.main{
        background-image: url(https://tenjikai2.web-can.com/wp-content/uploads/2022/01/webcan2-pc-back-1400-1000-300x214-1.png);
    }

.main main {
    background: url(https://tenjikai2.web-can.com/wp-content/uploads/2024/09/demo1-pc.png) center top no-repeat;
}

.container{
        background: #fff8ed;
    }
    
@media screen and (max-width: 768px) {
    .main{
        background-image: url(https://tenjikai2.web-can.com/wp-content/uploads/2022/01/webcan2-sp-back-640-1500-128x300-1.png);
    }

.main main {
    background: url(https://tenjikai2.web-can.com/wp-content/uploads/2024/09/demo1-sp.png) center top no-repeat;
}

.container{
        background: #fff8ed;
    }

}