You nailed it! Or rather you got me thinking about the right attribute and I sorted it out.
I am using WP 3.3.1, and Atahualpa 3.7.3. I realized I had not specified a border in either place I tried using the CSS, and when I did, it half worked. It made the rounded corners, but the footer (which I figured out was the ticket) was overlapping them with its squared corners.
Because I already had a border specified for the top of the footer, I added this to my code, and it works beautifully!
border-left: solid 1px #ffffff;
border-bottom: solid 1px #ffffff;
border-right: solid 1px #ffffff;
You can see the working CSS at http://debslosingit.com/
. I still want to tweak the radius of the corners a bit, but everything else is in place and working. It appears to be working fine in both Firefox & IE.
Thanks for the direction, once again!