Make Authentik transparent to improve user experience

[ybizeul]

Is your feature request related to a problem? Please describe.
In it's current implementation, Authentik goes through multiple spinning indicators, page reloads and on screen notification when a user logs in. This slows down the overall user experience and is an unnecessary distration

Describe the solution you'd like
I would like a clear and minimalist design that can be themed.
Note that it's probably already possible through CSS customization, but it is not well documented.

Describe alternatives you've considered
CSS customization, I managed to make it a little bit simpler, but it's more work than I anticipated

Additional context
Authelia, Keycloak, Zitadel all have more lightweight design and better sign in experience for the user.