.twitter-social {
 margin-bottom: 10px;
 width: 50px;
 height:50px;
 display:block;
 background:transparent url('../images/twitter-blk.png') center top no-repeat;
}

.twitter-social:hover {
   background-image: url('../images/twitter-icon.png');
}

.facebook-social {
 margin-bottom: 10px;
 width: 50px;
 height:50px;
 display:block;
 background:transparent url('../images/facebok-blk.png') center top no-repeat;
}

.facebook-social:hover {
   background-image: url('../images/facebok-icon.png');
}

.rss-social {
 margin-bottom: 10px;
 width: 50px;
 height:50px;
 display:block;
 background:transparent url('../images/rss-blk.png') center top no-repeat;
}

.rss-social:hover {
   background-image: url('../images/rss-icon.png');
}

.youtube-social {
 margin-bottom: 10px;
 width: 50px;
 height:50px;
 display:block;
 background:transparent url('../images/youtube-blk.png') center top no-repeat;
}

.youtube-social:hover {
   background-image: url('../images/youtube-icon.png');
}