Can’t you use <details> tag?

[ldidry]

The <details> tag is designed for the spoiler use case. It would be very simple to use, don’t you think.

Beside that, #15 would be very simple to solve by using <details>.

Example:

See? No spoiler (The text is even translated by the browser!)

<details>
    <p>See? No spoiler (The text is even translated by the browser!)</p>
</details>

Custom text. Click on it!

No spoiler

<details>
  <summary>Custom text. Click on it!</summary>
  <p>No spoiler</p>
</details>