$nav = ob_get_clean();
$nav = preg_replace_callback('{<a href="([^"]+)">(.*?)</a>}', function ($m) {
$request = $_SERVER['REQUEST_URI'];
$nav = ob_get_clean();
$nav = preg_replace_callback('{<a href="([^"]+)">(.*?)</a>}', function ($m) {
$request = $_SERVER['REQUEST_URI'];