I had a feeling that might not have been the best explanation in the world, let me see how to better put it …
Well, okay, if you look at the header area of http://www.westeros.org, you can see how it uses a border image with a lighter colour than the main background of the site, to get the effect of one piece of paper on top of another (that’s the intent, anyway!).
Note also the two shields to the left and right of the title. Lets say I wanted to apply these as fixed background images rather than as actual image elements. Is there any way that these could appear on top of the border image fill, or will that always appear on top, even if the background is applied to elements within the header, rather than to the main header element (the one that has the border defined)?
I am suspecting from your answer that the border will always appear on top even for elements within the header, but I am not entirely certain.