code: function rules() {
      var node;
      var rules = [];
      whitespace();
      comments(rules);
      while (css.length && css.charAt(0) != '}' && (node = atrule() || rule())) {
        if (node !== false) {
          rules.push(node);
          comments(rules);
        }
      }
      return rules;
    }
docs: Parse ruleset.