iPhone / iPad · Safari
- Open this page in Safari — Apple's browser, not inside another app.
- Tap the Share button — the square with an ↑ arrow (bottom of the screen).
- Scroll down the list and tap Add to Home Screen.
- Tap Add — it lands on your home screen as an app icon.
Then open it once on wi-fi and it keeps working offline afterward — no signal needed.
(Android: open in Chrome, tap ⋮ → Add to Home screen.)