How to customize the loading splash screen?

[Don]

Introducing Discourse Splash - A visual preloader displayed while site assets load

The splash lives in a different CSS scope, so sadly, you won’t be able to modify the CSS via themes. That said, we do have planned improvements, and I started with this one. Once the change is live on your site, the splash dots will use the colors from your current theme.

I think the point of splash screen is load it before and while every other assets. So now if you create a custom css to modify it it will only load ~after splash screen.