public static function saveConfig($theme_name)
    {
        if (!$theme_name) {
            return false;
        }

        $grav = Grav::instance();
        $locator = $grav['locator'];
        $filename = 'config://themes/' . $theme_name . '.yaml';
        $file = YamlFile::instance($locator->findResource($filename, true, true));
        $content = $grav['config']->get('themes.' . $theme_name);
        $file->save($content);
        $file->free();

        return true;
    }