Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.1)
// Compass (v0.13.alpha.10)
// ----

@mixin class {
  float: left;
  
  > img {
      height: 30px;
  }
}

.nav {
    @media (min-width: 320px) and (max-width: 480px) {
        @include class;
    }
    
    @media (min-width: 320px) and (max-width: 576px) {
        @include class;
    }
}

SassMeister-output.css

@media (min-width: 320px) and (max-width: 480px) {
  .nav {
    float: left;
  }
  .nav > img {
    height: 30px;
  }
}
@media (min-width: 320px) and (max-width: 576px) {
  .nav {
    float: left;
  }
  .nav > img {
    height: 30px;
  }
}