// randomise main background

var bgnds=new Array('../images/bg4.jpg', '../images/bg5.jpg', '../images/bg6.jpg', '../images/bg8.jpg', '../images/bg9.jpg', '../images/bg10.jpg');

function randbg()
{
      var mainbg=document.getElementById('main');
      var bgimg="url("+bgnds[Math.floor(Math.random()*6)]+")";
      main.style.backgroundImage=bgimg;
}