:default CSS pseudo-class

The `:default` pseudo-class matches checkboxes and radio buttons which are checked by default, `<option>`s with the `selected` attribute, and the default submit button (if any) of a form.

Customizable Select element

Customization of the `<select>` element's appearance. Previously envisioned as a separate element (`<selectlist>` or `<selectmenu>`).

htmloptionelement api: defaultselected

htmloptionelement api: selected

htmloptionscollection api: selectedindex

htmlselectelement api: selectedoptions

html element: option: selected