#wht-install-app-button {
  position: fixed;
  right: max(16px, env(safe-area-inset-right));
  bottom: max(16px, env(safe-area-inset-bottom));
  z-index: 2147483000;
  display: none;
  align-items: center;
  gap: 8px;
  border: 0;
  border-radius: 999px;
  padding: 11px 16px;
  background: #08745f;
  color: #fff;
  font: 600 14px/1.2 Sarabun, system-ui, sans-serif;
  box-shadow: 0 8px 24px rgba(0,0,0,.22);
  cursor: pointer;
}
#wht-install-app-button:hover { filter: brightness(1.06); }
#wht-install-app-button:active { transform: translateY(1px); }
#wht-install-app-button svg { width: 19px; height: 19px; flex: none; }
#wht-install-app-button.is-visible { display: inline-flex; }

#wht-install-guide {
  position: fixed;
  inset: 0;
  z-index: 2147483640;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: rgba(15,23,42,.55);
  font-family: Sarabun, system-ui, sans-serif;
}
#wht-install-guide.is-visible { display: flex; }
#wht-install-guide-card {
  width: min(420px, 100%);
  border-radius: 18px;
  background: #fff;
  padding: 22px;
  box-shadow: 0 22px 60px rgba(0,0,0,.28);
  color: #17202a;
}
#wht-install-guide-card h3 { margin: 0 0 10px; font-size: 19px; }
#wht-install-guide-card p { margin: 0 0 14px; line-height: 1.65; }
#wht-install-guide-card ol { margin: 0 0 18px; padding-left: 22px; line-height: 1.8; }
#wht-install-guide-close {
  width: 100%; border: 0; border-radius: 10px; padding: 10px 14px;
  background: #08745f; color: #fff; font: 600 14px Sarabun, system-ui, sans-serif; cursor: pointer;
}
@media (max-width: 640px) {
  #wht-install-app-button { right: 12px; bottom: max(12px, env(safe-area-inset-bottom)); padding: 10px 14px; }
}
@media print {
  #wht-install-app-button, #wht-install-guide { display: none !important; }
}