<nav>
    <ul>
      <li class="item"><a href="#">link 1</a></li>
      <li class="item"><a href="#">link 2</a></li>
      <li class="item"><a href="#">link 3</a></li>
      <li class="item"><a href="#">link 4</a></li>
      <li class="item"><a href="#">link 5</a></li>
    </ul>
  </nav>

ol, ul {
    list-style: none;
}
li {
    display: inline-block;
    padding: 20px 0 20px;
    vertical-align: middle;
}
a:hover, a:focus, a:active {
    color: #999;
    text-decoration: none;
}
a {
    font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif;
    text-decoration: none;
    transition: color 0.1s, background-color 0.1s;
}
a {
    position: relative;
    display: block;
    padding: 16px 0;
    margin: 0 12px;
    letter-spacing: 1px;
    font-size: 12px;
    line-height: 16px;
    font-weight: 900;
    text-transform: uppercase;
    transition: color 0.1s,background-color 0.1s,padding 0.2s ease-in;
    color: #000;
}
a::before {
    content: '';
    display: block;
    position: absolute;
    bottom: 3px;
    left: 0;
    height: 3px;
    width: 100%;
    background-color: #000;
    transform-origin: right top;
    transform: scale(0, 1);
    transition: color 0.1s,transform 0.2s ease-out;
}
a:active::before {
    background-color: #000;
}
a:hover::before, a:focus::before {
    transform-origin: left top;
    transform: scale(1, 1);
}