$(document).ready(function() {
    $('.cta-btn, .portf1, .portf2, .portf3, .portf4, .portf5, .btn-facebook, .btn-twitter, .btn-linkedin, .btn-studiofacebook, .btn-studiotwitter,.btn-studiolinkedin,.newsitem1, .newsitem2, .newsitem3').append('<span class="hover"></span>').each(function () {
        var $span = $('> span.hover', this).css('opacity', 0);
        $(this).hover(function () {
            $span.stop().fadeTo(200, 1);
        }, function () {
    $span.stop().fadeTo(400, 0);
        });
    });
});

$(function(){
     var stickyHeaderTop = $('#stickyheader').offset().top;

     $(window).scroll(function(){
             if( $(window).scrollTop() > stickyHeaderTop ) {
                     $('#stickyheader').css({position: 'fixed', top: '0px'});
                     $('#stickyalias').css('display', 'block');
             } else {
                     $('#stickyheader').css({position: 'static', top: '0px'});
                     $('#stickyalias').css('display', 'none');
             }
       });
});

<!-- portfolio -->
<div id="portfoliowrapper">
<div id="portfolioitems"></div>
<script>$("#portfolioitems").load("werk.html #portfolio");</script>
<div class="clear"></div>
<a href="werk.html" class="cta-btn"><h2 class="btn">Werk</h2></a>
</div>

$(function(){
   // code that depends on images being loaded here
});

$(window).load(function(){
   // here all images in the HTML are guaranteed to be loaded
});

$("#portfolio").offset() is null
Line 33