li {
  float: left;
}

li a {
  display: inline-block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  }
li a:after {
  content: "";
  display: block;
  margin: auto;
  height: 2px;
  width: 0px;
  transition: all .8s;
  }
li a:hover:after {
  width: 100%;
  background: #ffffff;
  }