The Offline Fallback page is displayed when the user performs an action that requires a connection but the device is offline.
You can add an offline fallback page to your PWA and customize it to suit your needs.
- In the App Builder go to Share Components
- Under Globalization click Text Messages
- Click button Create Text message
- Create messages APEX.PWA.OFFLINE.TITLE and APEX.PWA.OFFLINE.BODY
- Add some the content to be rendered on the offline fallback page