// ----
// libsass (v3.2.5)
// ----

@mixin typog--one-word-header() {
  font-size: 100px;
  font-weight: 800;
  color: #fff; // default
  @content;
}

// Now let's apply default
.thingy {
  @include typog--one-word-header();
}
.thingy--black {
  @include typog--one-word-header() {
    color: #000;
  }
}