function zeige (welche) {
         document.getElementById(welche).style.visibility = 'visible';
         }
function weg (welche) {
         document.getElementById(welche).style.visibility = 'hidden';
         }
function verstecke () {
         document.getElementById('gartenbau_nav').style.visibility = 'hidden';
         document.getElementById('outsource_nav').style.visibility = 'hidden';
}
function versteckegarten () {
         document.getElementById('gartenbau_nav').style.visibility = 'hidden';
}
function versteckeoutsourcing () {
         document.getElementById('outsource_nav').style.visibility = 'hidden';
}