function aufklappen(welches){
var vis = welches
if (vis == "pro1")
{
if (isNaN(document.getElementById("pro2"))){window.document.getElementById("pro2").style.visibility="hidden";}
if (isNaN(document.getElementById("pro3"))){window.document.getElementById("pro3").style.visibility="hidden";}
window.document.getElementById("pro1").style.visibility="visible";
}
if (vis == "pro2")
{
if (isNaN(document.getElementById("pro1"))){window.document.getElementById("pro1").style.visibility="hidden";}
if (isNaN(document.getElementById("pro3"))){window.document.getElementById("pro3").style.visibility="hidden";}
window.document.getElementById("pro2").style.visibility="visible";
}
if (vis == "pro3")
{
if (isNaN(document.getElementById("pro1"))){window.document.getElementById("pro1").style.visibility="hidden";}
if (isNaN(document.getElementById("pro2"))){window.document.getElementById("pro2").style.visibility="hidden";}
window.document.getElementById("pro3").style.visibility="visible";
}
}