main {
  font-family: "MicrosoftYaHei", "微軟正黑體", "Microsoft JhengHei", "PingFangSC-Regular", "sans-serif";
}

main section {
  width: 100%;
}
main section img {
  width: 100%;
  height: auto;
  object-fit: contain;
}
main section img:nth-child(1) {
  display: block;
}
main section img:nth-child(2) {
  display: none;
}

@media screen and (max-width: 800px) {
  main section img:nth-child(1) {
    display: none;
  }
  main section img:nth-child(2) {
    display: block;
  }
}