/* http://www.giphy.com/gifs/3o6ozldpkMnGJhVJja */
a {
position: relative
}
a:hover:after {
width: 100%;
}
a:after {
content: '';
overflow: hidden;
position: absolute;
left: 0;
bottom: -1px;
display: block;
width: 0;
height: 1px;
background: #000;
transition: all 300ms cubic-bezier(.175,.885,.32,1.075);
}