.scrollBox{box-sizing:border-box;overflow:auto;}
.scrollBox:nth-of-type(2n){margin-right:10px}
.scrollBox:nth-of-type(3),.scrollBox:nth-of-type(4){margin-top:0}
.contentBox1{width:100%;height:900px;background-image:url('../images/1.png');background-size:cover;background-repeat:no-repeat}
.contentBox2{width:1200px;height:100%;background-image:url('../images/2.png');background-size:cover;background-repeat:no-repeat}
.contentBox3{width:1200px;height:900px;background-image:url('../images/2.png');background-size:cover;background-repeat:no-repeat}
@media (max-width:1200px) {
  .scrollBox:nth-of-type(2n){margin-right:0px}
}