Just view the source and you will see this javascript:
(function(d) {
var login = d.getElementById('login');
login.addEventListener('submit', function(e) {
e.preventDefault();
if (login.username.value == 'secure' && login.password.value == 'enough') {
location.href = '../level2-secureenough/';
} else {
alert('Sorry, wrong username or password!');
}
});
})(document);
As you may guess, the username is "secure" and the password is "enough".