function showPopup() {
 var winW = 1024;
 var popup_width = 800;

 if (parseInt(navigator.appVersion)>3) {
  if (navigator.appName=="Netscape") {
	winW = window.innerWidth;
  }
  if (navigator.appName.indexOf("Microsoft")!=-1) {
	winW = document.body.offsetWidth;
  }
 }
 var popup = document.getElementById("popup_layer");
 popup.style.visibility = "visible";
}

function hidePopup() {
 var popup = document.getElementById("popup_layer");
 popup.style.visibility = "hidden";
}