ueber_pos=20;

function Set_ueber_pos(pos) {
	ueber_pos=ueber_pos - pos;
	if(ueber_pos>20){
		ueber_pos=20;
		document.getElementsByName("down")[0].style.visibility="hidden";
	}
	else{
		document.getElementsByName("down")[0].style.visibility="visible";
	}
	document.getElementById("ueber").style.top=ueber_pos+'px';
}