Hi,

I used to think that all block-level elements can contain block elements & inline elements.

In reference.sitepoint.com/html/h1, reference.sitepoint.com/html/h6 , reference.sitepoint.com/html/p etc. it's mentioned:

This element may contain any text content, but it can’t include any block-level elements: only inline or phrase elements can be included.
When I checked, I saw that <h1>, <h2>....<h6>, <p>, <li> inside <dir> or <menu> cannot contain block-level elements.

Are there any other block elements that cannot contain block elements?