window.onload = function() {
	
	var sidebarheight = document.getElementById('sidebar').offsetHeight;
	var mainheight = document.getElementById('main').offsetHeight;
	
	if( mainheight < sidebarheight ) {
		var sidebarheight = sidebarheight - 2;
		document.getElementById('main').style.height = (sidebarheight + "px");
	}
	
};