gistfile1.txt

pmf.LockingHeader = Backbone.View.extend({
    initialize: function() {
        _.bindAll(this, 'on_page_scroll');
        $(window).scroll(this.on_page_scroll);        
    },

    on_page_scroll: function() {
        var t = document.getElementById('nav-boundary').getBoundingClientRect().top;
        var nav = this.$el.find('#horizontal-nav');
        if(t < 0) {
            if(!nav.hasClass('fixed')){
                nav.addClass('fixed');
                nav.find('#sections a').addClass('change');
                nav.find('#horizontal-logo').stop().fadeIn(300);
                nav.find('.social').addClass('purple');
            }
        } else {
            nav.removeClass('fixed');
            nav.find('#sections a').removeClass('change');
            nav.find('#horizontal-logo').stop().fadeOut(50);
            nav.find('.social').removeClass('purple');
        }
    }
});