function showPopup() {
             var winW = 1024;
             var popup_width = 401;

             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.left = Math.round((winW-popup_width)/2)  + "px";
             popup.style.visibility = "visible";
          }
          function hidePopup() {
             var popup = document.getElementById("pop_up");
             popup.style.visibility = "hidden";
             popup.style.display = "none";
          }