body {
  font-family: Arial, sans-serif;
  margin: 0; padding: 0;
  background: #f9f9f9; color: #333;
}
header {
  background: #005f73; color: white; padding: 1em;
  display: flex; justify-content: space-between; align-items: center;
}
nav button {
  background: #0a9396; border: none; color: white;
  padding: 0.5em 1em; margin-left: 0.5em; cursor: pointer;
}
main {
  padding: 2em; max-width: 700px; margin: auto;
  background: white; box-shadow: 0 0 10px #ccc; border-radius: 5px;
}
a {
  display: inline-block; margin-top: 1em;
  background: #ee6c4d; color: white; padding: 0.5em 1em;
  text-decoration: none; border-radius: 3px;
}
@media (max-width: 600px) {
  header { flex-direction: column; align-items: flex-start; }
  nav button { margin: 0.2em 0 0 0; }
}