sticky script | http://kimsjongin.tumblr.com

<script>
$(function(){ // document ready

  var stickyTop = $('.sticky').offset().top; // returns number

  $(window).scroll(function(){ // scroll event

    var windowTop = $(window).scrollTop(); // returns number

    if (stickyTop < windowTop) {
      $('.sticky').css({ position: 'fixed', top: 0 });
    }
    else {
      $('.sticky').css('position','static');
    }

  });

});
</script>