/* ==========================================================================
   Mock Exam (Thi Thử) System Styles
   ========================================================================== */

:root {
  --me-primary: #2563eb;
  --me-primary-dark: #1d4ed8;
  --me-primary-light: #3b82f6;
  --me-bg: #f0f4ff;
  --me-white: #ffffff;
  --me-gray-50: #f9fafb;
  --me-gray-100: #f3f4f6;
  --me-gray-200: #e5e7eb;
  --me-gray-300: #d1d5db;
  --me-gray-400: #9ca3af;
  --me-gray-500: #6b7280;
  --me-gray-600: #4b5563;
  --me-gray-700: #374151;
  --me-gray-800: #1f2937;
  --me-green: #22c55e;
  --me-green-light: #dcfce7;
  --me-red: #ef4444;
  --me-red-light: #fee2e2;
  --me-orange: #f59e0b;
  --me-orange-light: #fef3c7;
  --me-radius: 12px;
  --me-radius-sm: 8px;
  --me-shadow: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
  --me-shadow-md: 0 4px 12px rgba(0,0,0,.1);
  --me-shadow-lg: 0 10px 30px rgba(0,0,0,.12);
  --me-transition: .2s ease;
}

/* ==========================================================================
   1. EXAM LISTING PAGE
   ========================================================================== */

.me-listing {
  max-width: 1200px;
  margin: 0 auto;
  padding: 32px 24px;
}

.me-listing__title {
  font-size: 28px;
  font-weight: 700;
  color: var(--me-gray-800);
  margin-bottom: 8px;
}

.me-listing__subtitle {
  font-size: 15px;
  color: var(--me-gray-500);
  margin-bottom: 32px;
}

/* Subject cards grid */
.me-subjects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  margin-bottom: 40px;
}

.me-subject-card {
  background: var(--me-white);
  border-radius: var(--me-radius);
  box-shadow: var(--me-shadow);
  padding: 24px;
  cursor: pointer;
  transition: transform var(--me-transition), box-shadow var(--me-transition);
  border: 2px solid transparent;
  position: relative;
  overflow: hidden;
}

.me-subject-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--me-shadow-md);
  border-color: var(--me-primary);
}

.me-subject-card.active {
  border-color: var(--me-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .15);
}

.me-subject-card__icon {
  width: 52px;
  height: 52px;
  border-radius: var(--me-radius-sm);
  background: var(--me-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  margin-bottom: 16px;
  color: var(--me-primary);
}

.me-subject-card__name {
  font-size: 17px;
  font-weight: 600;
  color: var(--me-gray-800);
  margin-bottom: 4px;
}

.me-subject-card__count {
  font-size: 13px;
  color: var(--me-gray-500);
}

.me-subject-card__badge {
  position: absolute;
  top: 16px;
  right: 16px;
  background: var(--me-primary);
  color: var(--me-white);
  font-size: 12px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 20px;
}

/* Exam set list */
.me-exam-list {
  background: var(--me-white);
  border-radius: var(--me-radius);
  box-shadow: var(--me-shadow);
  overflow: hidden;
}

.me-exam-list__header {
  padding: 20px 24px;
  border-bottom: 1px solid var(--me-gray-200);
}

.me-exam-list__header h3 {
  font-size: 18px;
  font-weight: 600;
  color: var(--me-gray-800);
  margin: 0;
}

.me-exam-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  border-bottom: 1px solid var(--me-gray-100);
  transition: background var(--me-transition);
}

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

.me-exam-item:hover {
  background: var(--me-gray-50);
}

.me-exam-item__info {
  flex: 1;
  min-width: 0;
}

.me-exam-item__name {
  font-size: 15px;
  font-weight: 600;
  color: var(--me-gray-800);
  margin-bottom: 4px;
}

.me-exam-item__meta {
  display: flex;
  gap: 16px;
  font-size: 13px;
  color: var(--me-gray-500);
}

.me-exam-item__meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.me-exam-item__btn {
  flex-shrink: 0;
  margin-left: 16px;
  padding: 10px 24px;
  background: var(--me-primary);
  color: var(--me-white);
  border: none;
  border-radius: var(--me-radius-sm);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--me-transition), transform var(--me-transition);
}

.me-exam-item__btn:hover {
  background: var(--me-primary-dark);
  transform: scale(1.03);
}

.me-exam-item__btn--outline {
  background: transparent;
  color: var(--me-primary);
  border: 1.5px solid var(--me-primary);
}

.me-exam-item__btn--outline:hover {
  background: var(--me-bg);
}

/* ==========================================================================
   2. EXAM TAKING PAGE – Layout
   ========================================================================== */

.me-exam {
  display: flex;
  min-height: 100vh;
  background: var(--me-bg);
}

.me-exam__main {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  padding-bottom: 72px; /* space for bottom bar */
}

.me-exam__sidebar {
  width: 340px;
  flex-shrink: 0;
  background: var(--me-white);
  border-left: 1px solid var(--me-gray-200);
  display: flex;
  flex-direction: column;
  height: 100vh;
  position: sticky;
  top: 0;
  overflow-y: auto;
}

/* ==========================================================================
   3. EXAM HEADER (inside main)
   ========================================================================== */

.me-exam__header {
  background: var(--me-white);
  padding: 16px 32px;
  border-bottom: 1px solid var(--me-gray-200);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.me-exam__header-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--me-gray-800);
}

.me-exam__header-tag {
  font-size: 13px;
  color: var(--me-gray-500);
  background: var(--me-gray-100);
  padding: 4px 12px;
  border-radius: 20px;
}

/* ==========================================================================
   4. QUESTION CONTENT AREA
   ========================================================================== */

.me-question {
  flex: 1;
  padding: 32px;
  max-width: 800px;
  margin: 0 auto;
  width: 100%;
}

.me-question__number {
  font-size: 13px;
  font-weight: 700;
  color: var(--me-primary);
  text-transform: uppercase;
  letter-spacing: .5px;
  margin-bottom: 8px;
}

.me-question__text {
  font-size: 17px;
  line-height: 1.7;
  color: var(--me-gray-800);
  margin-bottom: 28px;
}

.me-question__text img {
  max-width: 100%;
  border-radius: var(--me-radius-sm);
  margin: 12px 0;
}

/* Options */
.me-options {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.me-option {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  background: var(--me-white);
  border: 2px solid var(--me-gray-200);
  border-radius: var(--me-radius);
  padding: 16px 20px;
  cursor: pointer;
  transition: border-color var(--me-transition), background var(--me-transition), box-shadow var(--me-transition);
  user-select: none;
}

.me-option:hover {
  border-color: var(--me-primary-light);
  background: #f5f8ff;
}

.me-option.selected {
  border-color: var(--me-primary);
  background: #eef3ff;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .1);
}

.me-option.correct {
  border-color: var(--me-green);
  background: var(--me-green-light);
}

.me-option.incorrect {
  border-color: var(--me-red);
  background: var(--me-red-light);
}

.me-option__label {
  width: 32px;
  height: 32px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--me-gray-100);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 700;
  color: var(--me-gray-600);
  transition: background var(--me-transition), color var(--me-transition);
}

.me-option.selected .me-option__label {
  background: var(--me-primary);
  color: var(--me-white);
}

.me-option.correct .me-option__label {
  background: var(--me-green);
  color: var(--me-white);
}

.me-option.incorrect .me-option__label {
  background: var(--me-red);
  color: var(--me-white);
}

.me-option__text {
  flex: 1;
  font-size: 15px;
  line-height: 1.6;
  color: var(--me-gray-700);
  padding-top: 4px;
}

/* ==========================================================================
   5. SIDEBAR – Timer
   ========================================================================== */

.me-sidebar__timer {
  padding: 24px;
  text-align: center;
  border-bottom: 1px solid var(--me-gray-200);
}

.me-sidebar__timer-label {
  font-size: 13px;
  color: var(--me-gray-500);
  margin-bottom: 8px;
  font-weight: 500;
}

.me-sidebar__timer-value {
  font-size: 36px;
  font-weight: 700;
  color: var(--me-gray-800);
  font-variant-numeric: tabular-nums;
  letter-spacing: 1px;
}

.me-sidebar__timer-value.warning {
  color: var(--me-orange);
}

.me-sidebar__timer-value.danger {
  color: var(--me-red);
  animation: me-pulse 1s ease-in-out infinite;
}

@keyframes me-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: .5; }
}

.me-sidebar__submit {
  display: block;
  width: 100%;
  margin-top: 16px;
  padding: 12px;
  background: var(--me-red);
  color: var(--me-white);
  border: none;
  border-radius: var(--me-radius-sm);
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--me-transition), transform var(--me-transition);
}

.me-sidebar__submit:hover {
  background: #dc2626;
  transform: scale(1.02);
}

/* ==========================================================================
   6. SIDEBAR – Progress
   ========================================================================== */

.me-sidebar__progress {
  padding: 20px 24px;
  border-bottom: 1px solid var(--me-gray-200);
}

.me-sidebar__progress-text {
  font-size: 14px;
  color: var(--me-gray-600);
  margin-bottom: 10px;
  font-weight: 500;
}

.me-sidebar__progress-text strong {
  color: var(--me-primary);
}

.me-sidebar__progress-bar {
  height: 6px;
  background: var(--me-gray-200);
  border-radius: 3px;
  overflow: hidden;
}

.me-sidebar__progress-fill {
  height: 100%;
  background: var(--me-primary);
  border-radius: 3px;
  transition: width .4s ease;
}

/* ==========================================================================
   7. SIDEBAR – Color Legend
   ========================================================================== */

.me-sidebar__legend {
  padding: 16px 24px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  border-bottom: 1px solid var(--me-gray-200);
}

.me-legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--me-gray-600);
}

.me-legend-dot {
  width: 14px;
  height: 14px;
  border-radius: 4px;
}

.me-legend-dot--answered {
  background: var(--me-primary);
}

.me-legend-dot--current {
  background: var(--me-white);
  border: 2.5px solid var(--me-primary);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, .3);
}

.me-legend-dot--unanswered {
  background: var(--me-gray-200);
}

.me-legend-dot--flagged {
  background: var(--me-orange);
}

/* ==========================================================================
   8. SIDEBAR – Question Number Grid (6 columns)
   ========================================================================== */

.me-sidebar__grid {
  padding: 20px 24px;
  flex: 1;
  overflow-y: auto;
}

.me-qgrid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 8px;
}

.me-qgrid__item {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 600;
  border-radius: var(--me-radius-sm);
  cursor: pointer;
  transition: transform var(--me-transition), box-shadow var(--me-transition), background var(--me-transition);
  background: var(--me-gray-100);
  color: var(--me-gray-500);
  border: 2px solid transparent;
}

.me-qgrid__item:hover {
  transform: scale(1.1);
  box-shadow: var(--me-shadow);
}

.me-qgrid__item--answered {
  background: var(--me-primary);
  color: var(--me-white);
}

.me-qgrid__item--current {
  background: var(--me-white);
  border-color: var(--me-primary);
  color: var(--me-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .25);
  font-weight: 700;
}

.me-qgrid__item--flagged {
  background: var(--me-orange);
  color: var(--me-white);
}

.me-qgrid__item--flagged.me-qgrid__item--current {
  border-color: var(--me-orange);
  box-shadow: 0 0 0 3px rgba(245, 158, 11, .3);
}

/* ==========================================================================
   9. BOTTOM NAVIGATION BAR
   ========================================================================== */

.me-bottombar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 340px; /* sidebar width */
  height: 72px;
  background: var(--me-white);
  border-top: 1px solid var(--me-gray-200);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  z-index: 100;
  box-shadow: 0 -2px 8px rgba(0,0,0,.04);
}

.me-bottombar__left,
.me-bottombar__right {
  display: flex;
  align-items: center;
  gap: 12px;
}

.me-bottombar__center {
  font-size: 13px;
  color: var(--me-gray-500);
}

.me-bottombar__center strong {
  color: var(--me-gray-700);
}

.me-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--me-radius-sm);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: background var(--me-transition), transform var(--me-transition);
}

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

.me-btn--primary:hover {
  background: var(--me-primary-dark);
}

.me-btn--secondary {
  background: var(--me-gray-100);
  color: var(--me-gray-700);
}

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

.me-btn--ghost {
  background: transparent;
  color: var(--me-gray-600);
}

.me-btn--ghost:hover {
  background: var(--me-gray-100);
}

.me-btn--flag {
  background: transparent;
  color: var(--me-gray-400);
  padding: 10px 12px;
}

.me-btn--flag:hover {
  color: var(--me-orange);
  background: var(--me-orange-light);
}

.me-btn--flag.active {
  color: var(--me-orange);
  background: var(--me-orange-light);
}

.me-btn:disabled {
  opacity: .4;
  cursor: not-allowed;
}

/* ==========================================================================
   10. RESULT / REVIEW STATES
   ========================================================================== */

.me-result {
  max-width: 600px;
  margin: 40px auto;
  text-align: center;
  padding: 40px 32px;
  background: var(--me-white);
  border-radius: var(--me-radius);
  box-shadow: var(--me-shadow-md);
}

.me-result__score {
  font-size: 64px;
  font-weight: 800;
  color: var(--me-primary);
  line-height: 1;
  margin-bottom: 8px;
}

.me-result__score-label {
  font-size: 15px;
  color: var(--me-gray-500);
  margin-bottom: 32px;
}

.me-result__stats {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 32px;
}

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

.me-result__stat-value {
  font-size: 24px;
  font-weight: 700;
  color: var(--me-gray-800);
}

.me-result__stat-label {
  font-size: 13px;
  color: var(--me-gray-500);
  margin-top: 2px;
}

.me-result__stat--correct .me-result__stat-value {
  color: var(--me-green);
}

.me-result__stat--wrong .me-result__stat-value {
  color: var(--me-red);
}

.me-result__actions {
  display: flex;
  justify-content: center;
  gap: 12px;
}

/* Explanation box (shown in review mode) */
.me-explanation {
  margin-top: 20px;
  padding: 16px 20px;
  background: #f0fdf4;
  border-left: 4px solid var(--me-green);
  border-radius: 0 var(--me-radius-sm) var(--me-radius-sm) 0;
  text-align: left;
}

.me-explanation__title {
  font-size: 13px;
  font-weight: 700;
  color: var(--me-green);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: .5px;
}

.me-explanation__text {
  font-size: 14px;
  line-height: 1.6;
  color: var(--me-gray-700);
}

/* ==========================================================================
   11. CONFIRM MODAL (submit exam)
   ========================================================================== */

.me-modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity .25s ease;
}

.me-modal-overlay.show {
  opacity: 1;
  pointer-events: auto;
}

.me-modal {
  background: var(--me-white);
  border-radius: var(--me-radius);
  padding: 32px;
  max-width: 420px;
  width: 90%;
  box-shadow: var(--me-shadow-lg);
  transform: scale(.95);
  transition: transform .25s ease;
}

.me-modal-overlay.show .me-modal {
  transform: scale(1);
}

.me-modal__title {
  font-size: 18px;
  font-weight: 700;
  color: var(--me-gray-800);
  margin-bottom: 8px;
}

.me-modal__body {
  font-size: 14px;
  color: var(--me-gray-600);
  line-height: 1.6;
  margin-bottom: 24px;
}

.me-modal__actions {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
}

/* ==========================================================================
   12. LOADING / SKELETON
   ========================================================================== */

.me-skeleton {
  background: linear-gradient(90deg, var(--me-gray-100) 25%, var(--me-gray-200) 50%, var(--me-gray-100) 75%);
  background-size: 200% 100%;
  animation: me-shimmer 1.5s infinite;
  border-radius: var(--me-radius-sm);
}

@keyframes me-shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* ==========================================================================
   13. RESPONSIVE – Tablet
   ========================================================================== */

@media (max-width: 1024px) {
  .me-exam__sidebar {
    width: 280px;
  }

  .me-bottombar {
    right: 280px;
  }

  .me-question {
    padding: 24px;
  }
}

/* ==========================================================================
   14. RESPONSIVE – Mobile (sidebar becomes bottom sheet)
   ========================================================================== */

@media (max-width: 768px) {
  .me-exam {
    flex-direction: column;
  }

  .me-exam__sidebar {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    width: 100%;
    height: auto;
    max-height: 70vh;
    border-left: none;
    border-top: 1px solid var(--me-gray-200);
    border-radius: var(--me-radius) var(--me-radius) 0 0;
    box-shadow: 0 -4px 20px rgba(0,0,0,.12);
    z-index: 200;
    transform: translateY(calc(100% - 64px));
    transition: transform .35s cubic-bezier(.4,0,.2,1);
  }

  .me-exam__sidebar.open {
    transform: translateY(0);
  }

  .me-exam__sidebar::before {
    content: '';
    display: block;
    width: 40px;
    height: 4px;
    background: var(--me-gray-300);
    border-radius: 2px;
    margin: 10px auto 6px;
  }

  .me-sidebar__timer {
    padding: 12px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--me-gray-200);
  }

  .me-sidebar__timer-label {
    margin-bottom: 0;
  }

  .me-sidebar__timer-value {
    font-size: 22px;
  }

  .me-sidebar__submit {
    margin-top: 0;
    width: auto;
    padding: 8px 20px;
    font-size: 13px;
  }

  .me-bottombar {
    right: 0;
    padding: 0 16px;
    height: 64px;
    bottom: 64px; /* above collapsed sidebar handle */
  }

  .me-exam__main {
    padding-bottom: 140px; /* bottom bar + sidebar handle */
  }

  .me-question {
    padding: 20px 16px;
  }

  .me-option {
    padding: 14px 16px;
  }

  .me-qgrid {
    gap: 6px;
  }

  .me-sidebar__grid {
    padding: 16px 20px;
  }

  .me-sidebar__legend {
    padding: 12px 20px;
  }

  .me-subjects-grid {
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 12px;
  }

  .me-exam-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .me-exam-item__btn {
    margin-left: 0;
    width: 100%;
    text-align: center;
  }

  .me-result__stats {
    flex-direction: column;
    gap: 16px;
  }

  .me-result__actions {
    flex-direction: column;
  }

  .me-result__actions .me-btn {
    width: 100%;
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .me-subjects-grid {
    grid-template-columns: 1fr;
  }

  .me-listing {
    padding: 20px 16px;
  }

  .me-listing__title {
    font-size: 22px;
  }
}

/* ==========================================================================
   15. UTILITY
   ========================================================================== */

.me-sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

.me-fade-in {
  animation: me-fadeIn .3s ease forwards;
}

@keyframes me-fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.me-slide-up {
  animation: me-slideUp .35s cubic-bezier(.4,0,.2,1) forwards;
}

@keyframes me-slideUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   16. LISTING PAGE – Hero & Footer
   ========================================================================== */

.exam-hero {
  background: linear-gradient(135deg, #1e40af 0%, #3b82f6 100%);
  color: #fff;
  text-align: center;
  padding: 100px 24px 48px;
}

.exam-hero h1 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 12px;
}

.exam-hero h1 i {
  margin-right: 8px;
}

.exam-hero p {
  font-size: 16px;
  opacity: .9;
  max-width: 600px;
  margin: 0 auto;
}

.exam-cta {
  background: var(--me-bg, #f0f4ff);
}

.exam-cta h2 {
  font-size: 24px;
  font-weight: 700;
  color: var(--me-gray-800, #1f2937);
  margin-bottom: 8px;
}

.exam-cta p {
  color: var(--me-gray-500, #6b7280);
  font-size: 15px;
}

.exam-footer {
  text-align: center;
  padding: 24px;
  color: var(--me-gray-500, #6b7280);
  font-size: 14px;
  border-top: 1px solid var(--me-gray-200, #e5e7eb);
}

@media (max-width: 768px) {
  .exam-hero { padding: 40px 16px 32px; }
  .exam-hero h1 { font-size: 24px; }
  .exam-hero p { font-size: 14px; }
}