function adCheck() { var mitteDiv = document.getElementById('mitte'); var untenDiv = document.getElementById('unten'); var untenDivHeight = untenDiv.offsetHeight; mitteDiv.style.paddingBottom = untenDivHeight + 'px'; untenDiv.style.marginTop = '-' + untenDivHeight + 'px'; if (untenDivHeight > 91) { document.body.className = 'anzeigen_act'; }; }