Thank you so much for your reply dsonesuk!
Even though it's weird how I've never come across (or failed to notice) this important aspect of the overflow property -- that it restores a floated element's height. Is that what I should understand by what you refer to as substance?
Again, I appreciate your help!
Edit: Also, somewhat unrelated question, but I don't feel like it deserves a dedicated thread. Suppose I have a div container and some text in it that doesn't have any tags surrounding it like so:
<div>
Lorem ipsum dolor sit amet, consectetur adipiscing eli