gistfile1.js

(function($){ 

  $(document).ready(function(){ 

    $('.section-header').each(function(){
      var $this = $(this);
      // use .add() and .nextUntil() to get both the .section-header
      // and .section-item elements into a single set for our .wrapAll() call
      $this.add($this.nextUntil('.section-header', '.section-item'))
        .wrapAll('<div class="section-container"></div>');
    });

  });

})(jQuery);