Semantic & Interactive

<details> & <summary>

Native disclosure widget — no JavaScript needed.

1Click to Expand

<details> creates an expandable widget. <summary> is the always-visible label. Add the open attribute to start expanded.

Example Code

<details>
  <summary>Read more</summary>
  <p>Hidden content revealed when the user clicks.</p>
</details>

<details open>
  <summary>FAQ: Is this free?</summary>
  <p>Yes — every Instant CSS tool is free to use.</p>
</details>

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<aside> Tag

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<dialog> Modal