var scrolling = null;
  
function scroll_up() {
    var d = document.getElementById('inhalt');
    d.scrollTop = d.scrollTop - 10;
    scrolling = window.setTimeout(function() {
   scroll_up();
    }, 100);
}
  
function scroll_down() {
    var d = document.getElementById('inhalt');
    d.scrollTop = d.scrollTop + 10;
    scrolling = window.setTimeout(function() {
   scroll_down();
    }, 100);
}
  
function stop_scroll() {
    window.clearTimeout(scrolling);
}