浏览器实现颜色渐变效果(兼容)

filter:progid:DXImageTransform.Microsoft.Gradient(gradientType=0,startColorStr=#ffffff,endColorStr=#171717);
background: -ms-linear-gradient(top, #ffffff, #171717);
background: -moz-linear-gradient(top, #ffffff,#171717);
background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#ffffff),to(#171717));
background: -webkit-linear-gradient(top, #ffffff,#171717);
background: -o-linear-gradient(top, #ffffff,#171717);