<div class="container">
  <section>
    <a href="#">
      <i class="fab fa-instagram"></i>
      <span>Instagram</span>
    </a>
    <a href="#">
      <i class="fab fa-github"></i>
      <span>Github</span>
    </a>
  </section>
</div>

div.container {
  display: inline-block;
  position: absolute;
  top: 50%;
  left: 50%;
  -ms-transform: translate(-50%, -50%);
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}

a {
  color: #fff;
  background: #8a938b;
  border-radius: 4px;
  text-align: center;
  text-decoration: none;
  position: relative;
  display: inline-block;
  width: 120px;
  height: 100px;
  padding-top: 12px;
  margin: 0 2px;
  -o-transition: all 0.5s;
  -webkit-transition: all 0.5s;
  -moz-transition: all 0.5s;
  transition: all 0.5s;
  -webkit-font-smoothing: antialiased;
}
a:hover {
  background: #5a665e;
}
i {
  font-size: 45px;
  vertical-align: middle;
  display: inline-block;
  position: relative;
  top: 20%;
}

a span {
  color: #666;
  position: absolute;
  font-family: "Chelsea Market", cursive;
  bottom: 0;
  left: -15px;
  right: -15px;
  padding: 15px 7px;
  z-index: -1;
  font-size: 14px;
  border-radius: 5px;
  background: #fff;
  visibility: hidden;
  opacity: 0;
  -o-transition: all 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  -webkit-transition: all 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  -moz-transition: all 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  transition: all 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
} /* 当图标处于悬停状态时，文本将弹出 */
a:hover span {
  bottom: 130px;
  visibility: visible;
  opacity: 1;
}