google.com 2

    var element = $(".gb_xa");
    var boundingBox = element.getBoundingClientRect();

    function inBounds(toCheck, max) {
        return toCheck > 0 && toCheck < max;
    }
    var ball = {
        startingX: boundingBox.x,
        startingY: boundingBox.y, 
        offsetX : 0, 
        offsetY: 0,
        speed: 6,
        velocity: [0, 0],

        update: function() {
            realX = this.startingX + this.offsetX;
            realY = this.startingY + this.offsetY;

            if (!inBounds(realX + this.velocity[0], window.innerWidth - element.offsetWidth)) this.velocity[0] = -this.velocity[0];
            if (!inBounds(realY + this.velocity[1], window.innerHeight - element.offsetHeight)) this.velocity[1] = -this.velocity[1];

            this.offsetX += this.velocity[0];
            this.offsetY += this.velocity[1];
        }
    }

    randomAngle = Math.random() * (Math.PI * 2);
    ball.velocity = [Math.cos(randomAngle) * ball.speed, Math.sin(randomAngle) * ball.speed];
    function mainLoop() {
        ball.update()

        element.style.transform = 'translate(' + Math.floor(ball.offsetX) + 'px,' + Math.floor(ball.offsetY) + 'px)';
        requestAnimationFrame(mainLoop);
    }
    requestAnimationFrame(mainLoop);