<===> input.scss
@media (min-width: 1px) {
  .first {
    font-weight: 100;

    @media (min-width: 2px) {}
  }
  .second {
    font-weight: 200;
  }
}

<===> output.css
@media (min-width: 1px) {
  .first {
    font-weight: 100;
  }
  .second {
    font-weight: 200;
  }
}