* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Inter', sans-serif;
}

body {
  background: linear-gradient(135deg, #f0f4f8 0%, #d9e2ec 100%);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  padding: 20px;
  color: #334155;
}

.app-container {
  width: 100%;
  max-width: 700px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 10px;
}

.logo-area {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-circle {
  width: 40px;
  height: 40px;
  background: #2563eb;
  color: white;
  font-weight: 700;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 14px;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
}

.app-header h1 {
  font-size: 18px;
  font-weight: 700;
  color: #1e293b;
  letter-spacing: -0.5px;
}

.student-badge {
  font-size: 13px;
  font-weight: 600;
  color: #64748b;
  background: rgba(255, 255, 255, 0.6);
  padding: 6px 12px;
  border-radius: 20px;
  border: 1px solid #e2e8f0;
}

/* Main Quiz Card */
.quiz-card {
  background: #ffffff;
  padding: 40px;
  border-radius: 24px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.04), 0 1px 3px rgba(0,0,0,0.05);
  border: 1px solid #f1f5f9;
}

.quiz-card-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 2px dashed #e2e8f0;
}

.progress-badge, .score-badge {
  font-size: 14px;
  font-weight: 600;
  color: #475569;
  background: #f8fafc;
  padding: 8px 16px;
  border-radius: 12px;
  border: 1px solid #e2e8f0;
}

#score-val {
  color: #2563eb;
  font-size: 16px;
}

#question-text {
  font-size: 22px;
  font-weight: 700;
  color: #0f172a;
  line-height: 1.4;
  margin-bottom: 32px;
}

/* Options Styles */
#options-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.option-btn {
  padding: 16px 20px;
  border: 2px solid #e2e8f0;
  background-color: #ffffff;
  border-radius: 16px;
  text-align: left;
  cursor: pointer;
  font-size: 16px;
  font-weight: 500;
  color: #334155;
  display: flex;
  align-items: center;
  width: 100%;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.option-btn:hover:not(.disabled) {
  border-color: #cbd5e1;
  background-color: #f8fafc;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.03);
}

.label {
  width: 32px;
  height: 32px;
  background: #f1f5f9;
  border-radius: 10px;
  display: flex;
  justify-content: center;
  align-items: center;
  margin-right: 16px;
  font-weight: 700;
  color: #64748b;
  transition: all 0.2s;
}

/* States */
.option-btn.selected {
  background-color: #eff6ff;
  border-color: #3b82f6;
  color: #1e3a8a;
}

.selected .label {
  background: #3b82f6;
  color: #ffffff;
}

.option-btn.correct {
  background-color: #f0fdf4;
  border-color: #22c55e;
  color: #14532d;
}

.correct .label {
  background: #22c55e;
  color: #ffffff;
}

.option-btn.incorrect {
  background-color: #fef2f2;
  border-color: #ef4444;
  color: #7f1d1d;
}

.incorrect .label {
  background: #ef4444;
  color: #ffffff;
}

.disabled {
  pointer-events: none;
}

/* Action Area & Button */
.action-area {
  margin-top: 32px;
  display: flex;
  justify-content: flex-end;
}

#next-btn {
  padding: 16px 32px;
  background: #2563eb;
  color: white;
  border: none;
  border-radius: 14px;
  cursor: pointer;
  font-weight: 600;
  font-size: 16px;
  transition: all 0.2s;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}

#next-btn:hover:not(:disabled) {
  background: #1d4ed8;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

#next-btn:disabled {
  background: #cbd5e1;
  color: #94a3b8;
  cursor: not-allowed;
  box-shadow: none;
  transform: none;
}

@media (max-width: 600px) {
  .app-header {
    flex-direction: column;
    gap: 16px;
    align-items: flex-start;
  }
  .quiz-card {
    padding: 24px;
  }
  #question-text {
    font-size: 18px;
  }
}