function toggleDiv(elementId){
    document.getElementById(elementId).style.display = (document.getElementById(elementId).style.display == '') ? 'none' : '';
}
 function changePreview(tabNumber,totalTabs) {
  for (i = 1; i <= totalTabs; i++) {
        document.getElementById('tab-content-sect-' + i).style.display = 'none';
      }
      document.getElementById('tab-content-sect-' + tabNumber).style.display = 'block';
      lis = document.getElementById('tab-content-list').getElementsByTagName('li');
      for (i = 0; i < lis.length; i++) {
        if (lis[i].className == 'active')
          lis[i].className = 'menu';
      }
      document.getElementById('tab' + tabNumber).className = 'active';
      
    }