About CSS Accordion Builder

Build a zero-JS accordion using <details>/<summary> + CSS animation. Part of the DevTools Surf developer suite. Browse more tools in the CSS collection.

Use Cases

• Frontend developers building FAQ sections without JavaScript dependencies
• Content editors creating collapsible documentation sections
• UI designers prototyping accordion styles for settings and preference panels
• Accessibility engineers ensuring accordions work with screen readers natively

Tips

• Uses native HTML details/summary elements for zero-JavaScript interactivity
• Customize the open/close animation timing and easing curve
• Style the summary marker to match your design system's icon set

Fun Facts

• The HTML <details> and <summary> elements were first specified in HTML5 (2014) and provide built-in disclosure widgets without any JavaScript — but CSS animation support came later.
• Before <details>/<summary>, accordion UIs required JavaScript event listeners and DOM manipulation — jQuery UI's Accordion widget (2007) was the de facto solution for over a decade.
• Animating the <details> element's content height is still tricky in 2024 because content inside goes from display:none to block — CSS interpolate-size may finally solve this.

FAQ

How does a zero-JS accordion work?

HTML's <details>/<summary> elements. They open/close natively; CSS adds the animation and style. No JavaScript needed for the basic behavior.

Can I animate the open/close?

Yes — modern browsers support animating grid-template-rows or max-height for the smooth reveal. The tool generates the keyframes for you.

Is it accessible?

Native <details> has proper ARIA semantics built in (aria-expanded, role=group). No extra attributes needed for screen readers to announce it correctly.

What about controlling which panels are open?

Group multiple <details> with a shared `name` attribute to get radio-like behavior (only one open at a time). Without `name` they operate independently.