body {
  font-family: sans-serif;
  background-color: #f4f6f9;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
}

.quiz-container {
  background: #ffffff;
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  width: 90%;
  max-width: 500px;
}

h1 {
  font-size: 1.5rem;
  text-align: center;
  margin-bottom: 1.5rem;
  color: #333;
}

.progress {
  font-size: 0.9rem;
  color: #666;
  margin-bottom: 1rem;
}

.question {
  font-size: 1.1rem;
  font-weight: bold;
  margin-bottom: 1.2rem;
  color: #222;
}

.options {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.option-btn {
  padding: 0.8rem 1rem;
  border: 2px solid #e0e0e0;
  border-radius: 8px;
  background: #fff;
  font-size: 1rem;
  text-align: left;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
}

.option-btn:hover {
  background: #f0f7ff;
  border-color: #0070f3;
}

.option-btn.correct {
  background: #d4edda;
  border-color: #28a745;
  color: #155724;
}

.option-btn.wrong {
  background: #f8d7da;
  border-color: #dc3545;
  color: #721c24;
}

.explanation {
  margin-top: 1rem;
  padding: 0.8rem;
  background: #e9ecef;
  border-radius: 6px;
  font-size: 0.95rem;
  color: #495057;
  display: none;
}

.next-btn, .restart-btn {
  margin-top: 1.5rem;
  width: 100%;
  padding: 0.8rem;
  border: none;
  border-radius: 8px;
  background: #0070f3;
  color: white;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
}

.next-btn:hover, .restart-btn:hover {
  background: #0051a8;
}

.score {
  font-size: 1.4rem;
  text-align: center;
  font-weight: bold;
  margin: 1.5rem 0;
}