#grad {
height: 200px;
width:500px;
background: -webkit-linear-gradient(left, #338fdd , #14d3e3); /* Safari 5.1 - 6.0 */
background: -o-linear-gradient(right, #338fdd, #14d3e3); /* Opera 11.1 - 12.0 */
background: -moz-linear-gradient(right, #338fdd, #14d3e3); /* Firefox 3.6 - 15 */
background: linear-gradient(to right, #338fdd , #14d3e3); /* 标准的语法(必须放在最后) */
}
<div id="grad"></div>
效果图如下: