css 渐变透明,html透明度渐变设置

.linear {
background: -webkit-linear-gradient( top, rgba(0, 0, 0, 0),rgba(0, 0, 0, 0.2) ); /* Safari 5.1 - 6 /
background: -o-linear-gradient(bottom,rgba(0, 0, 0, 0),rgba(0, 0, 0, 0.2)); / Opera 11.1 - 12*/
background: -moz-linear-gradient( bottom, rgba(0, 0, 0, 0), rgba(0, 0, 0, 0.2)); /* Firefox 3.6 - 15*/
background: linear-gradient(to bottom,rgba(0, 0, 0, 0), rgba(0, 0, 0, 0.2)); /* 标准的语rrdmj/
}