How to nest media in media scss?

Question

Sass

There is a mixin:

@mixin m1199 () {
  @media (min-width: 992px) and (max-width: 1199px) {
    @content;
  }
}

if I write for example:

@include m991 {
  .features{
    background: red !important;
  }
}

@include m991 {
  .header{
    background: red !important;
  }
}

That styles are duplicated. I read in the sass documentation that if a media query is nested inside a media query, they will then be combined with an end statement, I'm not catching up. Maybe the end operator needs to be attached somewhere?

I need this so that I don’t write media rules after each style, but simply insert a mixin at the end of all styles of the finished one, for example _header.scss , and write styles there to make everything clear.