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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  padding: 20px;
}

.container {
  max-width: 600px;
  margin: 0 auto;
}

header {
  text-align: center;
  color: white;
  margin-bottom: 30px;
}

header h1 {
  font-size: 2.5rem;
  margin-bottom: 5px;
}

.subtitle {
  opacity: 0.9;
  font-size: 1.1rem;
}

.card {
  background: white;
  border-radius: 16px;
  padding: 24px;
  margin-bottom: 20px;
  box-shadow: 0 10px 40px rgba(0,0,0,0.1);
}

.card h2 {
  color: #333;
  margin-bottom: 12px;
  font-size: 1.3rem;
}

.card p {
  color: #666;
  line-height: 1.6;
}

.hidden {
  display: none !important;
}

/* Buttons */
.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.btn:active {
  transform: translateY(0);
}

.btn-primary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
}

.btn-secondary {
  background: #f0f0f0;
  color: #333;
}

.btn-danger {
  background: #ff4757;
  color: white;
}

.button-group {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 15px;
}

/* Question Section */
.question-text {
  font-size: 1.1rem;
  color: #333;
  margin-bottom: 20px;
  line-height: 1.6;
}

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

.option-btn {
  padding: 15px 20px;
  background: #f8f9fa;
  border: 2px solid #e9ecef;
  border-radius: 10px;
  text-align: left;
  cursor: pointer;
  transition: all 0.2s;
  font-size: 1rem;
}

.option-btn:hover {
  border-color: #667eea;
  background: #f0f1ff;
}

.option-btn.selected {
  border-color: #667eea;
  background: #667eea;
  color: white;
}

.option-btn.correct {
  border-color: #2ed573;
  background: #2ed573;
  color: white;
}

.option-btn.incorrect {
  border-color: #ff4757;
  background: #ff4757;
  color: white;
}

/* Result Section */
.result-header {
  padding: 20px;
  border-radius: 10px;
  text-align: center;
  margin-bottom: 20px;
  font-size: 1.3rem;
  font-weight: bold;
}

.result-header.correct {
  background: #d4edda;
  color: #155724;
}

.result-header.incorrect {
  background: #f8d7da;
  color: #721c24;
}

.explanation {
  background: #f8f9fa;
  padding: 15px;
  border-radius: 10px;
  margin: 15px 0;
}

.explanation h3 {
  color: #333;
  margin-bottom: 10px;
  font-size: 1rem;
}

.explanation p {
  font-size: 0.95rem;
  line-height: 1.7;
}

#result-section .btn {
  width: 100%;
  margin-top: 10px;
}

/* Schedule Section */
.schedule-options {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 15px;
  align-items: center;
}

.schedule-options select {
  flex: 1;
  min-width: 200px;
  padding: 12px;
  border: 2px solid #e9ecef;
  border-radius: 8px;
  font-size: 1rem;
}

.status {
  margin-top: 15px;
  padding: 10px;
  border-radius: 8px;
  font-size: 0.9rem;
}

.status.active {
  background: #d4edda;
  color: #155724;
}

.status.inactive {
  background: #f8f9fa;
  color: #666;
}

/* Stats Section */
.stats {
  display: flex;
  justify-content: space-around;
  margin-top: 15px;
}

.stat {
  text-align: center;
}

.stat-value {
  display: block;
  font-size: 2rem;
  font-weight: bold;
  color: #667eea;
}

.stat-label {
  color: #666;
  font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 480px) {
  .button-group, .schedule-options {
    flex-direction: column;
  }
  
  .btn, .schedule-options select {
    width: 100%;
  }
  
  header h1 {
    font-size: 2rem;
  }
}