HTML Guides for tabs

The W3C validator raises this error because ARIA roles must be compatible with the element they are applied to. A <ul> element has an implicit ARIA role of list, and overriding it with tabpanel creates a conflict. The tabpanel role signals to assistive technologies that the element is a panel of content activated by a corresponding tab. When this role is placed on a <ul>, screen readers lose the semantic meaning of the list (item count, list navigation, etc.) while also misrepresenting the element’s function in the tab interface.

This matters for several reasons:

• Accessibility: Screen reader users rely on correct roles to navigate and understand page structure. A <ul> marked as tabpanel confuses both its list semantics and its role in the tab interface.
• Standards compliance: The ARIA in HTML specification defines which roles are allowed on which elements. The tabpanel role is not permitted on <ul>.
• Browser behavior: Browsers may handle conflicting roles inconsistently, leading to unpredictable behavior across assistive technologies.

The fix is straightforward: wrap the <ul> inside a proper container element (like a <div> or <section>) and apply the tabpanel role to that container instead.

Examples

Incorrect: tabpanel role on a <ul>

This triggers the validation error because tabpanel is not a valid role for <ul>:

<div role="tablist" aria-label="Recipe categories">
  <button role="tab" aria-controls="panel-1" aria-selected="true" id="tab-1">Appetizers</button>
  <button role="tab" aria-controls="panel-2" aria-selected="false" id="tab-2">Desserts</button>
</div>

<ul role="tabpanel" id="panel-1" aria-labelledby="tab-1">
  <li>Bruschetta</li>
  <li>Spring rolls</li>
</ul>

<ul role="tabpanel" id="panel-2" aria-labelledby="tab-2" hidden>
  <li>Tiramisu</li>
  <li>Cheesecake</li>
</ul>

Correct: tabpanel role on a container wrapping the <ul>

Move the tabpanel role to a <div> and nest the <ul> inside it. This preserves both the tab panel semantics and the list semantics:

<div role="tablist" aria-label="Recipe categories">
  <button role="tab" aria-controls="panel-1" aria-selected="true" id="tab-1">Appetizers</button>
  <button role="tab" aria-controls="panel-2" aria-selected="false" id="tab-2">Desserts</button>
</div>

<div role="tabpanel" id="panel-1" aria-labelledby="tab-1">
  <ul>
    <li>Bruschetta</li>
    <li>Spring rolls</li>
  </ul>
</div>

<div role="tabpanel" id="panel-2" aria-labelledby="tab-2" hidden>
  <ul>
    <li>Tiramisu</li>
    <li>Cheesecake</li>
  </ul>
</div>

Correct: Using <section> as the tab panel

A <section> element also works well as a tab panel container, especially when the panel content is more complex:

<div role="tablist" aria-label="Project info">
  <button role="tab" aria-controls="tasks-panel" aria-selected="true" id="tasks-tab">Tasks</button>
  <button role="tab" aria-controls="notes-panel" aria-selected="false" id="notes-tab">Notes</button>
</div>

<section role="tabpanel" id="tasks-panel" aria-labelledby="tasks-tab">
  <h2>Current tasks</h2>
  <ul>
    <li>Review pull requests</li>
    <li>Update documentation</li>
  </ul>
</section>

<section role="tabpanel" id="notes-panel" aria-labelledby="notes-tab" hidden>
  <h2>Meeting notes</h2>
  <p>Discussed project timeline and milestones.</p>
</section>

In a properly structured tabbed interface:

• The tablist role goes on the container that holds the tab buttons.
• Each tab trigger gets role="tab" with aria-controls pointing to its panel’s id.
• Each content panel gets role="tabpanel" on a generic container like <div> or <section>, with aria-labelledby referencing the corresponding tab’s id.
• List elements like <ul> and <ol> should remain inside the panel as regular content, retaining their native list semantics.