.pc1{
  background: url('../image/product/pc1.jpg') center no-repeat;
  background-size: 100% 100%;
}
.mob1,.mob2,.mob3{
  display: none;
}
@media screen and (min-width: 1600px){
}
@media screen and (max-width:768px) {
 .pc1,.pc2,.pc3{
    display: none;
 }
 .mob1,.mob2,.mob3{
    display: block;
 }
 .mob1{
    background: url('../image/product/mob1.jpg') center no-repeat;
    background-size: 100% 100%;
 }
 .mob2{
  background: url('../image/product/mob2.jpg') center no-repeat;
  background-size: 100% 100%;
}
.mob3{
  background: url('../image/product/mob3.jpg') center no-repeat;
  background-size: 100% 100%;
}
}