Underline CSS transition

A simple CSS visual effect to animate links: when you hover text link, the link’s underline is revealed by animating it out from the center.

ThisĀ Underline CSS transition doesn’t require any additional DOM elements or js.

Underline CSS transition

a.animating-link {
position: relative;
color: #000;
text-decoration: none;
}
a.animating-link:hover {
color: #000;
}
a.animating-link:before {
content: "";
position: absolute;
width: 100%;
height: 2px;
bottom: 0;
left: 0;
background-color: #000;
visibility: hidden;
-webkit-transform: scaleX(0);
transform: scaleX(0);
-webkit-transition: all 0.3s ease-in-out 0s;
transition: all 0.3s ease-in-out 0s;
}
a.animating-link:hover:before {
visibility: visible;
-webkit-transform: scaleX(1);
transform: scaleX(1);
}

Support: Browsers that don’t support CSS animations will just show up a regular underline.

Link: http://tobiasahlin.com/blog/css-trick-animating-link-underlines/