.box{width:100%;height:100%;display:-webkit-box;display:-ms-flexbox;display:flex;-webkit-box-pack:center;-ms-flex-pack:center;justify-content:center}.box .mainBody{width:21cm;background:#fff;padding:0 40px;-webkit-box-sizing:border-box;box-sizing:border-box;min-height:100%}.exportBtn{position:fixed;top:20px;left:20px;z-index:3}