MatthiasMullie\Minify\CSS::moveImportsToTop PHP Метод

    protected function moveImportsToTop($content)
    {
        if (preg_match_all('/@import[^;]+;/', $content, $matches)) {
            // remove from content
            foreach ($matches[0] as $import) {
                $content = str_replace($import, '', $content);
            }
            // add to top
            $content = implode('', $matches[0]) . $content;
        }
        return $content;
    }