function hidediv() {
  if (document.getElementById) { // DOM3 = IE5, NS6
    document.getElementById('postitsch').style.visibility = 'hidden';
  } else {
    if (document.layers) { // Netscape 4
      document.postitsch.visibility = 'hidden';
    } else { // IE 4
      document.all.postitsch.style.visibility = 'hidden';
    }
  }
}

function showdiv() {
  if (document.getElementById) { // DOM3 = IE5, NS6
    document.getElementById('postitsch').style.visibility = 'visible';
  } else {
    if (document.layers) { // Netscape 4
      document.postitsch.visibility = 'visible';
    } else { // IE 4
      document.all.postitsch.style.visibility = 'visible';
    }
  }
}