function openPopupCart(url)
{
var w = 680, h = 440;
if (document.all || document.layers) {
   w = screen.availWidth;
   h = screen.availHeight;
}

var popW = 300, popH = 200;

var leftPos = (w-popW), topPos = (h-popH);

window.open(url,'popup','width=600,height=400,scrollbars=yes,resizable=yes,top=' + topPos + ',left=' + leftPos +',screenX='+w+',screenY='+h);


}