兼容主流浏览器的渐变颜色背景gradient的写法
/* Webkit: Safari 4-5, Chrome 1-9 */
background: -webkit-gradient(linear, 0%
0%, 0% 100%, from(#ff6600), to(#339900));
/* Webkit: Safari 5.1+, Chrome 10+
*/
background: -webkit-linear-gradient(top, #ff6600, #339900);
/*
Firefox 3.6+ */
background: -moz-linear-gradient(top, #ff6600, #339900);
/* Opera 11.10+ */
background: -o-linear-gradient(top, #ff6600,
#339900);
/* IE 10 */
background: -ms-linear-gradient(top, #ff6600,
#339900);
/* IE < 10 */
/* 注意：这一行必须写在最后 */
FILTER:
progid:DXImageTransform.Microsoft.Gradient(startColorStr=#ff6600,
endColorStr=#339900);
