public function config($key, $default = null)
    {
        if (Str::contains($key, '::')) {
            list($theme, $config) = explode('::', $key);
        } else {
            $theme = $this->getCurrent();
            $config = $key;
        }

        $theme = $this->find($theme);

        return $theme ? $theme->config($config) : $default;
    }