Sass doesn't support importing css files?

Question

css

Nothing in the docs about this.
But there are a lot of comments on the github that this is needed, but there is not a single answer that this is implemented.
On Habré I found a comment that already exists -

@import "CSS:../../bower_components/normalize.css/normalize.css";

But doesn't work, gulp-sass error:

Error: src/style/libs.scss
3:1 invalid top-level expression

UPD.
Both the variant above and the variant Andrey B. work . The problem was in the multi-line comment - did not pay attention to it.

Answer 1

@import "filename";

Answer 2

You need to rename .css to .scss.
And remove this:
CSS: