From: Daniel Piechnick
Hi bobburk. :) In some of my tutorials, I've used the term "sliver" to describe a piece of an image that repeats itself to fill up to the edge of the screen. This is necessary because people have different screen resolutions. You put your main image in a cell, and then set the sliver image as the background of that cell. Any area that's not covered by the main image gets filled up with repetitions of the sliver. Have a look at the Piglet Factory and Five Minute Website tutorials. They should provide some more information.