Show warning if user is offline

[simonwep]

Support guidelines

• [X] My request extends the functionality of Ocular in a meaningful way.
• [X] I've used the search and this has not been requested before.

Description

Unti #30 is resolved it'd be nice to show a warning if the user is offline since the app comes with a service-worker that loads the page as usual without having internet access.

Solution

Display a banner or disable the login button.

What are alternatives?

None, it just won't work.

Additional context

No response