7. 渐变兼容性写法( 兼容到IE8+ ）

#div1{ width: 200px; height: 200px; border: 1px solid #333;
    background: -moz-linear-gradient(top, red, yellow);
    background: -webkit-linear-gradient(top, red, yellow);
    background: -ms-linear-gradient(top, red, yellow); /* 支持IE10+ */
    background: linear-gradient(top, red, yellow);
    -ms-filter: "progid:DXImageTransform.Microsoft.gradient (GradientType=0, startColorstr=red, endColorstr=yellow)";  /* 只支持IE8-9 */
    +background: #ff7a00;
}