<!--
  var pic=new Array();
       pic[0]="/images/header/01.jpg";
       pic[1]="/images/header/02.jpg";
	   pic[2]="/images/header/03.jpg";
	   pic[2]="/images/header/04.jpg";
 
  var num=Math.floor(Math.random()*pic.length);
 
window.onload=function() {
     document.getElementById('header').style.backgroundImage='url('+pic[num]+')';
}
//-->