.pic_1{
    height:553px;
    background: url("http://heysou.oss-cn-shanghai.aliyuncs.com/93fba5ac-0977-4a13-8128-708ec1283f52.png");
    background-position: center 0px;
}
.pic_2{
    height:75px;
    background: url("http://heysou.oss-cn-shanghai.aliyuncs.com/ead6a9fe-7acb-449b-b7c3-15d817e0e078.png");
    background-position: center 0px;
}
.pic_3{
    height:330px;
    background: url("http://heysou.oss-cn-shanghai.aliyuncs.com/4d36e9a0-3202-40a0-8d0f-75a2c7fdde61.png");
    background-position: center 0px;
}
.pic_4{
    height:492px;
    background: url("http://heysou.oss-cn-shanghai.aliyuncs.com/f4e8fd24-3f30-4c37-8d81-e1a711b5b903.png");
    background-position: center 0px;
}