body {
  background-color: #f9fafb;
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
}

.container {
  background: #fff;
  padding: 2rem;
  margin-top: 4rem;
  border-radius: 1rem;
  box-shadow: 0 0 12px rgba(0, 0, 0, 0.08);
  width: 100%;
  max-width: 480px;
  text-align: center;
}

h1 {
  font-size: 1.8rem;
  margin-bottom: 0.5rem;
  color: #111827;
}

.subtitle {
  color: #6b7280;
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

.input-group {
  margin-bottom: 1rem;
  text-align: left;
}

.input-group label {
  display: block;
  font-weight: 500;
  margin-bottom: 0.25rem;
  color: #374151;
}

.input-group input {
  width: 100%;
  padding: 0.5rem;
  border: 1px solid #d1d5db;
  border-radius: 0.5rem;
  font-size: 1rem;
}

button {
  width: 100%;
  padding: 0.75rem;
  background-color: #2563eb;
  color: white;
  border: none;
  border-radius: 0.5rem;
  font-size: 1rem;
  cursor: pointer;
  margin-top: 1rem;
  transition: background-color 0.3s ease;
}

button:hover {
  background-color: #1e40af;
}

.result {
  margin-top: 1.5rem;
  font-weight: bold;
  color: #16a34a;
  font-size: 1.2rem;
}