function op() {
document.getElementById("con").style.visibility="visible";
document.getElementById("con").style.opacity=((document.getElementById("con").style.opacity*100)+5)/100;
t=setTimeout("op()",70);
}

function st() {
document.getElementById("con").style.opacity=0.01;
document.getElementById("con").style.visibility="hidden";
if(t) clearTimeout(t);}