body {
  font-family: Arial, sans-serif;
  background-color: #f0f0f0;
  margin: 0;
  padding: 20px;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.quiz-container {
  background: white;
  padding: 30px;
  max-width: 600px;
  width: 100%;
  border: 2px solid #e0e0e0;
}

.quiz-header {
  text-align: center;
  margin-bottom: 30px;
}

.quiz-header h1 {
  margin: 0 0 15px 0;
  font-size: 28px;
  color: #333;
}

#progress-text {
  font-size: 16px;
  color: #666;
  margin-bottom: 10px;
}

.progress-bar {
  width: 100%;
  height: 8px;
  background: #e0e0e0;
  margin: 20px 0;
}

.progress-fill {
  height: 100%;
  background: #4caf50;
  transition: width 0.3s;
}

.question-box {
  margin: 20px 0;
}

.question-text {
  font-size: 18px;
  font-weight: bold;
  margin-bottom: 20px;
  color: #333;
}

.options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.option-btn {
  padding: 15px;
  border: 2px solid #ddd;
  background: white;
  cursor: pointer;
  text-align: left;
  font-size: 16px;
  transition: all 0.3s;
}

.option-btn:hover {
  background: #f5f5f5;
  border-color: #999;
}

.option-btn.selected {
  background: #e3f2fd;
  border-color: #2196f3;
}

.option-btn.correct {
  background: #c8e6c9;
  border-color: #4caf50;
}

.option-btn.incorrect {
  background: #ffcdd2;
  border-color: #f44336;
}

.option-btn:disabled {
  cursor: not-allowed;
}

.result-box {
  margin: 20px 0;
  padding: 15px;
  background: #f5f5f5;
  border-left: 4px solid #2196f3;
  display: none;
}

.result-box.show {
  display: block;
}

.result-box.correct {
  background: #e8f5e9;
  border-color: #4caf50;
}

.result-box.incorrect {
  background: #ffebee;
  border-color: #f44336;
}

#result-message {
  font-size: 18px;
  font-weight: bold;
  margin-bottom: 10px;
}

.explanation {
  margin-top: 10px;
  font-size: 14px;
  color: #666;
}

.next-btn {
  width: 100%;
  padding: 15px;
  background: #2196f3;
  color: white;
  border: 2px solid #2196f3;
  font-size: 16px;
  cursor: pointer;
  margin-top: 20px;
  display: none;
  transition: all 0.3s;
}

.next-btn:hover {
  background: white;
  color: #2196f3;
}

.next-btn.show {
  display: block;
}

.completion-box {
  text-align: center;
  display: none;
}

.completion-box.show {
  display: block;
}

.completion-box h2 {
  font-size: 32px;
  color: #333;
  margin-bottom: 20px;
}

.score {
  font-size: 48px;
  font-weight: bold;
  color: #4caf50;
  margin: 20px 0;
}

.completion-box p {
  font-size: 18px;
  color: #666;
  margin-bottom: 30px;
}

.back-btn {
  display: inline-block;
  padding: 15px 30px;
  background: #2196f3;
  color: white;
  text-decoration: none;
  border: 2px solid #2196f3;
  transition: all 0.3s;
}

.back-btn:hover {
  background: white;
  color: #2196f3;
}

@media (max-width: 768px) {
  .quiz-container {
    padding: 20px;
  }

  .quiz-header h1 {
    font-size: 24px;
  }

  .question-text {
    font-size: 16px;
  }

  .option-btn {
    padding: 12px;
    font-size: 14px;
  }
}