html-details-element.md

The <details> element

The HTML details element represents a disclosure widget. It can also be used as a part of an accordion widget. The user experience more consistent, and generally better, in a number of areas:

• keyboard shortcuts and focus handling,
• exposure via ARIA to assistive technology, and
• integration with browser features such as find-in-page.

Exclusive Accordion:

<details name="my-accordion">
  <summary>Summary 1</summary>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit.</p>
</details>

<details name="my-accordion" open>
  <summary>Summary 2</summary>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit.</p>
</details>

The <details> elements that are part of an exclusive accordion don't necessarily need to be siblings. They can be scattered across the document.

• 2025-03-07 — Creating Animated Accordions with the Details Element and Modern CSS
• 2024-09-25 — Open & Close Transitions with <details>
• 2024-07-15 — Animated exclusive accordions with CSS
• 2024-07-08 — Comeau tweet on <details>: "🔥 It feels like magic"
• 2024-06-11 — More options for styling <details>
  • CodePen: Half opened disclosure widget
• Real-World sidebar build with <dialog>/<details>
• #9951 — ::details-content vs details::part(content) - Exposing the shadow tree could lead to UAs being restricted in how they can change the component in the future
• #9879 — Improve styling of <details>/<summary> elements

details::details-content {
  --open-close-duration: 500ms;
  height: 0;
  overflow: hidden;
  transition: height var(--open-close-duration), content-visibility var(--open-close-duration) allow-discrete;
}

details[open]::details-content {
  height: calc-size(max-content);
}

Accessibility

• Disallow interactive content in <summary>
• Mapping <summary> to Accessibility APIs
  • headings are allowed but UA implementations vary.