function NachOben () {
 var y = 0;
 if (window.pageYOffset) {y = window.pageYOffset;} 
 else if (document.body && document.body.scrollTop) {y = document.body.scrollTop;}
 
 if (y > 0) {
  window.scrollBy(0, -35)
  setTimeout("NachOben()", 10);
 }
}

function changeText(){
 document.getElementById('up').innerHTML = '<a href="javascript:NachOben()" style="text-decoration: none;" title="Nach oben">Nach oben<\/a>';
}