Some SCSS for a set of custom social share buttons.

elastic-share-btns.scss

body {
  background: #000;
  padding: 2em;
  text-align: center;
}

* {
  box-sizing: border-box;
}

.share-btns {
  position: absolute;
  width: 300px;
  height: 212px;
  padding-left: (300px / 2) - (36px / 2);
  top: 50%;
  left: 50%;
  margin-left: -(300px / 2);
  margin-top: -(212px / 2);
  
  .share-btn {
    float: left;
    margin-top: 15px;
    
    &:first-child {
      margin-top: 0;
    }
    
    &:after {
      clear: both;
      display: table;
    }
  }
}

.share-btn {
  display: block;
  position: relative;
  height: 36px;
  
  &:hover {
    cursor: pointer;
    
    .share-btn-primary {
      box-shadow: 1px 0 0 0 rgba(0, 0, 0, .1);
    }
    
    .share-btn-secondary-content {
      transform: translate3d(0, 0, 0);
    }
  }
}

.share-btn-primary {
  position: absolute;
  background: #fff;
  width: 36px;
  height: 36px;
  border-radius: (36px / 2);
  left: 0;
  top: 50%;
  margin-top: -(36px / 2);
}

.share-btn-icon {
  display: block;
  color: #242424;
  position: absolute;
  width: 36px;
  line-height: 36px;
  font-size: 16px;
  margin-top: 1px;
}

.share-btn-secondary {
  overflow: hidden;
  margin-left: (36px / 2);
  height: 36px;
}

.share-btn-secondary-content {
  font-family: sans-serif;
  font-size: .75em;
  background: #fff;
  display: block;
  height: 36px;
  text-align: left;
  padding-left: (36px * .8);
  padding-right: (36px * .6);
  line-height: 36px;
  color: #242424;
  border-radius: 0 (36px / 2) (36px / 2) 0;
  transform: translate3d(-100%, 0, 0);
  transition: transform 175ms ease;
}