Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.12)
// Compass (v1.0.3)
// ----

//Generator
@mixin theme-generator(
  $post__title: "",
  $post__subtitle: ""
) {
  
  //Use defaults to filter placeholders
  @if $post__title != "" {
    %theme--post__title {
      color: $post__title;
    }
  }

  @if $post__subtitle != "" {
    %theme--post__subtitle {
      color: $post__subtitle;
    }
  }
}

.post__title {
  @extend %theme--post__title !optional;
  color: black;
}

.post__subtitle {
  @extend %theme--post__subtitle !optional;
  color: black;
}

.theme--forest {
  @include theme-generator(
    $post__title: forestgreen,
    $post__subtitle: green
  );
}

.theme--ocean {
  @include theme-generator(
    $post__subtitle: navy
  );
}

SassMeister-output.css

.post__title {
  color: black;
}

.post__subtitle {
  color: black;
}

.theme--forest .post__title {
  color: forestgreen;
}
.theme--forest .post__subtitle {
  color: green;
}

.theme--ocean .post__subtitle {
  color: navy;
}