body {
  font-family: "Noto Sans TC", sans-serif;
  margin: 0;
  padding: 0;
  background-color: #fafafa;
  color: #333;
}

header {
  background-color: #2d89ef;
  color: white;
  text-align: center;
  padding: 1rem;
}

nav a {
  color: white;
  margin: 0 10px;
  text-decoration: none;
}

main {
  padding: 20px;
  text-align: center;
}

.responsive-img {
  max-width: 100%;
  height: auto;
}

@media screen and (max-width: 600px) {
  nav {
    display: flex;
    flex-direction: column;
  }
}