background:-webkit-linear-gradient(top, #599bb3 5%, #408c99 100%);
background:-o-linear-gradient(top, #599bb3 5%, #408c99 100%);
background:-moz-linear-gradient(top, #599bb3 5%, #408c99 100%);
background:-ms-linear-gradient(top, #599bb3 5%, #408c99 100%);
background:linear-gradient(to bottom, #599bb3 5%, #408c99 100%);
filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#599bb3', endColorstr='#408c99',GradientType=0);
1.从上到下
background: -webkit-linear-gradient(red, blue); /* Safari 5.1 - 6.0 */
background: -o-linear-gradient(red, blue); /* Opera 11.1 - 12.0 */
background: -moz-linear-gradient(red, blue); /* Firefox 3.6 - 15 */
background: linear-gradient(red, blue); /* 标准的语法 */
2、从左到右
background: -webkit-linear-gradient(left, red , blue); /* Safari 5.1 - 6.0 */
background: -o-linear-gradient(right, red, blue); /* Opera 11.1 - 12.0 */
background: -moz-linear-gradient(right, red, blue); /* Firefox 3.6 - 15 */
background: linear-gradient(to right, red , blue); /* 标准的语法 */
3、从左上角到右下角
background: -webkit-linear-gradient(left top, red , blue); /* Safari 5.1 - 6.0 */
background: -o-linear-gradient(bottom right, red, blue); /* Opera 11.1 - 12.0 */
background: -moz-linear-gradient(bottom right, red, blue); /* Firefox 3.6 - 15 */
background: linear-gradient(to bottom right, red , blue); /* 标准的语法 */
更多：http://www.runoob.com/css3/css3-gradients.html
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