body.container {
  font-family: sans-serif;
  padding: 1rem;
  max-width: 600px;
  margin: auto;
}

button {
  padding: 0.5rem 1rem;
  margin: 0.25rem 0;
}

input[type='file'] {
  margin: 0.5rem 0;
}

.correct {
  background: #4caf50;
  color: white;
}

.wrong {
  background: #f44336;
  color: white;
}

@media (prefers-color-scheme: dark) {
  body {
    background: #121212;
    color: #e0e0e0;
  }
  button {
    background: #333;
    color: #e0e0e0;
  }
}