title: A span can be a div, but a div can't be a span
body: <p>I'm wondering if that (my title) is ever incorrect, other than for HTML validation.  I've recently had to start supporting IE7 again (I've been lucky enough to not have to for the past 3 years or so) and the fact that div's can't be <code>inline-block</code> has gotten me about 10 times in the past month due to the fact that I make everything a <code>div</code> by default and then go back and stylize elements.  So I'm considering making <em><strong>everything</strong></em> a span so that if I later go back and make something inline-block I'm not trying to figure out why it's not working in IE7.</p>
  <p>So my question -- Is there ever a case, in any browser (IE7+, FF, Webkit, Opera), that anyone knows of where a span can not act like a div?  I'm not concerned about the HTML not validating due to having block elements inside inline ones.</p>