How to remove dots/dashes under image links in sidebar

Hi, I’ve searched high and low looking for answer to this one but can’t seem to find a solution. The social media buttons in the sidebar on my website have dots/dashes underneath them and I want to get rid of them.

http://kenya.footholds.net/~thedigit/WPDigitalPost/

From what I’ve gathered so far it probably involves editing/adding some code in the CSS style sheet. I’ve found 7 instances of the word underline in my style sheet. I only want to remove them from the image links so not quite sure how to approach. Help!