body {
  font-family: Arial, sans-serif;
  background: #f5f5f5;
  padding: 40px;
}

.container {
  max-width: 500px;
  margin: auto;
  background: white;
  padding: 24px;
  border-radius: 12px;
}

input {
  width: 100%;
  margin-bottom: 12px;
  padding: 10px;
  box-sizing: border-box;
}

button {
  padding: 10px 20px;
  cursor: pointer;
}

#result {
  margin-top: 20px;
  font-size: 24px;
  font-weight: bold;
}