:root {
      color-scheme: light;
      font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
      background: #f5f7fb;
      color: #17202a;
      font-size: 16px;
      --bg: #f5f7fb;
      --surface: #ffffff;
      --surface-muted: #eef3f7;
      --text: #17202a;
      --muted: #64748b;
      --border: #d7dee8;
      --border-strong: #aebacc;
      --primary: #0f766e;
      --primary-dark: #115e59;
      --primary-soft: #d9f6f1;
      --danger: #b42318;
      --danger-soft: #fee4e2;
      --success: #087443;
      --success-soft: #dcfae6;
      --warning: #b54708;
      --shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      background: var(--bg);
      color: var(--text);
    }

    main {
      width: min(1500px, calc(100% - 32px));
      margin: 0 auto;
      padding: 28px 0 56px;
    }

    .app-main {
      width: min(1500px, calc(100% - 32px));
    }

    .narrow {
      width: min(760px, calc(100% - 32px));
    }

    .public-main {
      padding-top: 64px;
    }

    .app-header {
      align-items: center;
      background: rgba(255, 255, 255, 0.94);
      border-bottom: 1px solid var(--border);
      display: grid;
      gap: 18px;
      grid-template-columns: auto minmax(0, 1fr) auto;
      padding: 14px max(16px, calc((100vw - 1500px) / 2));
      position: sticky;
      top: 0;
      z-index: 20;
    }

    .brand {
      align-items: center;
      color: var(--text);
      display: inline-flex;
      gap: 10px;
      min-width: 0;
      text-decoration: none;
    }

    .brand-mark {
      align-items: center;
      background: var(--primary);
      border-radius: 8px;
      color: #ffffff;
      display: inline-flex;
      font-weight: 850;
      height: 38px;
      justify-content: center;
      width: 38px;
    }

    .brand strong,
    .account-menu strong {
      display: block;
      font-size: 0.95rem;
      line-height: 1.1;
      white-space: nowrap;
    }

    .brand small,
    .account-menu small {
      color: var(--muted);
      display: block;
      font-size: 0.78rem;
      line-height: 1.2;
      white-space: nowrap;
    }

    .top-nav {
      align-items: center;
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }

    .nav-group {
      align-items: center;
      display: inline-flex;
      gap: 6px;
    }

    .nav-group-label {
      color: var(--muted);
      font-size: 0.72rem;
      font-weight: 800;
      padding-right: 2px;
      text-transform: uppercase;
    }

    .nav-link {
      border-radius: 7px;
      color: #334155;
      font-size: 0.92rem;
      font-weight: 750;
      padding: 9px 10px;
      text-decoration: none;
    }

    .nav-link:hover {
      background: var(--surface-muted);
      color: var(--primary-dark);
    }

    .nav-link.active {
      background: var(--primary-soft);
      color: var(--primary-dark);
    }

    .account-menu {
      align-items: center;
      display: inline-flex;
      gap: 12px;
      justify-content: end;
      min-width: 0;
    }

    .account-menu form {
      margin: 0;
    }

    .page-header,
    .intro {
      align-items: end;
      border-bottom: 1px solid var(--border);
      display: grid;
      gap: 18px;
      grid-template-columns: minmax(0, 1fr) auto;
      margin-bottom: 28px;
      padding-bottom: 22px;
    }

    .page-header-copy {
      min-width: 0;
    }

    .page-header p,
    .intro p {
      color: var(--muted);
      margin-bottom: 0;
      max-width: 76ch;
    }

    .page-header-actions {
      align-items: center;
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      justify-content: end;
    }

    .page-header-message {
      grid-column: 1 / -1;
    }

    .error {
      background: var(--danger-soft);
      border: 1px solid #fda29b;
      border-radius: 8px;
      color: var(--danger);
      padding: 12px;
    }

    .success {
      background: var(--success-soft);
      border: 1px solid #75e0a7;
      border-radius: 8px;
      color: var(--success);
      padding: 12px;
    }

    .field-error {
      color: var(--danger);
      font-size: 0.9rem;
      margin: 0;
    }

    [aria-invalid="true"] {
      border-color: #fda29b;
    }

    .eyebrow {
      color: var(--primary);
      font-size: 0.78rem;
      font-weight: 800;
      margin: 0 0 8px;
      text-transform: uppercase;
    }

    h1,
    h2,
    p {
      margin-top: 0;
    }

    h1 {
      font-size: 2rem;
      line-height: 1.12;
      margin-bottom: 10px;
    }

    h2 {
      font-size: 1.15rem;
      margin-bottom: 16px;
    }

    .layout {
      display: grid;
      gap: 32px;
      grid-template-columns: minmax(320px, 480px) minmax(0, 1fr);
      align-items: start;
    }

    .summary {
      color: var(--muted);
      border-bottom: 1px solid var(--border);
      margin-bottom: 24px;
      padding-bottom: 16px;
    }

    .editor-shell {
      display: grid;
      gap: 24px;
    }

    .editor-summary {
      align-items: start;
      display: grid;
      gap: 18px;
      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    }

    .summary-block {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      box-shadow: 0 10px 28px rgba(15, 23, 42, 0.04);
      padding: 18px;
    }

    .summary-block h3 {
      color: var(--primary);
      font-size: 0.85rem;
      margin: 0 0 10px;
      text-transform: uppercase;
    }

    .summary-code {
      background: #f8fafc;
      border: 1px solid var(--border);
      border-radius: 8px;
      margin: 0;
      min-height: 96px;
      overflow-x: auto;
      padding: 14px;
      white-space: pre-wrap;
    }

    .exercise-row-main {
      align-items: start;
      display: grid;
      gap: 14px;
      grid-template-columns: minmax(0, 180px) minmax(0, 1fr);
    }

    .exercise-row-main.no-preview {
      grid-template-columns: minmax(0, 1fr);
    }

    .exercise-row-copy {
      display: grid;
      gap: 6px;
    }

    .exercise-preview-card {
      align-items: center;
      background: #ffffff;
      border: 1px solid var(--border);
      border-radius: 8px;
      color: #111111;
      display: flex;
      justify-content: center;
      min-height: 110px;
      overflow: hidden;
      padding: 10px;
    }

    .exercise-preview-card svg {
      background: #ffffff;
      height: auto;
      max-height: 90px;
      max-width: 100%;
      width: 100%;
    }

    .editor-steps {
      display: grid;
      gap: 12px;
      grid-template-columns: repeat(3, minmax(0, 1fr));
      list-style: none;
      margin: 0;
      padding: 0;
    }

    .editor-steps li {
      align-items: center;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 999px;
      display: flex;
      gap: 12px;
      min-width: 0;
      padding: 12px 16px;
    }

    .editor-steps li.is-active {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.12);
    }

    .editor-steps li.is-complete {
      border-color: #75e0a7;
    }

    .editor-step-number {
      align-items: center;
      background: var(--surface-muted);
      border: 1px solid var(--border);
      border-radius: 999px;
      color: var(--text);
      display: inline-flex;
      font-size: 0.85rem;
      font-weight: 800;
      height: 32px;
      justify-content: center;
      min-width: 32px;
    }

    .editor-steps li.is-active .editor-step-number,
    .editor-steps li.is-complete .editor-step-number {
      background: var(--primary);
      border-color: var(--primary);
      color: #ffffff;
    }

    .editor-step-label {
      color: var(--text);
      font-size: 0.95rem;
      font-weight: 700;
      min-width: 0;
    }

    .editor-stage {
      display: grid;
      gap: 18px;
    }

    .editor-stage-copy {
      align-items: end;
      display: flex;
      flex-wrap: wrap;
      gap: 12px 18px;
      justify-content: space-between;
    }

    .editor-stage-copy p:last-child {
      color: var(--muted);
      flex: 1 1 340px;
      margin-bottom: 0;
      max-width: 72ch;
    }

    .latex-editor {
      align-items: start;
      display: grid;
      gap: 18px;
      grid-template-columns: minmax(0, 1fr) minmax(280px, 0.9fr);
    }

    .latex-editor.spacious {
      gap: 24px;
      grid-template-columns: minmax(0, 1.25fr) minmax(360px, 1fr);
    }

    .latex-preview {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      box-shadow: 0 10px 28px rgba(15, 23, 42, 0.04);
      min-height: 100%;
      padding: 18px;
    }

    .latex-preview h2 {
      color: var(--primary);
      font-size: 0.82rem;
      margin-bottom: 12px;
      text-transform: uppercase;
    }

    .preview-status {
      color: var(--muted);
      font-size: 0.9rem;
      margin-bottom: 12px;
      min-height: 1.5em;
    }

    .preview-status.is-loading {
      color: var(--warning);
    }

    .preview-status.is-ready {
      color: var(--success);
    }

    .preview-status.has-error {
      color: var(--danger);
    }

    .preview-surface {
      background: #ffffff;
      border: 1px solid var(--border);
      border-radius: 8px;
      color: #111111;
      min-height: 160px;
      overflow-x: auto;
      overflow-wrap: anywhere;
      padding: 14px;
    }

    .preview-surface.spacious {
      min-height: 360px;
      padding: 20px;
    }

    .preview-surface.is-loading {
      border-color: #fdb022;
    }

    .preview-surface.has-error {
      border-color: #fda29b;
    }

    .preview-surface svg {
      background: #ffffff;
      display: block;
      height: auto;
      margin: 0 auto;
      max-width: none;
    }

    .guide-grid,
    .example-grid {
      display: grid;
      gap: 20px;
      grid-template-columns: repeat(3, minmax(0, 1fr));
      margin-bottom: 32px;
    }

    .plain-list {
      display: grid;
      gap: 10px;
      margin: 0;
      padding-left: 20px;
    }

    code,
    pre {
      font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
    }

    code {
      color: var(--primary-dark);
    }

    .latex-example {
      min-width: 0;
    }

    .latex-example h3 {
      color: var(--primary);
      margin: 0 0 10px;
    }

    .latex-example pre {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      margin: 0;
      overflow-x: auto;
      padding: 14px;
      white-space: pre-wrap;
    }

    .status-badge {
      background: #ecfdf3;
      border: 1px solid #abefc6;
      border-radius: 999px;
      color: #067647;
      display: inline-block;
      font-size: 0.85rem;
      font-weight: 700;
      margin-top: 10px;
      padding: 5px 9px;
      width: fit-content;
    }

    .status-badge.warning {
      background: #fffaeb;
      border-color: #fedf89;
      color: #b54708;
    }

    .status-badge.danger {
      background: var(--danger-soft);
      border-color: #fecdca;
      color: var(--danger);
    }

    .exercise-form {
      display: grid;
      gap: 16px;
    }

    .editor-form {
      gap: 24px;
    }

    .asset-panel {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      display: grid;
      gap: 16px;
      padding: 18px;
    }

    .asset-panel-copy p {
      color: var(--muted);
      margin-bottom: 0;
    }

    .asset-upload-form {
      display: grid;
      gap: 14px;
    }

    .initial-asset-layout {
      display: grid;
      gap: 16px;
      grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .initial-asset-group {
      border: 1px solid var(--border);
      border-radius: 8px;
      margin: 0;
      min-width: 0;
      padding: 16px;
    }

    .asset-pending-list {
      background: #f8fafc;
      border: 1px dashed var(--border);
      border-radius: 8px;
      padding: 10px 12px;
    }

    .asset-pending-list code {
      display: block;
      overflow-x: auto;
      white-space: nowrap;
    }

    .pending-image-list {
      display: grid;
      gap: 12px;
    }

    .pending-image-list > h3 {
      margin-bottom: 0;
    }

    .pending-image-form {
      align-items: center;
      background: #f8fafc;
      border: 1px dashed var(--border);
      border-radius: 8px;
      display: grid;
      gap: 12px;
      grid-template-columns: minmax(0, 1.2fr) minmax(220px, 1fr) auto;
      padding: 12px;
    }

    .pending-image-meta {
      color: var(--muted);
      display: grid;
      font-size: 0.9rem;
      gap: 4px;
      margin-top: 4px;
    }

    .pending-image-dropzone {
      align-items: center;
      border: 1px solid var(--border);
      border-radius: 8px;
      cursor: pointer;
      display: flex;
      justify-content: center;
      min-height: 72px;
      padding: 12px;
      text-align: center;
    }

    .pending-image-dropzone.is-dragover {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgb(37 99 235 / 12%);
    }

    .pending-image-dropzone input {
      height: 1px;
      opacity: 0;
      position: absolute;
      width: 1px;
    }

    .asset-list-grid {
      display: grid;
      gap: 16px;
      grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .asset-list code {
      display: block;
      margin-top: 6px;
      overflow-x: auto;
      white-space: nowrap;
    }

    .catalog-grid {
      display: grid;
      gap: 32px;
      grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .catalog-section {
      min-width: 0;
    }

    .dashboard-grid {
      display: grid;
      gap: 16px;
      grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    }

    .dashboard-card {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      box-shadow: 0 10px 28px rgba(15, 23, 42, 0.04);
      color: var(--muted);
      display: grid;
      gap: 8px;
      min-height: 140px;
      padding: 20px;
      text-decoration: none;
    }

    .dashboard-card:hover {
      border-color: var(--primary);
      box-shadow: var(--shadow);
      color: #334155;
    }

    .dashboard-card-title {
      color: var(--text);
      display: block;
      font-size: 1.1rem;
      font-weight: 800;
    }

    .section-tabs {
      align-items: center;
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      justify-content: end;
    }

    .section-tabs a {
      background: #ffffff;
      border: 1px solid var(--border);
      border-radius: 999px;
      color: #334155;
      font-size: 0.9rem;
      font-weight: 750;
      padding: 8px 11px;
      text-decoration: none;
      white-space: nowrap;
    }

    .section-tabs a.active {
      background: var(--primary-soft);
      border-color: var(--primary);
      color: var(--primary-dark);
    }

    .catalog-form,
    .inline-form {
      display: grid;
      gap: 10px;
    }

    .field,
    fieldset {
      display: grid;
      gap: 8px;
    }

    .field-grid {
      display: grid;
      gap: 14px;
      grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    label,
    legend,
    th {
      color: #475569;
      font-size: 0.78rem;
      font-weight: 800;
      text-align: left;
      text-transform: uppercase;
    }

    input,
    select,
    textarea {
      width: 100%;
      border: 1px solid var(--border-strong);
      border-radius: 7px;
      background: #ffffff;
      color: var(--text);
      font: inherit;
      padding: 12px;
    }

    input:focus,
    select:focus,
    textarea:focus {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.12);
      outline: none;
    }

    textarea {
      resize: vertical;
    }

    fieldset {
      border: 1px solid var(--border);
      border-radius: 8px;
      margin: 0;
      padding: 14px;
    }

    .topic-list {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
    }

    .check {
      align-items: center;
      background: #ffffff;
      border: 1px solid var(--border);
      border-radius: 999px;
      color: var(--text);
      display: inline-flex;
      gap: 8px;
      padding: 8px 10px;
      text-transform: none;
    }

    .check input {
      width: auto;
    }

    button,
    .button-link {
      border: 1px solid var(--primary);
      border-radius: 7px;
      background: var(--primary);
      color: #ffffff;
      cursor: pointer;
      display: inline-block;
      font: inherit;
      font-weight: 750;
      padding: 12px 16px;
      text-decoration: none;
    }

    .button-link.secondary,
    button.secondary {
      background: #ffffff;
      border-color: var(--border-strong);
      color: #334155;
    }

    .button-link.danger,
    button.danger {
      background: #ffffff;
      border-color: #fca5a5;
      color: #b42318;
    }

    button.compact,
    .button-link.compact {
      padding: 8px 10px;
      font-size: 0.9rem;
    }

    .table-wrap {
      overflow-x: auto;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      box-shadow: var(--shadow);
    }

    .catalog-table {
      min-width: 680px;
    }

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

    .editor-actions {
      display: flex;
      flex-wrap: wrap;
      gap: 12px;
      justify-content: space-between;
    }

    table {
      width: 100%;
      border-collapse: collapse;
      min-width: 840px;
    }

    th,
    td {
      border-bottom: 1px solid var(--border);
      padding: 12px;
      vertical-align: top;
    }

    th {
      background: #f8fafc;
    }

    td span {
      color: var(--muted);
      display: block;
      font-size: 0.9rem;
      margin-top: 6px;
      max-width: 40ch;
      overflow-wrap: anywhere;
    }

    td .status-badge {
      color: #067647;
      display: inline-block;
      font-size: 0.85rem;
      max-width: none;
    }

    td .status-badge.warning {
      color: #b54708;
    }

    td .status-badge.danger {
      color: var(--danger);
    }

    @media (max-width: 980px) {
      .app-header {
        align-items: stretch;
        grid-template-columns: 1fr;
      }

      .account-menu,
      .page-header-actions {
        justify-content: start;
      }

      .page-header,
      .intro {
        align-items: start;
        grid-template-columns: 1fr;
      }

      .layout,
      .field-grid,
      .catalog-grid,
      .dashboard-grid,
      .latex-editor,
      .guide-grid,
      .example-grid,
      .initial-asset-layout,
      .pending-image-form,
      .editor-steps {
        grid-template-columns: 1fr;
      }

      .editor-actions {
        justify-content: stretch;
      }
    }