I believe that although javascript is an option here, you have a smoother animation through forcing hardware accelerate with CSS3. You can achieve this by setting the following CSS3 properties on the moving div:
div.hardware-accelarate {
-webkit-transform: translate3d(0,0,0);
-moz-transform: translate3d(0,0,0);
-ms-transform: translate3d(0,0,0);
-o-transform: translate3d(0,0,0);
transform: translate3d(0,0,0);
}
I've made a plunkr setup for ya'll to test and tweak...