:root {
      --primary: #4F46E5;
      --primary-dark: #4338CA;
      --primary-light: #818CF8;
      --secondary: #0EA5E9;
      --success: #10B981;
      --warning: #F59E0B;
      --error: #EF4444;
      --gray-50: #F9FAFB;
      --gray-100: #F3F4F6;
      --gray-200: #E5E7EB;
      --gray-300: #D1D5DB;
      --gray-400: #9CA3AF;
      --gray-500: #6B7280;
      --gray-600: #4B5563;
      --gray-700: #374151;
      --gray-800: #1F2937;
      --gray-900: #111827;
      --white: #FFFFFF;
      --shadow-sm: 0 1px 2px 0 rgb(0 0 0/.05);
      --shadow: 0 1px 3px 0 rgb(0 0 0/.1), 0 1px 2px -1px rgb(0 0 0/.1);
      --shadow-md: 0 4px 6px -1px rgb(0 0 0/.1), 0 2px 4px -2px rgb(0 0 0/.1);
      --shadow-lg: 0 10px 15px -3px rgb(0 0 0/.1), 0 4px 6px -4px rgb(0 0 0/.1);
      --shadow-xl: 0 20px 25px -5px rgb(0 0 0/.1), 0 8px 10px -6px rgb(0 0 0/.1);
      --radius-sm: 6px;
      --radius: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --radius-xl: 24px;
    }

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

    html {
      scroll-behavior: smooth
    }

    body {
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: linear-gradient(135deg, var(--gray-50) 0%, var(--gray-100) 100%);
      color: var(--gray-800);
      line-height: 1.6;
      min-height: 100vh;
      -webkit-font-smoothing: antialiased
    }

    input,
    textarea,
    select,
    button {
      font-family: inherit
    }

    a:focus-visible,
    button:focus-visible,
    [role="button"]:focus-visible,
    [role="menuitem"]:focus-visible,
    [role="option"]:focus-visible,
    [role="tab"]:focus-visible,
    input:focus-visible,
    select:focus-visible,
    textarea:focus-visible {
      outline: 2px solid var(--primary);
      outline-offset: 2px;
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .16);
    }

    button:focus:not(:focus-visible),
    a:focus:not(:focus-visible) {
      outline: none;
      box-shadow: none
    }

    .container {
      max-width: 1360px;
      margin: 0 auto;
      padding: 20px
    }

    .topbar {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 12px;
      padding: 14px 20px;
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      margin-bottom: 16px;
      position: static
    }

    .topbar-logo {
      display: flex;
      align-items: center;
      gap: 12px;
      min-width: 0;
      flex: 1 1 auto;
      text-decoration: none;
      color: inherit;
      cursor: pointer
    }

    .topbar-logo-icon {
      width: 38px;
      height: 38px;
      flex-shrink: 0;
      background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
      border-radius: var(--radius-md);
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--white)
    }

    .topbar-logo-icon svg {
      width: 22px;
      height: 22px
    }

    .topbar h1 {
      font-size: 1.15rem;
      font-weight: 700;
      letter-spacing: -0.025em;
      color: var(--gray-900);
      white-space: nowrap
    }

    .topbar-logo:hover .topbar-logo-icon {
      transform: translateY(-1px);
      box-shadow: 0 8px 18px rgba(79, 70, 229, .24);
    }

    .topbar-sub {
      font-size: .8125rem;
      color: var(--gray-500);
      margin-top: 1px;
      white-space: normal;
      overflow: visible;
      text-overflow: initial;
      max-width: 100%
    }

    .actions {
      display: flex;
      gap: 8px;
      flex-wrap: wrap;
      align-items: center
    }

    .study-pill {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      border: 1px solid var(--gray-300);
      background: var(--white);
      border-radius: 999px;
      padding: 7px 11px;
      font-size: .78rem;
      font-weight: 700;
      color: var(--gray-700)
    }

    .study-pill svg {
      width: 13px;
      height: 13px
    }

    .study-pill.due {
      border-color: rgba(245, 158, 11, .4);
      background: rgba(245, 158, 11, .08);
      color: #92400E
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 7px;
      border: 1px solid var(--gray-300);
      background: var(--white);
      color: var(--gray-700);
      border-radius: var(--radius);
      padding: 9px 14px;
      font-size: .85rem;
      font-weight: 600;
      cursor: pointer;
      transition: all .2s ease;
      white-space: nowrap
    }

    .btn:hover {
      border-color: var(--gray-400);
      color: var(--gray-900);
      background: var(--gray-50)
    }

    .btn:active {
      transform: scale(.97)
    }

    .btn.primary {
      background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
      border: none;
      color: var(--white);
      box-shadow: 0 4px 14px 0 rgba(79, 70, 229, .3)
    }

    .btn.primary:hover {
      opacity: .92;
      transform: translateY(-1px);
      box-shadow: 0 6px 20px 0 rgba(79, 70, 229, .4)
    }

    .btn.danger {
      border-color: rgba(239, 68, 68, .35);
      color: #991B1B;
      background: rgba(239, 68, 68, .06)
    }

    .btn.danger:hover {
      background: rgba(239, 68, 68, .12);
      border-color: rgba(239, 68, 68, .5)
    }

    .btn.cta {
      background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
      border: none;
      color: var(--white);
      padding: 14px 32px;
      font-size: 1rem;
      font-weight: 700;
      border-radius: var(--radius-md);
      box-shadow: 0 4px 14px 0 rgba(79, 70, 229, .35);
      width: 100%
    }

    .btn.cta:hover {
      opacity: .92;
      transform: translateY(-1px);
      box-shadow: 0 6px 20px 0 rgba(79, 70, 229, .45)
    }

    .btn svg {
      width: 16px;
      height: 16px;
      flex-shrink: 0
    }

    .grid {
      display: grid;
      grid-template-columns: 300px 1fr;
      gap: 16px
    }

    @media(max-width:1020px) {
      .grid {
        grid-template-columns: 1fr
      }
    }

    .panel {
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-xl);
      box-shadow: var(--shadow-lg);
      overflow: hidden
    }

    .grid>section.panel {
      overflow: visible
    }

    .panel-head {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      padding: 16px 20px;
      border-bottom: 1px solid var(--gray-200)
    }

    .panel-title {
      font-size: .95rem;
      font-weight: 700;
      color: var(--gray-900)
    }

    .panel-body {
      padding: 16px 20px
    }

    .pack-summary {
      display: none;
      padding: 16px;
      margin-bottom: 14px;
      background: linear-gradient(135deg, rgba(79, 70, 229, .06) 0%, rgba(14, 165, 233, .06) 100%);
      border: 1px solid rgba(79, 70, 229, .15);
      border-radius: var(--radius-md);
      animation: fadeSlideIn .3s ease-out
    }

    .pack-summary.visible {
      display: block
    }

    .pack-summary-title {
      font-size: 1rem;
      font-weight: 700;
      color: var(--gray-900);
      margin-bottom: 4px
    }

    .pack-summary-meta {
      font-size: .8rem;
      color: var(--gray-500);
      margin-bottom: 10px
    }

    .pack-summary-stats {
      display: flex;
      gap: 16px;
      flex-wrap: wrap
    }

    .pack-images-tip {
      margin-top: 8px;
      font-size: .78rem;
      color: var(--gray-500);
      font-style: italic;
      line-height: 1.4;
    }

    .pack-stat {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: .82rem;
      font-weight: 600;
      color: var(--gray-700)
    }

    .pack-stat-icon {
      width: 28px;
      height: 28px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      flex-shrink: 0
    }

    .pack-stat-icon svg {
      width: 14px;
      height: 14px
    }

    .pack-stat-icon.notes-icon {
      background: rgba(79, 70, 229, .1);
      color: var(--primary)
    }

    .pack-stat-icon.cards-icon {
      background: rgba(14, 165, 233, .1);
      color: var(--secondary)
    }

    .pack-stat-icon.test-icon {
      background: rgba(16, 185, 129, .1);
      color: var(--success)
    }

    .field {
      display: flex;
      flex-direction: column;
      gap: 5px
    }

    .field label {
      font-size: .75rem;
      color: var(--gray-500);
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .05em
    }

    .field input,
    .field textarea,
    .field select {
      border: 1px solid var(--gray-300);
      border-radius: var(--radius);
      padding: 10px 12px;
      font-size: .9rem;
      color: var(--gray-900);
      background: var(--white);
      transition: all .2s ease
    }

    .field input:focus,
    .field textarea:focus,
    .field select:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .1)
    }

    .field textarea {
      min-height: 78px;
      resize: vertical
    }

    .app-select {
      position: relative
    }

    .app-select-button {
      width: 100%;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 8px;
      border: 1px solid var(--gray-300);
      border-radius: var(--radius);
      padding: 10px 12px;
      font-size: .9rem;
      color: var(--gray-900);
      background: var(--white);
      cursor: pointer;
      transition: all .2s ease
    }

    .app-select-button:hover {
      border-color: var(--primary-light)
    }

    .app-select-button.open {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .1)
    }

    .app-select-button svg {
      width: 15px;
      height: 15px;
      color: var(--gray-500);
      transition: transform .2s ease
    }

    .app-select-button.open svg {
      transform: rotate(180deg)
    }

    .app-select-label {
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap
    }

    .app-select-menu {
      display: none;
      position: absolute;
      left: 0;
      right: 0;
      top: calc(100% + 6px);
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-lg);
      z-index: 80;
      max-height: 260px;
      overflow-y: auto
    }

    .app-select-menu.visible {
      display: block;
      animation: dropdownOpen .2s ease-out
    }

    .app-select-item {
      width: 100%;
      border: none;
      background: var(--white);
      text-align: left;
      padding: 10px 12px;
      font-size: .9rem;
      color: var(--gray-700);
      cursor: pointer;
      transition: background .15s ease
    }

    .app-select-item:hover {
      background: var(--gray-50)
    }

    .app-select-item.active {
      background: rgba(79, 70, 229, .1);
      color: var(--primary-dark);
      font-weight: 600
    }

    .q-answer-picker {
      margin-top: 4px
    }

    .search-box {
      margin-bottom: 12px
    }

    .list {
      display: flex;
      flex-direction: column;
      gap: 8px;
      max-height: 68vh;
      overflow-y: auto;
      padding-right: 2px
    }

    .item {
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      padding: 12px 14px;
      background: var(--white);
      cursor: pointer;
      transition: all .25s ease
    }

    .item:hover {
      border-color: var(--gray-300);
      box-shadow: var(--shadow-sm);
      transform: translateY(-1px)
    }

    .item.active {
      border-color: var(--primary);
      background: rgba(79, 70, 229, .04);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .08)
    }

    .item.dragging {
      opacity: .35;
      transform: scale(.985);
      border-style: dashed;
      border-color: var(--primary);
      background: rgba(79, 70, 229, .08)
    }

    .item.drop-target {
      border-color: var(--success);
      background: linear-gradient(135deg, rgba(16, 185, 129, .12) 0%, rgba(14, 165, 233, .08) 100%);
      box-shadow: 0 0 0 3px rgba(16, 185, 129, .15);
      transform: translateY(-2px)
    }

    .item-head {
      display: flex;
      justify-content: space-between;
      gap: 8px;
      align-items: center
    }

    .item-title {
      font-size: .9rem;
      font-weight: 700;
      color: var(--gray-900)
    }

    .item-sub {
      margin-top: 4px;
      font-size: .78rem;
      color: var(--gray-500)
    }

    .item-sub.pinned-note {
      margin-top: 6px;
      color: var(--primary-dark);
      font-weight: 600
    }

    .folder-head-actions {
      display: inline-flex;
      align-items: center;
      gap: 6px
    }

    .folder-mini-btn {
      padding: 5px 8px;
      font-size: .75rem
    }

    .item-sub.exam-countdown {
      margin-top: 6px;
      font-weight: 600;
      color: #92400E
    }

    .item-sub.exam-countdown.later {
      color: #0F766E
    }

    .item-sub.exam-countdown.overdue {
      color: #B91C1C
    }

    .split {
      display: grid;
      grid-template-columns: 320px 1fr;
      gap: 16px
    }

    @media(max-width:1200px) {
      .split {
        grid-template-columns: 1fr
      }
    }

    .meta-grid {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 10px;
      margin-bottom: 14px
    }

    @media(max-width:700px) {
      .meta-grid {
        grid-template-columns: 1fr
      }
    }

    .meta-advanced-toggle {
      display: flex;
      justify-content: flex-start;
      margin-top: 6px;
      margin-bottom: 10px
    }

    .meta-advanced-panel {
      display: none
    }

    .meta-advanced-panel.visible {
      display: grid
    }

    .editor-wrap {
      display: none
    }

    .editor-wrap.visible {
      display: block;
      animation: fadeSlideIn .3s ease-out
    }

    .empty {
      color: var(--gray-500);
      font-size: .9rem;
      padding: 20px;
      border: 1px dashed var(--gray-300);
      border-radius: var(--radius-md);
      background: var(--gray-50);
      text-align: center
    }

    .pack-empty-block {
      display: none
    }

    .pack-empty-block.visible {
      display: block
    }

    .pack-empty-title {
      font-size: 1rem;
      color: var(--gray-900);
      font-weight: 700;
      margin-bottom: 6px
    }

    .pack-empty-actions {
      margin-top: 12px;
      display: flex;
      justify-content: center;
      gap: 8px;
      flex-wrap: wrap
    }

    .editor-tabs {
      display: flex;
      gap: 4px;
      margin-bottom: 14px;
      background: var(--gray-100);
      border-radius: var(--radius-md);
      padding: 4px
    }

    .editor-tab {
      flex: 1;
      border: none;
      background: transparent;
      border-radius: var(--radius);
      padding: 10px 12px;
      font-size: .82rem;
      font-weight: 600;
      color: var(--gray-600);
      cursor: pointer;
      transition: all .2s ease;
      text-align: center;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px
    }

    .editor-tab:hover {
      color: var(--gray-900)
    }

    .editor-tab.active {
      background: var(--white);
      color: var(--gray-900);
      box-shadow: var(--shadow-sm)
    }

    .editor-tab svg {
      width: 15px;
      height: 15px
    }

    .editor-pane {
      display: none
    }

    .editor-pane.active {
      display: block;
      animation: fadeIn .25s ease-out
    }

    .notes-pane-shell {
      position: relative
    }

    .notes-view {
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      background: var(--gray-50);
      padding: 20px;
      max-height: 60vh;
      overflow-y: auto;
      font-size: .92rem;
      line-height: 1.7
    }

    .notes-view h1,
    .notes-view h2,
    .notes-view h3 {
      margin-top: 20px;
      margin-bottom: 10px;
      color: var(--gray-900)
    }

    .notes-view h1 {
      font-size: 1.4rem;
      border-bottom: 2px solid var(--gray-200);
      padding-bottom: 8px
    }

    .notes-pane-shell:fullscreen,
    .notes-pane-shell:-webkit-full-screen {
      display: flex;
      flex-direction: column;
      width: 100vw;
      height: 100vh;
      padding: 22px;
      background: linear-gradient(135deg, var(--gray-50) 0%, var(--gray-100) 100%);
      overflow: auto;
    }

    .notes-pane-shell:fullscreen .notes-view,
    .notes-pane-shell:-webkit-full-screen .notes-view {
      flex: 1;
      max-height: none;
      min-height: 0;
      height: auto;
      overflow-y: auto;
      background: var(--white);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      max-width: 1200px;
      width: 100%;
      margin: 0 auto;
      padding: 26px 28px;
      overscroll-behavior: contain;
    }

    .notes-controls {
      display: grid;
      grid-template-columns: minmax(0, 1fr) auto;
      align-items: start;
      gap: 10px;
      position: sticky;
      top: 0;
      z-index: 8;
      margin-bottom: 8px;
    }

    .notes-fullscreen-btn {
      position: relative;
      flex-shrink: 0;
      z-index: 6;
      width: 42px;
      height: 42px;
      border-radius: 10px;
      border: 1px solid rgba(129, 140, 248, .45);
      background: linear-gradient(135deg, #EEF2FF 0%, #E0E7FF 100%);
      color: var(--primary);
      box-shadow: 0 6px 16px rgba(79, 70, 229, .16);
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      opacity: .95;
      transition: opacity .8s ease, transform .2s ease, background .2s ease, border-color .2s ease, box-shadow .2s ease;
    }

    .notes-fullscreen-btn svg {
      width: 18px;
      height: 18px
    }

    .notes-fullscreen-btn:hover {
      transform: translateY(-1px);
      background: linear-gradient(135deg, #E0E7FF 0%, #DBEAFE 100%);
      border-color: rgba(79, 70, 229, .55);
      box-shadow: 0 8px 18px rgba(79, 70, 229, .2);
    }

    .notes-fullscreen-btn.idle {
      opacity: .18
    }

    .notes-pane-shell:hover .notes-fullscreen-btn,
    .notes-fullscreen-btn:focus-visible {
      opacity: 1
    }

    /* Highlight toolbar */
    .highlight-toolbar {
      display: flex;
      gap: 6px;
      align-items: center;
      padding: 8px 10px;
      background: var(--gray-100);
      border-radius: var(--radius-md);
      flex-wrap: wrap;
      flex: 1;
      min-height: 42px;
      position: relative;
      overflow-x: auto;
      overflow-y: visible;
    }

    .notes-pane-shell:fullscreen .notes-controls,
    .notes-pane-shell:-webkit-full-screen .notes-controls {
      top: -6px;
      padding-top: 4px;
    }

    .notes-pane-shell:fullscreen .highlight-toolbar,
    .notes-pane-shell:-webkit-full-screen .highlight-toolbar {
      background: rgba(30, 30, 60, .85);
      backdrop-filter: blur(8px)
    }

    .hl-btn {
      width: 40px;
      height: 40px;
      border-radius: 50%;
      border: 2px solid transparent;
      cursor: pointer;
      transition: all .15s;
      font-size: 13px;
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 0
    }

    .hl-btn:hover {
      transform: scale(1.15)
    }

    .hl-btn.active {
      border-color: var(--gray-900);
      box-shadow: 0 0 0 2px rgba(79, 70, 229, .35)
    }

    .notes-pane-shell:fullscreen .hl-btn.active {
      border-color: #fff
    }

    .hl-btn.hl-action {
      width: auto;
      border-radius: var(--radius-sm);
      min-height: 40px;
      padding: 8px 12px;
      background: var(--white);
      border: 1px solid var(--gray-300);
      color: var(--gray-700);
      font-size: .88rem;
      font-weight: 600;
      line-height: 1;
      transform: none;
      gap: 5px;
    }

    .hl-btn.hl-action:hover {
      transform: translateY(-1px);
      border-color: rgba(79, 70, 229, .35);
      color: var(--gray-900);
    }

    .notes-pane-shell:fullscreen .hl-btn.hl-action,
    .notes-pane-shell:-webkit-full-screen .hl-btn.hl-action {
      background: rgba(255, 255, 255, .97);
      color: var(--gray-900);
    }

    .hl-yellow {
      background: #fef08a
    }

    .hl-green {
      background: #bbf7d0
    }

    .hl-blue {
      background: #bfdbfe
    }

    .hl-pink {
      background: #fbcfe8
    }

    .hl-download-btn {
      margin-left: auto;
      gap: 8px;
      min-height: 42px;
      padding: 8px 16px;
      border-radius: var(--radius-md);
      font-size: .88rem;
      font-weight: 700;
      color: var(--gray-700);
      border: 1px solid var(--gray-300);
      background: var(--white);
      box-shadow: var(--shadow-sm);
    }

    .hl-download-btn:hover {
      color: var(--gray-900);
      border-color: rgba(79, 70, 229, .35);
      background: var(--gray-50);
    }

    .hl-download-btn svg {
      width: 14px;
      height: 14px
    }

    .hl-download-menu {
      position: absolute;
      top: calc(100% + 6px);
      right: 10px;
      min-width: 280px;
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: 10px;
      box-shadow: var(--shadow-lg);
      padding: 6px;
      display: none;
      z-index: 20;
    }

    .hl-download-menu.visible {
      display: block;
    }

    .hl-download-item {
      width: 100%;
      border: none;
      background: transparent;
      text-align: left;
      padding: 9px 10px;
      border-radius: 8px;
      color: var(--gray-700);
      font-size: .82rem;
      cursor: pointer;
    }

    .hl-download-item:hover {
      background: var(--gray-100);
      color: var(--gray-900);
    }

    .notes-pane-shell:fullscreen .hl-download-menu,
    .notes-pane-shell:-webkit-full-screen .hl-download-menu {
      background: rgba(255, 255, 255, .98);
    }

    .hl-clear-all:hover {
      background: var(--gray-200)
    }

    mark[data-hl] {
      cursor: pointer;
      border-radius: 2px;
      padding: 1px 0;
      transition: opacity .15s
    }

    mark[data-hl]:hover {
      opacity: .7
    }

    mark[data-hl="yellow"] {
      background: #fef08a
    }

    mark[data-hl="green"] {
      background: #bbf7d0
    }

    mark[data-hl="blue"] {
      background: #bfdbfe
    }

    mark[data-hl="pink"] {
      background: #fbcfe8
    }

    .editor-toolbar {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 8px;
      flex-wrap: wrap;
      margin-bottom: 10px
    }

    .editor-count {
      font-size: .82rem;
      color: var(--gray-500);
      font-weight: 600
    }

    .editor-list {
      display: flex;
      flex-direction: column;
      gap: 10px;
      max-height: 58vh;
      overflow-y: auto;
      padding-right: 2px
    }

    .editor-card {
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      background: var(--white);
      padding: 14px;
      transition: all .25s ease
    }

    .editor-card:hover {
      border-color: var(--gray-300);
      box-shadow: var(--shadow-sm)
    }

    .editor-card.newly-added {
      border-color: var(--success);
      box-shadow: 0 0 0 3px rgba(16, 185, 129, .12);
      animation: highlightPulse .6s ease-out
    }

    .editor-card-head {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 10px
    }

    .editor-card-title {
      font-size: .8rem;
      color: var(--gray-500);
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .05em
    }

    .q-options-grid {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 8px
    }

    @media(max-width:700px) {
      .q-options-grid {
        grid-template-columns: 1fr
      }
    }

    /* ── Setup overlay ── */
    .setup-overlay {
      position: fixed;
      inset: 0;
      z-index: 280;
      background: rgba(0, 0, 0, .5);
      display: none;
      align-items: center;
      justify-content: center;
      padding: 18px;
      opacity: 0;
      transition: opacity .25s ease
    }

    .setup-overlay.visible {
      display: flex;
      opacity: 1
    }

    .setup-overlay.entering {
      display: flex;
      opacity: 0
    }

    .setup-modal {
      width: min(720px, 100%);
      max-height: 90vh;
      overflow-y: auto;
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-xl);
      box-shadow: var(--shadow-xl);
      padding: 28px;
      transform: scale(.95);
      opacity: 0;
      transition: all .25s ease
    }

    .setup-overlay.visible .setup-modal {
      transform: scale(1);
      opacity: 1
    }

    .setup-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 20px
    }

    .setup-title {
      font-size: 1.2rem;
      font-weight: 700;
      color: var(--gray-900)
    }

    .setup-pack-name {
      font-size: .85rem;
      color: var(--gray-500);
      margin-top: 2px
    }

    .setup-tabs {
      display: flex;
      gap: 4px;
      background: var(--gray-100);
      border-radius: var(--radius-md);
      padding: 4px;
      margin-bottom: 20px
    }

    .setup-tab {
      flex: 1;
      border: none;
      background: transparent;
      border-radius: var(--radius);
      padding: 10px 6px;
      font-size: .78rem;
      font-weight: 600;
      color: var(--gray-600);
      cursor: pointer;
      transition: all .2s ease;
      text-align: center;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 5px
    }

    .setup-tab:hover {
      color: var(--gray-900)
    }

    .setup-tab.active {
      background: var(--white);
      color: var(--gray-900);
      box-shadow: var(--shadow-sm)
    }

    .setup-tab svg {
      width: 14px;
      height: 14px
    }

    .setup-pane {
      display: none
    }

    .setup-pane.active {
      display: block;
      animation: fadeIn .2s ease-out
    }

    /* Lessons */
    .lesson-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 12px
    }

    @media(max-width:500px) {
      .lesson-grid {
        grid-template-columns: 1fr
      }
    }

    .lesson-card {
      border: 2px solid var(--gray-200);
      border-radius: var(--radius-md);
      padding: 20px;
      cursor: pointer;
      transition: all .25s ease;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
      text-align: center;
      position: relative
    }

    .lesson-card:hover {
      border-color: var(--gray-300);
      box-shadow: var(--shadow-sm)
    }

    .lesson-card.selected {
      border-color: var(--primary);
      background: linear-gradient(135deg, rgba(79, 70, 229, .08) 0%, rgba(14, 165, 233, .06) 100%);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .1)
    }

    .lesson-card.unavailable {
      opacity: .4;
      cursor: not-allowed;
      pointer-events: none
    }

    .lesson-card-check {
      position: absolute;
      top: 10px;
      left: 10px;
      width: 22px;
      height: 22px;
      border: 2px solid var(--gray-300);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: all .2s ease
    }

    .lesson-card.selected .lesson-card-check {
      background: var(--primary);
      border-color: var(--primary)
    }

    .lesson-card-check svg {
      width: 13px;
      height: 13px;
      color: var(--white);
      opacity: 0;
      transition: opacity .2s ease
    }

    .lesson-card.selected .lesson-card-check svg {
      opacity: 1
    }

    .lesson-card-icon {
      width: 40px;
      height: 40px;
      color: var(--primary)
    }

    .lesson-card-icon svg {
      width: 100%;
      height: 100%
    }

    .lesson-card-title {
      font-size: 1rem;
      font-weight: 700;
      color: var(--gray-900)
    }

    .lesson-card-desc {
      font-size: .82rem;
      color: var(--gray-500)
    }

    .lesson-card-badge {
      font-size: .7rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .05em;
      color: var(--gray-400);
      background: var(--gray-100);
      padding: 3px 8px;
      border-radius: 20px
    }

    /* Mode picker (shown when multiple lessons enabled) */
    .mode-picker {
      display: none;
      animation: fadeIn .2s ease-out
    }

    .mode-picker.active {
      display: block
    }

    .mode-picker-title {
      text-align: center;
      font-size: 1rem;
      font-weight: 700;
      color: var(--gray-900);
      margin-bottom: 16px
    }

    .mode-picker-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 12px
    }

    @media(max-width:500px) {
      .mode-picker-grid {
        grid-template-columns: 1fr
      }
    }

    .mode-picker-card {
      border: 2px solid var(--gray-200);
      border-radius: var(--radius-md);
      padding: 24px 16px;
      cursor: pointer;
      transition: all .25s ease;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
      text-align: center
    }

    .mode-picker-card:hover {
      border-color: var(--primary-light);
      box-shadow: var(--shadow-md);
      transform: translateY(-2px)
    }

    .mode-picker-card svg {
      width: 36px;
      height: 36px;
      color: var(--primary)
    }

    .mode-picker-card-title {
      font-size: .95rem;
      font-weight: 700;
      color: var(--gray-900)
    }

    .mode-picker-card-desc {
      font-size: .8rem;
      color: var(--gray-500)
    }

    /* Algorithm */
    .algo-lane {
      display: flex;
      align-items: center;
      gap: 6px;
      justify-content: center;
      margin-bottom: 20px;
      flex-wrap: wrap
    }

    .algo-slot {
      width: 100px;
      height: 110px;
      border-radius: var(--radius-md);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 5px;
      font-size: .78rem;
      font-weight: 700;
      color: var(--white);
      cursor: pointer;
      transition: all .25s ease;
      box-shadow: var(--shadow-sm);
      user-select: none
    }

    .algo-slot:hover {
      transform: translateY(-3px);
      box-shadow: var(--shadow-md)
    }

    .algo-slot:active {
      transform: scale(.95)
    }

    .algo-slot svg {
      width: 26px;
      height: 26px
    }

    .algo-slot[data-type="new"] {
      background: linear-gradient(135deg, #38BDF8, #0EA5E9)
    }

    .algo-slot[data-type="familiar"] {
      background: linear-gradient(135deg, #34D399, #10B981)
    }

    .algo-slot[data-type="retry"] {
      background: linear-gradient(135deg, #FB7185, #EF4444)
    }

    .algo-slot[data-type="remaster"] {
      background: linear-gradient(135deg, #FBBF24, #F59E0B)
    }

    .algo-slot[data-type="hard"] {
      background: linear-gradient(135deg, #F87171, #DC2626)
    }

    .algo-slot[data-type="random"] {
      background: linear-gradient(135deg, #A78BFA, #7C3AED)
    }

    .algo-chevron {
      color: var(--gray-400);
      flex-shrink: 0
    }

    .algo-chevron svg {
      width: 16px;
      height: 16px
    }

    .algo-presets {
      display: flex;
      gap: 8px;
      justify-content: center;
      flex-wrap: wrap;
      margin-bottom: 20px
    }

    .algo-preset {
      border: 1px solid var(--gray-300);
      background: var(--white);
      border-radius: var(--radius);
      padding: 8px 14px;
      font-size: .82rem;
      font-weight: 600;
      color: var(--gray-700);
      cursor: pointer;
      transition: all .2s ease
    }

    .algo-preset:hover {
      border-color: var(--gray-400);
      color: var(--gray-900)
    }

    .algo-preset.active {
      background: var(--primary);
      color: var(--white);
      border-color: var(--primary)
    }

    /* Settings */
    .settings-list {
      display: flex;
      flex-direction: column;
      gap: 2px
    }

    .setting-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      padding: 14px 16px;
      border-radius: var(--radius);
      background: var(--gray-50);
      transition: background .15s ease;
      cursor: pointer
    }

    .setting-row:hover {
      background: var(--gray-100)
    }

    .setting-row.active {
      background: rgba(79, 70, 229, .06)
    }

    .setting-label {
      font-size: .9rem;
      color: var(--gray-800);
      font-weight: 500
    }

    .setting-toggle {
      width: 42px;
      height: 24px;
      border-radius: 12px;
      background: var(--gray-300);
      position: relative;
      flex-shrink: 0;
      transition: background .2s ease
    }

    .setting-toggle::after {
      content: '';
      position: absolute;
      top: 2px;
      left: 2px;
      width: 20px;
      height: 20px;
      border-radius: 50%;
      background: var(--white);
      box-shadow: var(--shadow-sm);
      transition: transform .2s ease
    }

    .setting-row.active .setting-toggle {
      background: var(--primary)
    }

    .setting-row.active .setting-toggle::after {
      transform: translateX(18px)
    }

    /* Mastery */
    .mastery-section {
      text-align: center
    }

    .mastery-rings {
      display: flex;
      justify-content: center;
      gap: 24px;
      margin: 20px 0;
      flex-wrap: wrap
    }

    .mastery-ring {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px
    }

    .mastery-ring-circle {
      width: 80px;
      height: 80px;
      border-radius: 50%;
      border: 4px solid var(--gray-200);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.25rem;
      font-weight: 800;
      color: var(--gray-900);
      transition: all .3s ease
    }

    .mastery-ring-circle.new-ring {
      border-color: #38BDF8;
      color: #0EA5E9
    }

    .mastery-ring-circle.familiar-ring {
      border-color: #34D399;
      color: #10B981
    }

    .mastery-ring-circle.mastered-ring {
      border-color: #FBBF24;
      color: #F59E0B
    }

    .mastery-ring-label {
      font-size: .75rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .05em;
      color: var(--gray-500)
    }

    .mastery-stat {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      padding: 10px 16px;
      background: var(--gray-50);
      border-radius: var(--radius);
      font-size: .85rem;
      color: var(--gray-600);
      margin-bottom: 16px
    }

    .mastery-stat strong {
      color: var(--gray-900)
    }

    .mastery-extra {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 8px;
      margin-bottom: 14px
    }

    .mastery-pill {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      padding: 9px 10px;
      border: 1px solid var(--gray-200);
      background: var(--white);
      border-radius: var(--radius);
      font-size: .8rem;
      color: var(--gray-700)
    }

    .mastery-pill strong {
      color: var(--gray-900)
    }

    .mastery-pill.due {
      border-color: rgba(245, 158, 11, .4);
      background: rgba(245, 158, 11, .08);
      color: #92400E
    }

    .difficulty-distribution {
      display: flex;
      gap: 8px;
      justify-content: center;
      flex-wrap: wrap;
      margin-top: 2px
    }

    .difficulty-chip {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 6px 10px;
      border-radius: 999px;
      font-size: .75rem;
      font-weight: 700;
      border: 1px solid
    }

    .difficulty-chip.retry {
      background: rgba(239, 68, 68, .12);
      color: #991B1B;
      border-color: rgba(239, 68, 68, .35)
    }

    .difficulty-chip.hard {
      background: rgba(245, 158, 11, .12);
      color: #92400E;
      border-color: rgba(245, 158, 11, .36)
    }

    .difficulty-chip.good {
      background: rgba(59, 130, 246, .12);
      color: #1D4ED8;
      border-color: rgba(59, 130, 246, .3)
    }

    .difficulty-chip.easy {
      background: rgba(16, 185, 129, .12);
      color: #065F46;
      border-color: rgba(16, 185, 129, .34)
    }

    .exam-recommendation {
      margin-top: 12px;
      padding: 10px 12px;
      border: 1px solid rgba(79, 70, 229, .22);
      background: rgba(79, 70, 229, .06);
      border-radius: var(--radius);
      font-size: .82rem;
      color: var(--gray-700);
      text-align: center
    }

    .exam-recommendation strong {
      color: var(--gray-900)
    }

    /* ── Learn stage ── */
    .learn-stage {
      position: fixed;
      inset: 0;
      z-index: 300;
      background: linear-gradient(135deg, var(--gray-50) 0%, var(--gray-100) 100%);
      display: none;
      opacity: 0;
      transition: opacity .35s ease
    }

    .learn-stage::before {
      content: '';
      position: absolute;
      inset: 0;
      pointer-events: none;
      background: radial-gradient(circle at 15% 15%, rgba(79, 70, 229, .12), transparent 50%), radial-gradient(circle at 85% 25%, rgba(14, 165, 233, .10), transparent 50%), radial-gradient(circle at 50% 85%, rgba(79, 70, 229, .06), transparent 50%)
    }

    .learn-stage.visible {
      display: block;
      opacity: 1
    }

    .learn-stage.entering {
      display: block;
      opacity: 0
    }

    .learn-shell {
      height: 100%;
      display: flex;
      flex-direction: column;
      padding: 20px;
      position: relative;
      z-index: 1
    }

    .learn-top {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 12px;
      background: rgba(255, 255, 255, .95);
      backdrop-filter: blur(12px);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      padding: 14px 20px
    }

    .learn-top-left {
      display: flex;
      align-items: center;
      gap: 12px;
      min-width: 0
    }

    .learn-top-left>div {
      min-width: 0
    }

    .learn-title {
      font-size: 1.05rem;
      font-weight: 700;
      color: var(--gray-900);
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis
    }

    .learn-sub {
      font-size: .82rem;
      color: var(--gray-500)
    }

    .learn-progress-bar {
      height: 4px;
      background: var(--gray-200);
      border-radius: 2px;
      flex: 1;
      min-width: 60px;
      max-width: 200px
    }

    .learn-progress-fill {
      height: 100%;
      background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
      border-radius: 2px;
      transition: width .3s ease
    }

    .learn-progress-text {
      font-size: .78rem;
      font-weight: 600;
      color: var(--gray-500);
      white-space: nowrap
    }

    .learn-progress-center {
      display: flex;
      align-items: center;
      gap: 10px;
      flex: 1;
      justify-content: center;
      min-width: 0
    }

    .learn-body {
      flex: 1;
      min-height: 0;
      display: grid;
      place-items: center;
      padding: 16px 0
    }

    .learn-card {
      width: min(1000px, 100%);
      max-height: 100%;
      background: rgba(255, 255, 255, .96);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-xl);
      box-shadow: var(--shadow-xl);
      padding: 24px;
      display: flex;
      flex-direction: column;
      gap: 16px;
      overflow-y: auto
    }

    /* No learn tabs in focused mode — they are hidden */
    .learn-mode-label {
      font-size: .82rem;
      font-weight: 700;
      color: var(--gray-500);
      text-transform: uppercase;
      letter-spacing: .05em;
      text-align: center;
      margin-bottom: 4px
    }

    .learn-pane {
      display: none;
      min-height: 0
    }

    .learn-pane.active {
      display: block;
      animation: fadeIn .25s ease-out
    }

    .learn-notes {
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      background: var(--gray-50);
      padding: 20px;
      max-height: 60vh;
      overflow-y: auto;
      font-size: .95rem;
      line-height: 1.75
    }

    .learn-notes h1,
    .learn-notes h2,
    .learn-notes h3 {
      margin-top: 20px;
      margin-bottom: 10px;
      color: var(--gray-900)
    }

    .difficulty-toolbar {
      display: none;
      align-items: center;
      justify-content: center;
      gap: 8px;
      flex-wrap: wrap;
      margin-top: 12px;
      opacity: 1;
      transition: opacity .8s ease
    }

    .difficulty-toolbar.list-mode {
      margin-top: 14px;
      margin-bottom: 8px;
      position: static;
      z-index: auto;
      border-top: 0;
      box-shadow: none;
      background: transparent;
      padding: 0;
    }

    .difficulty-toolbar.visible {
      display: flex
    }

    .difficulty-toolbar.faded {
      opacity: .15
    }

    .difficulty-toolbar:hover {
      opacity: 1
    }

    .difficulty-btn {
      border: 1px solid var(--gray-300);
      background: var(--white);
      border-radius: 999px;
      padding: 7px 10px;
      font-size: .78rem;
      font-weight: 700;
      cursor: pointer;
      transition: all .2s ease
    }

    .difficulty-btn:hover {
      border-color: var(--gray-500)
    }

    .difficulty-btn.retry.active {
      border-color: rgba(239, 68, 68, .45);
      background: rgba(239, 68, 68, .12);
      color: #991B1B
    }

    .difficulty-btn.hard.active {
      border-color: rgba(245, 158, 11, .45);
      background: rgba(245, 158, 11, .12);
      color: #92400E
    }

    .difficulty-btn.good.active {
      border-color: rgba(59, 130, 246, .45);
      background: rgba(59, 130, 246, .12);
      color: #1D4ED8
    }

    .difficulty-btn.easy.active {
      border-color: rgba(16, 185, 129, .45);
      background: rgba(16, 185, 129, .12);
      color: #065F46
    }

    .difficulty-hint {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      font-size: .75rem;
      color: var(--gray-500)
    }

    .flatpickr-calendar {
      border: 1px solid var(--gray-200) !important;
      border-radius: 16px !important;
      box-shadow: var(--shadow-xl) !important;
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif !important;
    }

    .flatpickr-months {
      background: linear-gradient(135deg, rgba(79, 70, 229, .1), rgba(14, 165, 233, .09));
      padding: 6px 6px 2px;
    }

    .flatpickr-current-month {
      font-size: 1rem !important;
      font-weight: 700 !important;
      padding-top: 6px !important;
    }

    .flatpickr-weekdays {
      background: var(--gray-50);
    }

    .flatpickr-weekday {
      font-weight: 700 !important;
      color: var(--gray-500) !important;
    }

    .flatpickr-day {
      border-radius: 10px !important;
      font-weight: 500 !important;
    }

    .flatpickr-day.selected,
    .flatpickr-day.startRange,
    .flatpickr-day.endRange,
    .flatpickr-day.selected:hover,
    .flatpickr-day.startRange:hover,
    .flatpickr-day.endRange:hover {
      background: linear-gradient(135deg, var(--primary), #2563EB) !important;
      border-color: transparent !important;
      box-shadow: 0 6px 16px rgba(79, 70, 229, .26);
    }

    .flatpickr-day.today {
      border-color: var(--primary-light) !important;
      background: rgba(79, 70, 229, .06) !important;
    }

    .flatpickr-day:hover {
      background: rgba(79, 70, 229, .11) !important;
    }

    .flatpickr-input,
    .flatpickr-input[readonly] {
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif !important;
      letter-spacing: 0;
    }

    /* ── Audio Sync Player ── */
    .audio-player-bar {
      position: fixed;
      left: 0;
      right: 0;
      bottom: 0;
      z-index: 360;
      display: flex;
      align-items: center;
      gap: 12px;
      padding: 10px 16px;
      background: rgba(17, 24, 39, .96);
      border-top: 1px solid rgba(255, 255, 255, .12);
      transform: translateY(100%);
      transition: transform .25s ease;
    }

    .audio-player-bar.visible {
      transform: translateY(0)
    }

    .audio-play-btn,
    .audio-close-btn {
      width: 34px;
      height: 34px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      border: 1px solid rgba(255, 255, 255, .2);
      background: rgba(255, 255, 255, .08);
      color: var(--white);
    }

    .audio-play-btn {
      background: linear-gradient(135deg, var(--primary), var(--secondary));
      border: none
    }

    .audio-play-btn svg,
    .audio-close-btn svg {
      width: 16px;
      height: 16px
    }

    .audio-time {
      font-size: .78rem;
      color: rgba(255, 255, 255, .82);
      font-variant-numeric: tabular-nums;
      min-width: 84px
    }

    .audio-progress-wrap {
      flex: 1;
      height: 5px;
      border-radius: 99px;
      background: rgba(255, 255, 255, .22);
      cursor: pointer;
      overflow: hidden
    }

    .audio-progress-fill {
      height: 100%;
      width: 0;
      background: linear-gradient(135deg, var(--primary), var(--secondary))
    }

    .audio-speed-btn {
      border: 1px solid rgba(255, 255, 255, .2);
      border-radius: var(--radius-sm);
      background: rgba(255, 255, 255, .08);
      color: var(--white);
      font-size: .74rem;
      font-weight: 700;
      padding: 4px 8px;
      cursor: pointer;
    }

    .audio-pack-title {
      color: rgba(255, 255, 255, .7);
      font-size: .72rem;
      font-weight: 600;
      max-width: 180px;
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
    }

    .export-menu {
      position: relative;
      z-index: 150
    }

    .export-menu-list {
      display: none;
      position: absolute;
      top: calc(100% + 6px);
      left: 0;
      min-width: 220px;
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-lg);
      z-index: 120;
      overflow: visible
    }

    .export-menu-list.visible {
      display: block;
      animation: dropdownOpen .2s ease-out
    }

    .export-menu-item {
      width: 100%;
      text-align: left;
      border: none;
      background: var(--white);
      padding: 10px 12px;
      font-size: .84rem;
      color: var(--gray-700);
      cursor: pointer;
      transition: background .15s ease
    }

    .export-menu-item:hover {
      background: var(--gray-50)
    }

    .export-menu-item span {
      display: block;
      font-size: .72rem;
      color: var(--gray-500);
      margin-top: 2px
    }

    .export-menu-item.has-submenu {
      position: relative;
      padding-right: 30px
    }

    .export-menu-item .submenu-arrow {
      position: absolute;
      right: 10px;
      top: 50%;
      transform: translateY(-50%);
      font-size: .82rem;
      color: var(--gray-400)
    }

    .export-submenu {
      display: none;
      position: absolute;
      right: calc(100% + 4px);
      left: auto;
      top: 0;
      min-width: 230px;
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-lg);
      overflow: hidden
    }

    .export-submenu.visible {
      display: block;
      animation: dropdownOpen .2s ease-out
    }

    .notes-audio-section {
      border-left: 3px solid transparent;
      padding-left: 12px;
      margin-left: -12px;
      border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
      transition: all .2s ease;
      position: relative;
    }

    .notes-audio-section.has-audio {
      cursor: pointer
    }

    .notes-audio-section.has-audio:hover {
      border-left-color: var(--primary-light);
      background: rgba(79, 70, 229, .04)
    }

    .notes-audio-section.audio-active {
      border-left-color: var(--primary);
      background: rgba(79, 70, 229, .08)
    }

    .notes-audio-btn {
      position: absolute;
      top: 4px;
      right: 4px;
      width: 24px;
      height: 24px;
      border-radius: 50%;
      border: none;
      background: var(--primary);
      color: var(--white);
      display: none;
      align-items: center;
      justify-content: center;
      cursor: pointer;
    }

    .notes-audio-btn svg {
      width: 12px;
      height: 12px
    }

    .notes-audio-section.has-audio:hover .notes-audio-btn,
    .notes-audio-section.audio-active .notes-audio-btn {
      display: flex
    }

    /* ── 3D Flashcard with slide transitions ── */
    .flashcard-stage {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 14px
    }

    .flashcard-view-tools {
      width: min(100%, 860px);
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 10px;
      flex-wrap: wrap;
    }

    .flashcard-view-tools .btn.active {
      background: rgba(79, 70, 229, .12);
      border-color: rgba(79, 70, 229, .35);
      color: var(--primary-dark);
    }

    .peek-switch {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      font-size: .84rem;
      font-weight: 700;
      color: var(--gray-700);
      cursor: pointer;
      text-transform: uppercase;
      letter-spacing: .04em;
    }

    .peek-switch input {
      position: absolute;
      opacity: 0;
      pointer-events: none;
    }

    .peek-switch-track {
      width: 44px;
      height: 24px;
      border-radius: 999px;
      background: var(--gray-300);
      position: relative;
      transition: background .2s ease;
    }

    .peek-switch-track::after {
      content: '';
      position: absolute;
      top: 3px;
      left: 3px;
      width: 18px;
      height: 18px;
      border-radius: 50%;
      background: var(--white);
      box-shadow: 0 1px 2px rgba(15, 23, 42, .22);
      transition: transform .2s ease;
    }

    .peek-switch input:checked+.peek-switch-track {
      background: var(--primary);
    }

    .peek-switch input:checked+.peek-switch-track::after {
      transform: translateX(20px);
    }

    .flashcard-list-view {
      width: min(100%, 1120px);
      display: grid;
      gap: 10px;
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      background: var(--gray-50);
      padding: 12px;
    }

    .peek-empty {
      padding: 12px;
      border-radius: var(--radius-sm);
      border: 1px dashed var(--gray-300);
      color: var(--gray-600);
      font-size: .88rem;
      text-align: center;
      background: var(--white);
    }

    .peek-row {
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-sm);
      background: var(--white);
      display: grid;
      grid-template-columns: auto minmax(0, 1fr) 1px minmax(220px, 42%);
      gap: 14px;
      align-items: start;
      width: 100%;
      text-align: left;
      padding: 12px 14px;
      cursor: pointer;
      transition: border-color .15s ease, box-shadow .15s ease;
      color: var(--gray-900);
    }

    .peek-row:hover {
      border-color: rgba(79, 70, 229, .35);
      box-shadow: 0 4px 10px rgba(15, 23, 42, .08);
    }

    .peek-row:focus-visible {
      outline: 2px solid rgba(79, 70, 229, .5);
      outline-offset: 2px;
    }

    .peek-row.active {
      border-color: rgba(79, 70, 229, .55);
      box-shadow: 0 0 0 1px rgba(79, 70, 229, .15);
    }

    .peek-index {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      min-width: 34px;
      height: 30px;
      border-radius: 999px;
      background: rgba(148, 163, 184, .25);
      color: var(--gray-700);
      font-size: .82rem;
      font-weight: 700;
      align-self: center;
    }

    .peek-front {
      font-size: 1.05rem;
      line-height: 1.45;
      font-weight: 600;
      color: var(--gray-800);
      padding-top: 2px;
    }

    .peek-divider {
      width: 1px;
      background: var(--gray-200);
      min-height: 28px;
      align-self: stretch;
    }

    .peek-right {
      display: flex;
      align-items: center;
      min-height: 32px;
    }

    .peek-answer {
      font-size: 1.02rem;
      line-height: 1.5;
      color: var(--gray-800);
      white-space: pre-wrap;
    }

    .peek-reveal-btn {
      border: 1px solid var(--gray-300);
      background: var(--white);
      border-radius: 999px;
      padding: 7px 12px;
      font-size: .94rem;
      font-weight: 700;
      color: var(--gray-600);
      display: inline-flex;
      align-items: center;
      gap: 8px;
      cursor: pointer;
    }

    .peek-reveal-btn:hover {
      border-color: rgba(79, 70, 229, .4);
      color: var(--primary-dark);
      background: rgba(79, 70, 229, .05);
    }

    .peek-reveal-btn svg {
      width: 16px;
      height: 16px;
    }

    #learn-pane-flashcards.list-mode .flashcard-3d,
    #learn-pane-flashcards.list-mode .learn-controls,
    #learn-pane-flashcards.list-mode .keyboard-hints {
      display: none;
    }

    .flashcard-3d {
      width: min(100%, 860px);
      height: 340px;
      perspective: 1200px;
      cursor: pointer;
      position: relative;
      overflow: hidden
    }

    .flashcard-inner {
      position: relative;
      width: 100%;
      height: 100%;
      transform-style: preserve-3d;
      transition: transform .55s ease
    }

    .flashcard-inner.flipped {
      transform: rotateY(180deg)
    }

    .flashcard-inner.slide-left {
      animation: slideLeft .3s ease-out
    }

    .flashcard-inner.slide-right {
      animation: slideRight .3s ease-out
    }

    .flashcard-face {
      position: absolute;
      inset: 0;
      backface-visibility: hidden;
      border-radius: var(--radius-lg);
      border: 1px solid var(--gray-200);
      background: linear-gradient(135deg, rgba(79, 70, 229, .06) 0%, rgba(14, 165, 233, .08) 100%);
      box-shadow: var(--shadow-md);
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 30px;
      text-align: center
    }

    .flashcard-face.back {
      transform: rotateY(180deg);
      background: linear-gradient(135deg, rgba(14, 165, 233, .08) 0%, rgba(79, 70, 229, .06) 100%)
    }

    .flashcard-label {
      position: absolute;
      top: 16px;
      left: 16px;
      font-size: .7rem;
      color: var(--gray-400);
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .06em
    }

    .flashcard-text {
      font-size: 1.15rem;
      color: var(--gray-900);
      line-height: 1.65;
      white-space: pre-wrap;
      max-height: 260px;
      overflow-y: auto
    }

    .learn-controls {
      display: flex;
      justify-content: center;
      align-items: center;
      flex-wrap: wrap;
      gap: 10px
    }

    .learn-progress-fc {
      font-size: .85rem;
      color: var(--gray-500);
      min-width: 120px;
      text-align: center;
      font-weight: 500
    }

    .keyboard-hints {
      display: flex;
      gap: 14px;
      justify-content: center;
      align-items: center;
      flex-wrap: wrap;
      font-size: .75rem;
      color: var(--gray-500);
      opacity: 1;
      transition: opacity .8s ease
    }

    .keyboard-hints.faded {
      opacity: .15
    }

    .keyboard-hints:hover {
      opacity: 1
    }

    .keyboard-hints span {
      display: inline-flex;
      align-items: center;
      gap: 6px
    }

    .kbd {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      min-width: 24px;
      height: 22px;
      padding: 0 6px;
      background: var(--gray-100);
      border: 1px solid var(--gray-300);
      border-radius: 6px;
      font-size: .68rem;
      font-weight: 700;
      color: var(--gray-600)
    }

    @keyframes slideLeft {
      0% {
        opacity: 1;
        transform: translateX(0)
      }

      40% {
        opacity: 0;
        transform: translateX(-40px)
      }

      41% {
        opacity: 0;
        transform: translateX(40px)
      }

      100% {
        opacity: 1;
        transform: translateX(0)
      }
    }

    @keyframes slideRight {
      0% {
        opacity: 1;
        transform: translateX(0)
      }

      40% {
        opacity: 0;
        transform: translateX(40px)
      }

      41% {
        opacity: 0;
        transform: translateX(-40px)
      }

      100% {
        opacity: 1;
        transform: translateX(0)
      }
    }

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

      .flashcard-inner.slide-left,
      .flashcard-inner.slide-right {
        animation: none
      }

      .flashcard-inner {
        transition: none
      }
    }

    /* ── Quiz ── */
    .quiz-head {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 10px;
      margin-bottom: 10px;
      font-size: .9rem;
      font-weight: 600;
      color: var(--gray-700)
    }

    .quiz-question {
      font-size: 1.1rem;
      font-weight: 700;
      margin-bottom: 14px;
      color: var(--gray-900);
      line-height: 1.5
    }

    .quiz-options {
      display: grid;
      gap: 10px
    }

    .quiz-option {
      width: 100%;
      text-align: left;
      border: 1px solid var(--gray-300);
      background: var(--white);
      border-radius: var(--radius);
      padding: 14px 18px;
      font-size: .9375rem;
      color: var(--gray-800);
      cursor: pointer;
      transition: all .2s ease
    }

    .quiz-option:hover:not(:disabled) {
      border-color: var(--primary-light);
      background: var(--gray-50);
      transform: translateY(-1px)
    }

    .quiz-option.correct {
      border-color: var(--success);
      background: rgba(16, 185, 129, .12);
      color: #065F46;
      transform: none
    }

    .quiz-option.wrong {
      border-color: var(--error);
      background: rgba(239, 68, 68, .12);
      color: #991B1B;
      transform: none
    }

    .quiz-option:disabled {
      cursor: default;
      transform: none
    }

    .quiz-expl {
      margin-top: 10px;
      border: 1px solid rgba(14, 165, 233, .2);
      border-radius: var(--radius);
      background: rgba(14, 165, 233, .06);
      padding: 14px 18px;
      font-size: .9rem;
      color: var(--gray-700);
      line-height: 1.5;
      display: none
    }

    .quiz-expl.visible {
      display: block;
      animation: fadeSlideIn .25s ease-out
    }

    /* ── Write mode ── */
    .write-stage {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 16px;
      width: 100%
    }

    .write-prompt {
      font-size: 1.15rem;
      font-weight: 700;
      color: var(--gray-900);
      text-align: center;
      padding: 24px;
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-lg);
      background: linear-gradient(135deg, rgba(79, 70, 229, .06) 0%, rgba(14, 165, 233, .08) 100%);
      width: 100%;
      min-height: 100px;
      display: flex;
      align-items: center;
      justify-content: center
    }

    .write-input-row {
      display: flex;
      gap: 8px;
      width: 100%;
      max-width: 600px
    }

    .write-input {
      flex: 1;
      border: 2px solid var(--gray-300);
      border-radius: var(--radius);
      padding: 14px 16px;
      font-size: 1rem;
      color: var(--gray-900);
      transition: border-color .2s ease
    }

    .write-input:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .1)
    }

    .write-input.correct-input {
      border-color: var(--success);
      background: rgba(16, 185, 129, .06)
    }

    .write-input.wrong-input {
      border-color: var(--error);
      background: rgba(239, 68, 68, .06)
    }

    .write-feedback {
      text-align: center;
      font-size: .9rem;
      padding: 12px 16px;
      border-radius: var(--radius);
      width: 100%;
      max-width: 600px;
      display: none
    }

    .write-feedback.visible {
      display: block;
      animation: fadeSlideIn .25s ease-out
    }

    .write-feedback.correct-fb {
      background: rgba(16, 185, 129, .1);
      border: 1px solid rgba(16, 185, 129, .3);
      color: #065F46
    }

    .write-feedback.wrong-fb {
      background: rgba(239, 68, 68, .1);
      border: 1px solid rgba(239, 68, 68, .3);
      color: #991B1B
    }

    /* ── Match mode ── */
    .match-stage {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 16px;
      width: 100%
    }

    .match-timer {
      font-size: 1.5rem;
      font-weight: 800;
      color: var(--gray-900);
      font-variant-numeric: tabular-nums
    }

    .match-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 10px;
      width: 100%
    }

    @media(max-width:600px) {
      .match-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 8px
      }
    }

    .match-cell {
      border: 2px solid var(--gray-200);
      border-radius: var(--radius-md);
      padding: 14px 8px;
      text-align: center;
      font-size: .85rem;
      font-weight: 600;
      color: var(--gray-800);
      cursor: pointer;
      transition: all .2s ease;
      min-height: 60px;
      display: flex;
      align-items: center;
      justify-content: center;
      word-break: break-word;
      background: var(--white)
    }

    .match-cell:hover:not(.matched):not(.selected) {
      border-color: var(--gray-400);
      background: var(--gray-50);
      transform: translateY(-1px)
    }

    .match-cell.selected {
      border-color: var(--primary);
      background: rgba(79, 70, 229, .08);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .12)
    }

    .match-cell.matched {
      border-color: var(--success);
      background: rgba(16, 185, 129, .1);
      color: #065F46;
      cursor: default;
      opacity: .7
    }

    .match-cell.wrong-flash {
      border-color: var(--error);
      background: rgba(239, 68, 68, .12);
      animation: shake .4s ease
    }

    .match-results {
      text-align: center;
      padding: 20px;
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-md);
      background: var(--gray-50);
      width: 100%
    }

    .match-results-time {
      font-size: 2rem;
      font-weight: 800;
      color: var(--gray-900)
    }

    .match-results-badge {
      font-size: 1rem;
      font-weight: 700;
      margin-top: 8px
    }

    .match-results-badge.gold {
      color: #F59E0B
    }

    .match-results-badge.silver {
      color: var(--gray-500)
    }

    .match-results-badge.bronze {
      color: #B45309
    }

    .match-results-history {
      margin-top: 12px;
      font-size: .82rem;
      color: var(--gray-500)
    }

    @keyframes shake {

      0%,
      100% {
        transform: translateX(0)
      }

      20% {
        transform: translateX(-6px)
      }

      40% {
        transform: translateX(6px)
      }

      60% {
        transform: translateX(-4px)
      }

      80% {
        transform: translateX(4px)
      }
    }

    /* ── Fullscreen Builder ── */
    .builder-overlay {
      position: fixed;
      inset: 0;
      z-index: 290;
      display: none;
      opacity: 0;
      transition: opacity .28s ease;
      background: linear-gradient(135deg, rgba(17, 24, 39, .44), rgba(31, 41, 55, .42))
    }

    .builder-overlay.visible {
      display: block;
      opacity: 1
    }

    .builder-overlay.entering {
      display: block;
      opacity: 0
    }

    .builder-shell {
      height: 100%;
      display: grid;
      grid-template-columns: 320px 1fr;
      gap: 0;
      background: linear-gradient(180deg, var(--gray-50), #eef3ff)
    }

    .builder-rail {
      border-right: 1px solid var(--gray-200);
      background: linear-gradient(180deg, #ffffff, #f7f9ff);
      padding: 22px 18px 18px;
      overflow-y: auto
    }

    .builder-brand {
      margin-bottom: 14px
    }

    .builder-brand h2 {
      font-size: 1.48rem;
      line-height: 1.15;
      letter-spacing: -.03em;
      color: var(--gray-900)
    }

    .builder-brand p {
      font-size: .8rem;
      color: var(--gray-500);
      margin-top: 5px
    }

    .builder-top-actions {
      display: grid;
      grid-template-columns: 1fr;
      gap: 8px;
      margin-bottom: 12px
    }

    .builder-duo {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 8px
    }

    .builder-nav {
      display: flex;
      flex-direction: column;
      gap: 8px;
      margin: 14px 0 16px
    }

    .builder-nav-btn {
      width: 100%;
      display: flex;
      align-items: center;
      gap: 8px;
      border: 1px solid var(--gray-300);
      background: var(--white);
      border-radius: var(--radius-md);
      padding: 10px 12px;
      font-size: .86rem;
      font-weight: 700;
      color: var(--gray-700);
      cursor: pointer;
      transition: all .2s ease
    }

    .builder-nav-btn:hover {
      border-color: var(--primary-light);
      box-shadow: var(--shadow-sm)
    }

    .builder-nav-btn.active {
      background: linear-gradient(135deg, rgba(79, 70, 229, .08), rgba(14, 165, 233, .08));
      border-color: rgba(79, 70, 229, .4);
      color: var(--gray-900);
      box-shadow: 0 0 0 2px rgba(79, 70, 229, .13)
    }

    .builder-nav-btn svg {
      width: 16px;
      height: 16px
    }

    .builder-mini-stats {
      display: grid;
      gap: 8px;
      margin-top: 10px
    }

    .builder-stat {
      padding: 9px 10px;
      border-radius: var(--radius);
      background: var(--gray-100);
      font-size: .78rem;
      color: var(--gray-600)
    }

    .builder-stat strong {
      color: var(--gray-900)
    }

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

    .builder-status.saved {
      border-color: rgba(16, 185, 129, .35);
      background: rgba(16, 185, 129, .12);
      color: #065F46;
    }

    .builder-status.pending {
      border-color: rgba(245, 158, 11, .4);
      background: rgba(245, 158, 11, .12);
      color: #92400E;
    }

    .builder-status.saving {
      border-color: rgba(79, 70, 229, .35);
      background: rgba(79, 70, 229, .1);
      color: var(--primary-dark);
    }

    .builder-main {
      padding: 22px 26px;
      overflow-y: auto;
      position: relative
    }

    .builder-main::before {
      content: '';
      position: absolute;
      inset: 0;
      pointer-events: none;
      background: radial-gradient(circle at 85% 18%, rgba(79, 70, 229, .08), transparent 42%), radial-gradient(circle at 20% 85%, rgba(14, 165, 233, .08), transparent 46%)
    }

    .builder-main-inner {
      position: relative;
      z-index: 1
    }

    .builder-headline {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 12px;
      margin-bottom: 16px
    }

    .builder-title {
      font-size: 1.2rem;
      font-weight: 800;
      color: var(--gray-900)
    }

    .builder-sub {
      font-size: .85rem;
      color: var(--gray-500)
    }

    .builder-pane {
      display: none
    }

    .builder-pane.active {
      display: block;
      animation: fadeIn .2s ease-out
    }

    .builder-card {
      background: rgba(255, 255, 255, .95);
      border: 1px solid var(--gray-200);
      border-radius: 18px;
      padding: 18px;
      box-shadow: var(--shadow-lg)
    }

    .builder-grid {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 12px
    }

    .builder-grid-3 {
      display: grid;
      grid-template-columns: repeat(3, minmax(0, 1fr));
      gap: 12px
    }

    .builder-list {
      display: flex;
      flex-direction: column;
      gap: 12px;
      max-height: 64vh;
      overflow-y: auto;
      padding-right: 3px
    }

    .builder-list-empty {
      padding: 22px;
      border: 1px dashed var(--gray-300);
      border-radius: var(--radius-md);
      background: var(--gray-50);
      text-align: center;
      color: var(--gray-500)
    }

    .builder-list-empty-actions {
      margin-top: 10px;
      display: flex;
      gap: 8px;
      justify-content: center;
      flex-wrap: wrap
    }

    .builder-row {
      border: 1px solid var(--gray-200);
      border-radius: 14px;
      padding: 14px;
      background: var(--white);
      box-shadow: var(--shadow-sm)
    }

    .builder-row-head {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 8px;
      margin-bottom: 9px
    }

    .builder-row-title {
      font-size: .78rem;
      letter-spacing: .05em;
      text-transform: uppercase;
      font-weight: 700;
      color: var(--gray-500)
    }

    .builder-split {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px
    }

    .builder-cta-strip {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      margin-bottom: 10px
    }

    .builder-info-banner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 10px;
      padding: 12px 14px;
      border: 1px solid rgba(79, 70, 229, .22);
      background: linear-gradient(135deg, rgba(79, 70, 229, .08), rgba(14, 165, 233, .08));
      border-radius: 12px;
      margin-bottom: 12px
    }

    .builder-info-banner span {
      font-size: .82rem;
      color: var(--gray-700);
      font-weight: 600
    }

    .builder-advanced-toggle {
      display: flex;
      justify-content: flex-start;
      margin-top: 6px;
      margin-bottom: 10px
    }

    .builder-advanced-panel {
      display: none
    }

    .builder-advanced-panel.visible {
      display: grid
    }

    .builder-drop {
      border: 2px dashed rgba(55, 65, 81, .34);
      border-radius: 16px;
      padding: 28px 16px;
      text-align: center;
      background: rgba(255, 255, 255, .8);
      transition: all .2s ease;
      cursor: pointer
    }

    .builder-drop:hover {
      border-color: rgba(79, 70, 229, .6);
      background: rgba(79, 70, 229, .04)
    }

    .builder-drop.dragover {
      border-color: var(--primary);
      background: rgba(79, 70, 229, .08);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .14)
    }

    .builder-import-tools {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 10px;
      margin: 12px 0
    }

    .builder-preview {
      margin-top: 12px;
      border: 1px solid var(--gray-200);
      border-radius: 12px;
      background: #fff;
      overflow: hidden
    }

    .builder-preview-head {
      padding: 10px 12px;
      font-size: .8rem;
      font-weight: 700;
      color: var(--gray-600);
      background: var(--gray-50);
      border-bottom: 1px solid var(--gray-200)
    }

    .builder-preview-table {
      width: 100%;
      border-collapse: collapse;
      font-size: .82rem
    }

    .builder-preview-table th,
    .builder-preview-table td {
      padding: 8px 10px;
      border-bottom: 1px solid var(--gray-100);
      text-align: left;
      vertical-align: top
    }

    .builder-preview-table th {
      font-size: .74rem;
      text-transform: uppercase;
      letter-spacing: .04em;
      color: var(--gray-500)
    }

    .builder-errors {
      margin-top: 10px;
      max-height: 160px;
      overflow-y: auto;
      padding: 10px;
      border-radius: 10px;
      background: rgba(239, 68, 68, .08);
      border: 1px solid rgba(239, 68, 68, .22);
      font-size: .78rem;
      color: #991B1B
    }

    .builder-helper {
      font-size: .8rem;
      color: var(--gray-500)
    }

    .builder-select {
      width: 100%;
      border: 1px solid var(--gray-300);
      border-radius: var(--radius);
      padding: 10px 12px;
      background: #fff;
      font-size: .88rem;
      color: var(--gray-800)
    }

    .builder-select:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(79, 70, 229, .1)
    }

    .builder-exit-modal .modal {
      max-width: 520px
    }

    .builder-exit-icon {
      width: 72px;
      height: 72px;
      border-radius: 50%;
      margin: 2px auto 10px;
      display: grid;
      place-items: center;
      color: var(--primary);
      background: linear-gradient(135deg, rgba(79, 70, 229, .12), rgba(14, 165, 233, .12));
      border: 1px solid rgba(79, 70, 229, .2)
    }

    .builder-exit-icon svg {
      width: 34px;
      height: 34px
    }

    /* ── Modals ── */
    .modal-overlay {
      position: fixed;
      inset: 0;
      z-index: 260;
      background: rgba(0, 0, 0, .5);
      display: none;
      align-items: center;
      justify-content: center;
      padding: 18px;
      opacity: 0;
      transition: opacity .25s ease
    }

    .modal-overlay.visible {
      display: flex;
      opacity: 1
    }

    .modal-overlay.entering {
      display: flex;
      opacity: 0
    }

    .modal {
      width: min(560px, 100%);
      background: var(--white);
      border: 1px solid var(--gray-200);
      border-radius: var(--radius-xl);
      box-shadow: var(--shadow-xl);
      padding: 24px;
      transform: scale(.95);
      opacity: 0;
      transition: all .25s ease
    }

    .modal-overlay.visible .modal {
      transform: scale(1);
      opacity: 1
    }

    .modal-head {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 16px
    }

    .modal-title {
      font-size: 1.1rem;
      font-weight: 700;
      color: var(--gray-900)
    }

    .modal-grid {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 10px
    }

    @media(max-width:620px) {
      .modal-grid {
        grid-template-columns: 1fr
      }
    }

    .modal-message {
      font-size: .92rem;
      color: var(--gray-700);
      margin-bottom: 16px;
      line-height: 1.5
    }

    .toast {
      position: fixed;
      bottom: 24px;
      left: 50%;
      transform: translateX(-50%) translateY(100px);
      background: var(--gray-900);
      color: var(--white);
      border-radius: var(--radius-md);
      padding: 14px 24px;
      font-size: .9375rem;
      font-weight: 500;
      box-shadow: var(--shadow-xl);
      opacity: 0;
      transition: all .3s ease;
      z-index: 500;
      display: flex;
      align-items: center;
      gap: 10px;
      max-width: calc(100vw - 48px)
    }

    .toast.visible {
      transform: translateX(-50%) translateY(0);
      opacity: 1
    }

    .toast.success {
      background: var(--success)
    }

    .toast.error {
      background: var(--error)
    }

    @keyframes dropdownOpen {
      from {
        opacity: 0;
        transform: translateY(-8px)
      }

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

    @keyframes fadeIn {
      from {
        opacity: 0
      }

      to {
        opacity: 1
      }
    }

    @keyframes fadeSlideIn {
      from {
        opacity: 0;
        transform: translateY(8px)
      }

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

    @keyframes highlightPulse {
      0% {
        box-shadow: 0 0 0 0 rgba(16, 185, 129, .35)
      }

      100% {
        box-shadow: 0 0 0 3px rgba(16, 185, 129, .12)
      }
    }

    @media(max-width:600px) {
      .container {
        padding: 10px
      }

      .topbar {
        padding: 10px 14px;
        flex-direction: column;
        align-items: stretch;
        gap: 10px;
        position: static;
        border-radius: var(--radius-md)
      }

      .topbar .actions {
        justify-content: flex-end
      }

      .topbar-sub {
        max-width: 100%
      }

      .panel {
        border-radius: var(--radius-lg)
      }

      .panel-head {
        padding: 12px 14px
      }

      .panel-body {
        padding: 12px 14px
      }

      .highlight-toolbar {
        gap: 8px;
        padding: 10px 12px;
        min-height: 48px;
      }

      .hl-btn {
        width: 44px;
        height: 44px;
      }

      .hl-btn.hl-action {
        min-height: 44px;
        font-size: .92rem;
        padding: 10px 12px;
      }

      .hl-download-btn {
        min-height: 44px;
        font-size: .92rem;
        padding: 10px 16px;
      }

      .split {
        grid-template-columns: 1fr;
        gap: 12px
      }

      .meta-grid {
        grid-template-columns: 1fr
      }

      .learn-shell {
        padding: 10px
      }

      .learn-top {
        flex-direction: column;
        align-items: stretch;
        gap: 10px;
        padding: 12px 14px;
        border-radius: var(--radius-md)
      }

      .learn-top .actions {
        justify-content: flex-end
      }

      .learn-progress-center {
        justify-content: flex-start
      }

      .learn-card {
        padding: 14px;
        border-radius: var(--radius-lg)
      }

      .flashcard-3d {
        height: 260px
      }

      .flashcard-view-tools {
        width: 100%;
      }

      .flashcard-list-view {
        width: 100%;
        padding: 8px;
      }

      .peek-row {
        grid-template-columns: auto minmax(0, 1fr);
        gap: 10px;
      }

      .peek-divider {
        display: none;
      }

      .peek-right {
        grid-column: 1 / -1;
        padding-left: 42px;
      }

      #learn-pane-flashcards .learn-controls {
        display: none;
      }

      .difficulty-toolbar {
        position: fixed;
        left: 0;
        right: 0;
        bottom: 0;
        z-index: 450;
        margin: 0;
        padding: 10px 10px calc(10px + env(safe-area-inset-bottom, 0px));
        border-top: 1px solid var(--gray-200);
        background: rgba(255, 255, 255, .98);
        box-shadow: 0 -8px 20px rgba(15, 23, 42, .12);
      }

      .difficulty-toolbar.visible {
        display: grid;
        grid-template-columns: repeat(4, minmax(0, 1fr));
        gap: 8px;
      }

      .difficulty-toolbar .difficulty-hint {
        display: none;
      }

      .difficulty-btn {
        min-height: 48px;
        border-radius: 12px;
        font-size: .86rem;
      }

      .learn-card {
        padding-bottom: 88px;
      }

      body.flashcard-list-mode .difficulty-toolbar {
        position: static;
        left: auto;
        right: auto;
        bottom: auto;
        margin-top: 14px;
        padding: 0;
        border-top: 0;
        box-shadow: none;
        background: transparent;
      }

      body.flashcard-list-mode .difficulty-toolbar.visible {
        display: flex;
        grid-template-columns: none;
      }

      body.flashcard-list-mode .difficulty-toolbar .difficulty-hint {
        display: inline-flex;
      }

      body.flashcard-list-mode .difficulty-btn {
        min-height: 40px;
      }

      body.flashcard-list-mode .learn-card {
        padding-bottom: 16px;
      }

      .algo-slot {
        width: 68px;
        height: 82px;
        font-size: .68rem
      }

      .algo-slot svg {
        width: 20px;
        height: 20px
      }

      .algo-chevron svg {
        width: 12px;
        height: 12px
      }

      .algo-lane {
        gap: 4px
      }

      .lesson-grid {
        grid-template-columns: 1fr
      }

      .lesson-card {
        padding: 14px
      }

      .setup-modal {
        padding: 18px
      }

      .setup-tabs {
        flex-wrap: wrap
      }

      .setup-tab {
        padding: 8px 4px;
        font-size: .72rem
      }

      .setup-tab svg {
        width: 12px;
        height: 12px
      }

      .mastery-extra {
        grid-template-columns: 1fr
      }

      .btn {
        padding: 8px 10px;
        font-size: .8rem
      }

      .btn.cta {
        padding: 12px 20px;
        font-size: .92rem
      }

      .keyboard-hints {
        display: none
      }

      .editor-tab {
        font-size: .75rem;
        padding: 8px 6px;
        gap: 4px
      }

      .editor-tab svg {
        width: 13px;
        height: 13px
      }

      .match-grid {
        grid-template-columns: repeat(3, 1fr)
      }

      .builder-shell {
        grid-template-columns: 1fr
      }

      .builder-rail {
        border-right: none;
        border-bottom: 1px solid var(--gray-200)
      }

      .builder-main {
        padding: 14px
      }

      .builder-grid,
      .builder-grid-3,
      .builder-split,
      .builder-import-tools {
        grid-template-columns: 1fr
      }
    }