var intId = 0;
function showBody() {
    document.getElementById('hidden').style.visibility = "hidden";
}
function reduceopacity() {
    var x = document.getElementById('hidden').style.opacity;
    if(x <= 0.10) {
        showBody();
    }
    if(x <= 0) {
        clearInterval(intId);
    }
    document.getElementById('hidden').style.opacity -= 0.20;
}
function fade() {
    intId = setInterval("reduceopacity()", 100);
}
function setopacity(op) {
    document.getElementById('hidden').style.opacity = op;
}