<main>
  <article>
    <h2>Complementary</h2>
    <div>
      <span class="origin"></span>
      <span class="complementary"></span>
    </div>
  </article>
  <article>
    <h2>Triadic</h2>
    <div>
      <span class="triadic-1"></span>
      <span class="origin"></span>
      <span class="triadic-2"></span>
    </div>
  </article>
</main>