code: public static Element selectFirst(String cssQuery, Element root) {
          Validate.notEmpty(cssQuery);
          return Collector.findFirst(QueryParser.parse(cssQuery), root);
      }
docs: Find the first element that matches the query.
  @param cssQuery CSS selector
  @param root root element to descend into
  @return the matching element, or <b>null</b> if none.