To reproduce the error, scroll down to the bottom of the page and click on the "Show Overlay" button.
In Safari, Chrome, and Internet Explorer, this text will not be visible when you show the overlay and when you close it. In Firefox (3.6), the page is scrolled to the top when the overlay is shown so that this text becomes visible, and when you close the overlay, it stays at the top of the page.

Test content at bottom of page.