body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: url('quiz.jpg') no-repeat center center fixed;
  background-size: cover;
  color: #333;
  margin: 0;
  padding: 20px;
  transition: background 0.5s ease, color 0.3s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(2px);
  z-index: -1;
}

body.dark {
  background: url('quiz.jpg') no-repeat center center fixed;
  background-size: cover;
  color: #f4f4f4;
}

body.dark::before {
  background: rgba(0, 0, 0, 0.4);
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

h1 {
  margin: 0;
}

#theme-toggle {
  background: none;
  border: none;
  font-size: 24px;
  cursor: pointer;
  padding: 10px;
  border-radius: 50%;
  transition: background-color 0.3s;
}

#theme-toggle:hover {
  background-color: rgba(0,0,0,0.1);
}

.container {
  max-width: 600px;
  margin: 0 auto;
  background-color: white;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0,0,0,0.2);
  padding: 20px;
  transition: background-color 0.3s;
}

body.dark .container {
  background-color: #444;
}

.hidden {
  display: none;
}

#question-number {
  font-size: 14px;
  color: #666;
  margin-bottom: 10px;
}

#question {
  margin-bottom: 20px;
}

#options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 20px;
}

.option {
  padding: 15px;
  border: 2px solid #ddd;
  border-radius: 10px;
  background-color: #fff;
  cursor: pointer;
  font-size: 16px;
  transition: all 0.3s;
}

.option:hover {
  transform: scale(1.03);
  border-color: #4CAF50;
}

.option.selected {
  border-color: #2196F3;
  background-color: #e3f2fd;
}

.option.correct {
  border-color: #4CAF50;
  background-color: #e8f5e8;
}

.option.incorrect {
  border-color: #F44336;
  background-color: #ffebee;
}

#next-btn {
  padding: 10px 20px;
  background-color: #4CAF50;
  color: white;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-size: 16px;
  transition: background-color 0.3s;
}

#next-btn:hover:not(:disabled) {
  background-color: #45a049;
}

#next-btn:disabled {
  background-color: #ccc;
  cursor: not-allowed;
}

#results h2 {
  text-align: center;
  margin-bottom: 20px;
}

#score {
  font-size: 18px;
  text-align: center;
  margin-bottom: 20px;
}

#restart-btn, #review-btn {
  display: block;
  width: 100%;
  padding: 15px;
  margin-bottom: 10px;
  background-color: #2196F3;
  color: white;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-size: 16px;
  transition: background-color 0.3s;
}

#restart-btn:hover, #review-btn:hover {
  background-color: #1976D2;
}

#review-container {
  margin-top: 20px;
}

#review-list {
  margin-top: 10px;
}

.review-item {
  margin-bottom: 15px;
  padding: 10px;
  border-radius: 10px;
  background-color: #f9f9f9;
}

body.dark .review-item {
  background-color: #555;
}

.review-item.correct {
  border-left: 5px solid #4CAF50;
}

.review-item.incorrect {
  border-left: 5px solid #F44336;
}

/* Responsive */
@media (max-width: 600px) {
  body {
    padding: 10px;
  }
  .container {
    padding: 15px;
  }
  #options {
    grid-template-columns: 1fr;
  }
  .option {
    padding: 12px;
  }
}