- return [200, ['Content-Type' => 'text/html', 'Content-Language' => $lang, 'Vary' => 'Accept-Language'], [$html] ]
+ return [200, ['Content-Type' => 'text/html', 'Content-Language' => $lang, 'Vary' => 'Accept-Language', 'X-Forever' => 1, 'Cache-Control' => 'max-age=300'], [$html] ]