</a> must match any element that is an
<a data-link-type="dfn" href="https://html.spec.whatwg.org/multipage/custom-elements.html#autonomous-custom-element" id="ref-for-autonomous-custom-element①">autonomous custom element</a> and whose <a data-link-type="dfn" href="#states-set" id="ref-for-states-set②">states set</a>
<a data-link-type="dfn" href="https://infra.spec.whatwg.org/#list-contain" id="ref-for-list-contain">contains</a> the specified <a class="production css" data-link-type="type" href="https:/