function fixHeight (els) {
// height of viewport
  var y;
  y = Math.max(document.body.scrollHeight, 
               document.body.offsetHeight, 
               document.documentElement.scrollHeight);  
  
  for (var i=0;i<els.length;i++) {
  	eH = els[i].offsetHeight;
	y = Math.max(eH,y);
  }
  
  for (i=0;i<els.length;i++) {
  	els[i].style.height = y + 'px';
  }
}