This property inserts another document into the current document, replacing the current element’s content. Any elements or CSS properties applied to or inherited by the current element are applied to the inserted content as well.
top: 100px; left: 300px;
width: 200px; height: 200px;
border: thin solid black;
[URL]: An absolute or relative URL pointing to a document. If rendering of the document is not possible by the browser, it should be ignored and the regular element content be displayed instead.