Summary

Super Cool; the Summary element is a reveal box that can be clicked to show additional information to the user. For browsers that don't support the element, it jsut defaults open - which is not a bad fallback.

Summary

Summary

If your browser supports the details element, it should allow you to expand and collapse this text by clicking the triangle.

<details closed>
  <summary>Summary</summary>
  <p>If your browser supports the details element, it should allow
you to expand and collapse this text by clicking the triangle.</p>
</details>