Customizable select

A real select element with appearance: base-select.

The button shows the chosen option through selectedcontent, a live copy of the option with its dot, and the list is the select's own ::picker(select), drawn as a RAMTT list: radius 12, 30 px rows inset 4 px, the checkmark on the right.
The picker enters with @starting-style, opacity in 40 ms and scale from 0.98, and leaves in 30 ms; keyboard, typeahead, form value and screen reader roles are the browser's own.
On a zoomed canvas the picker is placed from the button's drawn rectangle, because top-layer anchoring ignores the zoom.