[OT] HTML: div/iframe hybrid?

[Nick Sabalausky via Digitalmars-d]

(Pardon the ot, but I know there are other webdevs here). For various 
reasons, I like to keep my html...uhh...let's say "non-bleeding-edge" 
:), downside of course being I tend to not be quite as up on what's out 
there as I should be. So just tossing this question out there:

I know (at least historically) iframes don't normally resize based on 
their internal content, but only based on the the outer html page. Aside 
from the obvious JS, does modern HTML/CSS provide any way to have 
something like an iframe (ie, embed content from another URL), but 
otherwise behaves and flows more like a div, expanding (at least 
vertically, even if nothing else) as the embedded content expands?

Would it be too kludgey or questionable-compatibility (or just fail) to 
just use CSS to set the iframe element to block-style layout?