不支持CSS3渐变的浏览器只会使用该图像.

div {
            background-color: #1a82f7; /* fallback color */
            background-image: url(images/linear_bg_2.png); /* fallback image */
            background-image: -moz-linear-gradient(100% 100% 90deg,#2F2727,#1a82f7);
            background-image: -webkit-gradient(linear,0% 0%,0% 100%,from(#1a82f7),to(#2F2727));
}

Blog post about it on CSS Tricks