hostelement
A host element is the DOM element that owns or hosts a shadow tree in the Web Components architecture. When a shadow root is attached to an element, that element becomes the host of the shadow DOM, serving as the entry point for the encapsulated markup and behavior defined inside the shadow root. The host element can be any standard HTML element or a custom element.
In the Shadow DOM model, the shadow root is separate from the host element’s normal light DOM.
The host element often defines the public API of a custom element, including observed attributes, property
Common usage involves creating a custom element with a shadow root attached to itself. The host element