You can customize the colors of the social media widget with CSS that you can add in the Resources section, too. For instance, if you wanted to make the icons all the same purple color and make the background the gray that is 2 blocks from the purple one in your document, you could add the following CSS:
#share-wrap {
background-color: rgba(203,203,215,.65);
}
#share-wrap > a#sb-fb { background-color:#474077}
#share-wrap > a#sb-tw { background-color:#474077}
#share-wrap > a#sb-li { background-color:#474077}
The size change is doable, but it's a little trickier because it affects the placement of the icons. What sort of size change did you want?