Media Query mixin for sass

_media-query.scss

@mixin small-device {
  @media (min-width: #{$small-device}) {
    @content;
  }
}
@mixin mid-device {
  @media (min-width: #{$mid-device}) {
    @content;
  }
}
@mixin big-device {
  @media (min-width: #{$big-device}) {
    @content;
  }
}

_sample_use.scss

p{
  font-size: 30px;
  @include small-device {
    font-size: 35px;
  }
  @include mid-device {
    font-size: 40px;
  }
  @include big-device {
    font-size: 45px;
  }
}