function f_clientHeight() {
	return f_filterResults (
		window.innerHeight ? window.innerHeight : 0,
		document.documentElement ? document.documentElement.clientHeight : 0,
		document.body ? document.body.clientHeight : 0
	);
}

function f_filterResults(n_win, n_docel, n_body) {
	var n_result = n_win ? n_win : 0;
	if (n_docel && (!n_result || (n_result > n_docel)))
		n_result = n_docel;
	return n_body && (!n_result || (n_result > n_body)) ? n_body : n_result;
}

setHeight = function(){

     var maxHeight,divHeight,d;

     d = document.getElementById('main_div');

     if(d.offsetHeight){

         divHeight=d.offsetHeight;

     } else if(d.style.pixelHeight) {

         divHeight=d.style.pixelHeight;

     }

     maxHeight = 0;
     maxHeight = (f_clientHeight())-148;
     if ( maxHeight > divHeight) {
	d.style.height = maxHeight;
     }

} 

window.onload=function(){

     if(document.getElementsByTagName){

          setHeight();

     }

}