.img-center {
    text-align: center;
}

@media screen and (min-width: 768px) {
    .pc_only{
        max-width: 50%;
        margin: 15px;
    }
}
@media screen and (max-width: 530px) {
    .sp_only{
        max-width: 80%;
        margin: 15px;
    }
}