[Theme: Expound] How to center feature article image?

Howdy:

I’m using the Expound theme. I would like to center the image that goes with the featured article that appears at the top of the home page. The image should be centered between the left margin and the excerpt on the right.

I looked through the expound.css file and tried a few things but I can’t get it to work.

Any advice?

Thanks.