he particle
    var domNode = document.createElement('span');
    document.body.appendChild(domNode);

    // Set initial position to middle of screen
    domNode.style.left = x + "px";
    domNode.style.top = y + "px";

    // Set colour of element
    domNode.style.backgroundColor = colors[Math.floor(PerfTestHelper.random() * colors.length)];

    domNode.style.webkitTransitionProperty = 'left, top, width, height, color, background, -webkit-mask, -webkit-transform, border, bottom, clip, fill, fill-opacity