$(window).on('scroll', function() {

        var y = $(window).scrollTop(),
            siteHeader = $('header'),
            siteLogo = siteHeader.find('.logo'),
            triggerHeight = siteHeader.innerHeight();

       if (y > triggerHeight) {
          siteLogo.fadeOut();
       }
      else {
         siteLogo.fadeIn();
      }

    });