'', 'ja' => '_jp', 'zh' => '_zh'][$lang];
$h = fn(string $k) => htmlspecialchars(t($k), ENT_QUOTES, 'UTF-8');
// EN serves the shared/iframe flow; JP/ZH serve the localStorage-only flow
// with the red theme. Two real layouts behind one PHP entry point.
$isShared = ($lang === 'en');
$titleKey = $isShared ? 'guestbook.title' : 'guestbook.local_title';
$descKey = $isShared ? 'guestbook.desc' : 'guestbook.local_desc';
$h1Key = $isShared ? 'guestbook.h1' : 'guestbook.local_h1';
$subtitleKey = $isShared ? 'guestbook.subtitle' : 'guestbook.local_subtitle';
?>
<?= $h($titleKey) ?>
$lang, 'title'=>t($titleKey), 'desc'=>t($descKey), 'base'=>'guestbook']; include __DIR__ . '/partials/head_meta.php'; ?>