body {
  width: 100%;
  height: 100dvh;
  background: url("./attach/desktop.jpg") no-repeat fixed center / cover;
}

@media screen and (max-width: 600px) {
  body {
    width: 100%;
    height: 100dvh;
    background: url("./attach/mobile.jpeg") no-repeat fixed center / cover;
  }
}