// JavaScript Document
if (document.getElementById) { window.onload = swap };
function swap() {
var numimages=13;
rndimg = new Array("header/1.jpg", "header/2.jpg", "header/3.jpg", "header/4.jpg", "header/5.jpg", "header/6.jpg", "header/7.jpg", "header/8.jpg", "header/9.jpg", "header/10.jpg", "header/11.jpg", "header/12.jpg", "header/13.jpg"); 
x=(Math.floor(Math.random()*numimages));
randomimage=(rndimg[x]);
document.getElementById("logo_container").style.backgroundImage = "url("+ randomimage +")"; 
}