// JavaScript Document
function calcHeight()
{
  
  //find the height of the internal page
  var the_height=document.getElementById('textual').offsetHeight;
   
	if(the_height<500){
		the_height=500;
	document.getElementById('navigation').style.height=the_height-30+"px"; 
	
  }
  document.getElementById('textual').style.height=the_height-30+"px";
	
  document.getElementById('sidebar').style.height=the_height-30+"px";
  	document.getElementById('navigation').style.height=the_height-30+"px"; 
	
}