# File lib/nokogiri/xml/node_set.rb, line 90
      def css *paths
        ns = paths.last.is_a?(Hash) ? paths.pop :
          (document.root ? document.root.namespaces : {})

        sub_set = NodeSet.new(document)

        xpaths = paths.map { |rule|
          [
            CSS.xpath_for(rule.to_s, :prefix => ".//", :ns => ns),
            CSS.xpath_for(rule.to_s, :prefix => "self::", :ns => ns)
          ].join(' | ')
        }
        each do |node|
          sub_set += node.xpath(*(xpaths + [ns]))
        end
        document.decorate(sub_set)
        sub_set
      end