.share-btn {
    display: inline-block;
    color: #ffffff;
    border: none;
    padding: 0.5em;
    width: 4em;
    box-shadow: 0 2px 0 0 rgba(0,0,0,0.2);
    outline: none;
    text-align: center;
}

.share-btn:hover {
  color: #eeeeee;
}

.share-btn:active {
  position: relative;
  top: 2px;
  box-shadow: none;
  color: #e2e2e2;
  outline: none;
}

.share-btn.twitter     { background: #55acee; }
.share-btn.google-plus { background: #dd4b39; }
.share-btn.facebook    { background: #3B5998; }
.share-btn.linkedin    { background: #4875B4; }
.share-btn.email       { background: #CC181E; }