/* ============================================================
   PHÒNG THI TRẮC NGHIỆM — exams.css
   CSS thuần, dùng lại design token của style.css (dark mặc định,
   light qua body:not(.dark-mode)).
   ============================================================ */

.exam-page {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 20px 18px 60px;
}

/* ====== GATE (chưa sở hữu khóa — login dùng .lib-require-login trong style.css) ====== */
.exam-gate {
  min-height: 60vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px 20px;
}

.exam-gate .lib-rl-card {
  box-shadow: var(--shadow-md);
}

/* ====== THỐNG KÊ TỔNG ====== */
.exam-stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 22px;
}

.exam-stat {
  --stat-c: var(--accent);
  position: relative;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 15px 17px;
  display: flex;
  align-items: center;
  gap: 13px;
}

.exam-stat.s-blue { --stat-c: var(--accent); }
.exam-stat.s-violet { --stat-c: #8b5cf6; }
.exam-stat.s-amber { --stat-c: var(--accent-amber); }
.exam-stat.s-green { --stat-c: var(--accent-green); }

.exam-stat-icon {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--stat-c);
  background: color-mix(in srgb, var(--stat-c) 14%, transparent);
}

.exam-stat-icon svg { width: 21px; height: 21px; }

.exam-stat-info { min-width: 0; display: flex; flex-direction: column; gap: 3px; }

.exam-stat-num {
  font-size: 24px;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.exam-stat-label {
  font-size: 12px;
  color: var(--text-secondary);
  font-weight: 500;
}

/* ====== LAYOUT 2 CỘT ====== */
.exam-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 28px;
  align-items: start;
}

/* ====== SIDEBAR LỊCH SỬ ====== */
.exam-sidebar-title {
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  margin-bottom: 14px;
}

.exam-sidebar-title svg {
  flex-shrink: 0;
  width: 16px;
  height: 16px;
  color: var(--text-secondary);
}

.exam-history-list {
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--bg-surface);
}

.exam-history-empty {
  padding: 24px 16px;
  text-align: center;
  font-size: 12.5px;
  color: var(--text-tertiary);
  font-style: italic;
}

.exam-history-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border-bottom: 1px solid var(--border-subtle);
  cursor: pointer;
  transition: background var(--transition);
}

.exam-history-item:last-child { border-bottom: none; }
.exam-history-item:hover { background: var(--bg-surface-hover); }

.exam-history-score {
  flex-shrink: 0;
  width: 42px;
  height: 42px;
  border-radius: var(--radius-xs);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.score-good { background: color-mix(in srgb, var(--accent-green) 18%, transparent); color: var(--accent-green); }
.score-mid  { background: color-mix(in srgb, var(--accent-amber) 18%, transparent); color: var(--accent-amber); }
.score-bad  { background: color-mix(in srgb, var(--accent-red) 18%, transparent); color: var(--accent-red); }

.exam-history-meta { min-width: 0; flex: 1; }

.exam-history-name {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.exam-history-time {
  font-size: 11.5px;
  color: var(--text-tertiary);
  margin-top: 2px;
}

/* ====== MÀN HÌNH CHUNG ====== */
.exam-screen-head {
  margin-bottom: 22px;
}

.exam-screen-head h1 {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text-primary);
  margin: 0 0 5px;
}

.exam-screen-head p {
  font-size: 13.5px;
  color: var(--text-secondary);
  margin: 0;
}

.exam-back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  margin-bottom: 18px;
  transition: color var(--transition);
}

.exam-back-link:hover { color: var(--text-primary); }

/* ====== GRID CHỌN MÔN ====== */
.exam-course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
}

.exam-show-empty-btn {
  grid-column: 1 / -1;
  justify-self: start;
  margin-top: 4px;
  padding: 9px 14px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  background: var(--bg-surface);
  border: 1px dashed var(--border-medium);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition), background var(--transition);
}

.exam-show-empty-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--bg-surface-hover);
}

.exam-course-card {
  position: relative;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 18px;
  cursor: pointer;
  transition: background var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.exam-course-del {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  border: 1px solid var(--border-subtle);
  background: var(--bg-surface);
  color: var(--text-tertiary);
  cursor: pointer;
  opacity: 0;
  transition: opacity var(--transition), color var(--transition), border-color var(--transition), background var(--transition);
  z-index: 2;
}

.exam-course-card:hover .exam-course-del { opacity: 1; }

.exam-course-del:hover {
  color: var(--accent-red, #ef4444);
  border-color: var(--accent-red, #ef4444);
  background: color-mix(in srgb, var(--accent-red, #ef4444) 12%, transparent);
}

@media (hover: none) {
  .exam-course-del { opacity: 1; }
}

.exam-course-card:hover {
  background: var(--bg-surface-hover);
  box-shadow: var(--shadow-sm);
}

.exam-course-logo {
  width: 100%;
  height: 110px;
  border-radius: var(--radius-sm);
  object-fit: cover;
  background: var(--bg-elevated);
}

/* Placeholder khi môn chưa có logo */
div.exam-course-logo {
  position: relative;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  overflow: hidden;
}

div.exam-course-logo::after {
  content: "";
  position: absolute;
  inset: 0;
  background-repeat: no-repeat;
  background-position: center;
  background-size: 34px 34px;
  opacity: 0.28;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%23888' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M2 3h6a4 4 0 0 1 4 4v14a3 3 0 0 0-3-3H2z'/%3E%3Cpath d='M22 3h-6a4 4 0 0 0-4 4v14a3 3 0 0 1 3-3h7z'/%3E%3C/svg%3E");
}

.exam-course-name {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.35;
}

.exam-course-foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 12.5px;
  color: var(--text-secondary);
}

.exam-course-count {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-weight: 600;
}

.exam-course-pill {
  font-size: 11px;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--accent) 16%, transparent);
  color: var(--accent);
}

/* ====== DANH SÁCH ĐỀ ====== */
.exam-quizzes-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-bottom: 14px;
  margin-bottom: 18px;
  border-bottom: 1px solid var(--border-subtle);
}

.exam-quizzes-head h2 {
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text-primary);
  margin: 0;
}

.exam-admin-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--accent);
  color: #fff;
  border: none;
  font-size: 12.5px;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}

.exam-admin-btn:hover { background: var(--accent-hover); }

.exam-admin-btn.is-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-medium);
}

.exam-admin-btn.is-ghost:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}

.exam-quiz-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.exam-quiz-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 16px 18px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px 16px;
}

.exam-quiz-card:hover { background: var(--bg-surface-hover); }

.exam-quiz-icon {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--accent) 14%, transparent);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
}

.exam-quiz-body { flex: 1 1 240px; min-width: 0; }

.exam-quiz-title {
  font-size: 14.5px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.exam-quiz-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 12px;
  color: var(--text-secondary);
}

.exam-quiz-meta span {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.exam-quiz-best {
  flex-shrink: 0;
  text-align: center;
  font-size: 11px;
  color: var(--text-tertiary);
}

.exam-quiz-best strong {
  display: block;
  font-size: 16px;
  font-weight: 800;
  color: var(--accent-green);
  font-variant-numeric: tabular-nums;
}

.exam-quiz-actions {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}

.exam-quiz-start {
  background: var(--accent);
  color: #fff;
  border: none;
  font-size: 12.5px;
  font-weight: 700;
  padding: 9px 18px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}

.exam-quiz-start:hover { background: var(--accent-hover); }

.exam-icon-btn {
  width: 34px;
  height: 34px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-medium);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.exam-icon-btn:hover { background: var(--bg-surface-hover); color: var(--text-primary); }
.exam-icon-btn.is-danger:hover { color: var(--accent-red); border-color: var(--accent-red); }

.exam-empty {
  padding: 50px 20px;
  text-align: center;
  color: var(--text-tertiary);
  font-size: 13.5px;
}

/* Khi danh sách là lưới (màn rộng), ô trống/skeleton trải hết các cột để canh giữa đúng */
.exam-quiz-list .exam-empty,
.exam-quiz-list .exam-skeleton,
.exam-course-grid .exam-empty,
.exam-course-grid .exam-skeleton { grid-column: 1 / -1; }

.exam-empty svg {
  width: 38px;
  height: 38px;
  margin-bottom: 10px;
  opacity: 0.5;
}

/* ====== NÚT CHUNG ====== */
.exam-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  font-size: 13px;
  font-weight: 700;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: all var(--transition);
}

.exam-btn-primary { background: var(--accent); color: #fff; }
.exam-btn-primary:hover { background: var(--accent-hover); }
.exam-btn-primary:disabled { opacity: 0.45; cursor: not-allowed; }

.exam-btn-ghost {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-medium);
}

.exam-btn-ghost:hover { background: var(--bg-surface-hover); }
.exam-btn-ghost:disabled { opacity: 0.4; cursor: not-allowed; }

/* ============================================================
   MÀN HÌNH LÀM BÀI (FULLSCREEN OVERLAY)
   ============================================================ */
.quiz-taker {
  position: fixed;
  inset: 0;
  z-index: 99999;
  background: var(--bg-page);
  display: flex;
  flex-direction: column;
}

.quiz-taker-bar {
  flex-shrink: 0;
  height: 58px;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 22px;
}

.quiz-taker-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: color var(--transition);
}

.quiz-taker-back:hover { color: var(--text-primary); }

.quiz-taker-info { flex: 1; min-width: 0; }

.quiz-taker-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.quiz-taker-sub {
  font-size: 12px;
  color: var(--text-secondary);
  font-variant-numeric: tabular-nums;
}

.quiz-taker-timer {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 12px;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-medium);
  background: var(--bg-elevated);
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.quiz-taker-timer.timer-low {
  border-color: var(--accent-red);
  color: var(--accent-red);
  animation: timerPulse 1s infinite;
}

@keyframes timerPulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.55; }
}

.quiz-taker-submit {
  background: var(--accent);
  color: #fff;
  border: none;
  font-size: 13px;
  font-weight: 700;
  padding: 9px 18px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}

.quiz-taker-submit:hover { background: var(--accent-hover); }

.quiz-taker-progress {
  flex-shrink: 0;
  height: 3px;
  background: var(--bg-elevated);
}

.quiz-taker-progress-fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.3s ease;
}

.quiz-taker-body {
  flex: 1;
  overflow-y: auto;
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 26px 22px;
  display: grid;
  grid-template-columns: 1fr 260px;
  gap: 24px;
  align-items: start;
}

/* ----- Câu hỏi ----- */
.quiz-question-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.quiz-q-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 22px;
  border-bottom: 1px solid var(--border-subtle);
}

.quiz-q-num {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
}

.quiz-flag-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: none;
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-xs);
  padding: 6px 12px;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.quiz-flag-btn:hover { color: var(--text-primary); }

.quiz-flag-btn.is-flagged {
  color: var(--accent-amber);
  border-color: var(--accent-amber);
  background: color-mix(in srgb, var(--accent-amber) 12%, transparent);
}

.quiz-q-text {
  padding: 22px;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  font-weight: 500;
}

.quiz-q-image {
  padding: 0 22px 18px;
  display: flex;
  justify-content: center;
}

.quiz-q-image img {
  max-height: 300px;
  max-width: 100%;
  object-fit: contain;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-subtle);
  cursor: zoom-in;
}

.quiz-options {
  padding: 0 22px 22px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.quiz-option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 13px 16px;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
}

.quiz-option:hover {
  border-color: var(--border-medium);
  background: var(--bg-surface-hover);
}

.quiz-option.is-selected {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
}

.quiz-option-key {
  flex-shrink: 0;
  width: 26px;
  height: 26px;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-medium);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
  color: var(--text-secondary);
  font-variant-numeric: tabular-nums;
}

.quiz-option.is-selected .quiz-option-key {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.quiz-option-text {
  flex: 1;
  font-size: 14px;
  line-height: 1.45;
  color: var(--text-secondary);
}

.quiz-option.is-selected .quiz-option-text {
  color: var(--text-primary);
  font-weight: 500;
}

.quiz-nav-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 16px;
}

/* ----- Phiếu trả lời ----- */
.quiz-sheet-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 16px;
  position: sticky;
  top: 0;
}

.quiz-sheet-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-secondary);
}

.quiz-sheet-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 7px;
}

.quiz-sheet-cell {
  aspect-ratio: 1;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-medium);
  background: var(--bg-elevated);
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  font-variant-numeric: tabular-nums;
  transition: all var(--transition);
}

.quiz-sheet-cell:hover { border-color: var(--border-medium); }

.quiz-sheet-cell.is-answered {
  background: color-mix(in srgb, var(--accent-green) 20%, transparent);
  border-color: color-mix(in srgb, var(--accent-green) 45%, transparent);
  color: var(--accent-green);
}

.quiz-sheet-cell.is-current {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px color-mix(in srgb, var(--accent) 35%, transparent);
}

.quiz-sheet-cell.is-flagged::after {
  content: "";
  position: absolute;
  top: 3px;
  right: 3px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-amber);
}

.quiz-sheet-legend {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 12px;
  color: var(--text-secondary);
}

.quiz-sheet-legend > div {
  display: flex;
  align-items: center;
  gap: 8px;
}

.quiz-sheet-legend .dot {
  width: 12px;
  height: 12px;
  border-radius: 3px;
  flex-shrink: 0;
  position: relative;
}

.dot-answered { background: color-mix(in srgb, var(--accent-green) 25%, transparent); border: 1px solid color-mix(in srgb, var(--accent-green) 45%, transparent); }
.dot-empty { background: var(--bg-elevated); border: 1px solid var(--border-medium); }
.dot-current { background: color-mix(in srgb, var(--accent) 14%, transparent); border: 1px solid var(--accent); }
.dot-flagged { background: var(--bg-elevated); border: 1px solid var(--border-medium); }
.dot-flagged::after { content: ""; position: absolute; top: -2px; right: -2px; width: 6px; height: 6px; border-radius: 50%; background: var(--accent-amber); }

/* ----- Mobile bar + drawer ----- */
.quiz-mobile-bar {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 20;
  padding: 12px 16px;
  background: var(--bg-surface);
  border-top: 1px solid var(--border-subtle);
}

.quiz-mobile-toggle {
  width: 100%;
  background: var(--accent);
  color: #fff;
  border: none;
  font-size: 13px;
  font-weight: 700;
  padding: 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.quiz-mobile-drawer {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 50;
  background: var(--bg-surface);
  border-top: 1px solid var(--border-subtle);
  border-radius: 16px 16px 0 0;
  padding: 20px;
  transform: translateY(110%);
  transition: transform 0.3s ease;
  box-shadow: var(--shadow-xl);
  max-height: 75vh;
  display: flex;
  flex-direction: column;
}

.quiz-mobile-drawer.is-open { transform: translateY(0); }

.quiz-mobile-drawer-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 12px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--border-subtle);
  font-size: 13px;
  font-weight: 700;
  color: var(--text-primary);
}

.quiz-mobile-drawer-head button {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 18px;
  cursor: pointer;
}

.quiz-mobile-drawer-body {
  overflow-y: auto;
  flex: 1;
  padding: 4px 0 14px;
}

.quiz-mobile-submit { width: 100%; padding: 13px; }

/* ============================================================
   MÀN HÌNH KẾT QUẢ
   ============================================================ */
.exam-result-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 26px;
  margin-bottom: 24px;
}

.exam-result-top {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 28px;
  align-items: center;
}

.exam-score-ring {
  position: relative;
  width: 120px;
  height: 120px;
  flex-shrink: 0;
}

.exam-score-ring .ring-bg { stroke: var(--bg-elevated); }
.exam-score-ring .ring-fg {
  stroke: var(--accent-green);
  transition: stroke-dashoffset 1.1s ease;
}

.exam-score-center {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.exam-score-num {
  font-size: 26px;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.exam-score-label {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-tertiary);
  font-weight: 700;
  margin-top: 4px;
}

.exam-result-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.exam-rstat {
  border-radius: var(--radius-sm);
  padding: 16px 10px;
  text-align: center;
  border: 1px solid;
}

.rstat-correct { background: color-mix(in srgb, var(--accent-green) 10%, transparent); border-color: color-mix(in srgb, var(--accent-green) 28%, transparent); }
.rstat-wrong { background: color-mix(in srgb, var(--accent-red) 10%, transparent); border-color: color-mix(in srgb, var(--accent-red) 28%, transparent); }
.rstat-skip { background: color-mix(in srgb, var(--accent-amber) 10%, transparent); border-color: color-mix(in srgb, var(--accent-amber) 28%, transparent); }

.exam-rstat-num {
  font-size: 22px;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.rstat-correct .exam-rstat-num { color: var(--accent-green); }
.rstat-wrong .exam-rstat-num { color: var(--accent-red); }
.rstat-skip .exam-rstat-num { color: var(--accent-amber); }

.exam-rstat-label {
  font-size: 11px;
  text-transform: uppercase;
  color: var(--text-secondary);
  font-weight: 600;
  margin-top: 2px;
}

.exam-result-actions {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 10px;
  min-width: 180px;
}

.exam-result-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  text-align: center;
  margin-bottom: 2px;
}

.exam-rank-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  font-size: 12.5px;
  color: var(--text-secondary);
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 8px;
}

.exam-rank-badge strong { color: var(--text-primary); }

/* ----- Review ----- */
.exam-review-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.exam-review-head h3 {
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  margin: 0;
}

.exam-review-expand {
  background: none;
  border: none;
  font-size: 12.5px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: color var(--transition);
}

.exam-review-expand:hover { color: var(--text-primary); }

.exam-review-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.exam-review-item {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.exam-review-item.is-correct { border-left: 3px solid var(--accent-green); }
.exam-review-item.is-wrong { border-left: 3px solid var(--accent-red); }
.exam-review-item.is-skip { border-left: 3px solid var(--accent-amber); }

.exam-review-q {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
  cursor: pointer;
}

.exam-review-badge {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  border-radius: var(--radius-xs);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.is-correct .exam-review-badge { background: color-mix(in srgb, var(--accent-green) 18%, transparent); color: var(--accent-green); }
.is-wrong .exam-review-badge { background: color-mix(in srgb, var(--accent-red) 18%, transparent); color: var(--accent-red); }
.is-skip .exam-review-badge { background: color-mix(in srgb, var(--accent-amber) 18%, transparent); color: var(--accent-amber); }

.exam-review-qtext {
  flex: 1;
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--text-primary);
  font-weight: 500;
}

.exam-review-chevron {
  flex-shrink: 0;
  color: var(--text-tertiary);
  transition: transform var(--transition);
}

.exam-review-item.is-open .exam-review-chevron { transform: rotate(180deg); }

.exam-review-detail {
  display: none;
  padding: 0 16px 16px 52px;
}

.exam-review-item.is-open .exam-review-detail { display: block; }

.exam-review-opt {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-radius: var(--radius-xs);
  font-size: 13px;
  margin-bottom: 6px;
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.exam-review-opt.opt-correct {
  background: color-mix(in srgb, var(--accent-green) 12%, transparent);
  border-color: color-mix(in srgb, var(--accent-green) 35%, transparent);
  color: var(--accent-green);
  font-weight: 600;
}

.exam-review-opt.opt-chosen-wrong {
  background: color-mix(in srgb, var(--accent-red) 12%, transparent);
  border-color: color-mix(in srgb, var(--accent-red) 35%, transparent);
  color: var(--accent-red);
  font-weight: 600;
}

.exam-review-opt-key {
  flex-shrink: 0;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.exam-review-tag {
  margin-left: auto;
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
}

.exam-review-explain {
  margin-top: 10px;
  padding: 12px 14px;
  background: var(--bg-elevated);
  border-radius: var(--radius-xs);
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--text-secondary);
}

.exam-review-explain strong { color: var(--text-primary); }

.exam-review-image {
  margin-bottom: 12px;
}

.exam-review-image img {
  max-height: 220px;
  max-width: 100%;
  object-fit: contain;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-subtle);
  cursor: zoom-in;
}

/* ============================================================
   MODAL (leaderboard / admin editor)
   ============================================================ */
.exam-modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 100000;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(3px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 18px;
}

.exam-modal {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xl);
  width: 100%;
  max-width: 480px;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
}

.exam-modal-wide { max-width: 720px; }

.exam-modal-close {
  position: absolute;
  top: 14px;
  right: 16px;
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 18px;
  font-weight: 700;
  cursor: pointer;
  z-index: 2;
  transition: color var(--transition);
}

.exam-modal-close:hover { color: var(--text-primary); }

.exam-modal-title {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border-subtle);
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}

.exam-modal-body {
  padding: 20px;
  overflow-y: auto;
}

/* ----- Leaderboard rows ----- */
.lb-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  margin-bottom: 6px;
  background: var(--bg-elevated);
}

.lb-row.is-me {
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent) 35%, transparent);
}

.lb-rank {
  flex-shrink: 0;
  width: 30px;
  font-size: 14px;
  font-weight: 800;
  text-align: center;
  color: var(--text-secondary);
  font-variant-numeric: tabular-nums;
}

.lb-rank.top-1 { color: #f5a623; }
.lb-rank.top-2 { color: #b8c0cc; }
.lb-rank.top-3 { color: #cd7f32; }

.lb-name {
  flex: 1;
  min-width: 0;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lb-score {
  flex-shrink: 0;
  font-size: 13px;
  font-weight: 800;
  color: var(--accent-green);
  font-variant-numeric: tabular-nums;
}

/* ============================================================
   ADMIN: SOẠN ĐỀ — FULLSCREEN EDITOR (.qed)
   ============================================================ */

/* --- Layout --- */
.qed { position:fixed; inset:0; z-index:99999; background:var(--bg-page); display:flex; flex-direction:column; }

.qed-bar { flex-shrink:0; height:56px; background:var(--bg-surface); border-bottom:1px solid var(--border-subtle); display:flex; align-items:center; gap:14px; padding:0 20px; }
.qed-back { display:inline-flex; align-items:center; gap:6px; background:none; border:none; color:var(--text-secondary); font-size:13px; font-weight:600; cursor:pointer; transition:color var(--transition); }
.qed-back:hover { color:var(--text-primary); }
.qed-bar-info { flex:1; min-width:0; }
.qed-bar-title { font-size:14px; font-weight:700; color:var(--text-primary); white-space:nowrap; overflow:hidden; text-overflow:ellipsis; }
.qed-bar-right { display:flex; align-items:center; gap:12px; }
.qed-save-indicator { font-size:11.5px; color:var(--text-tertiary); }
.qed-save-btn { display:inline-flex; align-items:center; gap:7px; background:var(--accent); color:#fff; border:none; font-size:13px; font-weight:700; padding:9px 18px; border-radius:var(--radius-sm); cursor:pointer; transition:background var(--transition); }
.qed-save-btn:hover { background:var(--accent-hover); }

.qed-body { flex:1; overflow:hidden; display:grid; grid-template-columns:280px 1fr; }
.qed-sidebar { overflow-y:auto; padding:18px; border-right:1px solid var(--border-subtle); background:var(--bg-surface); }
.qed-main { overflow-y:auto; padding:24px; }
.qed-main.is-dragover { background:color-mix(in srgb, var(--accent) 6%, transparent); }

.qed-status { flex-shrink:0; height:34px; background:var(--bg-surface); border-top:1px solid var(--border-subtle); display:flex; align-items:center; justify-content:space-between; padding:0 20px; font-size:11.5px; color:var(--text-tertiary); }

/* --- Sidebar: Info --- */
.qed-info { margin-bottom:20px; }
.qed-info-title { font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.05em; color:var(--text-secondary); margin-bottom:12px; }
.qed-field { margin-bottom:10px; }
.qed-field label { display:block; font-size:11.5px; font-weight:600; color:var(--text-tertiary); margin-bottom:4px; }
.qed-input, .qed-textarea { width:100%; background:var(--bg-input); border:1px solid var(--border-medium); border-radius:var(--radius-sm); padding:8px 10px; font-size:13px; color:var(--text-primary); font-family:inherit; box-sizing:border-box; }
.qed-input:focus, .qed-textarea:focus { outline:none; border-color:var(--accent); }
.qed-textarea { resize:vertical; min-height:56px; }
.qed-field-row { display:grid; grid-template-columns:1fr 1fr; gap:10px; }

/* --- Sidebar: Navigator --- */
.qed-nav { margin-bottom:18px; }
.qed-nav-head { display:flex; align-items:center; justify-content:space-between; font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.05em; color:var(--text-secondary); margin-bottom:10px; }
.qed-nav-count { color:var(--text-tertiary); }
.qed-nav-grid { display:grid; grid-template-columns:repeat(5,1fr); gap:6px; }
.qed-nav-cell { aspect-ratio:1; border-radius:var(--radius-xs); border:1.5px solid var(--border-medium); background:var(--bg-elevated); color:var(--text-secondary); font-size:11px; font-weight:700; cursor:pointer; display:flex; align-items:center; justify-content:center; transition:all .15s; }
.qed-nav-cell:hover { border-color:var(--accent); }
.qed-nav-cell.is-done { background:color-mix(in srgb, var(--accent-green) 20%, transparent); border-color:color-mix(in srgb, var(--accent-green) 45%, transparent); color:var(--accent-green); }
.qed-nav-cell.is-none { border-color:color-mix(in srgb, var(--accent-red) 35%, transparent); color:var(--accent-red); }
.qed-nav-cell.is-active { border-color:var(--accent); box-shadow:0 0 0 2px color-mix(in srgb, var(--accent) 35%, transparent); }
.qed-nav-legend { margin-top:10px; display:flex; flex-wrap:wrap; gap:10px; font-size:10.5px; color:var(--text-tertiary); }
.qed-nav-legend > div { display:flex; align-items:center; gap:5px; }
.qed-dot { width:10px; height:10px; border-radius:3px; flex-shrink:0; }
.qed-dot-done { background:color-mix(in srgb, var(--accent-green) 25%, transparent); border:1px solid color-mix(in srgb, var(--accent-green) 45%, transparent); }
.qed-dot-none { background:var(--bg-elevated); border:1px solid color-mix(in srgb, var(--accent-red) 35%, transparent); }
.qed-dot-active { background:color-mix(in srgb, var(--accent) 14%, transparent); border:1px solid var(--accent); }

/* --- Sidebar: Actions & Shortcuts --- */
.qed-side-actions { display:flex; flex-direction:column; gap:8px; margin-bottom:18px; }
.qed-side-btn { width:100%; padding:9px 12px; font-size:12.5px; font-weight:600; border-radius:var(--radius-sm); border:1px solid var(--border-medium); background:transparent; color:var(--text-secondary); cursor:pointer; transition:all var(--transition); text-align:left; }
.qed-side-btn:hover { background:var(--bg-surface-hover); color:var(--text-primary); border-color:var(--accent); }
.qed-shortcuts { font-size:11px; color:var(--text-tertiary); line-height:1.8; }
.qed-shortcuts-title { font-weight:700; color:var(--text-secondary); margin-bottom:4px; }
.qed-shortcuts kbd { display:inline-block; background:var(--bg-elevated); border:1px solid var(--border-subtle); border-radius:3px; padding:1px 5px; font-size:10.5px; font-family:inherit; color:var(--text-secondary); }

/* --- Empty / Drop Zone --- */
.qed-empty-zone { border:2px dashed var(--border-medium); border-radius:var(--radius-md); padding:60px 30px; text-align:center; transition:all .2s; max-width:520px; margin:40px auto; }
.qed-empty-zone.is-dragover, .qed-main.is-dragover .qed-empty-zone { border-color:var(--accent); background:color-mix(in srgb, var(--accent) 8%, transparent); }
.qed-empty-zone svg { width:48px; height:48px; color:var(--text-tertiary); margin-bottom:14px; }
.qed-empty-title { font-size:16px; font-weight:700; color:var(--text-primary); margin-bottom:6px; }
.qed-empty-sub { font-size:13px; color:var(--text-tertiary); margin-bottom:18px; }
.qed-empty-btn { background:var(--accent); color:#fff; border:none; padding:10px 22px; border-radius:var(--radius-sm); font-size:13px; font-weight:600; cursor:pointer; transition:background var(--transition); }
.qed-empty-btn:hover { background:var(--accent-hover); }

/* --- Expanded View --- */
.qed-detail { max-width:780px; margin:0 auto 28px; }
.qed-detail-img { position:relative; border:1px solid var(--border-subtle); border-radius:var(--radius-md); overflow:hidden; margin-bottom:18px; background:var(--bg-elevated); text-align:center; }
.qed-detail-img img { max-width:100%; max-height:420px; object-fit:contain; display:block; margin:0 auto; cursor:zoom-in; }
.qed-img-actions { display:flex; gap:8px; padding:8px 12px; border-top:1px solid var(--border-subtle); }
.qed-img-action { background:none; border:1px solid var(--border-medium); border-radius:var(--radius-xs); padding:5px 12px; font-size:12px; font-weight:600; color:var(--text-secondary); cursor:pointer; transition:all var(--transition); }
.qed-img-action:hover { color:var(--text-primary); background:var(--bg-surface-hover); }
.qed-img-action.is-danger { color:var(--accent-red); }
.qed-img-action.is-danger:hover { border-color:var(--accent-red); }
.qed-detail-noimg { margin-bottom:18px; }

/* Upload progress overlay on detail image */
.qed-upload-bar { height:4px; background:var(--bg-elevated); border-radius:999px; overflow:hidden; margin-bottom:14px; }
.qed-upload-bar-fill { height:100%; background:var(--accent); transition:width .15s ease; }
.qed-upload-text { font-size:12px; color:var(--text-tertiary); text-align:center; margin-bottom:10px; }

/* Answer buttons */
.qed-ans-section { margin-bottom:16px; }
.qed-ans-label { font-size:12px; font-weight:700; text-transform:uppercase; letter-spacing:.04em; color:var(--text-secondary); margin-bottom:10px; }
.qed-ans-group { display:flex; gap:10px; flex-wrap:wrap; margin-bottom:8px; }
.qed-ans-btn { min-width:56px; height:46px; padding:0 16px; border-radius:var(--radius-sm); border:2px solid var(--border-medium); background:var(--bg-elevated); color:var(--text-primary); font-size:15px; font-weight:700; cursor:pointer; transition:all .15s; display:flex; align-items:center; justify-content:center; }
.qed-ans-btn:hover { border-color:var(--accent); background:color-mix(in srgb, var(--accent) 8%, transparent); }
.qed-ans-btn.is-correct { background:var(--accent-green); border-color:var(--accent-green); color:#fff; }
.qed-ans-btn.is-correct:hover { background:color-mix(in srgb, var(--accent-green) 85%, #000); }

/* Edit options toggle */
.qed-edit-toggle { background:none; border:none; font-size:12px; font-weight:600; color:var(--accent); cursor:pointer; padding:4px 0; transition:color var(--transition); }
.qed-edit-toggle:hover { color:var(--accent-hover); }
.qed-edit-opts { margin-top:8px; display:flex; flex-direction:column; gap:6px; }
.qed-edit-opt-row { display:flex; align-items:center; gap:8px; }
.qed-edit-opt-label { flex-shrink:0; width:22px; font-size:12px; font-weight:700; color:var(--text-tertiary); }
.qed-edit-opt-row .qed-input { flex:1; padding:6px 10px; font-size:12.5px; }

/* Explanation */
.qed-explain-row { margin-bottom:16px; }

/* Detail navigation */
.qed-detail-nav { display:flex; align-items:center; justify-content:space-between; gap:12px; padding:14px 0; border-top:1px solid var(--border-subtle); }
.qed-detail-pos { font-size:13px; font-weight:600; color:var(--text-secondary); }
.qed-nav-btn { display:inline-flex; align-items:center; gap:6px; background:none; border:1px solid var(--border-medium); border-radius:var(--radius-sm); padding:8px 16px; font-size:13px; font-weight:600; color:var(--text-primary); cursor:pointer; transition:all var(--transition); }
.qed-nav-btn:hover { background:var(--bg-surface-hover); }
.qed-nav-btn:disabled { opacity:.35; cursor:not-allowed; }

/* Delete / clone row */
.qed-q-actions { display:flex; gap:8px; align-items:center; margin-bottom:14px; }

/* --- Gallery (thumbnail overview below expanded view) --- */
.qed-gallery-section { border-top:1px solid var(--border-subtle); padding-top:20px; }
.qed-gallery-head { font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.05em; color:var(--text-secondary); margin-bottom:12px; }
.qed-gallery { display:grid; grid-template-columns:repeat(auto-fill, minmax(180px, 1fr)); gap:12px; }
.qed-gal-card { background:var(--bg-surface); border:1.5px solid var(--border-subtle); border-radius:var(--radius-sm); overflow:hidden; cursor:pointer; transition:all .15s; position:relative; }
.qed-gal-card:hover { border-color:var(--border-medium); box-shadow:var(--shadow-sm); }
.qed-gal-card.is-active { border-color:var(--accent); box-shadow:0 0 0 2px color-mix(in srgb, var(--accent) 30%, transparent); }
.qed-gal-card.no-answer { border-color:color-mix(in srgb, var(--accent-red) 50%, transparent); }
.qed-gal-img { width:100%; height:120px; object-fit:cover; display:block; background:var(--bg-elevated); }
.qed-gal-placeholder { width:100%; height:120px; display:flex; align-items:center; justify-content:center; padding:10px; font-size:12px; color:var(--text-tertiary); text-align:center; background:var(--bg-elevated); word-break:break-word; }
.qed-gal-footer { padding:7px 10px; display:flex; align-items:center; justify-content:space-between; }
.qed-gal-num { font-size:11px; font-weight:600; color:var(--text-secondary); }
.qed-gal-badge { font-size:11px; font-weight:800; padding:2px 7px; border-radius:999px; background:color-mix(in srgb, var(--accent-red) 14%, transparent); color:var(--accent-red); }
.qed-gal-badge.is-set { background:color-mix(in srgb, var(--accent-green) 16%, transparent); color:var(--accent-green); }

/* Upload progress on gallery card */
.qed-gal-progress { position:absolute; bottom:31px; left:0; right:0; height:3px; background:var(--bg-elevated); }
.qed-gal-progress-fill { height:100%; background:var(--accent); transition:width .15s ease; }

/* --- Mobile sidebar toggle --- */
.qed-sidebar-toggle { display:none; }

/* --- Responsive --- */
@media (max-width:900px) {
  .qed-body { grid-template-columns:1fr; }
  .qed-sidebar { display:none; position:fixed; left:0; top:56px; bottom:34px; width:280px; z-index:10; box-shadow:var(--shadow-xl); }
  .qed-sidebar.is-open { display:block; }
  .qed-sidebar-toggle { display:inline-flex; align-items:center; justify-content:center; width:36px; height:36px; border:1px solid var(--border-medium); border-radius:var(--radius-xs); background:var(--bg-elevated); color:var(--text-secondary); cursor:pointer; }
  .qed-gallery { grid-template-columns:repeat(auto-fill, minmax(150px, 1fr)); }
}
@media (max-width:600px) {
  .qed-bar { padding:0 12px; gap:10px; height:50px; }
  .qed-bar-title { font-size:13px; max-width:140px; }
  .qed-back span { display:none; }
  .qed-save-btn { padding:8px 13px; font-size:12px; }
  .qed-main { padding:16px 12px; }
  .qed-detail-img img { max-height:280px; }
  .qed-ans-btn { min-width:48px; height:40px; font-size:14px; }
  .qed-gallery { grid-template-columns:repeat(2, 1fr); gap:10px; }
  .qed-gal-img { height:100px; }
  .qed-empty-zone { padding:40px 18px; }
}

/* ====== ZOOM ẢNH ====== */
.exam-img-zoom {
  position: fixed;
  inset: 0;
  z-index: 100001;
  background: rgba(0, 0, 0, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.exam-img-zoom img {
  max-width: 92vw;
  max-height: 92vh;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.exam-img-zoom-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.14);
  border: none;
  border-radius: 50%;
  color: #fff;
  font-size: 22px;
  line-height: 1;
  cursor: pointer;
  transition: background var(--transition);
}

.exam-img-zoom-close:hover { background: rgba(255, 255, 255, 0.24); }

/* ====== SKELETON ====== */
.exam-skeleton {
  padding: 40px;
  text-align: center;
  color: var(--text-tertiary);
  font-size: 13px;
}

/* ============================================================
   NÂNG CẤP THẺ ĐỀ
   ============================================================ */
.exam-quiz-titlerow {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 6px;
}

.exam-quiz-titlerow .exam-quiz-title { margin-bottom: 0; }

.exam-quiz-diff {
  font-size: 10.5px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

.diff-easy { background: color-mix(in srgb, var(--accent-green) 16%, transparent); color: var(--accent-green); }
.diff-medium { background: color-mix(in srgb, var(--accent-amber) 18%, transparent); color: var(--accent-amber); }
.diff-hard { background: color-mix(in srgb, var(--accent-red) 16%, transparent); color: var(--accent-red); }

.exam-quiz-status {
  font-size: 10.5px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  border: 1px solid transparent;
}

.exam-quiz-status.st-none { color: var(--text-tertiary); background: var(--bg-elevated); }
.exam-quiz-status.st-pass { color: var(--accent-green); background: color-mix(in srgb, var(--accent-green) 14%, transparent); }
.exam-quiz-status.st-mid { color: var(--accent-amber); background: color-mix(in srgb, var(--accent-amber) 16%, transparent); }
.exam-quiz-status.st-low { color: var(--accent-red); background: color-mix(in srgb, var(--accent-red) 14%, transparent); }

.exam-quiz-progress {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 10px;
}

.exam-quiz-progress-track {
  flex: 1;
  height: 6px;
  border-radius: 999px;
  background: var(--bg-elevated);
  overflow: hidden;
}

.exam-quiz-progress-fill {
  height: 100%;
  width: 0;
  border-radius: 999px;
  background: var(--accent);
  transition: width 0.6s ease;
}

.exam-quiz-progress-fill.is-good { background: var(--accent-green); }
.exam-quiz-progress-fill.is-mid { background: var(--accent-amber); }
.exam-quiz-progress-fill.is-low { background: var(--accent-red); }

.exam-quiz-progress-val {
  flex-shrink: 0;
  font-size: 12px;
  font-weight: 800;
  color: var(--text-secondary);
  font-variant-numeric: tabular-nums;
  min-width: 26px;
  text-align: right;
}

.exam-quiz-top3 {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-top: 10px;
  min-height: 22px;
}

.exam-quiz-top3-label {
  font-size: 11px;
  color: var(--text-tertiary);
  font-weight: 600;
}

.exam-quiz-top3-empty {
  font-size: 11px;
  color: var(--text-tertiary);
  font-style: italic;
}

.exam-quiz-ava {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 800;
  color: #1a1a1f;
  border: 1.5px solid var(--bg-surface);
}

/* ============================================================
   MÀN KẾT QUẢ — PHÂN TÍCH
   ============================================================ */
.exam-result-bar {
  display: flex;
  height: 10px;
  border-radius: 999px;
  overflow: hidden;
  margin-top: 20px;
  background: var(--bg-elevated);
}

.exam-result-bar-seg { height: 100%; width: 0; transition: width 0.6s ease; }
.exam-result-bar-seg.seg-correct { background: var(--accent-green); }
.exam-result-bar-seg.seg-wrong { background: var(--accent-red); }
.exam-result-bar-seg.seg-skip { background: var(--accent-amber); }

.exam-insight-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 16px;
}

.exam-insight {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  text-align: center;
}

.exam-insight-label {
  font-size: 11px;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  font-weight: 600;
  margin-bottom: 4px;
}

.exam-insight-value {
  font-size: 16px;
  font-weight: 800;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

.exam-insight-value.is-up { color: var(--accent-green); }
.exam-insight-value.is-down { color: var(--accent-red); }

.exam-review-head-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.exam-redo-wrong { padding: 7px 14px; font-size: 12.5px; }

/* ============================================================
   MÀN LÀM BÀI — CHẾ ĐỘ TẬP TRUNG / PHÍM TẮT / TỚI CÂU CHƯA LÀM
   ============================================================ */
.quiz-taker-icon-btn {
  flex-shrink: 0;
  width: 38px;
  height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-medium);
  background: var(--bg-elevated);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.quiz-taker-icon-btn:hover { color: var(--text-primary); border-color: var(--border-medium); }
.quiz-taker-icon-btn.is-active { color: var(--accent); border-color: var(--accent); background: color-mix(in srgb, var(--accent) 12%, transparent); }

/* Khi bật chế độ tập trung: ẩn phiếu trả lời, câu hỏi chiếm trọn bề ngang */
.quiz-taker.is-focus .quiz-sheet-panel { display: none; }
.quiz-taker.is-focus .quiz-taker-body { grid-template-columns: 1fr; max-width: 820px; }

.quiz-jump-unanswered {
  width: 100%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin-bottom: 12px;
  padding: 8px 12px;
  font-size: 12px;
  font-weight: 600;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
}

.quiz-jump-unanswered:hover { background: var(--bg-surface-hover); }

/* ============================================================
   RESPONSIVE — 3 mức: Desktop màn lớn · iPad/Tablet · Mobile
   ============================================================ */

/* ===== 1) DESKTOP MÀN LỚN — trải nội dung ra, tránh dồn cụm ở giữa ===== */

/* ≥1200px: danh sách đề tự xếp nhiều cột theo bề ngang (không kéo giãn 1 thẻ) */
@media (min-width: 1200px) {
  .exam-quiz-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    gap: 14px;
    align-items: stretch;
  }
  .exam-course-grid { grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); }
}

/* ≥1440px: dùng phần lớn chiều ngang màn hình thay vì khung hẹp ở giữa */
@media (min-width: 1440px) {
  .exam-page { max-width: min(1640px, 94vw); }
  .exam-layout { grid-template-columns: 320px 1fr; gap: 32px; }
  .exam-course-grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 18px; }
  .quiz-taker-body { max-width: 1280px; grid-template-columns: 1fr 320px; }
  .quiz-sheet-grid { grid-template-columns: repeat(6, 1fr); }
}

/* ≥1900px: màn siêu rộng — vẫn trải rộng nhưng giới hạn để chữ không quá thưa */
@media (min-width: 1900px) {
  .exam-page { max-width: min(1880px, 94vw); }
}

/* ===== 2) TABLET / iPad (≤1024px) ===== */
@media (max-width: 1024px) {
  .exam-page { padding: 18px 16px 56px; }
  /* Lịch sử (sidebar) xuống dưới nội dung chính, không ẩn */
  .exam-layout { grid-template-columns: 1fr; gap: 22px; }
  .exam-main { order: 1; }
  .exam-sidebar { order: 2; }
  .exam-history-list { display: grid; grid-template-columns: repeat(2, 1fr); }
  .exam-history-item:nth-last-child(-n+2):nth-child(odd),
  .exam-history-item:last-child { border-bottom: none; }
  .exam-course-grid { grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); }
  /* Phòng làm bài: giữ 2 cột nhưng phiếu trả lời gọn hơn */
  .quiz-taker-body { grid-template-columns: 1fr 210px; gap: 18px; padding: 22px 18px; }
  .quiz-sheet-grid { grid-template-columns: repeat(5, 1fr); }
  /* Màn kết quả xếp dọc cho gọn */
  .exam-result-top { grid-template-columns: 1fr; gap: 20px; justify-items: center; }
  .exam-result-stats { width: 100%; max-width: 460px; }
  .exam-result-actions { width: 100%; max-width: 460px; min-width: 0; }
}

/* iPad dọc & màn nhỏ hơn: bỏ phiếu trả lời cạnh, dùng thanh + drawer */
@media (max-width: 820px) {
  .quiz-taker-body { grid-template-columns: 1fr; padding: 20px 16px 96px; }
  .quiz-sheet-panel { display: none; }
  .quiz-mobile-bar { display: block; }
}

/* ===== 3) MOBILE (≤600px) ===== */
@media (max-width: 600px) {
  .exam-page { padding: 14px 12px 48px; }
  .exam-stats-row { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .exam-stat { padding: 12px 13px; gap: 10px; }
  .exam-stat-icon { width: 36px; height: 36px; border-radius: 9px; }
  .exam-stat-icon svg { width: 18px; height: 18px; }
  .exam-stat-num { font-size: 21px; }
  .exam-screen-head { padding-left: 11px; }
  .exam-screen-head h1 { font-size: 18px; }
  .exam-screen-head p { font-size: 12.5px; }
  .exam-course-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .exam-history-list { grid-template-columns: 1fr; }
  .exam-history-item { border-bottom: 1px solid var(--border-subtle); }
  .exam-history-item:last-child { border-bottom: none; }

  /* Thanh trên cùng phòng thi */
  .quiz-taker-bar { height: 52px; gap: 10px; padding: 0 12px; }
  .quiz-taker-title { max-width: 120px; font-size: 13px; }
  .quiz-taker-back span { display: none; }
  .quiz-taker-submit { padding: 8px 13px; font-size: 12px; }
  .quiz-taker-timer { padding: 6px 9px; font-size: 12px; }

  /* Thân câu hỏi */
  .quiz-taker-body { padding: 14px 12px 96px; gap: 14px; }
  .quiz-q-head { padding: 13px 15px; }
  .quiz-q-text { padding: 15px; font-size: 15px; }
  .quiz-q-image { padding: 0 15px 14px; }
  .quiz-options { padding: 0 15px 15px; }
  .quiz-option { padding: 11px 13px; gap: 10px; }
  .quiz-option-key { width: 24px; height: 24px; }

  /* Danh sách đề: thẻ tự wrap (tiêu đề ở trên, cụm nút xuống hàng) */
  .exam-quiz-icon { width: 38px; height: 38px; }

  /* Kết quả */
  .exam-result-card { padding: 18px 16px; }
  .exam-result-stats { grid-template-columns: repeat(3, 1fr); gap: 8px; }
  .exam-rstat { padding: 12px 6px; }
  .exam-rstat-num { font-size: 19px; }

  /* Phân tích kết quả */
  .exam-insight-grid { gap: 8px; }
  .exam-insight { padding: 10px 8px; }
  .exam-insight-value { font-size: 14px; }
  .exam-insight-label { font-size: 10px; }

  /* Modal & trình soạn đề */
  .exam-modal { max-width: 100%; }
  .qe-row, .qe-row.qe-row-3 { grid-template-columns: 1fr; }
  .qe-img-row { flex-wrap: wrap; }
  .qe-upload-btn { width: 100%; }
}

/* ===== Mobile rất nhỏ (≤380px) ===== */
@media (max-width: 380px) {
  .exam-stats-row { grid-template-columns: repeat(2, 1fr); }
  .exam-course-grid { grid-template-columns: 1fr; }
}