/* ================================================================
   HỆ THỐNG THI GPLX - Admin & Exam CSS v2.1
   Kết hợp thiết kế nội bộ + chuẩn từ mẫu tham chiếu
   ================================================================ */

/* Google Fonts đã load trong header */
:root {
  /* Brand */
  --primary: #1d4ed8;
  --primary-light: #3b82f6;
  --primary-hover: #1e40af;
  --primary-soft: #eff6ff;

  /* Status */
  --success: #16a34a;
  --danger: #dc2626;
  --warning: #d97706;
  --info: #0891b2;

  /* Greys */
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, .05);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, .1), 0 1px 2px rgba(0, 0, 0, .06);
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, .1), 0 2px 4px -1px rgba(0, 0, 0, .06);
  --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, .1), 0 4px 6px -2px rgba(0, 0, 0, .05);

  /* Layout */
  --sidebar-w: 220px;
  --topbar-h: 60px;
  --radius: 8px;
  --radius-lg: 12px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans', sans-serif;
}

/* ── Reset ── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font);
  color: var(--gray-800);
  background: var(--gray-100);
  line-height: 1.5;
  font-size: 15px;
}

a {
  color: var(--primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

img {
  max-width: 100%;
}

/* ── Scrollbar ── */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: #f1f1f1;
  border-radius: 3px;
}

::-webkit-scrollbar-thumb {
  background: #aab;
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: #778;
}

/* ── Typography ── */
h1 {
  font-size: 1.75rem;
  font-weight: 700;
}

h2 {
  font-size: 1.4rem;
  font-weight: 700;
}

h3 {
  font-size: 1.15rem;
  font-weight: 600;
}

.text-center {
  text-align: center;
}

.text-right {
  text-align: right;
}

.text-muted {
  color: var(--gray-500);
}

.text-sm {
  font-size: 0.875rem;
}

.text-xs {
  font-size: 0.75rem;
}

.text-success {
  color: var(--success);
}

.text-danger {
  color: var(--danger);
}

.text-warning {
  color: var(--warning);
}

.font-semibold {
  font-weight: 600;
}

.font-bold {
  font-weight: 700;
}

/* Spacing utils */
.mt-1 {
  margin-top: .25rem
}

.mt-2 {
  margin-top: .5rem
}

.mt-3 {
  margin-top: .75rem
}

.mt-4 {
  margin-top: 1rem
}

.mt-6 {
  margin-top: 1.5rem
}

.mb-1 {
  margin-bottom: .25rem
}

.mb-2 {
  margin-bottom: .5rem
}

.mb-3 {
  margin-bottom: .75rem
}

.mb-4 {
  margin-bottom: 1rem
}

.mb-6 {
  margin-bottom: 1.5rem
}

.mr-2 {
  margin-right: .5rem
}

.ml-2 {
  margin-left: .5rem
}

.ml-auto {
  margin-left: auto
}

.d-flex {
  display: flex
}

.align-center {
  align-items: center
}

.justify-between {
  justify-content: space-between
}

.gap-2 {
  gap: .5rem
}

.gap-3 {
  gap: .75rem
}

.gap-4 {
  gap: 1rem
}

.w-full {
  width: 100%
}

.d-none {
  display: none
}

/* ── Loading Spinner ── */
.spinner {
  display: inline-block;
  width: 18px;
  height: 18px;
  border: 2px solid rgba(255, 255, 255, 0.35);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.75s linear infinite;
  vertical-align: middle;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* ── Modal animation ── */
.modal-enter {
  animation: modalIn 0.2s ease-out;
}

@keyframes modalIn {
  from {
    opacity: 0;
    transform: scale(0.95) translateY(8px);
  }

  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

/* ======= MODAL ======= */
.modal {
  position: fixed;
  inset: 0;
  z-index: 1000;
  background: rgba(15, 23, 42, 0.6);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: all 0.2s;
}

.modal.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-content {
  background: #fff;
  width: 90%;
  max-width: 500px;
  border-radius: var(--radius-lg);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  transform: scale(0.95) translateY(10px);
  transition: all 0.2s;
  overflow: hidden;
}

.modal.active .modal-content {
  transform: scale(1) translateY(0);
}

.modal-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--gray-200);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.modal-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--gray-800);
  margin: 0;
}

.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  line-height: 1;
  color: var(--gray-500);
  cursor: pointer;
  padding: 0.25rem;
  transition: color 0.15s;
}

.modal-close:hover {
  color: var(--danger);
}

.modal-body {
  padding: 1.25rem;
  max-height: 70vh;
  overflow-y: auto;
}

.modal-footer {
  padding: 1rem 1.25rem;
  border-top: 1px solid var(--gray-100);
  background: var(--gray-50);
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

/* ────────────────────────────────────────────────────────────────
   ADMIN SIDEBAR LAYOUT
──────────────────────────────────────────────────────────────── */
.admin-body {
  display: flex;
  min-height: 100vh;
  background: var(--gray-100);
}

/* ── Sidebar ── */
.admin-sidebar {
  width: var(--sidebar-w);
  background: var(--gray-900);
  min-height: 100vh;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  display: flex;
  flex-direction: column;
  z-index: 200;
  overflow-y: auto;
}

.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 18px 16px;
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}

.sidebar-brand-icon {
  width: 38px;
  height: 38px;
  background: var(--primary);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  flex-shrink: 0;
  color: white;
}

.sidebar-brand-text {
  color: white;
  font-weight: 700;
  font-size: .95rem;
  line-height: 1.2;
}

.sidebar-brand-sub {
  color: var(--gray-400);
  font-size: 0.7rem;
}

.sidebar-section-label {
  color: var(--gray-500);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 14px 18px 5px;
}

.sidebar-menu {
  list-style: none;
  padding: 4px 0;
}

.sidebar-menu li {
  padding: 1px 10px;
}

.sidebar-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  color: #94a3b8;
  border-radius: var(--radius);
  font-weight: 500;
  font-size: 0.875rem;
  transition: all 0.15s;
}

.sidebar-link:hover {
  background: rgba(255, 255, 255, .07);
  color: white;
  text-decoration: none;
}

.sidebar-link.active {
  background: var(--primary);
  color: white;
}

.sidebar-link-icon {
  font-size: 1rem;
  width: 18px;
  text-align: center;
  flex-shrink: 0;
}

.sidebar-user {
  margin-top: auto;
  padding: 14px 16px;
  border-top: 1px solid rgba(255, 255, 255, .08);
}

.sidebar-user-name {
  color: var(--gray-300);
  font-size: 0.83rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.sidebar-user-role {
  font-size: 0.72rem;
}

.sidebar-logout {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-top: 8px;
  color: #fca5a5;
  font-size: 0.82rem;
  font-weight: 500;
}

.sidebar-logout:hover {
  color: #f87171;
  text-decoration: none;
}

/* ── Topbar ── */
.admin-topbar {
  height: var(--topbar-h);
  background: white;
  border-bottom: 1px solid var(--gray-200);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  position: fixed;
  top: 0;
  left: var(--sidebar-w);
  right: 0;
  z-index: 100;
  box-shadow: var(--shadow-xs);
}

.topbar-greeting {
  font-size: 0.875rem;
  color: var(--gray-600);
}

.topbar-greeting strong {
  color: var(--gray-800);
}

.topbar-role-badge {
  display: inline-block;
  padding: 2px 8px;
  background: #ede9fe;
  color: #6d28d9;
  border-radius: 99px;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  margin-left: 6px;
  letter-spacing: .03em;
}

.topbar-role-badge.admin {
  background: #fef9c3;
  color: #854d0e;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.btn-exam-link {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--primary-soft);
  color: var(--primary);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius);
  padding: 6px 14px;
  font-size: 0.83rem;
  font-weight: 500;
  transition: all 0.15s;
}

.btn-exam-link:hover {
  background: var(--primary);
  color: white;
  text-decoration: none;
  border-color: var(--primary);
}

/* ── Main content ── */
.admin-content {
  margin-left: var(--sidebar-w);
  margin-top: var(--topbar-h);
  flex: 1;
  padding: 1.75rem;
  min-height: calc(100vh - var(--topbar-h));
}

/* ── Page header ── */
.page-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1.25rem;
}

.page-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 2px;
}

.page-subtitle {
  color: var(--gray-500);
  font-size: 0.85rem;
}

/* ── Flash alert ── */
.flash-bar {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 9999;
  min-width: 320px;
  padding: 14px 20px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 15px;
  font-weight: 600;
  font-size: .9rem;
  box-shadow: var(--shadow-md);
  animation: slideInUp 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes slideInUp {
  from {
    transform: translateY(120%);
    opacity: 0;
  }

  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.flash-bar.success {
  background: #f0fdf4;
  color: #15803d;
  border: 1px solid #bbf7d0;
}

.flash-bar.error {
  background: #fef2f2;
  color: #b91c1c;
  border: 1px solid #fecaca;
}

.flash-bar.danger {
  background: #fef2f2;
  color: #b91c1c;
  border: 1px solid #fecaca;
}

.flash-bar.info {
  background: #eff6ff;
  color: #1d4ed8;
  border: 1px solid #bfdbfe;
}

.flash-bar.warning {
  background: #fffbeb;
  color: #92400e;
  border: 1px solid #fde68a;
}

.flash-close {
  background: none;
  border: none;
  cursor: pointer;
  color: inherit;
  opacity: .4;
  font-size: 1.2rem;
  line-height: 1;
}

.flash-close:hover {
  opacity: 1;
}

/* Alert */
.alert {
  padding: 11px 16px;
  border-radius: var(--radius);
  margin-bottom: 1rem;
  font-size: .875rem;
}

.alert-info {
  background: #eff6ff;
  color: #1e40af;
  border: 1px solid #93c5fd;
}

.alert-success {
  background: #dcfce7;
  color: #166534;
  border: 1px solid #86efac;
}

.alert-warning {
  background: #fffbeb;
  color: #92400e;
  border: 1px solid #fcd34d;
}

.alert-error {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fca5a5;
}

/* ── Cards ── */
.card {
  background: white;
  border-radius: var(--radius-lg);
  border: 1px solid var(--gray-200);
  box-shadow: var(--shadow-xs);
  overflow: hidden;
}

.card-header {
  padding: .9rem 1.25rem;
  border-bottom: 1px solid var(--gray-100);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-title {
  font-size: .95rem;
  font-weight: 600;
  color: var(--gray-800);
}

.card-body {
  padding: 1.25rem;
}

.card>form {
  padding: 1.25rem;
}

/* ── Stat cards ── */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.stat-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.35rem;
  border: 1px solid var(--gray-200);
  box-shadow: var(--shadow-xs);
  display: flex;
  align-items: center;
  gap: 1rem;
  transition: box-shadow 0.2s, transform 0.2s;
}

.stat-card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.stat-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  flex-shrink: 0;
}

.stat-icon-blue {
  background: #dbeafe;
  color: #2563eb;
}

.stat-icon-green {
  background: #dcfce7;
  color: #16a34a;
}

.stat-icon-yellow {
  background: #fef9c3;
  color: #b45309;
}

.stat-icon-purple {
  background: #ede9fe;
  color: #7c3aed;
}

.stat-value {
  font-size: 1.7rem;
  font-weight: 800;
  color: var(--gray-900);
  line-height: 1;
}

.stat-label {
  color: var(--gray-500);
  font-size: 0.78rem;
  font-weight: 500;
  margin-top: 4px;
}

/* ── Grid layouts ── */
.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
}

.grid-12-5 {
  display: grid;
  grid-template-columns: 7fr 5fr;
  gap: 1.25rem;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 0.5rem 1.1rem;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  white-space: nowrap;
  line-height: 1.4;
}

.btn:hover {
  text-decoration: none;
}

.btn-sm {
  padding: 0.28rem 0.7rem;
  font-size: 0.8rem;
}

.btn-lg {
  padding: 0.65rem 1.4rem;
  font-size: 0.95rem;
}

.btn-block {
  display: flex;
  width: 100%;
  justify-content: center;
}

.btn-icon {
  padding: 0.38rem 0.45rem;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-hover);
  color: white;
}

.btn-success {
  background: var(--success);
  color: white;
}

.btn-success:hover {
  background: #15803d;
  color: white;
}

.btn-danger {
  background: var(--danger);
  color: white;
}

.btn-danger:hover {
  background: #b91c1c;
  color: white;
}

.btn-warning {
  background: var(--warning);
  color: white;
}

.btn-info {
  background: var(--info);
  color: white;
}

.btn-gray {
  background: var(--gray-100);
  color: var(--gray-700);
  border: 1px solid var(--gray-200);
}

.btn-gray:hover {
  background: var(--gray-200);
}

.btn-outline {
  background: transparent;
  border: 1px solid var(--gray-300);
  color: var(--gray-600);
}

.btn-outline:hover {
  background: var(--gray-50);
  border-color: var(--gray-400);
}

/* ── Badges ── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  padding: 2px 8px;
  border-radius: 9999px;
  font-size: 11px;
  font-weight: 600;
  line-height: 1.5;
}

.badge-blue {
  background: #eff6ff;
  color: #1e40af;
}

.badge-green {
  background: #dcfce7;
  color: #166534;
}

.badge-red {
  background: #fef2f2;
  color: #991b1b;
}

.badge-yellow {
  background: #fffbeb;
  color: #92400e;
}

.badge-gray {
  background: #f3f4f6;
  color: #374151;
}

.badge-purple {
  background: #f5f3ff;
  color: #6d28d9;
}

/* ── Status badges ── */
.status-active {
  background: #dcfce7;
  color: #166534;
}

.status-pending {
  background: #fffbeb;
  color: #92400e;
}

.status-paused {
  background: #fef3c7;
  color: #b45309;
}

.status-finished {
  background: #f3f4f6;
  color: #6b7280;
}

.status-closed {
  background: #f3f4f6;
  color: #6b7280;
}

/* ── Tables ── */
.table-wrap {
  overflow-x: auto;
  width: 100%;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
}

.data-table th {
  background: #f8fafc;
  color: #64748b;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 10px 14px;
  border-bottom: 2px solid #e2e8f0;
  text-align: left;
}

.data-table td {
  padding: 11px 14px;
  border-bottom: 1px solid #f1f5f9;
  font-size: 13px;
  color: #374151;
  vertical-align: middle;
}

.data-table tbody tr:hover td {
  background: #f8fafc;
}

.data-table tbody tr:last-child td {
  border-bottom: none;
}

/* ── Forms ── */
.form-group {
  margin-bottom: 1rem;
}

.form-label {
  display: block;
  margin-bottom: 0.35rem;
  font-weight: 600;
  font-size: 13px;
  color: #374151;
}

.form-input,
.form-select,
.form-textarea {
  padding: 10px 12px;
  line-height: 1.5;
  border: 1.5px solid #d1d5db;
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: 14px;
  color: var(--gray-800);
  background: white;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--primary-light);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.12);
}

.form-input.error {
  border-color: #ef4444;
}

.form-input-sm {
  padding: 0.3rem 0.65rem;
  font-size: 0.8rem;
}

.form-textarea {
  resize: vertical;
  min-height: 80px;
}

.form-hint {
  font-size: 0.78rem;
  color: var(--gray-500);
  margin-top: 4px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

/* ── Question cards (Q Bank) ── */
.q-card {
  background: white;
  border: 1px solid var(--gray-200);
  border-left: 4px solid var(--primary-light);
  border-radius: var(--radius-lg);
  padding: 1rem 1.15rem;
  transition: box-shadow 0.18s;
}

.q-card:hover {
  box-shadow: var(--shadow-sm);
}

.q-card.fatal {
  border-left-color: #f87171;
}

.q-opt-row {
  display: flex;
  align-items: flex-start;
  gap: 7px;
  padding: 5px 8px;
  border-radius: 6px;
  background: #f9fafb;
  border: 1px solid #f3f4f6;
}

.q-opt-row.correct {
  background: #f0fdf4;
  border-color: #bbf7d0;
  color: #166534;
  font-weight: 600;
}

.q-opt-badge {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #e5e7eb;
  color: #374151;
  font-size: 0.7rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.q-opt-row.correct .q-opt-badge {
  background: #16a34a;
  color: white;
}

.btn-icon-edit {
  background: none;
  border: 1px solid transparent;
  border-radius: 6px;
  padding: 4px 7px;
  cursor: pointer;
  color: var(--primary);
  font-size: .85rem;
  flex-shrink: 0;
  transition: background .15s;
}

.btn-icon-edit:hover {
  background: #eff6ff;
  border-color: #bfdbfe;
}

/* Answer rows in question form modal */
.ans-row {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  margin-bottom: .6rem;
  padding: .65rem;
  background: #f9fafb;
  border-radius: 8px;
  border: 1px solid #f3f4f6;
}

.ans-letter {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: #e5e7eb;
  color: #374151;
  font-size: .78rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 6px;
}

.ans-radio-label {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  cursor: pointer;
  flex-shrink: 0;
}

.ans-radio-check {
  font-size: .65rem;
  color: var(--gray-500);
  white-space: nowrap;
}

.ans-radio-label input[type=radio]:checked~.ans-radio-check {
  color: var(--success);
  font-weight: 700;
}

/* Media picker */
.mp-tab {
  padding: .5rem 1rem;
  font-size: .83rem;
  font-weight: 500;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--gray-500);
  border-bottom: 2px solid transparent;
  transition: color .15s;
}

.mp-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.mp-img-item {
  border-radius: 8px;
  overflow: hidden;
  border: 2px solid #e5e7eb;
  cursor: pointer;
  transition: border-color .15s;
  aspect-ratio: 1;
  position: relative;
}

.mp-img-item:hover,
.mp-img-item.selected {
  border-color: var(--primary);
}

.mp-img-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.mp-img-name {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 3px 6px;
  background: rgba(0, 0, 0, .6);
  color: white;
  font-size: .62rem;
  line-height: 1.2;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Bộ đề chips */
.qset-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: .3rem .7rem;
  background: white;
  border: 1px solid var(--gray-200);
  border-radius: 99px;
  box-shadow: var(--shadow-xs);
  font-size: .82rem;
}

.qset-chip.active {
  border-color: var(--primary);
  background: #eff6ff;
}

/* ── Audit log terminal ── */
.audit-log {
  background: var(--gray-900);
  color: #34d399;
  font-family: 'Courier New', monospace;
  padding: 1rem;
  height: 300px;
  overflow-y: auto;
  font-size: 0.8rem;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

.audit-line {
  padding: 2px 0;
  border-bottom: 1px solid rgba(255, 255, 255, .04);
}

/* ── Login page ── */
.login-body {
  background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 50%, #0f172a 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}

.login-wrapper {
  width: 100%;
  max-width: 420px;
  padding: 1rem;
}

.login-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-md);
}

.login-logo {
  font-size: 3rem;
  text-align: center;
  margin-bottom: 0.5rem;
}

.login-title {
  text-align: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

.login-sub {
  text-align: center;
  color: var(--gray-500);
  font-size: 0.875rem;
  margin-bottom: 2rem;
}

.login-note {
  margin-top: 1rem;
  font-size: 0.78rem;
  color: var(--danger);
  text-align: center;
}

/* ── Misc ── */
.divider {
  height: 1px;
  background: var(--gray-100);
  margin: 1rem 0;
}

.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--gray-500);
}

.empty-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.profile-photo {
  width: 120px;
  height: 160px;
  object-fit: cover;
  border-radius: var(--radius);
  border: 2px solid var(--gray-200);
}

.profile-photo-placeholder {
  width: 120px;
  height: 160px;
  background: var(--gray-100);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  margin: 0 auto;
}

/* ── Result items (Dashboard) ── */
.result-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0;
  border-bottom: 1px solid var(--gray-100);
}

.result-item:last-child {
  border-bottom: none;
}

.result-name {
  font-weight: 600;
  font-size: 0.875rem;
}

.result-meta {
  font-size: 0.75rem;
  color: var(--gray-500);
}

.result-score {
  font-size: 1rem;
  font-weight: 700;
}

.result-score.pass {
  color: var(--success);
}

.result-score.fail {
  color: var(--danger);
}

/* ── Pagination ── */
.pagination {
  display: flex;
  align-items: center;
  gap: 4px;
}

.page-item {
  min-width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  font-size: 0.875rem;
  cursor: pointer;
  border: 1px solid var(--gray-200);
  color: var(--gray-700);
  transition: all .15s;
}

.page-item.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
  font-weight: 600;
}

.page-item:hover:not(.active) {
  background: var(--gray-50);
  border-color: var(--gray-300);
}

.page-item:disabled {
  opacity: .4;
  cursor: not-allowed;
}

/* ════════════════════════════════════════════════════════════
   STUDENT / EXAM UI (Mobile First)
   Lấy từ chuẩn mẫu — tối ưu cho màn hình nhỏ và touch
════════════════════════════════════════════════════════════ */
.exam-body {
  background: var(--gray-100);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  -webkit-user-select: none;
  user-select: none;
}

/* Intro / Login */
.exam-intro-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 1rem;
}

.exam-intro-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-md);
  width: 100%;
  max-width: 400px;
  text-align: center;
}

.intro-logo {
  font-size: 4rem;
  margin-bottom: 1rem;
}

/* Exam header */
.exam-header {
  background: var(--primary);
  color: white;
  padding: 10px 15px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}

.exam-title {
  font-weight: 700;
  font-size: 1.05rem;
}

.exam-student {
  font-size: 0.83rem;
  opacity: .9;
}

.exam-timer {
  font-size: 1.45rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  background: rgba(0, 0, 0, .2);
  padding: 5px 14px;
  border-radius: 6px;
}

.btn-submit-exam {
  font-weight: 700;
  font-size: 1rem;
  padding: 8px 20px;
}

/* Question area */
.exam-layout {
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - 60px);
}

.exam-content-area {
  flex: 1;
  padding: 15px;
  padding-bottom: 250px;
  overflow-y: auto;
  max-width: 800px;
  margin: 0 auto;
  width: 100%;
}

.question-card {
  background: white;
  border-radius: 12px;
  padding: 20px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--gray-200);
}

.question-number {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--primary);
  border-bottom: 2px solid var(--gray-100);
  padding-bottom: 10px;
  margin-bottom: 14px;
}

.question-text {
  font-size: 1.1rem;
  font-weight: 500;
  line-height: 1.65;
}

/* Answer options — chuẩn mẫu */
.answer-option {
  width: 100%;
  padding: 14px 16px;
  border: 2px solid #e5e7eb;
  border-radius: 12px;
  background: white;
  text-align: left;
  cursor: pointer;
  font-size: 14px;
  line-height: 1.5;
  color: #374151;
  transition: all 0.15s;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  min-height: 48px;
}

.answer-option:active {
  transform: scale(0.98);
}

.answer-option:hover {
  border-color: #93c7af;
  background: #f0fdf4;
}

.answer-option.selected {
  border-color: #16a34a;
  background: #dcfce7;
  color: #166534;
  font-weight: 500;
}

.answer-option.correct {
  border-color: #16a34a;
  background: #dcfce7;
}

.answer-option.wrong {
  border-color: #ef4444;
  background: #fef2f2;
}

.answer-letter {
  min-width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 2px solid currentColor;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 12px;
  flex-shrink: 0;
  margin-top: -1px;
}

.answer-option.selected .answer-letter {
  background: #16a34a;
  border-color: #16a34a;
  color: white;
}

.answer-option.correct .answer-letter {
  background: #16a34a;
  border-color: #16a34a;
  color: white;
}

.answer-option.wrong .answer-letter {
  background: #ef4444;
  border-color: #ef4444;
  color: white;
}

/* Legacy option styles */
.options-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.option-item {
  display: flex;
  align-items: center;
  padding: 13px;
  border: 2px solid var(--gray-200);
  border-radius: 10px;
  cursor: pointer;
  transition: all .15s;
  background: white;
}

.option-item input[type="radio"] {
  display: none;
}

.option-label {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--gray-100);
  color: var(--gray-700);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: .95rem;
  margin-right: 12px;
  flex-shrink: 0;
}

.option-text {
  font-size: .95rem;
  line-height: 1.5;
}

.option-item.selected {
  border-color: var(--primary);
  background: var(--primary-soft);
}

.option-item.selected .option-label {
  background: var(--primary);
  color: white;
}

/* Question nav grid */
.exam-nav-grid {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: white;
  border-top: 1px solid var(--gray-200);
  padding: 10px;
  box-shadow: 0 -4px 6px -1px rgba(0, 0, 0, .08);
  z-index: 90;
}

.grid-title {
  text-align: center;
  font-weight: 700;
  font-size: 0.78rem;
  color: var(--gray-500);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: .05em;
}

.grid-buttons {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 5px;
  max-width: 800px;
  margin: 0 auto;
  max-height: 180px;
  overflow-y: auto;
}

/* Nav buttons — chuẩn mẫu */
.nav-btn,
.q-nav-btn {
  width: 100%;
  aspect-ratio: 1;
  border-radius: 6px;
  background: white;
  border: 1.5px solid #e5e7eb;
  color: #6b7280;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.1s;
}

.nav-btn.answered,
.q-nav-btn.answered {
  background: #16a34a;
  border-color: #16a34a;
  color: white;
}

.nav-btn.active,
.q-nav-btn.current {
  border-color: #2563eb;
  color: #2563eb;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.25);
}

.nav-btn.active.answered,
.q-nav-btn.current.answered {
  background: #16a34a;
  border-color: #2563eb;
  color: white;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.25);
}

/* ── Student header ── */
.student-header {
  background: var(--primary);
  color: white;
  padding: 12px 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.student-header-brand {
  font-weight: 700;
  font-size: 1.05rem;
  display: flex;
  align-items: center;
  gap: 8px;
}

.student-main {
  max-width: 900px;
  margin: 0 auto;
  padding: 1.5rem 1rem;
}

/* ── Responsive ── */
@media (max-width: 640px) {
  .hide-mobile {
    display: none;
  }

  .stats-grid {
    grid-template-columns: 1fr 1fr;
  }

  .grid-2,
  .form-row {
    grid-template-columns: 1fr;
  }

  .data-table {
    display: block;
    overflow-x: auto;
  }
}

@media (min-width: 1024px) {
  .hide-desktop {
    display: none;
  }

  .exam-layout {
    flex-direction: row;
  }

  .exam-content-area {
    padding-bottom: 20px;
  }

  .exam-nav-grid {
    position: sticky;
    top: 80px;
    align-self: flex-start;
    width: 300px;
    border-left: 1px solid var(--gray-200);
    border-top: none;
    padding: 20px;
    height: calc(100vh - 80px);
    overflow: hidden;
  }

  .grid-buttons {
    grid-template-columns: repeat(5, 1fr);
    max-height: none;
  }
}

/* ================================================================
   SIM EXAM CSS (Moved from sim_exam.php)
   ================================================================ */
.sim-nav-btn {
  transition: all 0.2s;
}

.sim-nav-btn.active {
  background: #3b82f6 !important;
  color: #fff !important;
  border: 2px solid #1e3a8a !important;
  transform: scale(1.1);
  z-index: 10;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.sim-nav-btn.partial {
  background: #facc15 !important;
  color: #fff !important;
  border-color: #ca8a04 !important;
}

.sim-nav-btn.done {
  background: #22c55e !important;
  color: #fff !important;
  border-color: #16a34a !important;
}

/* Scrollbar for right column */
.sim-right-col::-webkit-scrollbar {
  width: 6px;
}

.sim-right-col::-webkit-scrollbar-track {
  background: #f1f1f1;
}

.sim-right-col::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 3px;
}

.sim-right-col::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}