function toggle(id) {
  var e = document.getElementById(id)
	e.style.display = (e.style.display != 'none' ? 'none' : '' );
}
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("popup_layer");
    popup.style.visibility = "hidden";
}