bem.scss

@mixin e($element) {
  @at-root {
    #{&}__#{$element} {
      @content;
    }
  }
}

@mixin m($modifier) {
  @at-root {
    #{&}--#{$modifier} {
      @content;
    }
  }
}

.category-header {
  position: relative;

  @include e(icon){
    position: relative;
    
    @include m(red) {
      color: red;
    }
  }
  
  @include m(red) {
    color: red;
  }
}