body {
  font-family: Arial, sans-serif;
  background: #f4f4f4;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.container {
  background: white;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
  text-align: center;
}

input, button {
  margin: 10px 0;
  padding: 10px;
  font-size: 16px;
}

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