//Event.onDOMReady(function() {

    var dir = "/site/images/headers/";
    var arr = ["home-1.jpg", "home-2.jpg", "home-3.jpg"];

    // choose random number in range
    function randomNum(low, high) { return Math.floor(Math.random() * (1 + high - low) + low); }

    // choose random array value
    function getRandom() { return arr[randomNum(0, arr.length - 1)]; }

    // get random swf file
    var imgFile = dir + getRandom();

    document.getElementById("header").style.backgroundImage = "url(" + imgFile + ")";

//});