var speed=5;
var moveupvar;
var movedownvar;
var content_obj;
var content_height;

function move_up(){
if(parseInt(content_obj.style.top)<=0)
 {
  content_obj.style.top=parseInt(content_obj.style.top)+speed+"px";
 }
if(parseInt(content_obj.style.top)>0)
 {
  content_obj.style.top="0px";
 }
moveupvar=setTimeout("move_up()",20);
}

function move_down(){
if(parseInt(content_obj.style.top)>=(content_height*(-1)+200))
 {
  content_obj.style.top=parseInt(content_obj.style.top)-speed+"px";
 }
if(parseInt(content_obj.style.top)<(content_height*(-1)+200))
 {
  content_obj.style.top=(content_height*(-1)+200)+"px";
 }
movedownvar=setTimeout("move_down()",20);
}

function get_height(){
 content_obj=document.getElementById("inhalt");
 content_height=content_obj.offsetHeight;
}