Hi lmilesw, and thanks. This works great. I had to adapt it slightly to my particular situation:
1) one blog-body-wide top image, not repeated, placed at top center (establishing a top edge of a parchment background). I put this code in ATO>Body, Text & Links>Body Style:
background: url(/blog/wp-content/themes/atahualpa353/images/parchment_top.gif) no-repeat top center;
2) repeating blog-body-wide tile images that repeat lengthwise (establinsing the left and right edges of a parchment background). I put this code into the CSS inserts section of the HTML/CSS inserts:
This works fine, but one qwirk with repeat-y that I discovered... and I doubt there's a good fix:
repeat-y ignores any y-position I place with the background-position property. That is, if I put it as background-position: center 240px; (as the top image is 240px tall), the repeat-y ignores the vertical position and repeats the entire length of the page regardless, from top to bottom. What this means is: If I make the parchment tiles png's with nice transparent edges, then behind the edges of parchment_top, we can see the edges of parchment_center behind it.
The work around I'm using right now: not as elegant: is to not make the edges of the parchment transparent, but solid and matching the color I'm using for the blog background. This way, the edges behind parchment_top are now solid and cover the repeating parchment_center in the top region of the page.
Is there a way to control this repeat-y? Primarily, so that I can have better control over the background without returning to Photoshop.
You can see what I'm talking about at http://www.derekbeck.com/1775/
(still under construction)
I'm using WordPress 3.0.1 and Atahualpa 3.5.3.