if(document.images) {
 // preload
  ban1 = new Image; ban1.src = "/img/ban1_.gif";
  ban2 = new Image; ban2.src = "/img/ban2_.gif";
  ban3 = new Image; ban3.src = "/img/ban3_.gif";
}

function roll(iName, iPath) {
  document.images[iName].src = iPath;
} 

function aga(){
docwidth=document.body.scrollWidth;
cliwidth=document.body.offsetWidth;
if (docwidth > 1600) {
document.getElementById('ban1').style.posWidth = cliwidth - 21;
}
}