.oss-upload-box {
    width: 200px;
    /*margin: 2% auto 0;*/
    position: relative;
    height: 200px;
    background: black url(/aliyunuploader/images/add.png) center center no-repeat;
    background-size: 30% auto;
    overflow: hidden;
}

.oss-upload-box .preview {
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
}

.oss-upload-box .preview img {
    height: 100%;
    width: 100%;
    display: block;
    object-fit: cover;
}