I don't know if this is a problem with the theme or with the plugin:
I'm using the Flickr Gallery plugin to show images on one of my pages.
When I have the header image/top navigation visible on my screen while I click on a thumbnail, the lightbox pops up over everything on the screen, except it is UNDER the header/nav bar. So I can't see most of the image.
If I scroll down the page until the header isn't visible, the lightbox pops up and looks fine.