Hi Jac
Try adding the following to the Custom CSS field of your templates parameters editing to your own taste...
.social-facebook a {background-color: rgba(0, 0, 0, 0.1); }
.social-twitter a {background-color: rgba(0, 0, 0, 0.1); }
.social-googleplus a {background-color: rgba(0, 0, 0, 0.1); }
.social-youtube a {background-color: rgba(0, 0, 0, 0.1); }
.social-pinterest a {background-color: rgba(0, 0, 0, 0.1); }
.social-blogger a {background-color: rgba(0, 0, 0, 0.1); }
.social-dribbble a {background-color: rgba(0, 0, 0, 0.1); }
.social-flickr a {background-color: rgba(0, 0, 0, 0.1); }
.social-skype a {background-color: rgba(0, 0, 0, 0.1); }
.social-digg a {background-color: rgba(0, 0, 0, 0.1); }
.social-linkedin a {background-color: rgba(0, 0, 0, 0.1); }
.social-vimeo a {background-color: rgba(0, 0, 0, 0.1); }
.social-yahoo a {background-color: rgba(0, 0, 0, 0.1); }
.social-tumblr a {background-color: rgba(0, 0, 0, 0.1); }
.social-deviantart a {background-color: rgba(0, 0, 0, 0.1); }
.social-delicious a {background-color: rgba(0, 0, 0, 0.1); }
.social-rss a {background-color: rgba(0, 0, 0, 0.1); }
Ciarán