protected function _findTokens($tokens) {
        $list = [];

        foreach ($tokens as $token) {
            $index = 0;
            while (true) {
                $index = strpos($this->_cssLC, $token, $index);
                if ($index === false) {
                    break;
                }
                $list[] = [
                    'token' => $token,
                    'index' => $index
                ];
                $index ++;
            }
        }

        usort($list, function($a, $b) {
            return $a['index'] - $b['index'];
        });
        return $list;
    }