function ChangeCSSBgImg() {
if (!document.getElementById) return false;

var MyElement = "siteUst"
var ImgPath = "http://www.fantezikgiyim.com/style/img/"

if (!document.getElementById(MyElement)) return false;
var random_images = new Array ();
random_images[0] = "header_bg_1.jpg";
random_images[1] = "header_bg_2.jpg";
random_images[2] = "header_bg_3.jpg";
var $header = document.getElementById(MyElement);
var $backgroundurl = $header.style.backgroundImage;
var ImgURL = "url(" + ImgPath + random_images[rand(random_images.length)] + ")";
if ($backgroundurl != ImgURL) {
$header.style.backgroundImage = ImgURL;	
}

movement = setTimeout("ChangeCSSBgImg()",7000);
}
function rand(n) {
    return ( Math.floor ( Math.random ( ) * n ) );
}

function addLoadEvent(func) {
    var oldonload = window.onload;
        if (typeof window.onload != 'function') {
        window.onload = func;
        } else {
        window.onload = function() {
    oldonload();
func();
}
}
}
addLoadEvent(ChangeCSSBgImg);