function nav_size(){
	var left_nav_end = find_position_top(document.getElementById('left_nav_bottom'));
	var footer_begin = find_position_top(document.getElementById('sub_nav'));
	if(left_nav_end < footer_begin){ document.getElementById('left_nav_bottom').style.height = (parseInt(document.body.offsetHeight) - parseInt(left_nav_end) + 10)+'px'; }
}

function find_position_top(obj) {
	var curtop = 0;
	if(obj.offsetParent){
		curtop = obj.offsetTop
		while (obj = obj.offsetParent){
			curtop += obj.offsetTop
		}
	}
	
	return (curtop);
}