Absolutely-positioned div not displaying with print stylesheet applied

I am trying to add print functionality to one of our web maps, and am having trouble getting an absolutely-positioned div to display when I print. It displays correctly on my page, even when just the print stylesheet is applied to the page. But when I print it doesn't show up at all.

Rather than trying to add all the code here, I just put up a quick demo page to demonstrate the problem: http://maps.nps.gov/maps/rich/footstepsofhistory. To see the problem:

1. Load the page
2. Clic开发者_如何转开发k on a point on the map
3. Try to print it

The print capability works exactly as expected, other than the fact that the InfoBox does not display.

Any help is much appreciated, and I can supply more information, if needed.