protected function _filterCssFile($fileName)
    {
        try {
            //pobranie kontentu
            $content = file_get_contents(BASE_PATH . '/web/' . $fileName);
        } catch (\Exception $e) {
            return '/* CSS file not found: ' . $fileName . ' */';
        }
        //lokalizacja zasobów z uwzględnieniem baseUrl
        $location = $this->view->baseUrl . '/' . trim(dirname($fileName), '/') . '/';
        //usuwanie nowych linii i tabów
        return preg_replace(['/\r\n/', '/\n/', '/\t/'], '', str_replace(['url(\'', 'url("'], ['url(\'' . $location, 'url("' . $location], $content));
    }