arvindang/Sticky header using waypoint plugin

## Sticky header using waypoint plugin
$('#opening, #film, #practical, #conference, #guide')

    .waypoint(function(direction) {
        // sticky header
        $(this).find('> div > header').toggleClass('sticky', direction === 'down');
        // nav .current
        currentNav($(this).attr('id'), direction === 'down');
    })

    .waypoint(function(direction) {
        // nav .current
        currentNav($(this).attr('id'), direction === 'up');
    }, {
        offset: function() {
            return - $(this).outerHeight();
        }
    })
    .waypoint(function(direction) {
        // sticky header
        $(this).find('> div > header').toggleClass('sticky-bottom', direction === 'down');
    }, {
        offset: function() {
            return - $(this).outerHeight() + $(this).find('> div > header').outerHeight();
        }
    });

    $('body > header + section').waypoint(function(direction) {
        $nav.toggleClass('wide', direction === 'down');
    });