As others have noted only the div is allowed. This isn't a unique situation either, the HTML spec despite being lenient in syntax is quite restrictive in behavior. It's unfortunate that XHTML (and XML parsing) didn't become the default as it's the opposite, more restrictive syntax, but lenient behavior.

For example in XHTML you can use custom elements as table rows or cells (provided you give them the correct role and CSS display property). This is because XHTML does not modify the tree during parsing, unlike HTML which will hoist out custom element children of the table to the table's parent.