A string of CSS3 only easing function || only applied to CSS3 compliant browsers.
complete A function to call once the animation is complete.
delay A string or number determining how long the animation will be delayed.
jQuery('#child').transition({
"left": "200px",
"top": "20px"
},300,"ease-in-out",function(){
//when animation is complete
},20)