Simple underline slide transition

HTML

<a href="https://google.com">GOOGLE</a>

CSS

html, body{
  width:100%;
  height:100%;
  margin:0;
  padding:0;
}
body{
  display:flex;
  align-items:center;
  justify-content:center;
  background:black;
}
a{
  all:unset;
  position:relative;
  color:white;
  font-size:5em;
  cursor:pointer;
}
a::after{
  content:'';
  position:absolute;
  top: calc(100% + 2px);
  left:0;
  width:0;
  height:2px;
  background:red;
  transition: .2s all;
}
a:hover::after{
  width:100%;
}