Since the theme settings in future versions will only be known after a user has been authenticated, the design of the loading screen (splash screen) should no longer depend on the theme settings of the admin user.
Styles have been updated for the upcoming release, see:
Related issues:
Screenshot with JS disabled so that a hint is displayed at the bottom:

Since the theme settings in future versions will only be known after a user has been authenticated, the design of the loading screen (splash screen) should no longer depend on the theme settings of the admin user.
Styles have been updated for the upcoming release, see:
Related issues:
Screenshot with JS disabled so that a hint is displayed at the bottom: