$(function showPopup() {
  var winW = 1024;
  var popup_width = 400;

  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("popup-layer");
 popup.style.visibility = "hidden";
}