A button element must have both a start tag and an end tag.
any element that can contain phrasing elements
interface HTMLButtonElement : HTMLElement { attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement form; attribute DOMString formAction; attribute DOMString formEnctype; attribute DOMString formMethod; attribute DOMString formNoValidate; attribute DOMString formTarget; attribute DOMString name; attribute DOMString type; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); readonly attribute NodeList labels; };