Signin on mastodon shows empty field

[dingens]

After clicking "sign in with mastodon", an empty form field is displayed. It is completely unclear that one is supposed to enter the server domain there.

(When one submits with the field empty, you get an error message saying "Invalid URL host", which makes it somewhat clear, so it's not a horrible bug, but still it's very bad UX :) )

Bonus: Some link saying "I don't have an account yet". It could point to joinmastodon.org, for example.