joesc

The the site-description class has a float left property you need to remove, check out this link: [Redacted]

Hi joanwalsh,
I think your above method should work.
Since the issue happens to specific page only, not all pages or posts on your site, you can try to switch to twenty twelve theme first, then recreate a new page with same content, after that switch back to Pinboard theme see if any update.

You can also compare the page in problem with other pages, see if any special code or layout settings in this page.

Good luck