SuperBanner

Props

• label: string (optional) -- accessible label for the super banner
• dismissable: boolean (default: false) -- whether the banner can be dismissed
• ondismiss: callback (optional) -- handler called when banner is dismissed
• children: slot (required) -- banner content
• ...restProps: Any additional HTML attributes

Keyboard Interactions

• Tab: Focus the dismiss button (if dismissable)
• Enter/Space: Dismiss the banner (if dismissable)

ARIA

• role="alert" -- announces the banner content immediately to screen readers
• aria-live="assertive" -- interrupts current speech for high-priority messages
• aria-label -- optional description of the banner purpose

When to Use

• Use to communicate a high-priority state that affects the entire application, such as a system outage or emergency alert
• Use for global maintenance notices that must be visible on every page
• Use when the message requires immediate attention and cannot be missed, such as a security incident or data breach notification
• Use for regulatory or legal notices that must interrupt the user experience until acknowledged

When Not to Use

• Do not use for page-specific messages -- use Banner instead
• Do not use for form validation errors -- use ErrorSummary to summarize field errors
• Do not use for success confirmations -- use Banner with a success variant or Alert
• Do not use for routine notifications -- use Notification or Toast for transient messages

Headless

This component provides a <div> with role="alert" and aria-live="assertive" for immediate screen reader announcements, with zero visual styling. The consumer is responsible for all CSS including background color, text color, positioning, dismiss button, and responsive behavior.

Styles

The consumer provides all CSS styling. The component renders with a .super-banner class for targeting. No default styles are included -- this is a fully headless component.

Testing

• Verify the component renders a <div> element with class super-banner
• Verify role="alert" is present
• Verify aria-live="assertive" is present
• Verify dismiss functionality works when dismissable
• Verify pass-through attributes are applied

Advice

• Designers: Use bold, high-contrast colors to distinguish super banners from regular content. Keep the message concise and actionable. Position at the very top of the viewport.
• Developers: Use role="alert" for critical messages that need immediate attention. Provide a dismiss mechanism for non-persistent messages.

Implementation Notes

• Uses <div> element with role="alert" for immediate screen reader announcement
• aria-live="assertive" interrupts current speech to announce the message
• Positioned at the top of the page above all other content
• May include a dismiss button for user-dismissable banners

Related components

• announcement-banner — a banner highlighting important messages for all users
• banner — a prominent message bar across the top of a page
• banner-box — a banner box that is inside a banner component, using flexbox horizontal
• government-banner — a banner identifying a website as belonging to a government, with an expandable details panel
• medical-banner — a prominent message bar across the top of a page, with medical information
• medical-banner-box — a medical banner box that is inside a medical-banner component, using flexbox horizontal, with medical information

References

• MDN div element