CSS3 Gradient

线性渐变：

background:-webkit-gradient(linear,0 80%,0 100%,color-stop(0%,rgba(0,0,0,0)),color-stop(100%,rgba(0,0,0,0.6)));

/*Old gradient for webkit*/
background: -webkit-linear-gradient(top, rgba(0,0,0,0) 80%,rgba(0,0,0,0.6) 100%);/*兼容苹果浏览器*/
background: linear-gradient(to bottom,  rgba(0,0,0,0) 80%,rgba(0,0,0,0.6) 100%);/*谷歌ie火狐等浏览器*/

径向渐变：