<a href="javascript:void(0);">
キャプションが入ります。
</a>
body{
	font-size: 14px;
	color: #333;
}
a{
	color: #333;
	text-decoration: none;
	position:relative;
}
a:after{
	content: "";
	position: absolute;
	left: 0;
	bottom: -6px;
	width: 0;
	height: 2px;
	background-color: #337ab7;
	transition-duration: 3s;
}
a:hover:after{
	width: 100%;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.