popover
Native popover elements. The content appears with a WebGL dissolve; the top layer, light dismiss, focus and popovertarget buttons stay native. Esc and light dismiss close instantly: the browser does them and they cannot be vetoed.
popover="auto"
Closes with Esc or by clicking outside, natively.
popover="manual"
No light dismiss: only the button or a script closes it.
popover="hint"
A hint does not close auto popovers.