Business Product Theme .css Help

I am using the Business Product theme and am having trouble identifying which id is used for what appears to be a <HR> on a page. This <HR> is below the Edit this entry. and above the Leave a Comment text on any given page. If comments are turned off it simply shows at the bottom of the content. I want to replace this blank <HR> with a background graphic. I am attaching a screenshot with the <HR> higlighted with a red border as a sample.

I have searched all over layout.css and cannot find this? Thoughts?