Generated by SassMeister.com.

SassMeister-input-HTML.html

<label>foo</label>
<label class="blue">foo</label>

SassMeister-input.scss

// ----
// Sass (v3.4.6)
// Compass (v1.0.1)
// ----

@mixin mymixin
{
    $small-size: 100px;
    $med-size: 200px;

    @media (max-width:500px)
    {
        .my-image
        {
            width: $small-size;
        }
    }

    @media (min-width:501px)
    {
        .my-image
        {
            width: $med-size;
        }
    }
}

.mymixin {
  @include mymixin;
}

SassMeister-output.css

@media (max-width: 500px) {
  .mymixin .my-image {
    width: 100px;
  }
}
@media (min-width: 501px) {
  .mymixin .my-image {
    width: 200px;
  }
}

SassMeister-rendered.html

<label>foo</label>
<label class="blue">foo</label>