/* styles.css - Theme THUẾ VIỆT NAM LMS & ÔN TẬP */
:root {
  --tax-red: #b71c1c;
  --tax-red-dark: #8b0000;
  --tax-gold: #f59e0b;
  --tax-gold-light: #fef3c7;
  --tax-blue: #1e40af;
  --tax-blue-light: #eff6ff;
  --tax-dark: #0f172a;
  --tax-slate: #334155;
  --tax-bg: #f8fafc;
  --tax-card: #ffffff;
  --tax-border: #e2e8f0;
  --tax-green: #10b981;
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--tax-bg);
  color: #0f172a;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Question & Reading clarity enhancements */
#practice-q-text, #off-q-text {
  font-size: 1.18rem !important; /* ~19px */
  line-height: 1.65 !important;
  color: #090d16 !important; /* Đậm nét tuyệt đối, không bị xám mờ */
  font-weight: 700 !important;
  letter-spacing: -0.01em;
}

.tax-header {
  background: linear-gradient(135deg, #a81c1c 0%, #800000 100%);
  color: white;
  box-shadow: 0 4px 12px rgba(183, 28, 28, 0.15);
}

.nav-link {
  transition: all 0.2s ease;
  border-bottom: 2px solid transparent;
}
.nav-link:hover {
  color: #fef08a;
}
.nav-link.active {
  color: #ffffff;
  border-bottom: 2px solid #fef08a;
  font-weight: 600;
}

.badge-tag {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.6rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.question-btn {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  font-weight: 700;
  font-size: 0.9rem;
  transition: all 0.15s ease;
  border: 1.5px solid #cbd5e1;
  background: white;
  color: #1e293b;
}
.question-btn:hover {
  border-color: #3b82f6;
  background: #eff6ff;
}
.question-btn.answered {
  background: #2563eb;
  color: white;
  border-color: #1d4ed8;
}
.question-btn.flagged {
  border-color: #f59e0b;
  background: #fffbeb;
  color: #b45309;
}
.question-btn.answered.flagged {
  background: #f59e0b;
  color: white;
  border-color: #d97706;
}
.question-btn.current {
  outline: 2.5px solid #dc2626;
  outline-offset: 2px;
}
.question-btn.correct {
  background: #10b981;
  color: white;
  border-color: #059669;
}
.question-btn.wrong {
  background: #ef4444;
  color: white;
  border-color: #dc2626;
}

.option-card {
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border: 1.5px solid #cbd5e1;
  background-color: #ffffff;
  color: #0f172a;
  font-size: 1.02rem !important; /* ~16.5px, rõ ràng */
  font-weight: 500 !important;
  line-height: 1.6 !important;
}
.option-card:hover {
  border-color: #3b82f6;
  background-color: #f8fafc;
}
.option-card.selected {
  border-color: #2563eb;
  background-color: #eff6ff;
  box-shadow: 0 0 0 1.5px #2563eb;
  font-weight: 600 !important;
}
.option-card.correct-ans {
  border-color: #10b981;
  background-color: #ecfdf5;
  box-shadow: 0 0 0 1.5px #10b981;
}
.option-card.wrong-ans {
  border-color: #ef4444;
  background-color: #fef2f2;
  box-shadow: 0 0 0 1.5px #ef4444;
}

.timer-box {
  font-family: "Courier New", Courier, monospace;
  font-weight: 700;
  letter-spacing: 1px;
}
.timer-warning {
  color: #dc2626;
  animation: pulse 1s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

/* Modal animation */
.modal-overlay {
  background-color: rgba(15, 23, 42, 0.6);
  backdrop-filter: blur(2px);
}