For page https://www.mediawiki.org/wiki/Special:SpecialPages the https://validator.w3.org/ shows the following error:
https://validator.w3.org/nu/?doc=https://www.mediawiki.org/wiki/Special:SpecialPages
Error: Element div not allowed as child of element h3 in this context. (Suppressing further errors from this subtree.) From line 210, column 29; to line 210, column 33 nts</span><div></div> Contexts in which element div may be used: Where flow content is expected. As a child of a dl element.
Error: Element div not allowed as child of element h3 in this context. (Suppressing further errors from this subtree.) From line 226, column 50; to line 226, column 54 ore</span><div></div> Contexts in which element div may be used: Where flow content is expected. As a child of a dl element.
The problematic part is
<h3 id="p-variants-label"><span>Variants</span><div></div></h3>