No event listeners. No state tracking. No ARIA updates handled in JavaScript. I focused the button, and the tooltip appeared. I pressed the Esc key, and it disappeared.

• popovertarget connects the button to a popover element
• popovertargetaction specifies what should happen (show, hide, toggle as default)
• popover declares an HTML element can be targeted by popovertarget (ou .showPopover())

Note Floating UI already solves many of these issues. CSS anchor positioning should solve most of the layout stuff

A decision tree: https://res.cloudinary.com/indysigner/image/fetch/f_auto,q_80/w_1200/https://files.smashing.media/articles/getting-started-popover-api/5-popover-api-browser-support.png