function maxHeight() { 
        
  dh = document.documentElement.clientHeight;
  wh = document.documentElement.scrollHeight;
        
  if (dh > wh) {
    $('content').setStyle({
      height: dh - 261 + 'px'
    });
  } else {
    $('content').setStyle({
      height: wh - 261 + 'px'
    });
  }
        
  nh  = $('news').getHeight();
  ch  = $('categories').getHeight();
  cth = $('content').getHeight();
        
  if ((nh + ch) < cth) {
    nh = cth - ch - 20 + 'px';
    $('news').setStyle({
      height: nh
    });
  }   

}

Event.observe(window, 'load',   maxHeight);
Event.observe(window, 'resize', maxHeight);