#stem .katex {
      font-size: 1.00em;
    }

    .opt-text .katex {
      font-size: 1.10em;
    }

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

    :root {
      --bg: #f7f5f0;
      --surface: #ffffff;
      --surface-2: #f0ede6;
      --border: #e2ddd5;
      --text: #1a1714;
      --text-2: #5a534a;
      --text-3: #9a8f83;
      --accent: #2563a8;
      --accent-light: #dbeafe;
      --correct: #166534;
      --correct-bg: #dcfce7;
      --correct-ring: #4ade80;
      --wrong: #991b1b;
      --wrong-bg: #fee2e2;
      --wrong-ring: #f87171;
      --hint: #92400e;
      --hint-bg: #fef3c7;
      --radius: 10px;
      --radius-lg: 16px;
      --shadow: 0 1px 3px rgba(0, 0, 0, .07), 0 4px 16px rgba(0, 0, 0, .06);
      --shadow-lg: 0 4px 6px rgba(0, 0, 0, .07), 0 12px 32px rgba(0, 0, 0, .1);
      --font-serif: 'Crimson Pro', Georgia, serif;
      --font-sans: 'DM Sans', system-ui, sans-serif;
      --font-mono: 'DM Mono', monospace;
      --transition: 200ms cubic-bezier(.4, 0, .2, 1);

      /* Liquid Glass Constants */
      --anim--hover-time: 400ms;
      --anim--hover-ease: cubic-bezier(0.25, 1, 0.5, 1);
    }

    @property --angle-1 {
      syntax: "<angle>";
      inherits: false;
      initial-value: -75deg;
    }

    @property --angle-2 {
      syntax: "<angle>";
      inherits: false;
      initial-value: -45deg;
    }

    body.embed-mode .sidebar,
    body.embed-mode .sidebar-toggle,
    body.embed-mode .app-header,
    body.embed-mode .kbd-hints {
      display: none !important;
    }

    body.embed-mode .main-content {
      padding: 10px 15px 40px !important;
      height: 100vh !important;
      overflow-y: auto !important;
    }

    body.embed-mode .card {
      max-width: 100%;
      margin: 0;
      border: none;
      box-shadow: none;
      border-radius: 0;
      display: flex;
      flex-direction: column;
    }

    body.embed-mode .note-wrap {
      display: none !important;
      /* Hide notes in embedded sample to focus on the quiz */
    }


    body {
      font-family: var(--font-sans);
      background: var(--bg);
      color: var(--text);
      min-height: 100vh;
      display: flex;
      flex-direction: row;
      align-items: flex-start;
      overflow: hidden;
    }

    .full-screen {
      position: fixed;
      inset: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      background: var(--bg);
      z-index: 1100;
      gap: 16px;
    }

    .full-screen.hidden {
      display: none;
    }

    .loading-spinner {
      width: 36px;
      height: 36px;
      border: 3px solid var(--border);
      border-top-color: var(--accent);
      border-radius: 50%;
      animation: spin .7s linear infinite;
    }

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

    .loading-label {
      font-family: var(--font-mono);
      font-size: .8rem;
      color: var(--text-3);
    }

    .error-icon {
      font-size: 2.5rem;
    }

    .error-title {
      font-family: var(--font-serif);
      font-size: 1.4rem;
      font-weight: 600;
    }

    .error-msg {
      font-size: .85rem;
      color: var(--text-2);
    }

    /* Sidebar */
    /* overflow: visible so .sidebar-toggle (right: -12px) is not clipped; z-index keeps it above .main-content */
    .sidebar {
      width: 320px;
      height: 100vh;
      background: var(--surface);
      border-right: 1.5px solid var(--border);
      flex-shrink: 0;
      display: flex;
      flex-direction: column;
      transition: width var(--transition);
      position: relative;
      z-index: 1;
      min-height: 0;
      overflow: visible;
    }

    .sidebar-header {
      font-family: var(--font-serif);
      font-size: 1.3rem;
      font-weight: 600;
      margin-bottom: 8px;
      padding-bottom: 12px;
      border-bottom: 1px solid var(--border);
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-left: 8px;
      margin-right: 8px;
    }



    /* Vertical-mode collapse button — only visible on mobile (shown via media query) */
    .vertical-sidebar-toggle {
      display: none;
      align-items: center;
      justify-content: center;
      gap: 8px;
      padding: 6px 14px;
      border-radius: 99px;
      background: var(--surface-2);
      border: 1.5px solid var(--border);
      cursor: pointer;
      flex-shrink: 0;
      color: var(--text-2);
      font-size: 0.75rem;
      font-weight: 700;
      transition: all var(--transition);
      font-family: var(--font-sans);
    }
    .vertical-sidebar-toggle:hover {
      background: var(--accent-light);
      border-color: var(--accent);
      color: var(--accent);
    }
    .vertical-sidebar-toggle svg {
      transition: transform .25s ease;
    }
    .sidebar.vertical-collapsed .vertical-sidebar-toggle svg {
      transform: rotate(180deg);
    }

    .q-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(42px, 1fr));
      gap: 8px;
      margin-top: 20px;
      margin-bottom: 24px;
      align-content: start;
    }

    .q-grid-item {
      aspect-ratio: 1;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 6px;
      border: 1.5px solid var(--border);
      font-family: var(--font-mono);
      font-size: 0.85rem;
      font-weight: 600;
      cursor: pointer;
      position: relative;
      color: var(--text-2);
      background: var(--bg);
      transition: all 0.2s;
    }

    .q-grid-item:hover {
      border-color: var(--text-3);
    }

    .q-grid-item.active {
      border-color: var(--accent);
      box-shadow: 0 0 0 3px var(--accent-light);
      color: var(--accent);
    }

    .q-grid-item.correct {
      background: var(--correct-bg);
      border-color: var(--correct-ring);
      color: var(--correct);
    }

    .q-grid-item.wrong {
      background: var(--wrong-bg);
      border-color: var(--wrong-ring);
      color: var(--wrong);
    }

    .q-grid-item.skipped {
      background: var(--surface-2);
      border-color: var(--text-3);
      color: var(--text-2);
      opacity: .8;
    }

    .flag-icon {
      position: absolute;
      top: -6px;
      right: -6px;
      font-size: 12px;
      background: #fff;
      border-radius: 50%;
      box-shadow: 0 1px 2px rgba(0, 0, 0, .2);
      display: none;
      width: 16px;
      height: 16px;
      align-items: center;
      justify-content: center;
      z-index: 2;
    }

    .q-grid-item.flagged .flag-icon {
      display: flex;
    }

    .q-grid-item.low-yield .flag-icon {
      display: none;
    }

    /* Same hazard tape as #quizCard.quiz-card--low-yield — ring follows cell border curve */
    .q-grid-item.low-yield::after {
      content: '';
      position: absolute;
      inset: -1.5px;
      border-radius: inherit;
      pointer-events: none;
      z-index: 1;
      padding: 3px;
      background: repeating-linear-gradient(
        -45deg,
        #0a0a0a 0 7px,
        #ffe205 7px 14px
      );
      -webkit-mask:
        linear-gradient(#fff 0 0) content-box,
        linear-gradient(#fff 0 0);
      -webkit-mask-composite: xor;
      mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
      mask-composite: exclude;
      box-sizing: border-box;
    }

    #quizCard {
      position: relative;
    }

    #quizCard.quiz-card--low-yield::after {
      content: '';
      position: absolute;
      /* Padding edge of #quizCard is inside .card border — extend outward so stripe follows outer curve */
      inset: -1.5px;
      border-radius: inherit;
      pointer-events: none;
      z-index: 40;
      padding: 5px;
      background: repeating-linear-gradient(
        -45deg,
        #0a0a0a 0 7px,
        #ffe205 7px 14px
      );
      -webkit-mask:
        linear-gradient(#fff 0 0) content-box,
        linear-gradient(#fff 0 0);
      -webkit-mask-composite: xor;
      mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
      mask-composite: exclude;
      box-sizing: border-box;
    }

    body.embed-mode #quizCard.quiz-card--low-yield::after {
      inset: 0;
    }

    /* Golden shimmer ring — same gradient + animation as .flag-bar */
    #quizCard.quiz-card--flagged::after {
      content: '';
      position: absolute;
      inset: -1.5px;
      border-radius: inherit;
      pointer-events: none;
      z-index: 40;
      padding: 5px;
      /* Shimmer on a 60° diagonal (CSS angle: 0 = up, 90 = right) */
      background: linear-gradient(60deg, #f59e0b, #fbbf24, #fde68a, #f59e0b, #fbbf24);
      background-size: 200% 100%;
      animation: shimmer 40s linear infinite;
      -webkit-mask:
        linear-gradient(#fff 0 0) content-box,
        linear-gradient(#fff 0 0);
      -webkit-mask-composite: xor;
      mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
      mask-composite: exclude;
      box-sizing: border-box;
    }

    body.embed-mode #quizCard.quiz-card--flagged::after {
      inset: 0;
    }

    .note-icon {
      position: absolute;
      top: -5px;
      left: -5px;
      font-size: 9px;
      background: var(--accent-light);
      border: 1px solid var(--accent);
      border-radius: 50%;
      display: none;
      width: 14px;
      height: 14px;
      align-items: center;
      justify-content: center;
      z-index: 3;
    }

    .q-grid-item.has-note .note-icon {
      display: flex;
    }

    /* --- Sidebar --- */
    .sidebar.collapsed {
      width: 72px;
    }

    .sidebar-toggle {
      position: absolute;
      top: 16px;
      right: -12px;
      width: 24px;
      height: 24px;
      border-radius: 50%;
      background: var(--surface);
      border: 1.5px solid var(--border);
      box-shadow: 0 1px 3px rgba(0, 0, 0, .1);
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 2;
      transition: transform var(--transition);
    }

    .sidebar-toggle:hover {
      background: var(--accent-light);
      border-color: var(--accent);
    }

    .sidebar.collapsed .sidebar-toggle {
      transform: rotate(180deg);
    }

    /* Middle scrolls; Copy / Finish stay at bottom of sidebar and do not scroll with it. */
    /* Horizontal padding so .note-icon / .flag-icon (negative inset on .q-grid-item) stay inside the scrollport; overflow-x:hidden would otherwise clip them like an invisible edge. */
    .sidebar-content {
      padding: 24px;
      display: flex;
      flex-direction: column;
      flex: 1;
      min-height: 0;
      overflow: hidden;
    }

    .sidebar-body {
      display: flex;
      flex-direction: column;
      flex: 1;
      min-height: 0;
      overflow: hidden; /* For animation masking on mobile */
    }

    .sidebar-scroll {
      flex: 1;
      min-height: 0;
      overflow-y: auto;
      overflow-x: hidden;
      padding-left: 8px;
      padding-right: 8px;
      scrollbar-width: none;
      -ms-overflow-style: none;
    }

    .sidebar-scroll::-webkit-scrollbar {
      display: none;
    }

    .sidebar-footer-actions {
      flex-shrink: 0;
      display: flex;
      flex-direction: column;
      gap: 8px;
      margin-top: 8px;
      padding-top: 16px;
      border-top: 1px solid var(--border);
      position: relative;
      z-index: 1;
      background: var(--surface);
    }

    @media (min-width: 1001px) {
      .sidebar-content>.sidebar-footer-actions {
        flex-shrink: 0;
      }
    }

    .sidebar.collapsed .sidebar-content {
      display: none;
    }

    /* Collapsed Sidebar */
    /*
 * quiz.html — Collapsed sidebar scrollbars: when .sidebar has .collapsed, the question
 * strip (.collapsed-q-list) may still scroll (wheel / touch) but scrollbars must not
 * show — same approach as .sidebar-scroll above (scrollbar-width / webkit). If you
 * change overflow or flex here, re-check both axes and update MASTER_NOTES.md at repo root.
 */
    .sidebar-collapsed-content {
      display: none;
      padding: 16px 0;
      flex: 1;
      min-height: 0;
      flex-direction: column;
      align-items: center;
      gap: 12px;
      overflow-x: hidden;
      overflow-y: hidden;
    }

    .sidebar.collapsed .sidebar-collapsed-content {
      display: flex;
    }

    .collapsed-q-list {
      display: flex;
      flex-direction: column;
      gap: 8px;
      flex: 1;
      min-height: 0;
      overflow-y: auto;
      overflow-x: hidden;
      width: 100%;
      align-items: center;
      padding: 0 12px;
      scrollbar-width: none;
      -ms-overflow-style: none;
    }

    .collapsed-q-list::-webkit-scrollbar {
      display: none;
    }

    .collapsed-q-item {
      width: 42px;
      height: 42px;
      flex-shrink: 0;
    }

    .sidebar-collapsed-divider {
      width: 32px;
      height: 1px;
      background: var(--border);
      margin: 4px 0;
      flex-shrink: 0;
    }

    .sidebar-collapsed-actions {
      display: flex;
      flex-direction: column;
      gap: 12px;
      align-items: center;
      flex-shrink: 0;
    }

    .collapsed-icon-btn {
      width: 42px;
      height: 42px;
      border-radius: 8px;
      background: var(--bg);
      border: 1.5px solid var(--border);
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.2rem;
      color: var(--text-2);
      transition: all var(--transition);
    }

    .collapsed-icon-btn:hover {
      background: var(--surface-2);
      border-color: var(--text-3);
    }

    #collapsedHideModeBtn.active,
    #collapsedRandomiseModeBtn.active {
      background: var(--accent-light);
      border-color: var(--accent);
      color: var(--accent);
    }

    .collapsed-status {
      font-family: var(--font-mono);
      font-size: .8rem;
      font-weight: 600;
      color: var(--text-2);
      padding: 8px 0;
    }

    /* Main */
    .main-content {
      flex: 1;
      height: 100vh;
      overflow-y: auto;
      padding: 16px 32px 80px;
      overflow-x: hidden;
    }

    .app-header {
      width: 100%;
      max-width: 1060px;
      margin: 0 auto 8px;
      display: grid;
      grid-template-columns: 1fr auto;
      grid-template-areas: "center right";
      align-items: center;
      gap: 24px;
      padding: 0 0 4px;
    }

    .header-left {
      display: none;
    }

    .header-center {
      grid-area: center;
      display: none; 
      width: 100%;
    }

    /* Progress visibility logic */
    #progressWrap, #srsProgWrap {
      display: none !important;
    }

    body:not(.srs-mode) #progressWrap:not(.hidden) {
      display: flex !important;
      justify-content: flex-start;
    }

    body.srs-mode #srsProgWrap {
      display: flex !important;
      justify-content: flex-start;
    }

    .hc-prog-meta {
      display: flex;
      flex-direction: column;
      gap: 6px;
      width: 100%;
    }

    .hc-prog-labels {
      display: flex;
      justify-content: space-between;
      align-items: flex-end;
      width: 100%;
    }

    .hc-prog-count {
      font-family: var(--font-mono);
      font-size: 0.85rem;
      color: var(--text-2);
      font-weight: 600;
      white-space: nowrap;
    }

    .hc-prog-bar-container {
      width: 100%;
      display: flex;
      flex-direction: column;
    }

    .header-right {
      grid-area: right;
      display: flex;
      align-items: center;
      gap: 12px;
      min-width: 140px;
      justify-content: flex-end;
    }

    .logo {
      font-family: var(--font-serif);
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--text);
      text-decoration: none;
    }
    .logo span { color: var(--accent); }

    .score-pill {
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: 99px;
      padding: 5px 14px;
      font-size: 0.8rem;
      font-weight: 700;
      color: var(--text-2);
      font-family: var(--font-sans);
      display: inline-flex;
      align-items: center;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
      white-space: nowrap;
    }
    
    .score-num { font-weight: 700; color: var(--text); }
    .score-pct { margin-left: 6px; opacity: 0.8; font-weight: 600; }

    .user-email {
      display: none !important;
    }

    .version-badge-inline {
      font-size: .65rem;
      font-family: var(--font-mono);
      font-weight: 500;
      color: var(--text-3);
      background: var(--surface-2);
      border: 1px solid var(--border);
      border-radius: 99px;
      padding: 1px 6px;
      margin-left: 4px;
      display: inline-flex;
      align-items: center;
      vertical-align: middle;
      line-height: 1;
    }
    .stats-tooltip-popup {
      position: fixed;
      z-index: 99999;
      background: rgba(30, 30, 30, 0.95);
      color: #fff;
      padding: 6px 12px;
      border-radius: 8px;
      font-size: .7rem;
      max-width: 240px;
      white-space: pre-wrap;
      pointer-events: none;
      font-family: var(--font-sans);
      font-weight: 500;
      box-shadow: 0 4px 20px rgba(0,0,0,0.25);
      opacity: 0;
      transform: translateY(8px);
      transition: opacity 0.15s ease, transform 0.15s ease;
      display: block !important;
      visibility: hidden;
    }
    .stats-tooltip-popup.visible {
      opacity: 1;
      transform: translateY(0);
      visibility: visible;
    }

    .header-btn {
      background: var(--surface-2);
      border: 1.5px solid var(--border);
      border-radius: 99px;
      padding: 5px 14px;
      font-size: 0.75rem;
      font-weight: 700;
      color: var(--text-2);
      cursor: pointer;
      transition: all var(--transition);
      font-family: var(--font-sans);
      text-decoration: none;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }
    .header-btn:hover { 
      background: var(--border); 
      color: var(--text);
      transform: translateY(1px);
      box-shadow: inset 0 1px 2px rgba(0,0,0,0.1);
    }

    .version-badge {
      font-size: .65rem;
      font-family: var(--font-mono);
      font-weight: 500;
      color: var(--text-3);
      background: var(--bg);
      border: 1px solid var(--border);
      border-radius: 99px;
      padding: 2px 8px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    .srs-mode-badge {
      font-size: .62rem;
      font-family: var(--font-mono);
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: .02em;
      background: #eef5ff;
      color: var(--accent);
      border: 1px solid #b9d5ff;
      border-radius: 4px;
      padding: 1px 5px;
      display: none;
    }
    .IS_SRS_MODE .srs-mode-badge { display: block; }
    
    /* Responsive Header Layout */
    @media (max-width: 1000px) {
      .app-header {
        gap: 12px;
      }
      .user-email { display: none; }
    }

    @media (max-width: 768px) {
      .app-header {
        grid-template-columns: auto 1fr;
        grid-template-areas: 
          "labels right"
          "bar bar";
        gap: 8px 16px;
        align-items: center;
      }
      /* Pull progress components out of wrappers to participate in app-header grid */
      body:not(.srs-mode) #progressWrap:not(.hidden),
      body.srs-mode #srsProgWrap {
        display: contents !important;
      }
      .hc-prog-meta {
        display: contents;
      }
      .hc-prog-labels {
        grid-area: labels;
        width: auto;
        padding-top: 2px;
      }
      .hc-prog-bar-container {
        grid-area: bar;
        width: 100%;
        padding-bottom: 4px;
      }
      .header-right {
        grid-area: right;
        justify-content: flex-end;
      }
    }

    @media (max-width: 390px) {
      .logo { font-size: 1.2rem; }
      .hc-prog-meta { gap: 10px; }
      .score-pill { padding: 4px 12px; font-size: 0.75rem; }
      .header-btn { padding: 5px 10px; font-size: 0.7rem; }
    }

    /* Progress */
    .prog-bar {
      display: flex;
      height: 8px;
      border-radius: 99px;
      overflow: hidden;
      background: var(--border);
    }

    .seg {
      height: 100%;
      transition: width .4s ease;
    }

    .seg-correct {
      background: #4ade80;
    }

    .seg-wrong {
      background: #f87171;
    }

    .flag-bar {
      height: 3px;
      border-radius: 99px;
      margin-top: 4px;
      background: linear-gradient(90deg, #f59e0b, #fbbf24, #fde68a, #f59e0b, #fbbf24);
      background-size: 200% 100%;
      animation: shimmer 2s linear infinite;
      width: 0%;
      transition: width .4s ease;
    }

    /* Exam mode pre-reveal: hide every signal of correctness. Sidebar dots
       collapse to a neutral "answered" tone; progress segments share a single
       muted accent fill; accuracy text and feedback panels are blanked. */
    body.exam-hidden .q-grid-item.correct,
    body.exam-hidden .q-grid-item.wrong {
      background: var(--surface-2);
      border-color: var(--text-3);
      color: var(--text);
    }
    body.exam-hidden #seg-correct,
    body.exam-hidden #seg-wrong {
      background: var(--accent);
      opacity: .55;
    }
    body.exam-hidden #progressPct,
    body.exam-hidden .score-num,
    body.exam-hidden .score-pct {
      visibility: hidden;
    }
    body.exam-hidden #feedbackMsg.correct,
    body.exam-hidden #feedbackMsg.wrong {
      visibility: hidden !important;
    }
    body.exam-hidden #attemptHistoryPanel {
      display: none !important;
    }
    /* Soft "exam in progress" cue on the quiz card border. */
    body.exam-hidden #quizCard {
      box-shadow: 0 0 0 2px var(--accent-light, rgba(0, 0, 0, .04));
    }

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

      100% {
        background-position: -200% 0
      }
    }

    /* Card */
    .card {
      width: 100%;
      max-width: 1060px;
      margin: 0 auto;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow);
      overflow: visible;
      animation: fadeUp .3s ease both;
      display: grid;
      grid-template-columns: minmax(0, 1fr) 260px;
      grid-template-rows: auto auto auto auto auto 1fr auto; /* 7 rows total */
      min-height: 580px;
    }

    @keyframes fadeUp {
      from {
        opacity: 0;
        transform: translateY(12px)
      }

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

    .card-header {
      grid-column: 1;
      grid-row: 1;
      padding: 20px 28px 0;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .q-label {
      font-family: var(--font-mono);
      font-size: .7rem;
      font-weight: 500;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .08em;
      flex-shrink: 0;
    }

    .part-tag {
      font-family: var(--font-mono);
      font-size: .7rem;
      font-weight: 500;
      background: var(--surface-2);
      border: 1px solid var(--border);
      border-radius: 99px;
      padding: 2px 8px;
      line-height: 1;
      color: var(--text-3);
      /* Content-sized but allowed to shrink; min-width:0 lets text be truncated/marquee'd. */
      flex: 0 1 auto;
      min-width: 0;
      max-width: 100%;
      overflow: hidden;
      white-space: nowrap;
      cursor: default;
      user-select: none;
      -webkit-user-select: none;
      display: flex;
      align-items: center;
    }

    .part-tag-inner {
      display: inline-block;
      white-space: nowrap;
      flex-shrink: 0;
      line-height: 1;
      min-width: 0;
      position: relative;
      top: 5%;
    }

    .part-tag-inner.marquee {
      will-change: transform;
    }

    @media (max-width: 600px) {
      .q-label {
        /* Bumped from .6rem so the question number isn't cramped on mobile. */
        font-size: .7rem;
      }
      /* Normal-mode breadcrumb: content-sized, shrinks + marquees when too long. */
      .part-tag {
        font-size: .7rem;
        padding: 2px 8px;
      }
      /* SRS breadcrumb: match the part-tag sizing rules. */
      body.srs-mode .srs-source-tag {
        font-size: .7rem;
        padding: 2px 8px;
      }
    }

    .stem {
      grid-column: 1;
      grid-row: 2;
      font-family: var(--font-serif);
      font-size: 1.25rem;
      line-height: 1.65;
      color: var(--text);
      padding: 16px 28px 24px;
    }

    /* Hint */
    .hint-wrap {
      position: relative;
      z-index: 100;
      container-type: inline-size;
      grid-column: 1;
      grid-row: 5;
      padding: 0 28px;
      margin-top: 20px;
    }

    /* Responsive hint buttons via Container Queries */
    .btn-text {
      max-width: 150px;
      overflow: hidden;
      white-space: nowrap;
      opacity: 1;
      transition: max-width var(--anim--hover-time) var(--anim--hover-ease),
        opacity calc(var(--anim--hover-time) / 2) var(--anim--hover-ease);
      display: inline-block;
      vertical-align: middle;
      line-height: 1.6;
      padding-bottom: 2px;
    }

    @container (max-width: 650px) {

      .hint-actions .nb-btn.hint .btn-text,
      .hint-actions .nb-btn.claude .btn-text,
      .hint-actions .nb-btn.chatgpt .btn-text,
      .hint-actions .nb-btn.perplexity .btn-text {
        max-width: 0;
        opacity: 0;
      }

      .hint-actions .nb-btn.hint:not(.ai-dot),
      .hint-actions .nb-btn.claude:not(.ai-dot),
      .hint-actions .nb-btn.chatgpt:not(.ai-dot),
      .hint-actions .nb-btn.perplexity:not(.ai-dot) {
        width: auto;
        min-width: 29px;
      }

      .hint-actions .nb-btn.hint:not(.ai-dot) span,
      .hint-actions .nb-btn.claude:not(.ai-dot) span,
      .hint-actions .nb-btn.chatgpt:not(.ai-dot) span,
      .hint-actions .nb-btn.perplexity:not(.ai-dot) span {
        box-sizing: content-box;
        padding: 0;
        width: 32px;
        height: 32px;
        justify-content: center;
        gap: 0;
      }
    }

    /* 
       On Mobile Mode (Screen < 600px), force Google to collapse at the same 650px container threshold as others.
       On Desktop, it continues to use the 260px container threshold below, allowing it to "hold out" even in narrow containers.
    */
    @media (max-width: 600px) {
      @container (max-width: 650px) {
        .hint-actions .nb-btn.google .btn-text {
          max-width: 0;
          opacity: 0;
        }

        .hint-actions .nb-btn.google:not(.ai-dot) {
          width: auto;
          min-width: 29px;
        }

        .hint-actions .nb-btn.google:not(.ai-dot) span {
          box-sizing: content-box;
          padding: 0;
          width: 32px;
          height: 32px;
          justify-content: center;
          gap: 0;
        }
      }
    }

    @container (max-width: 260px) {
      .hint-actions .nb-btn.google .btn-text {
        max-width: 0;
        opacity: 0;
      }

      .hint-actions .nb-btn.google:not(.ai-dot) {
        width: auto;
        min-width: 29px;
      }

      .hint-actions .nb-btn.google:not(.ai-dot) span {
        box-sizing: content-box;
        padding: 0;
        width: 32px;
        height: 32px;
        justify-content: center;
        gap: 0;
      }
    }

    /* ── AI split-button (hover to reveal quick / long) ────────────── */
    .ai-split-outer {
      position: relative;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }

    #hintActions:not(.search-active) .ai-split-outer:hover {
      z-index: 10005;
      /* Lift above neighboring AI buttons */
    }

    .ai-main-state {
      transition: opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1), transform 0.2s cubic-bezier(0.4, 0, 0.2, 1);
      transform-origin: center;
    }

    #hintActions:not(.search-active) .ai-split-outer:hover .ai-main-state {
      opacity: 0;
      transform: scale(0.9);
      pointer-events: none;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .ai-split-state {
      position: absolute;
      left: -12px;
      bottom: -12px;
      transform: scale(0.9);
      transform-origin: bottom left;
      display: grid;
      grid-template-columns: auto auto auto;
      grid-template-rows: auto auto;
      gap: 8px;
      padding: 12px;
      align-items: start;
      justify-items: start;
      opacity: 0;
      visibility: hidden;
      pointer-events: none;
      transition: opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1), transform 0.2s cubic-bezier(0.4, 0, 0.2, 1), visibility 0.2s linear;
      white-space: nowrap;
      z-index: 10000;
    }

    /* Invisible hit-area extension to prevent hover flickering - Tight to the 2x2 grid */
    .ai-split-state::before {
      content: '';
      position: absolute;
      inset: 0; /* Matches the grid bounds exactly */
      background: transparent;
      z-index: -2;
      pointer-events: auto;
    }

    #hintActions:not(.search-active) .ai-split-outer:hover .ai-split-state {
      opacity: 1;
      visibility: visible;
      transform: scale(1);
      pointer-events: auto;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s linear;
    }

    /* Soft background-matched "cloud" fade behind the buttons (Blured Squircle Haze) */
    .ai-split-state::after {
      content: '';
      position: absolute;
      inset: -5px; /* Slightly larger to account for blur-edge thinning */
      background: rgba(255, 255, 255, 0.95); /* Slightly denser for blur compensation */
      border-radius: 28px;
      z-index: -1;
      pointer-events: none;
      opacity: 0;
      visibility: hidden;
      /* Filter blur on the element itself creates a perfect Squircle-shaped gradient */
      filter: blur(8px);
      /* Animation: smooth opacity fade (Unified Squircle Haze) */
      box-shadow: 0 0 45px 22px rgba(255, 255, 255, 0.90);
      transition: opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1), visibility 0.2s linear;
      -webkit-backface-visibility: hidden;
      backface-visibility: hidden;
      will-change: box-shadow, opacity, filter;
    }

    #hintActions:not(.search-active) .ai-split-outer:hover {
      z-index: 10005;
      isolation: isolate; /* Create a stable stacking context for the expansion */
    }

    #hintActions:not(.search-active) .ai-split-outer:hover .ai-split-state::after {
      opacity: 1;
      visibility: visible;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s linear;
    }

    /* Sibling fade-out is now handled within @container queries above to only trigger in icon mode */
    .ai-split-state .button-wrap {
      opacity: 0;
      transform: scale(0.9);
      transition: opacity 0.18s cubic-bezier(0.4, 0, 0.2, 1), transform 0.18s cubic-bezier(0.4, 0, 0.2, 1);
    }

    .ai-split-state .button-wrap:nth-child(1) {
      transition-delay: 0.04s;
    }

    .ai-split-state .button-wrap:nth-child(2) {
      transition-delay: 0.08s;
    }

    /* child(3) is the .ai-spacer placeholder — no delay rule needed */
    .ai-split-state .button-wrap:nth-child(4) {
      transition-delay: 0.12s;
    }

    .ai-split-state .button-wrap:nth-child(5) {
      transition-delay: 0.16s;
    }

    .ai-split-state .button-wrap:nth-child(6) {
      transition-delay: 0.20s;
    }

    #hintActions:not(.search-active) .ai-split-outer:hover .ai-split-state .button-wrap {
      opacity: 1;
      transform: scale(1);
      transition: opacity 0.25s cubic-bezier(0.16, 1, 0.3, 1), transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .nb-btn.ai-dot {
      min-width: 32px;
    }

    .nb-btn.ai-dot>span {
      padding: 0 11px;
      min-width: 32px;
      gap: 0;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .dot-row {
      display: flex;
      gap: 3.5px;
      align-items: center;
      justify-content: center;
      overflow: visible;
    }

    .dot {
      width: 5.5px;
      height: 5.5px;
      border-radius: 50%;
      flex-shrink: 0;
      border: 1px solid transparent;
    }

    .nb-btn.google.ai-dot .dot {
      background: #4285F4;
      border-color: #4285F4;
    }

    .nb-btn.claude.ai-dot .dot {
      background: #D97757;
      border-color: #D97757;
    }

    .nb-btn.chatgpt.ai-dot .dot {
      background: #10a37f;
      border-color: #10a37f;
    }

    .nb-btn.perplexity.ai-dot .dot {
      background: #20808D;
      border-color: #20808D;
    }

    .nb-btn.ai-dot.hollow .dot {
      background: transparent !important;
      border: 1px solid;
    }

    .ai-dot-label {
      position: absolute;
      bottom: calc(100% + 7px);
      left: 50%;
      transform: translateX(-50%);
      background: rgba(30, 30, 30, 0.82);
      color: #fff;
      font-size: 0.7rem;
      font-weight: 500;
      padding: 3px 8px;
      border-radius: 6px;
      white-space: nowrap;
      pointer-events: none;
      opacity: 0;
      transition: opacity 0.15s ease;
    }

    .button-wrap:has(.nb-btn.ai-dot:hover) .ai-dot-label {
      opacity: 1;
    }

    /* Position labels for the second row (children 4-6) below the buttons */
    .ai-split-state .button-wrap:nth-child(n+4) .ai-dot-label {
      bottom: auto;
      top: calc(100% + 7px);
    }

    /* Empty spacer for 3rd column of row 1 */
    .ai-spacer {
      pointer-events: none;
    }

    /* Verify note tick icon — coloured per provider */
    .nb-btn.google.ai-dot .verify-check    { stroke: #4285F4; }
    .nb-btn.claude.ai-dot .verify-check    { stroke: #D97757; }
    .nb-btn.chatgpt.ai-dot .verify-check   { stroke: #10a37f; }
    .nb-btn.perplexity.ai-dot .verify-check { stroke: #20808D; }

    .hint-actions {
      display: flex;
      align-items: center;
      flex-wrap: nowrap;
      gap: 10px;
      overflow: visible !important; /* Ensure the large AI cloud isn't clipped by the container */
    }

    /* Timer Animation */
    .quiz-timer-wrap {
      grid-column: 1;
      grid-row: 4;
      width: 100%;
      margin: 0;
      height: 2px;
      background: var(--border);
      position: relative;
      overflow: hidden;
      z-index: 5;
      opacity: 0.8;
    }
    .quiz-timer-bar {
      height: 100%;
      width: 100%;
      background: linear-gradient(90deg, var(--accent), #4ade80);
      transform-origin: left;
      transition: none;
      box-shadow: 0 0 10px rgba(37, 99, 168, 0.4);
    }
    .quiz-timer-bar.expired {
      background: #ef4444; /* Red */
      box-shadow: 0 0 10px rgba(239, 68, 68, 0.4);
    }

    .ai-search-wrap {
      width: 100%;
      margin-top: 20px;
      position: relative;
      z-index: 10; /* Lower than expanded AI dots */
    }



    .ai-search-bar {
      position: relative;
      width: 100%;
      background: #ffffff !important;
      z-index: 2147483646 !important;
    }

    /* ── Note Verify AI Button (2x2 Grid) ── */
    .note-body {
      position: relative;
    }

    .note-verify-outer {
      z-index: 100;
      flex-shrink: 0;
    }

    .note-footer {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      margin-top: 6px;
      min-height: 32px;
    }

    .note-verify-outer .ai-split-state {
      grid-template-columns: repeat(4, auto);
      grid-template-rows: auto;
      left: auto;
      right: -12px;
      bottom: -12px;
      transform-origin: bottom right;
    }

    /* Transition delays for 1x4 horizontal row (expanding leftward) */
    .note-verify-outer .ai-split-state .button-wrap:nth-child(4) { transition-delay: 0.04s; }
    .note-verify-outer .ai-split-state .button-wrap:nth-child(3) { transition-delay: 0.08s; }
    .note-verify-outer .ai-split-state .button-wrap:nth-child(2) { transition-delay: 0.12s; }
    .note-verify-outer .ai-split-state .button-wrap:nth-child(1) { transition-delay: 0.16s; }

    /* Hover logic for standalone outer (not under #hintActions) */
    .note-verify-outer:hover {
      z-index: 10005;
      isolation: isolate;
    }
    .note-verify-outer:hover .ai-main-state {
      opacity: 0;
      transform: scale(0.9);
      pointer-events: none;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }
    .note-verify-outer:hover .ai-split-state {
      opacity: 1;
      visibility: visible;
      transform: scale(1);
      pointer-events: auto;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s linear;
    }
    .note-verify-outer:hover .ai-split-state::after {
      opacity: 1;
      visibility: visible;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s linear;
    }
    .note-verify-outer:hover .ai-split-state .button-wrap {
      opacity: 1;
      transform: scale(1);
      transition: opacity 0.25s cubic-bezier(0.16, 1, 0.3, 1), transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    }

    /* Tap-to-expand for mobile (mirrors hover state) */
    .note-verify-outer.expanded {
      z-index: 10005;
      isolation: isolate;
    }
    .note-verify-outer.expanded .ai-main-state {
      opacity: 0;
      transform: scale(0.9);
      pointer-events: none;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }
    .note-verify-outer.expanded .ai-split-state {
      opacity: 1;
      visibility: visible;
      transform: scale(1);
      pointer-events: auto;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s linear;
    }
    .note-verify-outer.expanded .ai-split-state::after {
      opacity: 1;
      visibility: visible;
      transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s linear;
    }
    .note-verify-outer.expanded .ai-split-state .button-wrap {
      opacity: 1;
      transform: scale(1);
      transition: opacity 0.25s cubic-bezier(0.16, 1, 0.3, 1), transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    }

    /* Position labels for the 1x4 row correctly above the buttons */
    .note-verify-outer .ai-split-state .button-wrap .ai-dot-label {
      bottom: calc(100% + 7px);
      top: auto;
    }

    .note-verify-outer .ai-split-state::after {
      /* Background cloud set to transparent per user request. 
         To restore, change background to rgba(255, 255, 255, 0.95) and restore the box-shadow. */
      background: transparent;
      box-shadow: none;
    }

    /* Smaller buttons for the note panel */
    .note-verify-outer .nb-btn.ai-dot {
      min-width: 29px;
    }
    .note-verify-outer .nb-btn.ai-dot > span {
      height: 29px;
      padding: 0 8px;
      min-width: 29px;
    }
    .note-verify-outer .nb-btn.ai-dot svg {
      width: 13px;
      height: 13px;
    }

    .nb-btn.gold { --tint: #b45309; }
    .nb-btn.gold.ai-dot .verify-check { stroke: #b45309; }

    .ai-search-input {
      width: 100%;
      box-sizing: border-box;
      background: #fff;
      border: 1.5px solid var(--border);
      border-radius: 999vw;
      padding: 7px 34px 7px 14px;
      font-size: .85rem;
      font-family: var(--font-sans);
      color: var(--text);
      outline: none;
      transition: border-color 0.22s ease, box-shadow 0.22s ease;
    }

    .ai-search-input:hover {
      border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
      box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 10%, transparent);
    }

    .ai-search-input:focus {
      border-color: var(--accent);
      box-shadow: 0 0 0 3px var(--accent-light);
    }

    .ai-search-clear {
      position: absolute;
      right: 10px;
      top: 50%;
      transform: translateY(-50%);
      background: none !important;
      border: none !important;
      width: 22px !important;
      height: 22px !important;
      border-radius: 50% !important;
      padding: 0 !important;
      padding-top: 1px !important;
      margin: 0 !important;
      color: #ccc !important;
      font-size: 18px !important;
      line-height: 1 !important;
      cursor: pointer;
      display: none;
      align-items: center;
      justify-content: center;
      z-index: 5;
      backdrop-filter: none !important;
      -webkit-backdrop-filter: none !important;
      transition: none !important;
    }

    .ai-search-clear:hover {
      background: #f0f0f0 !important;
      color: #999 !important;
    }

    .ai-search-clear.visible {
      display: flex;
    }

    @media (max-width: 600px) {
      .ai-search-bar {
        background: white !important;
        backdrop-filter: none !important;
        -webkit-backdrop-filter: none !important;
      }
      .ai-search-input {
        font-size: 16px !important;
      }

      /* Ensure the split state doesn't steal the first tap during animation */
      .ai-split-outer:hover .ai-split-state {
        /* Safety window: sub-buttons are non-interactive for the first 300ms of expansion */
        transition: pointer-events 0s linear 0.3s !important;
      }

      .undo-toast {
        left: 16px;
        transform: none;
      }

      .undo-toast.visible {
        animation: undoFadeInMobile 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
      }

      @keyframes undoFadeInMobile {
        from { opacity: 0; transform: translateY(10px); }
        to { opacity: 1; transform: none; }
      }

      @keyframes undoFadeOutMobile {
        from { opacity: 1; transform: none; }
        to { opacity: 0; transform: translateY(10px); }
      }

      .undo-toast.visible.hiding {
        animation: undoFadeOutMobile 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards !important;
      }
    }



    #aiSearchDropdown {
      position: absolute !important;
      left: 0 !important;
      right: 0 !important;
      top: calc(100% + 6px) !important;
      background-color: #ffffff !important;
      background: #ffffff !important;
      opacity: 1;
      visibility: visible;
      border: 1.5px solid var(--border);
      border-radius: 14px;
      box-shadow: 0 10px 30px rgba(0,0,0,0.15);
      z-index: 2147483647 !important;
      display: none;
      flex-direction: column;
      overflow: hidden !important;
      padding: 0 !important;
      backdrop-filter: none !important;
      -webkit-backdrop-filter: none !important;
      transform: translate3d(0,0,1px);
      -webkit-transform: translate3d(0,0,1px);
      isolation: isolate !important;
    }

    #aiSearchDropdown.open {
      display: flex !important;
      animation: dropdownSlideIn 0.2s cubic-bezier(0.16, 1, 0.3, 1) forwards;
      transform-origin: top center;
    }

    @keyframes dropdownSlideIn {
      from { opacity: 0; transform: translateY(-10px) scale(0.98); }
      to { opacity: 1; transform: translateY(0) scale(1); }
    }

    .ai-search-history-label {
      padding: 10px 14px;
      font-size: 11px;
      color: #999;
      text-transform: uppercase;
      font-weight: 700;
      letter-spacing: 0.5px;
      border-bottom: 1px solid #eee;
    }

    .ai-search-history-list {
      overflow-y: auto;
      max-height: 273px; /* 6.5 items */
      position: relative;
      -webkit-mask-image: linear-gradient(to bottom, black calc(100% - 24px), transparent 100%);
      mask-image: linear-gradient(to bottom, black calc(100% - 24px), transparent 100%);
    }

    .ai-search-history-item {
      display: flex;
      align-items: center;
      padding: 10px 14px;
      border-bottom: 1px solid #f5f5f5;
      cursor: pointer;
      background: #fff;
      transition: background 0.15s ease;
    }

    .ai-search-history-item:last-child {
      border-bottom: none;
    }

    .ai-search-history-item:hover {
      background: #f8fafc;
    }

    .ai-search-history-item-text {
      flex: 1;
      font-size: 14px;
      color: var(--text);
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
    }

    .ai-search-history-del {
      background: none;
      border: none;
      padding: 4px 8px;
      color: #ccc;
      font-size: 18px;
      cursor: pointer;
      border-radius: 4px;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: all 0.2s ease;
    }

    .ai-search-history-del:hover {
      background: #fee2e2;
      color: #ef4444;
    }

    .ai-search-history-list {
      overflow-y: auto;
      /* 10.5 items: item height is ~33px (14px padding + 1.4 line-height on .84rem) */
      max-height: 346px; 
      position: relative;
      /* Removed mask-image to fix iOS Safari transparency issues */
    }

    /* Custom scrollbar to keep it sleek */
    .ai-search-history-list::-webkit-scrollbar {
      width: 6px;
    }
    .ai-search-history-list::-webkit-scrollbar-track {
      background: transparent;
    }
    .ai-search-history-list::-webkit-scrollbar-thumb {
      background: var(--border);
      border-radius: 10px;
    }
    .ai-search-history-list::-webkit-scrollbar-thumb:hover {
      background: var(--text-3);
    }

    .ai-search-history-label {
      padding: 8px 14px 4px;
      font-size: .72rem;
      font-weight: 600;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .06em;
    }

    .ai-search-history-item {
      display: flex;
      align-items: center;
      gap: 8px;
      padding: 7px 10px 7px 14px;
      cursor: pointer;
      font-size: .84rem;
      line-height: 1.4;
      color: var(--text);
      transition: background 0.1s ease;
      flex-shrink: 0;
    }

    .ai-search-history-item:hover {
      background: var(--surface-2);
    }

    .ai-search-history-item-text {
      flex: 1;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }

    .ai-search-history-del {
      background: none;
      border: none;
      cursor: pointer;
      font-size: .85rem;
      color: var(--text-3);
      padding: 2px 5px;
      border-radius: 5px;
      line-height: 1;
      flex-shrink: 0;
      transition: color 0.1s ease, background 0.1s ease;
    }

    .ai-search-history-del:hover {
      color: var(--text);
      background: rgba(0,0,0,.07);
    }

    /* 
       HARD LOCK: When search is active, we completely disable the expansion mechanism.
       This prevents the "moment of indecision" where the browser might try to 
       trigger expansion rules before realizing it should stay fixed.
    */
    #hintActions.search-active .ai-split-state {
      display: none !important;
      visibility: hidden !important;
      opacity: 0 !important;
      transition: none !important;
    }
    #hintActions.search-active .ai-split-state::after {
      display: none !important;
      visibility: hidden !important;
      opacity: 0 !important;
      transition: none !important;
    }
    #hintActions.search-active .ai-main-state {
      opacity: 1 !important;
      transform: none !important;
      transition: none !important;
      pointer-events: auto !important;
    }
    /* Suppress parent hover state entirely when search is active */
    #hintActions.search-active .ai-split-outer {
      z-index: 2 !important;
    }

    /* Ensure AI expansion is on top of search bar */
    .ai-split-outer:hover {
      z-index: 100;
    }


    /* Liquid Glass Buttons */
    .button-wrap {
      position: relative;
      z-index: 2;
      border-radius: 999vw;
      background: transparent;
      pointer-events: none;
      transition: all var(--anim--hover-time) var(--anim--hover-ease);
      flex-shrink: 0;
      display: flex;
    }

    .button-shadow {
      --shadow-cuttoff-fix: 2em;
      position: absolute;
      width: calc(100% + var(--shadow-cuttoff-fix));
      height: calc(100% + var(--shadow-cuttoff-fix));
      top: calc(0% - var(--shadow-cuttoff-fix) / 2);
      left: calc(0% - var(--shadow-cuttoff-fix) / 2);
      filter: blur(clamp(2px, 0.125em, 12px));
      -webkit-filter: blur(clamp(2px, 0.125em, 12px));
      overflow: visible;
      pointer-events: none;
    }

    .button-shadow::after {
      content: "";
      position: absolute;
      z-index: 0;
      inset: 0;
      border-radius: 999vw;
      background: linear-gradient(180deg,
          color-mix(in srgb, var(--tint, black) 20%, rgba(0, 0, 0, 0.2)),
          color-mix(in srgb, var(--tint, black) 10%, rgba(0, 0, 0, 0.1)));
      width: calc(100% - var(--shadow-cuttoff-fix) - 0.25em);
      height: calc(100% - var(--shadow-cuttoff-fix) - 0.25em);
      top: calc(var(--shadow-cuttoff-fix) - 0.5em);
      left: calc(var(--shadow-cuttoff-fix) - 0.875em);
      padding: 0.125em;
      box-sizing: border-box;
      mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
      mask-composite: exclude;
      -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
      -webkit-mask-composite: xor;
      transition: all var(--anim--hover-time) var(--anim--hover-ease);
      overflow: visible;
      opacity: 0.8;
    }

    .nb-btn {
      --border-width: 2px;
      all: unset;
      display: block;
      width: 100%;
      box-sizing: border-box;
      cursor: pointer;
      position: relative;
      -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
      pointer-events: auto;
      z-index: 3;
      text-decoration: none;
      background: linear-gradient(-75deg,
          color-mix(in srgb, var(--tint, transparent) 5%, rgba(255, 255, 255, 0.05)),
          color-mix(in srgb, var(--tint, transparent) 15%, rgba(255, 255, 255, 0.4)),
          color-mix(in srgb, var(--tint, transparent) 5%, rgba(255, 255, 255, 0.05)));
      border-radius: 999vw;
      box-shadow:
        inset 0 0.125em 0.125em rgba(0, 0, 0, 0.05),
        inset 0 -0.125em 0.125em rgba(255, 255, 255, 0.8),
        0 0.25em 0.125em -0.125em color-mix(in srgb, var(--tint, black) 20%, rgba(0, 0, 0, 0.2)),
        0 0 0.1em 0.25em inset rgba(255, 255, 255, 0.2),
        0 0 0 0 rgba(255, 255, 255, 1);
      backdrop-filter: blur(4px);
      -webkit-backdrop-filter: blur(4px);
      transition: all var(--anim--hover-time) var(--anim--hover-ease);
    }

    .nb-btn:hover,
    .nb-btn:focus-visible {
      transform: translateY(1.5px) scale(0.985);
      backdrop-filter: blur(0.01em);
      -webkit-backdrop-filter: blur(0.01em);
      box-shadow:
        inset 0 0.125em 0.125em rgba(0, 0, 0, 0.05),
        inset 0 -0.125em 0.125em rgba(255, 255, 255, 1),
        0 0.15em 0.05em -0.1em color-mix(in srgb, var(--tint, black) 25%, rgba(0, 0, 0, 0.25)),
        0 0 0.05em 0.1em inset rgba(255, 255, 255, 0.8),
        0 0 0 0 rgba(255, 255, 255, 1);
    }

    .nb-btn>span {
      position: relative;
      z-index: 10;
      width: 100%;
      box-sizing: border-box;
      user-select: none;
      -webkit-user-select: none;
      text-shadow: 0em 0.15em 0.05em rgba(0, 0, 0, 0.05);
      transition: all var(--anim--hover-time) var(--anim--hover-ease);
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 9px;
      padding: 0 15px;
      height: 32px;
      font-family: var(--font-sans), system-ui, sans-serif;
      font-weight: 600;
      font-size: 0.94rem;
      color: var(--tint, var(--text));
      line-height: 1;
      transform: translateY(1px);
    }

    .nb-btn:hover>span,
    .nb-btn:focus-visible>span {
      text-shadow: 0.025em 0.025em 0.025em rgba(0, 0, 0, 0.08);
    }

    .nb-btn>span::after {
      content: "";
      display: block;
      position: absolute;
      width: calc(100% - var(--border-width));
      height: calc(100% - var(--border-width));
      top: calc(0% + var(--border-width) / 2);
      left: calc(0% + var(--border-width) / 2);
      box-sizing: border-box;
      border-radius: 999vw;
      overflow: clip;
      background: linear-gradient(var(--angle-2), rgba(255, 255, 255, 0) 0%, rgba(255, 255, 255, 0.6) 40% 50%, rgba(255, 255, 255, 0) 55%);
      z-index: 3;
      mix-blend-mode: screen;
      pointer-events: none;
      background-size: 200% 200%;
      background-position: 0% 50%;
      background-repeat: no-repeat;
      transition: background-position calc(var(--anim--hover-time) * 1.25) var(--anim--hover-ease), --angle-2 calc(var(--anim--hover-time) * 1.25) var(--anim--hover-ease);
    }

    .nb-btn:hover>span::after,
    .nb-btn:focus-visible>span::after {
      background-position: 25% 50%;
    }

    .nb-btn:active>span::after {
      background-position: 50% 15%;
      --angle-2: -15deg;
    }

    .nb-btn::after {
      content: "";
      position: absolute;
      z-index: 1;
      inset: 0;
      border-radius: 999vw;
      width: calc(100% + var(--border-width));
      height: calc(100% + var(--border-width));
      top: calc(0% - var(--border-width) / 2);
      left: calc(0% - var(--border-width) / 2);
      padding: var(--border-width);
      box-sizing: border-box;
      background: conic-gradient(from var(--angle-1) at 50% 50%,
          color-mix(in srgb, var(--tint, black) 20%, rgba(0, 0, 0, 0.25)),
          rgba(0, 0, 0, 0) 5% 40%,
          color-mix(in srgb, var(--tint, black) 20%, rgba(0, 0, 0, 0.25)) 50%,
          rgba(0, 0, 0, 0) 60% 95%,
          color-mix(in srgb, var(--tint, black) 20%, rgba(0, 0, 0, 0.25))),
        linear-gradient(180deg,
          color-mix(in srgb, var(--tint, white) 20%, rgba(255, 255, 255, 0.8)),
          color-mix(in srgb, var(--tint, white) 20%, rgba(255, 255, 255, 0.8)));
      mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
      mask-composite: exclude;
      -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
      -webkit-mask-composite: xor;
      transition: all var(--anim--hover-time) var(--anim--hover-ease), --angle-1 500ms ease;
      box-shadow: inset 0 0 0 calc(var(--border-width) / 2) rgba(255, 255, 255, 0.5);
    }

    .nb-btn:hover::after,
    .nb-btn:focus-visible::after {
      --angle-1: -125deg;
    }

    .nb-btn:active::after {
      --angle-1: -75deg;
    }

    .button-wrap:has(.nb-btn:hover) .button-shadow,
    .button-wrap:has(.nb-btn:focus-visible) .button-shadow {
      filter: blur(clamp(2px, 0.0625em, 6px));
      -webkit-filter: blur(clamp(2px, 0.0625em, 6px));
      transition: filter var(--anim--hover-time) var(--anim--hover-ease);
    }

    .button-wrap:has(.nb-btn:hover) .button-shadow::after,
    .button-wrap:has(.nb-btn:focus-visible) .button-shadow::after {
      top: calc(var(--shadow-cuttoff-fix) - 0.875em);
      opacity: 0.9;
    }

    .button-wrap:has(.nb-btn:active) {
      transform: rotate3d(1, 0, 0, 20deg);
    }

    .button-wrap:has(.nb-btn:active) .nb-btn {
      box-shadow: inset 0 0.125em 0.125em rgba(0, 0, 0, 0.05), inset 0 -0.125em 0.125em rgba(255, 255, 255, 0.5),
        0 0.125em 0.125em -0.125em rgba(0, 0, 0, 0.2), 0 0 0.1em 0.25em inset rgba(255, 255, 255, 0.2),
        0 0.225em 0.05em 0 rgba(0, 0, 0, 0.05), 0 0.25em 0 0 rgba(255, 255, 255, 0.75), inset 0 0.25em 0.05em 0 rgba(0, 0, 0, 0.15);
    }

    .button-wrap:has(.nb-btn:active) .button-shadow {
      filter: blur(clamp(2px, 0.125em, 12px));
      -webkit-filter: blur(clamp(2px, 0.125em, 12px));
    }

    .button-wrap:has(.nb-btn:active) .button-shadow::after {
      top: calc(var(--shadow-cuttoff-fix) - 0.5em);
      opacity: 0.6;
    }

    .button-wrap:has(.nb-btn:active)>.nb-btn>span {
      text-shadow: 0.025em 0.15em 0.05em rgba(0, 0, 0, 0.1);
    }

    .nb-btn.google {
      --tint: #4285F4;
    }

    .nb-btn.claude {
      --tint: #D97757;
    }

    .nb-btn.chatgpt {
      --tint: #10a37f;
    }

    .nb-btn.hint {
      --tint: #d97706;
    }

    .nb-btn.perplexity {
      --tint: #20808D;
    }

    .hint-body {
      margin-top: 10px;
      padding: 12px 16px;
      background: var(--hint-bg);
      border-left: 3px solid #f59e0b;
      border-radius: 0 var(--radius) var(--radius) 0;
      font-size: .9rem;
      color: var(--hint);
      line-height: 1.55;
      display: none;
    }

    .hint-body.open {
      display: block;
      animation: fadeIn .2s ease;
    }

    /* Notes panel */
    .note-wrap {
      grid-column: 2;
      grid-row: 1 / 8; /* Spans all 7 rows */
      border-left: 1.5px solid var(--border);
      padding: 20px 18px;
      display: flex;
      flex-direction: column;
      background: var(--surface-2);
      /* Align with .card inner curve on the outer edge; keep inner edge square against main column */
      border-top-right-radius: calc(var(--radius-lg) - 1.5px);
      border-bottom-right-radius: calc(var(--radius-lg) - 1.5px);
    }

    .note-side-header {
      display: flex;
      align-items: center;
      gap: 7px;
      font-size: .72rem;
      font-weight: 600;
      color: var(--text-3);
      font-family: var(--font-mono);
      text-transform: uppercase;
      letter-spacing: .07em;
      margin-bottom: 10px;
      padding-bottom: 10px;
      border-bottom: 1px solid var(--border);
    }

    .note-toggle {
      display: none;
    }

    .note-body {
      display: flex;
      flex-direction: column;
      flex: 1;
      min-height: 0;
    }

    .note-textarea {
      flex: 1;
      min-height: 140px;
      height: 100%;
      width: 100%;
      padding: 12px 14px;
      font-family: var(--font-sans);
      font-size: .92rem;
      color: var(--text);
      background: var(--surface);
      border: 1.5px solid var(--border);
      /* Square top-left matches sharp sidebar inner edge; other corners follow panel/card curve */
      border-radius: 0 var(--radius) var(--radius) var(--radius);
      resize: none;
      outline: none;
      transition: border-color var(--transition);
      line-height: 1.55;
    }

    .note-textarea:focus {
      border-color: var(--accent);
    }

    .note-save-status {
      font-size: .7rem;
      color: var(--text-3);
      text-align: right;
      font-family: var(--font-mono);
      min-height: 1em;
      flex: 1;
    }

    .note-save-status.unsaved {
      color: #d97706;
      font-weight: 600;
    }

    .review-note {
      margin-top: 8px;
      padding: 12px 16px;
      background: var(--accent-light);
      border-radius: 8px;
      font-size: .88rem;
      color: var(--text-2);
      line-height: 1.6;
      border-left: 4px solid var(--accent);
    }

    .review-note ul {
      margin: 8px 0;
      padding-left: 20px;
    }

    .review-note li {
      margin-bottom: 6px;
    }

    .review-note strong {
      color: var(--text);
      font-weight: 600;
    }

    /* Undo button */
    .undo-toast {
      position: fixed;
      bottom: 24px;
      left: 24px;
      z-index: 10500;
      display: none;
      align-items: center;
      animation: undoFadeIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .undo-toast.visible {
      display: flex;
    }

    @keyframes undoFadeIn {
      from { opacity: 0; transform: translateX(-20px); }
      to { opacity: 1; transform: translateX(0); }
    }

    @keyframes undoFadeOut {
      from { opacity: 1; transform: translateX(0); }
      to { opacity: 0; transform: translateX(-20px); }
    }

    .undo-toast.hiding {
      animation: undoFadeOut 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    }

    .undo-btn {
      width: 44px;
      height: 44px;
      border-radius: 50%;
      background: #fff;
      border: 1.5px solid var(--border);
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      font-size: 1.4rem;
      color: var(--text-2);
      transition: all 0.2s ease;
      position: relative;
      box-shadow: 0 4px 12px rgba(0,0,0,0.1);
      padding: 0;
      outline: none;
    }

    .undo-icon {
      transform: translateX(-10%) rotate(-80deg);
      display: flex;
      align-items: center;
      justify-content: center;
      line-height: 1;
      padding-bottom: 2px; /* Optical alignment */
    }

    .undo-btn:hover {
      background: var(--accent);
      border-color: var(--accent);
      color: #fff;
      transform: scale(1.05);
    }

    .undo-svg-timer {
      position: absolute;
      inset: -1.5px; /* Cover the border */
      width: 44px;
      height: 44px;
      transform: rotate(-90deg);
      pointer-events: none;
    }

    .undo-circle {
      fill: none;
      stroke: var(--accent);
      stroke-width: 2.5;
      /* Circumference = 2 * PI * r. For r=20.75 (center of a 41.5px path inside 44px box) */
      /* Let's use 130 as a safe dasharray value */
      stroke-dasharray: 130;
      stroke-dashoffset: 0;
      stroke-linecap: round;
    }
    
    .undo-btn:hover .undo-circle {
      stroke: rgba(255,255,255,0.8);
    }

    .undo-toast.visible .undo-circle {
      animation: undoCircleCountdown 3s linear forwards;
    }

    @keyframes undoCircleCountdown {
      from { stroke-dashoffset: 0; }
      to { stroke-dashoffset: 130; }
    }

    .review-note em {
      font-style: italic;
      color: var(--text-2);
    }

    .review-note a {
      color: var(--accent);
      text-decoration: underline;
      text-decoration-thickness: 1px;
      text-underline-offset: 2px;
    }

    @keyframes fadeIn {
      from {
        opacity: 0
      }

      to {
        opacity: 1
      }
    }

    /* Options */
    .options {
      padding: 0 28px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .option {
      display: flex;
      align-items: flex-start;
      gap: 14px;
      padding: 14px 16px;
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      cursor: pointer;
      background: var(--surface);
      transition: border-color var(--transition), background var(--transition), box-shadow var(--transition);
      text-align: left;
      width: 100%;
      position: relative;
      overflow: hidden;
    }

    .opt-hold-progress {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      height: 3px;
      background: linear-gradient(90deg, var(--accent), #4ade80);
      transform-origin: left center;
      transform: scaleX(0);
      animation: optHoldFill 1.2s linear forwards;
      border-radius: 0 0 var(--radius) var(--radius);
      pointer-events: none;
    }

    @keyframes optHoldFill {
      0% {
        transform: scaleX(0);
      }

      100% {
        transform: scaleX(1);
      }
    }

    .option:hover:not(.locked) {
      border-color: var(--accent);
      background: var(--accent-light);
      box-shadow: 0 0 0 3px rgba(37, 99, 168, .1);
    }

    .option.selected:not(.locked) {
      border-color: var(--accent);
      background: var(--accent);
      color: #fff;
      box-shadow: 0 0 0 3px rgba(37, 99, 168, .2);
    }

    .option:focus-visible {
      outline: 2px solid var(--accent);
      outline-offset: 2px;
    }

    .option.selected:not(.locked) .opt-text,
    .option.selected:not(.locked) .opt-rationale {
      color: #fff;
    }

    .option.correct {
      border-color: var(--correct-ring);
      background: var(--correct-bg);
      box-shadow: 0 0 0 3px rgba(74, 222, 128, .2);
    }

    .option.wrong {
      border-color: var(--wrong-ring);
      background: var(--wrong-bg);
      box-shadow: 0 0 0 3px rgba(248, 113, 113, .2);
    }

    .option.dimmed {
      opacity: .5;
    }

    .opt-letter {
      flex-shrink: 0;
      width: 28px;
      height: 28px;
      border-radius: 50%;
      background: var(--surface-2);
      border: 1.5px solid var(--border);
      display: flex;
      align-items: center;
      justify-content: center;
      font-family: var(--font-mono);
      font-size: .78rem;
      font-weight: 500;
      color: var(--text-2);
      transition: background var(--transition), border-color var(--transition), color var(--transition);
    }

    .option.correct .opt-letter {
      background: #4ade80;
      border-color: #4ade80;
      color: #14532d;
    }

    .option.wrong .opt-letter {
      background: #f87171;
      border-color: #f87171;
      color: #7f1d1d;
    }

    .option.selected:not(.locked) .opt-letter {
      background: #fff;
      border-color: #fff;
      color: var(--accent);
    }

    .opt-body {
      flex: 1;
    }

    .opt-text {
      font-size: .95rem;
      line-height: 1.5;
      color: var(--text);
      overflow-wrap: break-word;
      word-break: break-word;
    }

    .opt-rationale {
      margin-top: 8px;
      font-size: .83rem;
      color: var(--text-2);
      line-height: 1.5;
      padding-top: 8px;
      border-top: 1px solid rgba(0, 0, 0, .06);
      display: none;
    }

    .opt-rationale.visible {
      display: block;
      animation: fadeIn .25s ease;
    }

    .opt-icon {
      flex-shrink: 0;
      font-size: 1.1rem;
      margin-top: 2px;
      display: none;
    }

    .option.correct .opt-icon,
    .option.wrong .opt-icon {
      display: block;
    }

    .opt-eliminate {
      flex-shrink: 0;
      align-self: flex-start;
      width: 28px;
      height: 28px;
      border-radius: 50%;
      background: transparent;
      border: 1.5px solid transparent;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      padding-top: 1px;
      font-size: .65rem;
      font-weight: 400;
      color: transparent;
      transition: color var(--transition), background var(--transition), border-color var(--transition);
      user-select: none;
      -webkit-user-select: none;
    }

    .option:hover:not(.locked) .opt-eliminate {
      opacity: 1;
      color: var(--text-2);
    }

    .option.selected:not(.locked) .opt-eliminate {
      color: rgba(255, 255, 255, 0.7);
    }

    .option.selected:not(.locked) .opt-eliminate:hover {
      color: #fff;
      opacity: 1;
    }

    .opt-eliminate:hover {
      background: var(--wrong-bg) !important;
      color: var(--wrong) !important;
      border-color: var(--wrong-ring) !important;
    }

    .option.eliminated .opt-eliminate {
      color: var(--text-3);
      border-color: var(--border);
      background: var(--surface-2);
    }

    .option.locked .opt-eliminate {
      display: none;
    }

    .option.eliminated .opt-text {
      text-decoration: line-through;
      color: var(--text-3);
    }

    .option.eliminated .opt-letter {
      opacity: .4;
    }

    .option.eliminated:not(.locked) {
      opacity: .6;
    }

    .option.eliminated:hover:not(.locked) {
      border-color: var(--border);
      background: var(--surface);
      box-shadow: none;
    }

    /* Alt-key eliminate hover: whole option turns red */
    body.alt-down .option:hover:not(.locked):not(.eliminated) {
      border-color: var(--wrong-ring);
      background: var(--wrong-bg);
      color: var(--text);
      box-shadow: 0 0 0 3px rgba(248, 113, 113, .2);
      cursor: crosshair;
    }

    body.alt-down .option:hover:not(.locked):not(.eliminated) .opt-text,
    body.alt-down .option:hover:not(.locked):not(.eliminated) .opt-rationale,
    body.alt-down .option:hover:not(.locked):not(.eliminated) .opt-eliminate {
      color: var(--text);
    }

    body.alt-down .option:hover:not(.locked):not(.eliminated) .opt-letter {
      background: #f87171;
      border-color: #f87171;
      color: #7f1d1d;
    }

    /* Footer */
    .card-footer {
      grid-column: 1;
      grid-row: 7;
      padding: 0 28px 28px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
    }

    #flagBtn {
      padding: 6px 14px;
      font-size: .8rem;
    }

    .btn {
      font-family: var(--font-sans);
      font-size: 1rem;
      font-weight: 600;
      border-radius: 99px;
      padding: 12px 28px;
      cursor: pointer;
      border: 1.5px solid transparent;
      transition: all var(--transition);
      display: inline-flex;
      align-items: center;
      gap: 8px;
      justify-content: center;
    }

    .btn-primary {
      background: var(--accent);
      color: #fff;
      border-color: var(--accent);
    }

    .btn-primary:hover {
      background: #1d4f8a;
      box-shadow: 0 4px 14px rgba(37, 99, 168, .3);
    }

    .btn-primary:disabled {
      opacity: .4;
      cursor: not-allowed;
      box-shadow: none;
    }

    .btn-ghost {
      background: transparent;
      color: var(--text-2);
      border-color: var(--border);
    }

    .btn-ghost:hover {
      background: var(--surface-2);
      color: var(--text);
    }

    .feedback-msg {
      font-size: .88rem;
      font-weight: 600;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .feedback-msg.correct {
      color: var(--correct);
    }

    .feedback-msg.wrong {
      color: var(--wrong);
    }

    /* Results */
    .results-screen {
      width: 100%;
      max-width: 780px;
      margin: 0 auto;
      display: none;
      flex-direction: column;
      gap: 24px;
      animation: fadeUp .4s ease both;
    }

    .results-screen.visible {
      display: flex;
    }

    .results-hero {
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      padding: 48px 40px;
      text-align: center;
    }

    .results-grade {
      font-family: var(--font-serif);
      font-size: 5rem;
      font-weight: 600;
      line-height: 1;
      margin-bottom: 8px;
      background: linear-gradient(135deg, #1a1714 0%, #2563a8 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    .results-label {
      font-size: 1.05rem;
      color: var(--text-2);
      margin-bottom: 32px;
    }

    .results-stats {
      display: flex;
      justify-content: center;
      gap: 40px;
      flex-wrap: wrap;
    }

    .stat {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 4px;
    }

    .stat-num {
      font-family: var(--font-mono);
      font-size: 1.8rem;
      font-weight: 500;
      color: var(--text);
    }

    .stat-num.green {
      color: var(--correct);
    }

    .stat-num.red {
      color: var(--wrong);
    }

    .stat-label {
      font-size: .78rem;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .06em;
    }

    .results-actions {
      display: flex;
      justify-content: center;
      gap: 12px;
      margin-top: 32px;
      flex-wrap: wrap;
    }

    /* Export Notes popup */
    .export-popup-wrap {
      position: relative;
    }

    .export-popup {
      position: absolute;
      bottom: calc(100% + 10px);
      right: 0;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      box-shadow: var(--shadow-lg);
      padding: 14px 14px 10px;
      min-width: 280px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      opacity: 0;
      transform: translateY(6px) scale(.97);
      pointer-events: none;
      transition: opacity 160ms ease, transform 160ms ease;
      z-index: 200;
    }

    .export-popup::after {
      content: '';
      position: absolute;
      top: 100%;
      right: 18px;
      border: 6px solid transparent;
      border-top-color: var(--border);
    }

    .export-popup::before {
      content: '';
      position: absolute;
      top: 100%;
      right: 19px;
      border: 5px solid transparent;
      border-top-color: var(--surface);
      z-index: 1;
    }

    .export-popup.open {
      opacity: 1;
      transform: translateY(0) scale(1);
      pointer-events: auto;
    }

    .export-popup-section {
      display: flex;
      flex-direction: column;
      gap: 7px;
    }

    .export-popup-label {
      font-family: var(--font-sans);
      font-size: .72rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .07em;
      color: var(--text-3);
    }

    .export-src-tabs {
      display: inline-flex;
      background: var(--surface-2);
      border: 1.5px solid var(--border);
      border-radius: 999px;
      padding: 3px;
      gap: 2px;
      width: 100%;
    }

    .export-src-tab {
      flex: 1;
      background: transparent;
      border: 0;
      cursor: pointer;
      padding: 5px 10px;
      border-radius: 999px;
      font-family: var(--font-sans);
      font-size: .75rem;
      font-weight: 600;
      color: var(--text-3);
      transition: all var(--transition);
      white-space: nowrap;
    }

    .export-src-tab:hover {
      color: var(--text-2);
    }

    .export-src-tab.active {
      background: var(--surface);
      color: var(--accent);
      box-shadow: 0 1px 2px rgba(0,0,0,.08);
    }

    .export-popup-actions {
      display: flex;
      gap: 6px;
      padding-top: 2px;
      border-top: 1px solid var(--border);
      margin-top: 2px;
    }

    .export-popup-action-btn {
      flex: 1;
      background: var(--surface-2);
      border: 1.5px solid var(--border);
      cursor: pointer;
      padding: 7px 10px;
      text-align: center;
      font-size: .8rem;
      font-weight: 600;
      color: var(--text);
      border-radius: 8px;
      font-family: var(--font-sans);
      transition: all var(--transition);
      white-space: nowrap;
    }

    .export-popup-action-btn:hover {
      background: var(--accent-light);
      border-color: var(--accent);
      color: var(--accent);
    }

    /* Natural-language toggle row */
    .export-nl-row {
      display: flex;
      align-items: center;
      gap: 9px;
      cursor: pointer;
      user-select: none;
      padding: 2px 0;
    }

    .export-nl-toggle-wrap {
      position: relative;
      width: 32px;
      height: 18px;
      flex-shrink: 0;
    }

    .export-nl-toggle-wrap input {
      opacity: 0;
      width: 0;
      height: 0;
      position: absolute;
    }

    .export-nl-slider {
      position: absolute;
      inset: 0;
      background: var(--border);
      border-radius: 999px;
      transition: background var(--transition);
      cursor: pointer;
    }

    .export-nl-slider::before {
      content: '';
      position: absolute;
      width: 12px;
      height: 12px;
      left: 3px;
      top: 3px;
      background: #fff;
      border-radius: 50%;
      transition: transform var(--transition);
      box-shadow: 0 1px 2px rgba(0,0,0,.18);
    }

    .export-nl-toggle-wrap input:checked + .export-nl-slider {
      background: var(--accent);
    }

    .export-nl-toggle-wrap input:checked + .export-nl-slider::before {
      transform: translateX(14px);
    }

    .export-nl-label {
      font-family: var(--font-sans);
      font-size: .82rem;
      font-weight: 600;
      color: var(--text);
    }

    .export-nl-hint {
      font-weight: 400;
      color: var(--text-3);
      font-size: .78rem;
    }

    /* Review */
    .filter-btn {
      padding: 5.5px 15px;
      font-size: 0.88rem;
      font-weight: 600;
      border-radius: 99px;
      cursor: pointer;
      border: 1.5px solid var(--border);
      background: transparent;
      color: var(--text-2);
      transition: all var(--transition);
    }

    .filter-btn.active {
      background: var(--surface-2);
      color: var(--text);
      border-color: var(--text-3);
    }

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

    .review-item {
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      padding: 16px 20px;
      cursor: pointer;
      display: flex;
      align-items: flex-start;
      gap: 14px;
      transition: box-shadow var(--transition);
    }

    .review-item:hover {
      box-shadow: var(--shadow);
    }

    .review-dot {
      flex-shrink: 0;
      width: 10px;
      height: 10px;
      border-radius: 50%;
      margin-top: 6px;
    }

    .review-dot.correct {
      background: var(--correct-ring);
    }

    .review-dot.wrong {
      background: var(--wrong-ring);
    }

    .review-text {
      flex: 1;
      font-size: .9rem;
      color: var(--text-2);
      line-height: 1.4;
    }

    .review-answer {
      font-size: .8rem;
      font-weight: 600;
      font-family: var(--font-mono);
      color: var(--text-3);
      flex-shrink: 0;
    }

    .status-Unanswered {
      color: var(--text-3);
    }

    .status-Correct {
      color: var(--correct);
    }

    .status-Wrong {
      color: var(--wrong);
    }

    .hidden {
      display: none !important;
    }

    /* Login */
    #loginScreen {
      position: fixed;
      inset: 0;
      background: var(--bg);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      z-index: 1000;
      padding: 24px;
    }

    #loginScreen.hidden {
      display: none;
    }

    .login-logo {
      font-family: var(--font-serif);
      font-size: 2.4rem;
      font-weight: 600;
      margin-bottom: 6px;
      text-align: center;
    }

    .login-logo span {
      color: var(--accent);
    }

    .login-sub {
      font-size: .85rem;
      color: var(--text-3);
      margin-bottom: 48px;
      text-align: center;
    }

    .google-btn {
      display: flex;
      align-items: center;
      gap: 10px;
      padding: 13px 28px;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: 99px;
      font-family: var(--font-sans);
      font-size: .9rem;
      font-weight: 600;
      cursor: pointer;
      transition: all var(--transition);
    }

    .google-btn:hover {
      border-color: var(--accent);
      background: var(--accent-light);
    }

    .login-error {
      margin-top: 16px;
      font-size: .8rem;
      color: var(--wrong);
      min-height: 1em;
      text-align: center;
    }

    .made-by-login {
      position: fixed;
      bottom: 20px;
      font-size: .72rem;
      color: var(--text-3);
      font-family: var(--font-mono);
    }

    .made-by {
      font-size: .68rem;
      color: var(--text-3);
      font-family: var(--font-mono);
      text-align: center;
      padding-top: 8px;
      margin-top: 8px;
      border-top: 1px solid var(--border);
    }

    /* Keyboard hints */
    .kbd-hints {
      width: 100%;
      max-width: 1060px;
      margin: 10px auto 0;
      display: flex;
      align-items: center;
      gap: 16px;
      flex-wrap: wrap;
      padding: 0 4px;
      opacity: 0;
      animation: fadeIn .4s ease .3s forwards;
    }

    .kbd-group {
      display: flex;
      align-items: center;
      gap: 4px;
      font-size: .68rem;
      color: var(--text-3);
      font-family: var(--font-mono);
      white-space: nowrap;
    }

    .kbd-sep {
      color: var(--border);
      margin: 0 2px;
    }

    kbd {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      background: var(--surface);
      border: 1px solid var(--border);
      border-bottom: 2px solid var(--border);
      border-radius: 4px;
      padding: 1px 5px;
      font-family: var(--font-mono);
      font-size: .65rem;
      color: var(--text-2);
      min-width: 20px;
      line-height: 1.6;
      box-shadow: 0 1px 0 rgba(0, 0, 0, .06);
      transition: background var(--transition), border-color var(--transition), color var(--transition);
    }

    kbd.pressed {
      background: var(--accent-light);
      border-color: var(--accent);
      color: var(--accent);
    }

    /* Responsive */
    @media (max-width: 1000px) {
      .sidebar-toggle {
        display: none;
      }

      /* Show vertical collapse button on mobile */
      .vertical-sidebar-toggle {
        display: flex;
      }

      /* Vertical-collapsed state: hide sidebar body, keep header visible */
      .sidebar-header {
        transition: margin-bottom 0.4s cubic-bezier(0.4, 0, 0.2, 1), padding-bottom 0.4s cubic-bezier(0.4, 0, 0.2, 1), border-color 0.4s ease;
      }
      .sidebar-content {
        transition: padding 0.4s cubic-bezier(0.4, 0, 0.2, 1);
      }
      .sidebar-body {
        transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s ease, transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
        max-height: 100000px; /* Safe upper bound for thousands of questions */
        opacity: 1;
        transform: translateY(0) scale(1);
        overflow: hidden;
      }
      .sidebar-scroll {
        overflow: visible;
      }
      .sidebar.vertical-collapsed .sidebar-body {
        max-height: 0;
        opacity: 0;
        transform: translateY(-10px) scale(0.98);
        pointer-events: none;
        transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.15s ease, transform 0.3s ease;
      }
      .sidebar.vertical-collapsed .sidebar-content {
        padding: 8px 16px;
      }
      /* Remove bottom border on sidebar when collapsed to look clean */
      .sidebar.vertical-collapsed {
        border-bottom: 1.5px solid var(--border);
      }
      /* Remove bottom margin on sidebar-header when sidebar is vertical-collapsed */
      .sidebar.vertical-collapsed .sidebar-header {
        margin-bottom: 0;
        padding-bottom: 0;
        border-bottom-color: transparent;
      }
      /* Keep home button visible when collapsed on mobile */
      .sidebar.vertical-collapsed .sidebar-home-btn {
        display: inline-flex;
      }

      body {
        flex-direction: column;
        overflow-y: auto;
      }

      .sidebar {
        width: 100%;
        height: auto;
        border-right: none;
        border-bottom: 1.5px solid var(--border);
        flex-shrink: 0;
        overflow: visible;
      }

      .main-content {
        width: 100%;
        height: auto;
        overflow: visible;
        padding: 20px 16px 80px;
      }

      .card {
        display: flex;
        flex-direction: column;
        min-height: unset;
      }

      .note-wrap {
        grid-column: unset;
        grid-row: unset;
        border-left: none;
        border-top: 1.5px solid var(--border);
        background: var(--surface-2);
        padding: 16px 20px;
        border-bottom: 1.5px solid var(--border);
        margin-bottom: 10px;
        /* Override sidebar radii: straight horizontal divider above this band */
        border-radius: 0;
      }

      .note-side-header {
        display: none;
      }

      .note-toggle {
        display: inline-flex;
        align-items: center;
        gap: 8px;
        font-size: 0.88rem;
        font-weight: 500;
        color: var(--text-2);
        cursor: pointer;
        background: var(--surface-2);
        border: 1.5px solid var(--border);
        border-radius: 99px;
        padding: 5.5px 15px;
        transition: all var(--transition);
      }

      .note-toggle:hover {
        background: var(--border);
      }

      .note-toggle.has-note {
        color: var(--accent);
        border-color: var(--accent);
        background: var(--accent-light);
      }

      .note-body {
        display: none;
        flex: none;
        margin-top: 10px;
      }

      .note-body.open {
        display: flex;
        flex-direction: column;
        animation: fadeIn .2s ease;
      }

      .note-textarea {
        min-height: 90px;
        resize: vertical;
        flex: none;
        font-size: 16px;
        border-radius: var(--radius);
      }


      .attempt-history-panel {
        padding: 16px 18px 18px;
        margin-top: 14px;
      }

      /* .card-footer intentionally left empty */

      .kbd-hints {
        display: none;
      }

      #backBtn .btn-label,
      #skipBtn .btn-label,
      #flagBtn .btn-label {
        display: none;
      }

      #backBtn,
      #skipBtn {
        padding: 11px 16px;
        font-size: 1rem;
      }

      #flagBtn {
        padding: 11px 16px;
        font-size: 1rem;
      }

      #submitBtn .submit-answer-suffix {
        display: none;
      }

      #submitBtn {
        padding-left: 21px;
        padding-right: 21px;
      }

      .sidebar.collapsed {
        width: 100%;
      }

      .sidebar.collapsed .sidebar-content {
        display: flex;
      }

      .sidebar.collapsed .sidebar-collapsed-content {
        display: none;
      }

      .sidebar-content {
        flex: none;
        min-height: unset;
        overflow: visible;
      }

      .sidebar-scroll {
        flex: none;
        min-height: unset;
        overflow: visible;
      }

      #qGrid {
        flex: none !important;
        min-height: unset !important;
        overflow: visible !important;
      }
    }


    /* ── Hide-options mode ───────────────────────────────────── */
    .mode-btn {
      display: flex;
      align-items: center;
      gap: 8px;
      width: 100%;
      padding: 9px 12px;
      background: var(--bg);
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      font-family: var(--font-sans);
      font-size: .78rem;
      font-weight: 600;
      color: var(--text-2);
      cursor: pointer;
      transition: all var(--transition);
      margin-bottom: 8px;
    }

    .mode-btn:hover {
      background: var(--surface-2);
    }

    .mode-btn.active {
      background: var(--accent-light);
      border-color: var(--accent);
      color: var(--accent);
    }

    .mode-btn-label {
      flex: 1;
      text-align: left;
    }

    .mode-btn-switch {
      width: 28px;
      height: 16px;
      border-radius: 8px;
      background: var(--border);
      position: relative;
      transition: background var(--transition);
      flex-shrink: 0;
    }

    .mode-btn.active .mode-btn-switch {
      background: var(--accent);
    }

    .mode-btn-switch::after {
      content: '';
      position: absolute;
      width: 12px;
      height: 12px;
      border-radius: 50%;
      background: #fff;
      top: 2px;
      left: 2px;
      transition: transform var(--transition);
      box-shadow: 0 1px 2px rgba(0, 0, 0, .2);
    }

    .mode-btn.active .mode-btn-switch::after {
      transform: translateX(12px);
    }

    .options-wrap {
      position: relative;
      grid-column: 1;
      grid-row: 6;
      margin-top: 28px;
      margin-bottom: 32px;
    }

    /* Attempt history: separate panel under quiz card, above keyboard hints */
    .attempt-history-panel {
      width: 100%;
      max-width: 1060px;
      margin: 16px auto 0;
      padding: 18px 22px 20px;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow);
      animation: fadeUp .3s ease both;
      overflow: visible;
      position: relative;
      z-index: 1;
    }

    .attempt-history-header {
      font-size: .72rem;
      font-weight: 600;
      color: var(--text-3);
      font-family: var(--font-mono);
      text-transform: uppercase;
      letter-spacing: .07em;
      margin-bottom: 10px;
    }

    .attempt-history-body {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(42px, 1fr));
      gap: 8px;
    }

    .attempt-history-empty {
      grid-column: 1 / -1;
      font-size: .82rem;
      color: var(--text-3);
      font-style: italic;
      padding: 4px 0 8px;
    }

    .attempt-tile {
      aspect-ratio: 1;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 6px;
      border: 1.5px solid var(--border);
      font-family: var(--font-mono);
      background: var(--bg);
      color: var(--text-2);
      cursor: default;
      transition: border-color var(--transition), box-shadow var(--transition);
    }

    .attempt-tile:hover {
      border-color: var(--text-3);
    }

    .attempt-tile.correct {
      background: var(--correct-bg);
      border-color: var(--correct-ring);
      color: var(--correct);
    }

    .attempt-tile.wrong {
      background: var(--wrong-bg);
      border-color: var(--wrong-ring);
      color: var(--wrong);
    }

    .attempt-tile-idx {
      position: absolute;
      top: 3px;
      left: 4px;
      font-size: 0.55rem;
      font-weight: 600;
      color: var(--text-3);
      line-height: 1;
      pointer-events: none;
    }

    .attempt-tile.correct .attempt-tile-idx {
      color: var(--correct);
      opacity: 0.85;
    }

    .attempt-tile.wrong .attempt-tile-idx {
      color: var(--wrong);
      opacity: 0.85;
    }

    .attempt-tile-letter {
      font-size: 1.05rem;
      font-weight: 600;
      line-height: 1;
      pointer-events: none;
    }

    /* Floating tooltip follows cursor (JS); horizontal strip */
    .attempt-hover-tooltip {
      position: fixed;
      left: 0;
      top: 0;
      z-index: 3000;
      pointer-events: none;
      padding: 6px 12px;
      font-family: var(--font-mono);
      font-size: 0.72rem;
      font-weight: 500;
      line-height: 1.25;
      color: var(--text);
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      box-shadow: var(--shadow-lg);
      white-space: nowrap;
      max-width: min(92vw, 720px);
      overflow-x: auto;
      overflow-y: hidden;
      visibility: hidden;
      opacity: 0;
      transition: opacity 0.06s ease;
    }

    .attempt-hover-tooltip.visible {
      visibility: visible;
      opacity: 1;
    }

    /* Before submit: same grid tiles, greyed; only attempt index in corner */
    .attempt-history-panel--pending .attempt-tile {
      background: var(--surface-2);
      border-color: var(--border);
      color: var(--text-3);
      opacity: 0.9;
    }

    .attempt-history-panel--pending .attempt-tile:hover {
      border-color: var(--text-3);
    }

    .attempt-history-panel--pending .attempt-tile.correct,
    .attempt-history-panel--pending .attempt-tile.wrong {
      background: var(--surface-2);
      border-color: var(--border);
      color: var(--text-3);
    }

    .attempt-history-panel--pending .attempt-tile.correct .attempt-tile-idx,
    .attempt-history-panel--pending .attempt-tile.wrong .attempt-tile-idx {
      color: var(--text-3);
      opacity: 1;
    }

    .attempt-history-panel--pending .attempt-tile-letter {
      opacity: 0;
      visibility: hidden;
      position: absolute;
      width: 1px;
      height: 1px;
      overflow: hidden;
    }

    .options.veiled {
      filter: blur(6px);
      pointer-events: none;
      user-select: none;
      -webkit-user-select: none;
    }

    .options-veil {
      position: absolute;
      inset: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 5;
      border-radius: var(--radius);
      background: rgba(247, 245, 240, .7);
      backdrop-filter: blur(1px);
      -webkit-backdrop-filter: blur(1px);
    }

    .options-veil-btn {
      font-family: var(--font-sans);
      font-size: .88rem;
      font-weight: 600;
      color: var(--text-2);
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: 99px;
      padding: 10px 24px;
      cursor: pointer;
      transition: all var(--transition);
      box-shadow: var(--shadow);
    }

    .options-veil-btn:hover,
    .options-veil-btn:active {
      border-color: var(--accent);
      color: var(--accent);
      background: var(--accent-light);
    }

    /* Topic onboarding + pills */
    .topic-modal-overlay {
      position: fixed;
      inset: 0;
      z-index: 1200;
      background: rgba(26, 23, 20, .45);
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 24px;
      backdrop-filter: blur(2px);
      -webkit-backdrop-filter: blur(2px);
    }

    .topic-modal-overlay.hidden {
      display: none;
    }

    .topic-modal {
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      max-width: 460px;
      width: 100%;
      padding: 24px 26px;
      font-family: var(--font-sans);
    }

    .topic-modal h2 {
      font-family: var(--font-serif);
      font-size: 1.25rem;
      margin-bottom: 8px;
      color: var(--text);
    }

    .topic-modal p {
      font-size: .88rem;
      color: var(--text-2);
      line-height: 1.5;
      margin-bottom: 18px;
    }

    .topic-modal-field {
      margin-bottom: 16px;
    }

    .topic-modal-field label {
      display: block;
      font-size: .78rem;
      font-weight: 600;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .06em;
      margin-bottom: 8px;
    }

    .topic-modal-field label.inline {
      display: flex;
      align-items: center;
      gap: 10px;
      text-transform: none;
      font-weight: 500;
      font-size: .9rem;
      color: var(--text);
      cursor: pointer;
    }

    .topic-modal-field input[type="radio"] {
      accent-color: var(--accent);
    }

    .topic-modal-source-block {
      margin-bottom: 14px;
    }

    .topic-modal-source-block:last-of-type {
      margin-bottom: 0;
    }

    .topic-modal-subhead {
      font-size: .72rem;
      font-weight: 600;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .06em;
      margin-bottom: 8px;
    }

    .topic-modal-pill-preview {
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
      margin-bottom: 10px;
      max-height: 120px;
      overflow-y: auto;
      padding: 2px 0;
    }

    .topic-modal-chip {
      font-family: var(--font-sans);
      font-size: .68rem;
      font-weight: 500;
      padding: 4px 9px;
      border-radius: 99px;
      border: 1.5px solid var(--border);
      background: var(--surface-2);
      color: var(--text-2);
      max-width: 100%;
      text-overflow: ellipsis;
      white-space: nowrap;
      overflow: hidden;
    }

    .topic-modal-chip.more {
      border-style: dashed;
      color: var(--text-3);
    }

    .topic-modal-actions {
      display: flex;
      gap: 10px;
      justify-content: flex-end;
      margin-top: 20px;
    }

    .note-conflict-section {
      margin-bottom: 14px;
    }

    .note-conflict-label {
      font-size: .72rem;
      font-weight: 600;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .06em;
      margin-bottom: 6px;
    }

    .note-conflict-box {
      background: var(--surface-2);
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      padding: 10px 12px;
      font-size: .85rem;
      color: var(--text);
      max-height: 100px;
      overflow-y: auto;
      white-space: pre-wrap;
      word-break: break-word;
    }

    .note-conflict-box:empty::before {
      content: '(empty)';
      color: var(--text-3);
      font-style: italic;
    }

    /* Mini popup for note conflicts */
    .mini-popup {
      position: fixed;
      bottom: 24px;
      right: 24px;
      z-index: 1300;
      width: 340px;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: 0 8px 32px rgba(0, 0, 0, .12), 0 2px 8px rgba(0, 0, 0, .08);
      padding: 16px 18px;
      font-family: var(--font-sans);
      animation: miniPopupSlide 250ms cubic-bezier(.4, 0, .2, 1);
    }

    .mini-popup.hidden {
      display: none;
    }

    @keyframes miniPopupSlide {
      from {
        opacity: 0;
        transform: translateY(16px);
      }

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

    .mini-popup-header {
      display: flex;
      align-items: center;
      gap: 8px;
      margin-bottom: 8px;
    }

    .mini-popup-icon {
      font-size: 1.1rem;
    }

    .mini-popup-header h3 {
      font-family: var(--font-serif);
      font-size: 1rem;
      font-weight: 600;
      color: var(--text);
      margin: 0;
    }

    .mini-popup-desc {
      font-size: .82rem;
      color: var(--text-2);
      line-height: 1.4;
      margin-bottom: 12px;
    }

    .mini-popup-versions {
      display: flex;
      flex-direction: column;
      gap: 10px;
      margin-bottom: 14px;
    }

    .mini-popup-version {
      display: flex;
      flex-direction: column;
      gap: 4px;
    }

    .mini-popup-label {
      font-size: .65rem;
      font-weight: 600;
      color: var(--text-3);
      text-transform: uppercase;
      letter-spacing: .05em;
    }

    .mini-popup-box {
      background: var(--surface-2);
      border: 1px solid var(--border);
      border-radius: 8px;
      padding: 8px 10px;
      font-size: .78rem;
      color: var(--text);
      max-height: 70px;
      overflow-y: auto;
      white-space: pre-wrap;
      word-break: break-word;
      line-height: 1.4;
    }

    .mini-popup-box:empty::before {
      content: '(empty)';
      color: var(--text-3);
      font-style: italic;
    }

    .mini-popup-actions {
      display: flex;
      gap: 8px;
      justify-content: flex-end;
    }

    .btn-sm {
      padding: 6px 12px;
      font-size: .75rem;
      min-height: 32px;
    }

    .topic-pills-wrap {
      margin-bottom: 8px;
      display: none;
      flex-direction: column;
      gap: 10px;
    }

    .topic-pills-wrap.visible {
      display: flex;
    }

    @keyframes topicPillsFadeSlide {
      from {
        opacity: 0;
        transform: translate3d(0, 10px, 0);
      }

      to {
        opacity: 1;
        transform: translate3d(0, 0, 0);
      }
    }

    @keyframes topicPillPop {
      from {
        opacity: 0;
        transform: translate3d(0, 8px, 0) scale(0.94);
      }

      to {
        opacity: 1;
        transform: translate3d(0, 0, 0) scale(1);
      }
    }

    .topic-pills-toolbar {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      gap: 8px;
    }

    .topic-pills-wrap.visible:not(.topic-pills-closing) .topic-pills-toolbar {
      animation: topicPillsFadeSlide 0.5s cubic-bezier(0.22, 1, 0.36, 1) both;
    }

    .topic-pills-wrap.visible:not(.topic-pills-closing) .topic-pill {
      animation: topicPillPop 0.48s cubic-bezier(0.22, 1, 0.36, 1) both;
      animation-delay: calc(0.05s + 0.038s * var(--topic-pill-i, 0));
    }

    .topic-pills-wrap.visible:not(.topic-pills-closing) .topic-pills-meta {
      animation: topicPillsFadeSlide 0.45s cubic-bezier(0.22, 1, 0.36, 1) both;
      animation-delay: var(--topic-meta-delay, 0.28s);
    }

    /* Single quick dismiss on the whole block — avoids staggered “unwind” */
    @keyframes topicPillsDismiss {
      from {
        opacity: 1;
        transform: translate3d(0, 0, 0) scale(1);
      }

      to {
        opacity: 0;
        transform: translate3d(0, 3px, 0) scale(0.99);
      }
    }

    .topic-pills-wrap.visible.topic-pills-closing {
      pointer-events: none;
      animation: topicPillsDismiss 0.2s cubic-bezier(0.4, 0, 0.95, 1) forwards;
    }

    .topic-pills-wrap.visible.topic-pills-closing .topic-pills-toolbar,
    .topic-pills-wrap.visible.topic-pills-closing .topic-pill,
    .topic-pills-wrap.visible.topic-pills-closing .topic-pills-meta {
      animation: none !important;
    }

    @media (prefers-reduced-motion: reduce) {

      .topic-pills-wrap.visible:not(.topic-pills-closing) .topic-pills-toolbar,
      .topic-pills-wrap.visible:not(.topic-pills-closing) .topic-pill,
      .topic-pills-wrap.visible:not(.topic-pills-closing) .topic-pills-meta {
        animation: none !important;
        opacity: 1 !important;
        transform: none !important;
      }
    }

    .topic-pills-toolbar input[type="search"] {
      flex: 1;
      min-width: 120px;
      font-size: .8rem;
      padding: 6px 10px;
      border-radius: 8px;
      border: 1.5px solid var(--border);
      background: var(--bg);
      font-family: var(--font-sans);
    }

    .topic-pills-toolbar input[type="search"]:focus {
      outline: none;
      border-color: var(--accent);
    }

    .topic-pills-row {
      display: flex;
      flex-wrap: wrap;
      gap: 6px;
      max-height: 140px;
      overflow-y: auto;
      padding: 2px 0;
    }

    .topic-pills-row.topic-pills-expanded {
      max-height: none;
      overflow: visible;
    }

    .topic-pill {
      font-family: var(--font-sans);
      font-size: .72rem;
      font-weight: 500;
      padding: 5px 10px;
      border-radius: 99px;
      border: 1.5px solid var(--border);
      background: var(--bg);
      color: var(--text-2);
      cursor: pointer;
      transition: all var(--transition);
      max-width: 100%;
      text-overflow: ellipsis;
      white-space: nowrap;
      overflow: hidden;
    }

    .topic-pill:hover {
      border-color: var(--text-3);
      color: var(--text);
    }

    .topic-pill[aria-pressed="true"] {
      border-color: var(--accent);
      background: var(--accent-light);
      color: var(--accent);
      font-weight: 600;
    }

    .topic-pills-meta {
      font-size: .68rem;
      color: var(--text-3);
      font-family: var(--font-mono);
    }

    .topic-sidebar-controls {
      display: flex;
      align-items: stretch;
      gap: 8px;
      margin-bottom: 8px;
    }

    .topic-sidebar-controls .mode-btn {
      flex: 1;
      margin-bottom: 0;
      min-width: 0;
    }

    .unanswered-filter-btn {
      margin-bottom: 8px;
    }

    .unanswered-filter-btn-label {
      display: flex;
      flex-direction: column;
      align-items: flex-start;
      gap: 3px;
      min-width: 0;
    }

    .unanswered-filter-btn-stats {
      font-size: 0.68rem;
      font-weight: 500;
      color: var(--text-3);
      font-family: var(--font-mono);
      line-height: 1.25;
    }

    .topic-gear-btn {
      flex-shrink: 0;
      width: 44px;
      padding: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      background: var(--bg);
      border: 1.5px solid var(--border);
      border-radius: var(--radius);
      color: var(--text-2);
      cursor: pointer;
      transition: all var(--transition);
    }

    .topic-gear-btn:hover {
      background: var(--surface-2);
      border-color: var(--text-3);
      color: var(--accent);
    }

    .topic-gear-btn svg {
      display: block;
    }

    .topic-suggest-list {
      position: absolute;
      left: 0;
      right: 0;
      top: 100%;
      margin-top: 4px;
      z-index: 20;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: 8px;
      box-shadow: var(--shadow);
      max-height: 160px;
      overflow-y: auto;
      display: none;
      font-size: .8rem;
    }

    .topic-suggest-list.open {
      display: block;
    }

    .topic-suggest-item {
      padding: 8px 12px;
      cursor: pointer;
      border: none;
      width: 100%;
      text-align: left;
      background: transparent;
      font-family: var(--font-sans);
    }

    .topic-suggest-item:hover {
      background: var(--surface-2);
    }

    .topic-search-wrap {
      position: relative;
      flex: 1;
      min-width: 120px;
    }

    .topic-search-wrap input {
      font-family: var(--font-sans);
    }

    .q-grid-item.topic-hidden,
    .collapsed-q-item.topic-hidden {
      display: none !important;
    }

    /* Topic multi-select bar (matches index parent-selection-bar) */
    .topic-selection-bar {
      display: none;
      position: fixed;
      left: 50%;
      bottom: 0;
      transform: translateX(-50%);
      width: min(760px, calc(100% - 32px));
      max-width: calc(100% - 32px);
      margin-bottom: max(12px, env(safe-area-inset-bottom, 0px));
      padding: 12px 16px;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      flex-wrap: wrap;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow);
      z-index: 900;
      font-family: var(--font-sans);
    }

    .topic-selection-bar.visible {
      display: flex;
    }

    .topic-selection-bar-text {
      font-size: .85rem;
      color: var(--text-2);
      font-family: var(--font-mono);
    }

    .topic-selection-bar-text strong {
      color: var(--text);
      font-weight: 600;
    }

    .topic-selection-bar-actions {
      display: flex;
      align-items: center;
      gap: 8px;
      flex-shrink: 0;
    }

    .topic-selection-bar button {
      font-family: var(--font-sans);
      font-size: .78rem;
      font-weight: 600;
      cursor: pointer;
      border-radius: 99px;
      padding: 8px 14px;
      border: 1.5px solid var(--border);
      background: var(--bg);
      color: var(--text-2);
      transition: border-color 150ms, background 150ms, color 150ms;
    }

    .topic-selection-bar button:hover {
      border-color: var(--text-3);
      color: var(--text);
    }

    .topic-selection-bar .topic-selection-start {
      border-color: var(--accent);
      background: var(--accent);
      color: #fff;
    }

    .topic-selection-bar .topic-selection-start:hover {
      filter: brightness(1.06);
      color: #fff;
    }

    body.has-topic-selection-bar .main-content {
      padding-bottom: calc(72px + env(safe-area-inset-bottom, 0px));
    }

    /* AI topic chips under question stem (aggregate merged tags) */
    .question-topic-chips-wrap {
      grid-column: 1;
      grid-row: 3;
      display: none;
      flex-wrap: wrap;
      gap: 6px;
      align-items: center;
      padding: 0 28px 12px;
      font-family: var(--font-sans);
    }

    .question-topic-chips-wrap.visible {
      display: flex;
    }

    .question-topic-chips-wrap .question-topic-chip {
      display: inline-flex;
      align-items: center;
      padding: 3px 10px;
      border-radius: 99px;
      border: 1.5px solid var(--border);
      background: var(--surface-2);
      font-size: .72rem;
      font-weight: 600;
      color: var(--text-2);
    }

    /* ═══════════════════════════════════════════════════════════
   SRS MODE — styles only active when body.srs-mode is present
   ═══════════════════════════════════════════════════════════ */

    /* Hide quiz chrome in SRS mode */
    body.srs-mode #progressWrap {
      display: none !important;
    }

    body.srs-mode #resultsScreen {
      display: none !important;
    }

    body.srs-mode #backBtn {
      display: none !important;
    }

    body.srs-mode #skipBtn {
      display: none !important;
    }

    body.srs-mode #kbdHints .kbd-sep:nth-child(n+5) {
      display: none;
    }

    /* hide ← → shortcut sep */
    body.srs-mode #kbdHints .kbd-group:nth-child(5) {
      display: none;
    }

    /* hide ← → group */
    body.srs-mode .part-tag {
      display: none !important;
    }

    body.srs-mode #topicSelectionBar {
      display: none !important;
    }

    body.srs-mode .question-topic-chips-wrap {
      display: none !important;
    }

    /* Hide quiz-specific sidebar controls in SRS mode */
    body.srs-mode #randomiseModeBtn {
      display: none !important;
    }

    body.srs-mode #unansweredOnlyBtn {
      display: none !important;
    }

    body.srs-mode .topic-sidebar-controls {
      display: none !important;
    }

    body.srs-mode #topicPillsWrap {
      display: none !important;
    }

    body.srs-mode .sidebar-footer-actions {
      display: none !important;
    }

    body.srs-mode .sidebar-collapsed-actions .collapsed-icon-btn:nth-child(n+2):nth-child(-n+3) {
      display: none !important;
    }

    /* SRS specific elements in app-header */
    body.srs-mode #srsQuitBtn {
      display: inline-flex !important;
    }

    body.srs-mode #srsModeBadgeSidebar {
      display: inline-flex !important;
      align-items: center;
    }

    .srs-mode-badge {
      font-family: var(--font-mono);
      font-size: .7rem;
      font-weight: 500;
      padding: 3px 10px;
      border-radius: 99px;
      border: 1px solid var(--border);
      color: var(--text-3);
      display: none;
    }

    .srs-mode-badge.due {
      border-color: var(--accent);
      color: var(--accent);
      background: var(--accent-light);
    }

    /* SRS progress bar */
    .srs-prog-wrap {
      margin-bottom: 24px;
      display: none;
    }

    body.srs-mode .srs-prog-wrap {
      display: block;
    }

    /* Interval badge (shown in card footer after SRS answer) */
    .interval-badge {
      font-family: var(--font-mono);
      font-size: .75rem;
      color: var(--text-3);
      background: var(--surface-2);
      border: 1px solid var(--border);
      border-radius: 6px;
      padding: 3px 10px;
      margin-right: auto;
    }

    .interval-badge.correct {
      color: var(--correct);
      border-color: var(--correct-ring);
      background: var(--correct-bg);
    }

    .interval-badge.wrong {
      color: var(--wrong);
      border-color: var(--wrong-ring);
      background: var(--wrong-bg);
    }

    /* Source tag in card header (shows which quiz a card is from) */
    .srs-source-tag {
      font-family: var(--font-mono);
      font-size: .7rem;
      font-weight: 500;
      background: var(--surface-2);
      border: 1px solid var(--border);
      border-radius: 99px;
      padding: 2px 8px;
      line-height: 1;
      color: var(--text-3);
      /* Content-sized first; shrinks (and marquees) only when text exceeds available header width. */
      flex: 0 1 auto;
      min-width: 0;
      max-width: 100%;
      overflow: hidden;
      white-space: nowrap;
      cursor: default;
      user-select: none;
      -webkit-user-select: none;
      display: none;
      align-items: center;
    }

    .srs-source-tag-inner {
      display: inline-block;
      white-space: nowrap;
      flex-shrink: 0;
      line-height: 1;
      min-width: 0;
      position: relative;
      top: 5%;
    }

    .srs-source-tag-inner.marquee {
      will-change: transform;
    }

    body.srs-mode .srs-source-tag {
      display: flex;
    }

    .srs-btn-filter {
      background: var(--surface-2);
      color: var(--text-2);
      border-color: var(--border);
      display: flex;
      align-items: center;
      gap: 8px;
      justify-content: space-between;
    }

    .srs-btn-filter:hover {
      border-color: var(--accent);
      color: var(--accent);
      background: var(--accent-light);
    }

    .srs-btn-filter.active {
      border-color: var(--accent);
      color: var(--accent);
      background: var(--accent-light);
    }

    .srs-filter-badge {
      font-size: .7rem;
      background: var(--accent);
      color: white;
      padding: 2px 6px;
      border-radius: 99px;
      font-weight: 600;
      min-width: 20px;
      text-align: center;
    }

    .srs-filter-badge.hidden {
      display: none;
    }

    .srs-card-subtitle {
      font-size: .85rem;
      color: var(--text-3);
      margin-bottom: 16px;
    }

    .srs-filter-stats {
      font-size: .9rem;
      color: var(--text-2);
      margin: 16px 0;
      padding: 12px;
      background: var(--surface-2);
      border-radius: 6px;
      text-align: center;
    }

    .srs-filter-page-actions {
      display: flex;
      flex-direction: column;
      gap: 10px;
      margin-top: 20px;
    }

    .srs-filter-page-actions .srs-btn {
      width: 100%;
    }

    .srs-filter-group {
      margin-bottom: 20px;
      padding-bottom: 20px;
      border-bottom: 1px solid var(--border);
    }

    .srs-filter-group:last-child {
      border-bottom: none;
    }

    .srs-filter-group-title {
      font-size: .75rem;
      font-family: var(--font-mono);
      text-transform: uppercase;
      color: var(--text-3);
      margin-bottom: 8px;
      font-weight: 600;
      letter-spacing: 0.5px;
    }

    .srs-filter-help {
      font-size: .78rem;
      color: var(--text-3);
      font-style: italic;
      margin-bottom: 10px;
    }

    .srs-filter-checkbox-row {
      margin-bottom: 8px;
    }

    .srs-filter-pills-row {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      margin-bottom: 8px;
    }

    .srs-sidebar-filter-panel {
      padding: 12px 0;
      border-top: 1px solid var(--border);
      border-bottom: 1px solid var(--border);
      margin: 8px 0;
    }

    .srs-sidebar-filter-panel.hidden {
      display: none;
    }

    .srs-filter-count-chip {
      font-size: .75rem;
      color: var(--text-2);
      margin-left: 4px;
    }

    .srs-sidebar-filter-action {
      padding: 10px;
      background: var(--warn-light, rgba(255, 193, 7, 0.1));
      border-left: 3px solid var(--warn, #ffc107);
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: .85rem;
      color: var(--text);
      margin-bottom: 10px;
      border-radius: 4px;
    }

    .srs-sidebar-filter-action.hidden {
      display: none;
    }

    .srs-bootstrap-info {
      font-size: .8rem;
      color: var(--text-3);
      font-family: var(--font-mono);
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .srs-bootstrap-dot {
      width: 6px;
      height: 6px;
      border-radius: 50%;
      background: var(--accent);
      flex-shrink: 0;
    }

    .srs-sync-status {
      font-size: .78rem;
      color: var(--text-3);
      font-family: var(--font-mono);
      min-height: 1.2em;
      transition: color .2s;
    }

    .srs-sync-status.error {
      color: var(--wrong, #e05);
    }

    .srs-sync-status.success {
      color: var(--correct, #2c8);
    }

    /* Topic filter banner — shown when SRS is scoped to selected parent pills */
    .srs-topic-filter-banner {
      display: flex;
      align-items: center;
      gap: 8px;
      margin-top: 10px;
      padding: 8px 12px;
      background: color-mix(in srgb, #b45309 12%, var(--surface));
      border: 1px solid color-mix(in srgb, #b45309 35%, transparent);
      border-radius: var(--radius);
      font-size: .8rem;
      font-family: var(--font-mono);
      color: #92400e;
      flex-wrap: wrap;
    }

    .srs-topic-filter-icon {
      flex-shrink: 0;
    }

    #srsTopicFilterBannerText {
      flex: 1;
      min-width: 0;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }

    .srs-topic-filter-dismiss {
      background: none;
      border: 1px solid color-mix(in srgb, #b45309 40%, transparent);
      border-radius: 99px;
      color: #92400e;
      font-size: .72rem;
      font-family: var(--font-sans);
      font-weight: 600;
      cursor: pointer;
      padding: 2px 10px;
      flex-shrink: 0;
      transition: background 150ms;
    }

    .srs-topic-filter-dismiss:hover {
      background: color-mix(in srgb, #b45309 18%, transparent);
    }

    .srs-breakdown-card {
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow);
      overflow: hidden;
    }

    .srs-breakdown-header {
      font-family: var(--font-serif);
      font-size: 1.2rem;
      font-weight: 600;
      margin-bottom: 16px;
      color: var(--text);
    }

    .srs-bd-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 12px 0;
      border-bottom: 1px solid var(--border);
    }

    .srs-bd-row:last-child {
      border-bottom: none;
    }

    .srs-bd-title {
      font-size: 0.9rem;
      font-weight: 500;
      color: var(--text);
      max-width: 50%;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }

    .srs-bd-stats {
      display: flex;
      gap: 14px;
    }

    .srs-bd-stat {
      font-size: 0.75rem;
      color: var(--text-2);
      font-family: var(--font-mono);
      display: flex;
      flex-direction: column;
      align-items: flex-end;
    }

    .srs-bd-stat strong {
      font-size: 0.9rem;
      color: var(--text);
      font-weight: 600;
    }

    .srs-bd-stat.due strong {
      color: var(--wrong);
    }

    /* ── SRS Complete screen ── */
    #srsCompleteScreen {
      position: fixed;
      inset: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      background: var(--bg);
      z-index: 200;
      padding: 24px;
    }

    #srsCompleteScreen.hidden {
      display: none;
    }

    .srs-complete-wrap {
      width: 100%;
      max-width: 480px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 24px;
      text-align: center;
      animation: fadeUp .3s ease both;
    }

    .srs-complete-emoji {
      font-size: 3.5rem;
    }

    .srs-complete-title {
      font-family: var(--font-serif);
      font-size: 2rem;
      font-weight: 600;
    }

    .srs-complete-sub {
      font-size: .95rem;
      color: var(--text-2);
    }

    .srs-complete-stats {
      display: flex;
      gap: 28px;
      justify-content: center;
      flex-wrap: wrap;
      padding: 20px 24px;
      background: var(--surface);
      border: 1.5px solid var(--border);
      border-radius: var(--radius-lg);
      width: 100%;
    }

    .srs-c-stat {
      display: flex;
      flex-direction: column;
      gap: 4px;
    }

    .srs-c-stat-num {
      font-family: var(--font-serif);
      font-size: 2rem;
      font-weight: 600;
      line-height: 1;
    }

    .srs-c-stat-num.green {
      color: var(--correct);
    }

    .srs-c-stat-num.red {
      color: var(--wrong);
    }

    .srs-c-stat-label {
      font-size: .78rem;
      color: var(--text-3);
    }

    .srs-complete-actions {
      display: flex;
      gap: 12px;
      flex-wrap: wrap;
      justify-content: center;
      align-items: center;
    }

    /* Uses shared .srs-idx-btn* from srs-dash.css; normalize <button> UA chrome */
    .srs-complete-actions .srs-idx-btn {
      box-sizing: border-box;
      font: inherit;
      -webkit-appearance: none;
      appearance: none;
    }
    @media (max-width: 650px) {
      .main-content {
        padding: 24px 16px 80px;
      }
    }