uthors want to expose these states in a similar fashion
as the built-in elements.</p>
   <h3 class="heading settled" data-level="1.2" id="solution"><span class="secno">1.2. </span><span class="content">Solution</span><a class="self-link" href="#solution"></a></h3>
   <p>This specification defines an API to inform <a data-link-type="dfn" href="https://html.spec.whatwg.org/multipage/custom-elements.html#custom-element" id="ref-for-custom-element②">custom element</a>’s states to the
user agent, and a <a da