Generated by SassMeister.com. (demonstrating how you *can* use mixins inside of @media blocks, unlike @extends, for @felixjet on #sass)

SassMeister-input-HTML.html

<div class="foo">foo</div>

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.2)
// Compass (v1.0.0.alpha.17)
// ----

@mixin foo {
  color: red;
}

@media all and (min-width: 600px) {
  .bar {
    @include foo;
  }
}

.dave {
  @media screen and (max-width: 320) {
    @include foo;
  }
}

SassMeister-output.css

@media all and (min-width: 600px) {
  .bar {
    color: red;
  }
}
@media screen and (max-width: 320) {
  .dave {
    color: red;
  }
}

SassMeister-rendered.html

<div class="foo">foo</div>