Markdown Dropdown:

How do I dropdown?
This is how you dropdown.

<details>
<summary>How do I dropdown?</summary>
<br>
This is how you dropdown.
</details>

Want to ruin the surprise?
Well, you asked for it!

<details open>
<summary>Want to ruin the surprise?</summary>
<br>
Well, you asked for it!
</details>