body {
  font-family: Arial, sans-serif;
  max-width: 900px;
  margin: 40px auto;
  padding: 20px;
}

button {
  padding: 8px 15px;
  margin-left: 10px;
  cursor: pointer;
}

h1 {
  margin-bottom: 5px;
}

details {
  margin-top: 10px;
}