public function themedCSS($name, $media = null)
    {
        $path = ThemeResourceLoader::inst()->findThemedCSS($name, SSViewer::get_themes());
        if ($path) {
            $this->css($path, $media);
        } else {
            throw new InvalidArgumentException(
                "The css file doesn't exist. Please check if the file $name.css exists in any context or search for "
                . "themedCSS references calling this file in your templates."
            );
        }
    }