.content .banner :nth-child(1) {
    font-size: 0;
}
.content .banner :nth-child(1) img{
    height: auto;
    width: 100%;
}
.content .banner :nth-child(2) {
    margin-top: 60px;
    font-size: 0;
}
.content .banner :nth-child(2) img{
    height: auto;
    width: 100%;
}
.content .banner :nth-child(3) {
    font-size: 0;
    margin-top: 50px;
}
.content .banner :nth-child(3) img{
    height: auto;
    width: 100%;
}
.content .banner :nth-child(4) {
    text-align: center;
    font-size: 0;
}
.content .banner :nth-child(4) img{
    height: auto;
    width: 1200px;
}