pseudo-code to have nice slide in and out of twitter logo for twitter category articles

gistfile1.css

.category-twitter:hover {
  background-position: -50px -50px;
  -webkit-transition: all 0.5s ease-out;
}

.category-twitter {
  background: url(http://a2.twimg.com/a/1314204713/images/logos/twitter_newbird_boxed_blueonwhite.png);
  background-repeat: no-repeat;
  background-position: -300px -50px;
  -webkit-transition: all 0.5s ease-out;
}