/**
   * equal height columns
   *
   */
  document.observe('dom:loaded', function() {
    var heights = $$('#center_container, #left_container, #right_container').invoke('getHeight');
    var max_height = heights.sortBy(function(a, b) { return a - b; }).reverse().first();

    if (heights[0] < max_height)
    {
      $('body_container').setStyle({
        height: (max_height - $('header_container').getHeight()) +'px'
      });
    }
  });