$(document).ready(function()
{	
	var nav_links = document.getElementById('main_menu').getElementsByTagName('a');
	var selected = location.href;
	
	for (var i = 0; i < nav_links.length; i++) {
		var link = nav_links[i].href;
	
		if (link == selected /*|| link.indexOf(selected) != -1*/)
			$(nav_links[i]).css({textDecoration:'underline'});
	}
});