怎样用CSS做渐变背景

background: #6cab26;
background-image: url(IMAGE_URL); /* fallback */
background-image: url(IMAGE_URL), -webkit-gradient(linear, left top, left bottom, from(#6cab26), to(#6ceb86)); /* Saf4+, Chrome */
background-image: url(IMAGE_URL), -webkit-linear-gradient(top, #6cab26, #6ceb86); /* Chrome 10+, Saf5.1+ */
background-image: url(IMAGE_URL),    -moz-linear-gradient(top, #6cab26, #6ceb86); /* FF3.6+ */
background-image: url(IMAGE_URL),     -ms-linear-gradient(top, #6cab26, #6ceb86); /* IE10 */
background-image: url(IMAGE_URL),      -o-linear-gradient(top, #6cab26, #6ceb86); /* Opera 11.10+ */
background-image: url(IMAGE_URL),         linear-gradient(top bottom, #6cab26, #6ceb86); /* W3C */

浏览器兼容性说明详见：http://stackoverflow.com/questions/2504071/is-it-possible-to-combine-a-background-image-and-css3-gradients