function closemenu(name) {
  if(document.getElementById("submenu_" + name)) {
    document.getElementById("submenu_" + name).style.visibility = "hidden";
  }
}

function openmenu(name) {
  var myarray = new Array('Verantwortung', 'Leistungen','Über MLL','Kontakt','Impressum', 'Responsibility', 'Services', 'About MLL', 'Contact', 'Imprint');
  for(i = 0; i < myarray.length; i++) {
    if(myarray[i] != name) {
      closemenu(myarray[i]);
    }
  }
  if(document.getElementById("submenu_" + name)) {
    document.getElementById("submenu_" + name).style.visibility = "visible";
  }
}