(function($) {
  
  var shadow = function() {
    
    $(this)
      .css({position: 'relative'})
      .prepend('<span class="shadow top left"></span>')
      .prepend('<span class="shadow top center"></span>')
      .prepend('<span class="shadow top right"></span>')
      .prepend('<span class="shadow middle left"></span>')
      .prepend('<span class="shadow middle right"></span>')
      .prepend('<span class="shadow bottom left"></span>')
      .prepend('<span class="shadow bottom center"></span>')
      .prepend('<span class="shadow bottom right"></span>');
    
    $(this).children('span.shadow.top.center, span.shadow.bottom.center')
      .css({width: $(this).outerWidth() - 10});
    
    $(this).children('span.shadow.middle.left, span.shadow.middle.right')
      .css({height: $(this).outerHeight() - 10});
    
  };
  
  $.fn.shadow = function() {
    
    this.each(shadow);
    
  };
  
})(jQuery);