$text: blue;
$accent: green;

.article {
  &__title {
    color: $accent;
  }

  // Applies margin only, when .article__title is present
  &__title + &__text {
    margin-top: 15px;
  }

  &__text {
    color: $text;
  }
}


/* compiled css */
.article__title {
  color: green;
}
.article__title + .article__text {
  margin-top: 15px;
}
.article__text {
  color: blue;
}