@media (min-width:768px) {
  .banner_1 {
    background-image: url(https://static.readboy.com/web/products/A6E/pc/1.jpg);
  }
  .banner_2 {
    position: relative;
    width: 100%;
    padding-top: 47.396%;
    background-image: url(https://static.readboy.com/web/products/A6E/pc/2.jpg);
    background-size: 100% 100%;
    background-repeat: no-repeat;
    overflow: hidden;
    color: #000
  }
  .banner_18 { 
    background-image: url(https://static.readboy.com/web/products/A6E/pc/18-1.jpg);
  }
}

@media (max-width:767px) {
  .banner_1 {
    background-image: url(https://static.readboy.com/web/products/A6E/mobile/1.jpg);
  }
   .banner_2 {
    position: relative;
    width: 100%;
    padding-top: 220%;
    background-image: url(https://static.readboy.com/web/products/A6E/mobile/2.jpg);
    background-size: 100% 100%;
    background-repeat: no-repeat;
    overflow: hidden;
    color: #000
  }
  .banner_18 { 
    background-image: url(https://static.readboy.com/web/products/A6E/mobile/18-2.jpg);
  }
}