$(document).ready(function(){ 
    $("ul#main_nav").superfish({ 
        pathClass:  'current',
        hoverClass: 'sfHover',
		delay: '1300'
    });
	$(".what_challenge").click(function(){
		$("#what_challenge_text").dialog('open');
		
	});
	$("#what_challenge_text").dialog({ autoOpen: false, width: '500', title:'Challenge-response Authentication' });
});