.main-container {
  font-family: system-ui, sans-serif;
  max-width: 600px;
  margin: 2rem auto;
  padding: 2rem;
}

.light-theme {
  background: #ffffff;
  color: #1a1a1a;
  border: 1px solid #e0e0e0;
}

.dark-theme {
  background: #1a1a1a;
  color: #ffffff;
  border: 1px solid #333;
}

.controls {
  display: flex;
  gap: 1rem;
  margin: 2rem 0;
}

.btn {
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: opacity 0.2s;
}

.btn:disabled {
  opacity: 0.7;
  cursor: not-allowed;
}

.display {
  padding: 2rem;
  border-radius: 8px;
  margin-top: 2rem;
}