Can I make external styles outside of blazor CSS isolation?

Question

I have a website with Header, Main, Footer styles divided into blocks, etc. and it looks something like this:

In Style, I import all this and link it to html (and I use preprocessor)

@import "Core.css"
@import "Header/Header.css"
@import "Main/Main.css"
@import "Footer/Footer.css"
@import "etc and so on"

So I decided to move my site to Blazor and use the separation of styles into blocks on it, it turned out something like this:

It just turned out that all styles are in a static folder, and imports are in isolation of MainLayout.style.

And if connect styles in a static index, then imports in isolation will not be needed.

And now my questions:

1. Is it possible to do this and does it correspond to the Blazor Style Guide?
2. If I can't do this, then how is it better to do this?
3. If I can do this, then how is it better to do this?
4. If I make a MainLayout into a preprocessor that will output css, will it be better than the above options?