Login page looks bad when narrow

[mofojed]

Description
The pre-shared-key login page looks really bad when it's narrow.

Steps to reproduce

1. Start up Deephaven with pre-shared key auth
2. Open the Web UI without entering a token
3. Resize the window to be very narrow

Expected results
3. Login page should resize gracefully, and look something like the following where the top and bottom line up:

Actual results
3. The top does not line up correctly with the bottom:

Versions

Engine Version: 0.26.0
Web UI Version: 0.42.0
Java Version: 11.0.19
Barrage Version: 0.6.0