Popover accessibility · Needless UI

Keyboard interaction

Key	Action
`Enter or Space on the trigger`	Opens or closes the popover.
`Tab`	Moves into an open popover, which comes right after its trigger.
`Escape`	Closes the popover and returns focus to its trigger, or hides the hovercard.

The popover is a non-modal dialog: name it with aria-label or aria-labelledby. Its trigger gets aria-haspopup and the browser’s aria-expanded.
The hovercard is a tooltip and its trigger’s aria-describedby, so its text is read with the trigger. Keep controls out of it; use a popover for those.
The hovercard meets WCAG 1.4.13: Escape hides it without moving focus, the pointer can move onto it, and it stays while hovered or focused.