body {
  font-family: Arial, sans-serif;
  background: #f5f5f5;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.quiz-container {
  background: white;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0px 4px 8px rgba(0,0,0,0.1);
  width: 400px;
  text-align: center;
}

.btn {
  display: block;
  background: #3498db;
  color: white;
  padding: 10px;
  margin: 10px 0;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.3s;
  width: 100%;
}

.btn:hover {
  background: #2980b9;
}

#next-btn {
  background: #27ae60;
  display: none;
}