 defines the <a data-link-type="dfn" href="#custom-state-pseudo-class" id="ref-for-custom-state-pseudo-class">custom state pseudo class</a> <span class="css">:--foo</span> matching
to a custom element exposing a state. This specification is intended to be
merged to <a data-link-type="biblio" href="#biblio-html" title="HTML Standard">[HTML]</a> and <a data-link-type="biblio" href="#biblio-selectors-4" title="Selectors Level 4">[selectors-4]</a> in the future.</p>
  </div>
  <div data-fill-with="at-risk"></di