code: function inject_stylesheet_shim () {
        if (options.include_css) {
          var style_tag = '<link rel="stylesheet" type="text/css" href="' + options.include_css + '">';
          if (options.css_insert_marker && html.indexOf(options.css_insert_marker) !== -1) {
            html = html.replace(options.css_insert_marker, style_tag);
          }
          else {
            var shims = ["</head>", "<body>", "</html>"];
            inject(style_tag, shims);
          }
        }
      }
docs: Inject a style tag pointed at the minified CSS. Attempt to insert the shim before the closing head tag.