Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.4)
// Compass (v1.0.1)
// ----

@mixin media($queryString){
    @media #{$queryString} {
      @content;
    }
}

.container {
    width: 900px;
    @include media("(max-width: 767px)"){
        width: 100%;
    }
}

SassMeister-output.css

.container {
  width: 900px;
}
@media (max-width: 767px) {
  .container {
    width: 100%;
  }
}