.box {
    width: 90%;
    height: 80vh;
}

.chart{
	height: 100%;
}
.backBtn{
    position: absolute;
    top: -30px;
    background-color: #ff6700;
    border: 0;
    color:#fff;
    height: 27px;
    font-family: Microsoft Yahei;
    font-size: 1em;
    cursor: pointer;
}