Tutorial Gradient Underlines
a {
position: relative;
padding-bottom: 6px;
}
a:hover::after {
content: "";
position: absolute;
bottom: 2px;
left: 0;
height: 1px;
width: 100%;
background: #444;
background: -webkit-gradient(linear, left top, right top, color-stop(0%,transparent), color-stop(50%,#444), color-stop(100%,transparent));
background: -webkit-linear-gradient(left, transparent 0%,#444 50%,transparent 100%);
background: -moz-linear-gradient(left, transparent 0%, #444 50%, #transparent 100%);
background: -ms-linear-gradient(left, transparent 0%,#444 50%,#transparent 100%);
background: -o-linear-gradient(left, transparent 0%,#444 50%,transparent 100%);
background: linear-gradient(left, transparent 0%,#444 50%,transparent 100%);
}