Customized built-in elementsCustomized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.custom-elementsCustom elementslimitedhttps://html.spec.whatwg.org/multipage/custom-elements.html#customized-built-in-elementhttps://developer.mozilla.org/docs/Web/HTML/Reference/Global_attributes/isapi.CustomElementRegistry.builtin_element_supporthtml.global_attributes.ishttps://nowyoucanuse.com/features--customized-built-in-elements.html