function updateHeight() {
var el = document.getElementById('maintext');
if(document.defaultView && document.defaultView.getComputedStyle){ // DOM //;
   obj=top.document.getElementById("maincontent");
   obj.style.height=document.defaultView.getComputedStyle(el, null).getPropertyValue('height', null);
   obj=document.getElementById("content");
   obj.style.height=document.defaultView.getComputedStyle(el, null).getPropertyValue('height', null);
}

else if(document.uniqueID && el.currentStyle){ // IE //;
   obj=top.document.getElementById("maincontent");
   obj.style.height=( ( el.offsetHeight ) + 'px' );
   obj=document.getElementById("content");
   obj.style.height=( ( el.offsetHeight ) + 'px' );
   }

}