坑爹的css

拉伸背景

open-btn {
    background: url("../images/ml-open-demo.png") no-repeat scroll left top rgba(0, 0, 0, 0);
    display: block;
    height: 48px;
    opacity: 0.6;
    overflow: hidden;
    text-indent: 100%;
    white-space: nowrap;
    width: 48px;
    30% 60%;: ;
    30% 60%;: ;
    background-size: 50% 50%; //是这个
}