// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
window.requestAnimFrame = (function () {
    return window.requestAnimationFrame ||
        window.webkitRequestAnimationFrame ||
        window.mozRequestAnimationFrame ||
        window.oRequestAnimationFrame ||
        window.msRequestAnimationFrame ||
        function (/* function */ callback, /* DOMElement */ element) {
            window.setTimeout(callback, 1000 / 60);
        };
})();