body {
  font-family: Arial, sans-serif;
  margin: 0; padding: 0;
  background: #f4f4f4;
  color: #333;
}
header {
  background: #0077cc;
  color: white;
  padding: 1em;
  text-align: center;
}
nav a {
  margin: 0 1em;
  color: white;
  text-decoration: none;
}
main {
  padding: 1em;
  text-align: center;
}
form {
  max-width: 400px;
  margin: 1em auto;
  display: flex;
  flex-direction: column;
}
input, textarea {
  margin-bottom: 1em;
  padding: 0.8em;
  border: 1px solid #ccc;
}
button {
  padding: 0.8em;
  background: #0077cc;
  color: white;
  border: none;
}
.success {
  color: green;
  text-align: center;
}
@media (max-width: 600px) {
  header, main {
    padding: 1em;
  }
  nav a {
    display: block;
    margin: 0.5em 0;
  }
}