f="#custom-state-pseudo-class" id="ref-for-custom-state-pseudo-class②">custom state pseudo class</a> must start with <span class="css">:</span>,
followed by one <a class="production css" data-link-type="type" href="https://drafts.csswg.org/css-values-4/#typedef-dashed-ident" id="ref-for-typedef-dashed-ident①">&lt;dashed-ident></a>, otherwise the selector is invalid.</p>
   <p>The <a data-link-type="dfn" href="#custom-state-pseudo-class" id="ref-for-custom-state-pseudo-class③">custom state pseudo class