function clearContainer() {
  if (!document.getElementsByTagName) return;
  var container = document.getElementById('container');
  var leftcolumn = document.getElementById('leftcolumn');
  if (!container)
    alert("Couldn't find container");
  if (!leftcolumn)
    alert("Couldn't find leftcolumn");
  
  var lowestLeftcolumnPixel = leftcolumn.offsetHeight + leftcolumn.offsetTop;
  if (lowestLeftcolumnPixel > container.offsetHeight)
    container.style.height = lowestLeftcolumnPixel + 'px';
}