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);