JSFiddle - React, Tailwind, and code Playground

HTML

<h2 class='uno'>
  <a href=''>:hover, please</a>
</h2>

<h2 class='dos'>
  <a href=''>Animate above text</a>
</h2>

CSS

@import url(http://fonts.googleapis.com/css?family=Quando);
*, *:after, *:before {
  box-sizing: border-box;
  -moz-box-sizing: border-box;
}
* {margin:0;padding:0;border:0 none;position: relative; outline: none;
}
html, body {
  background:  #004050;
  font-family: Quando;
  font-weight: 300;
  width: 100%;
}
h2 {
  background: #0D757D;
  width: 100%;
  min-height: 200px;
  line-height: 200px;
  font-size: 3rem;
  font-weight: normal;
  text-align: center;
  color: rgba(0,0,0,.4);
  margin: 3rem auto 0;
}
.dos {background: #ff5e33;}

h2 > a, h3 > a {
  text-decoration: none;
  color: rgba(0,0,0,.4);
  z-index: 1;
}

h2 > a:before {
  content: "";
  position: absolute;
  width: 100%;
  height: 3px;
  bottom: 0;
  left: 0;
  background: #9CF5A6;
  visibility: hidden;
  border-radius: 5px;
  transform: scaleX(0);
  transition: .25s linear;
}
h2.uno > a:hover:before,
h2.uno > a:focus:before {
  visibility: visible;
  transform: scaleX(1);
}