body {
  font-family: Arial, sans-serif;
  margin: 20px;
}

h1 {
  text-align: center;
}

form {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 5px;
}

input[type="number"] {
  width: 100%;
  padding: 8px;
  font-size: 16px;
}

button[type="button"] {
  padding: 8px 16px;
  font-size: 16px;
}

#result {
  text-align: center;
  font-size: 18px;
  white-space: pre;
}