Hi there! I understand that the Elfster app on your Mac running OS X 10.15.7 won’t open, while the Elfster website works fine. Let's get this sorted out together.

To better diagnose the problem, could you tell me if you see any error message when you try to open the app, or does it just not respond at all? Also, have you tried any troubleshooting steps already?

Meanwhile, here are some general steps you can take to fix the app issue:

1. Force Quit and Restart the App
- Click the Apple menu → Force Quit, select Elfster if it’s listed, and force quit.
- Try relaunching the app again.

2. Restart Your Mac
- Sometimes a fresh start clears temporary glitches. Please restart your Mac and then try opening Elfster again.

3. Update the Elfster App
- Go to the App Store → Updates tab, and check if there's an update for Elfster. If yes, install it.
- App updates often fix bugs and improve compatibility.

4. Delete and Reinstall the App
- Drag the Elfster app to the Trash to uninstall it.
- Then, reinstall it fresh from the App Store.
- This step clears any corrupted app data.

5. Check for macOS Updates
- Sometimes app compatibility requires the latest OS version.
- Go to System Preferences → Software Update to ensure your OS X 10.15.7 is the latest patch for Catalina.

If after these steps the app still won’t open, it might be a deeper compatibility or account-related issue. At that point, contacting Elfster’s support directly via [email protected] could get you dedicated assistance1.

Let me know if you’d like me to guide you through any of these steps! Are you seeing any messages when you try to open the app?