widget/link images centering where in css

I have setup/copied a blog as a favor. I used WordPress 3.5, theme NomNom 1.7.2 with child theme Twenty Eleven. This is the formating they used before on another server. I looked everywhere and can not seam to find a place to edit the code to correct a centering issue of link images. The blog/web page is: http://autopromods.com/ On the page the sponsors and track images on the right side bar need to be centered and spaced. I also enabled the links in WordPress 3.5. I looked over all the css code and just can not find it. Any help pointing me in the right directions would be appreciated.