* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Main body styling with centered layout and responsive design */
body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

/* Main quiz container with clean, minimal design */
.quiz-container {
  background: white;
  border-radius: 20px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
  padding: 40px;
  max-width: 600px;
  width: 100%;
}

/* Quiz header styling */
.quiz-header {
  text-align: center;
  margin-bottom: 30px;
}

.quiz-title {
  font-size: 2.5rem;
  color: #333;
  margin-bottom: 10px;
  font-weight: 700;
}

.quiz-subtitle {
  color: #666;
  font-size: 1.1rem;
}

/* Question container styling */
.question-container {
  margin-bottom: 30px;
}

.question-text {
  font-size: 1.3rem;
  color: #333;
  line-height: 1.6;
  margin-bottom: 25px;
  font-weight: 500;
}

/* Answer options grid layout */
.answer-options {
  display: grid;
  gap: 15px;
  margin-bottom: 30px;
}

/* Individual answer option buttons with hover effects */
.answer-option {
  background: #f8f9fa;
  border: 2px solid #e9ecef;
  border-radius: 12px;
  padding: 15px 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-size: 1rem;
  text-align: left;
  color: #333;
}

/* Hover effect for answer options */
.answer-option:hover {
  background: #e9ecef;
  border-color: #667eea;
  transform: translateY(-2px);
}

/* Selected state for answer options */
.answer-option.selected {
  background: #667eea;
  border-color: #667eea;
  color: white;
}

/* Submit button with gradient background and hover effects */
.submit-button {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  border-radius: 12px;
  padding: 15px 30px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  width: 100%;
  margin-bottom: 20px;
}

/* Hover effect for submit button */
.submit-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

/* Disabled state for submit button */
.submit-button:disabled {
  background: #ccc;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* Next button styling - similar to submit button */
.next-button {
  background: linear-gradient(135deg, #28a745 0%, #20c997 100%);
  color: white;
  border: none;
  border-radius: 12px;
  padding: 15px 30px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  width: 100%;
  margin-bottom: 20px;
}

/* Hover effect for next button */
.next-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(40, 167, 69, 0.3);
}

/* Disabled state for next button */
.next-button:disabled {
  background: #ccc;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* Focus state for next button */
.next-button:focus {
  outline: 2px solid #28a745;
  outline-offset: 2px;
}

/* Quiz completion screen styling */
.completion-container {
  text-align: center;
  padding: 20px 0;
}

.completion-title {
  font-size: 2.5rem;
  color: #333;
  margin-bottom: 30px;
  font-weight: 700;
}

.final-score {
  margin-bottom: 30px;
}

.final-score h3 {
  font-size: 1.5rem;
  color: #666;
  margin-bottom: 15px;
  font-weight: 600;
}

.score-display-large {
  font-size: 3rem;
  font-weight: 700;
  color: #667eea;
  margin-bottom: 20px;
}

.completion-message {
  font-size: 1.3rem;
  color: #333;
  margin-bottom: 30px;
  line-height: 1.6;
}

.restart-button {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  border-radius: 12px;
  padding: 15px 30px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  width: 100%;
}

.restart-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

.restart-button:focus {
  outline: 2px solid #667eea;
  outline-offset: 2px;
}

/* Feedback container for displaying correct/incorrect messages */
.feedback-container {
  margin-top: 20px;
  padding: 20px;
  border-radius: 12px;
  text-align: center;
  font-weight: 600;
  font-size: 1.1rem;
  display: none;
}

/* Correct answer feedback styling */
.feedback-correct {
  background: #d4edda;
  color: #155724;
  border: 1px solid #c3e6cb;
}

/* Incorrect answer feedback styling */
.feedback-incorrect {
  background: #f8d7da;
  color: #721c24;
  border: 1px solid #f5c6cb;
}

/* Score display styling */
.score-display {
  text-align: center;
  font-size: 1.2rem;
  color: #333;
  font-weight: 600;
  margin-top: 15px;
}

/* Progress bar container */
.progress-bar {
  width: 100%;
  height: 8px;
  background: #e9ecef;
  border-radius: 4px;
  margin-bottom: 20px;
  overflow: hidden;
}

/* Progress bar fill animation */
.progress-fill {
  height: 100%;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  width: 0%;
  transition: width 0.3s ease;
}

/* NEW: Mobile responsive design improvements */
@media (max-width: 768px) {
  .quiz-container {
    padding: 20px;
    margin: 10px;
  }
  
  .quiz-title {
    font-size: 2rem;
  }
  
  .question-text {
    font-size: 1.1rem;
  }
  
  .answer-option {
    padding: 12px 16px;
    font-size: 0.95rem;
  }
  
  .submit-button {
    padding: 12px 24px;
    font-size: 1rem;
  }
}

/* NEW: Tablet responsive design */
@media (max-width: 1024px) and (min-width: 769px) {
  .quiz-container {
    max-width: 500px;
  }
}

/* NEW: Focus states for accessibility */
.answer-option:focus,
.submit-button:focus {
  outline: 2px solid #667eea;
  outline-offset: 2px;
}

/* NEW: Smooth transitions for better UX */
* {
  transition: all 0.2s ease;
}

/* Loading state styling */
.loading-container {
  text-align: center;
  padding: 40px 20px;
}

.loading-container h2 {
  font-size: 2rem;
  color: #333;
  margin-bottom: 15px;
  font-weight: 600;
}

.loading-container p {
  font-size: 1.1rem;
  color: #666;
  margin-bottom: 30px;
}

.loading-spinner {
  width: 50px;
  height: 50px;
  border: 4px solid #e9ecef;
  border-top: 4px solid #667eea;
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin: 0 auto;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* Error state styling */
.error-container {
  text-align: center;
  padding: 40px 20px;
}

.error-container h2 {
  font-size: 2rem;
  color: #721c24;
  margin-bottom: 20px;
  font-weight: 600;
}

.error-container p {
  font-size: 1.1rem;
  color: #666;
  margin-bottom: 15px;
}

.error-details {
  font-size: 0.9rem;
  color: #721c24;
  background: #f8d7da;
  padding: 10px;
  border-radius: 8px;
  margin: 20px 0;
}

.retry-button {
  background: linear-gradient(135deg, #dc3545 0%, #c82333 100%);
  color: white;
  border: none;
  border-radius: 12px;
  padding: 15px 30px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  width: 100%;
  margin-top: 20px;
}

.retry-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px rgba(220, 53, 69, 0.3);
}

.retry-button:focus {
  outline: 2px solid #dc3545;
  outline-offset: 2px;
}