使用具有梯度背景的CSS 3过渡
rgba()
#container div a {
-webkit-transition: background 0.2s linear;
-moz-transition: background 0.2s linear;
-o-transition: background 0.2s linear;
transition: background 0.2s linear;
position: absolute;
width: 200px;
height: 150px;
border: 1px #000 solid;
margin: 30px;
z-index: 2}#container div a:hover {
background: -webkit-gradient(radial, 100 75, 100, 100 75, 0, from(rgba(0, 0, 0, .7)), to(rgba(0, 0, 0, .4)))}