Fixed-width text not appearing correctly in Safari after Lion upgrade

Question

I recently updated to Lion, and have found that at least some HTML tagged as <pre> or <tt> shows up looking like this

I've tried changing the fixed-width font in Safari. I've tried rebooting. The same page looks fine in Chrome, and when I copy the text in question out of Safari into BBedit, it looks fine. I'm at a bit of a loss.