protected function fontsUrl($fonts): string
    {
        $font_families = \array_keys($fonts);

        $query_args = [
            'family' => \rawurlencode(\implode('|', $font_families)),
            'subset' => \rawurlencode('latin,latin-ext'),
        ];

        return \add_query_arg($query_args, 'https://fonts.googleapis.com/css');
    }