.box{
    height: 100%;
    width: 420px;
    margin:0 10px;
    position: relative;
}
.top{
    height:50%;
}
.topList{
    height: calc(100% - 60px);
    overflow: hidden;
    overflow-y: auto;
    box-sizing: border-box;
    margin: 30px 20px;
}
.bottom{
    height: calc(50% - 10px);
    margin-top: 10px;
    position: relative;
    color: #7BA7BE;
    font-size: 18px;
    line-height: 1.6em;
}
.introduce{
    padding:40px 20px;
    text-indent: 2em;
    overflow: hidden;
    overflow-y: auto;
    height: 90%;
}