function centerPopUp(){
    var winW = 300, winH = 300;
        if (parseInt(navigator.appVersion)>3) {
            if (navigator.appName=="Netscape") {
                winW = window.innerWidth;
                winH = window.innerHeight;
            }
            
            if (navigator.appName.indexOf("Microsoft")!=-1) {
                winW = document.body.offsetWidth;
                winH = document.body.offsetHeight;
            }
        }
    try {document.getElementById('oferta').style.left = (winW-300) / 2 + 'px';}
    catch(err){}
}

function Esconde(){
    document.getElementById('oferta').style.visibility = "hidden";
}

onload = centerPopUp;
onresize = centerPopUp;
tempo = setTimeout("fecha()", 15000);

function fecha(){
    clearTimeout(tempo);
    try {
    if (document.layers){
        document.oferta.visibility = "hidden";
    }
    if (document.all){
        document.all.oferta.style.visibility = "hidden";
    }
    if (document.getElementById){
        document.getElementById("oferta").style.visibility = "hidden";
    }
    }
    catch(err){}
}