@media all {
  .bar { content: baz; }

  @media (min-width: 1337px) {
    .foo { content: bar; }
  }
}

@media all {
  .bar { content: baz; }

  @media (min-width: 1337px) {
    .baz { content: foo; }

    @media (max-width: 42em) {
      .foo { content: bar; }
    }
  }
}