protected function getStyleCssMedia(array $tag_frag, $test_for_css = true)
    {
        if ($test_for_css && !$this->isStyleTagFragCss($tag_frag)) {
            return ''; // This tag does not contain CSS.
        }
        if (preg_match('/\smedia\s*\=\s*(["\'])(?P<value>.+?)\\1/ui', $tag_frag['style_open_tag'], $_m)) {
            return trim(mb_strtolower($_m['value']));
        } // unset($_m); // Just a little housekeeping.

        return ''; // Unable to find a `media` attribute value.
    }