/* ── Docs shell ── */
    .docs-shell {
      display: flex;
      align-items: flex-start;
      max-width: var(--page-max-w);
      margin: 0 auto;
      padding: 0 var(--page-px);
      gap: 0;
    }

    /* ── Left sidebar (GitBook style) ── */
    .docs-sidebar {
      position: sticky;
      top: calc(var(--header-h) + 0px);
      width: 232px;
      min-width: 232px;
      height: calc(100vh - var(--header-h));
      overflow-y: auto;
      padding: 32px 0 60px;
      border-right: 1px solid var(--border);
      scrollbar-width: thin;
      scrollbar-color: var(--border) transparent;
    }
    .docs-sidebar::-webkit-scrollbar { width: 3px; }
    .docs-sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

    .sidebar-section-label {
      font-size: 10.5px;
      font-weight: 700;
      letter-spacing: 0.09em;
      text-transform: uppercase;
      color: var(--text-dim);
      padding: 0 20px;
      margin: 24px 0 6px;
    }
    .sidebar-section-label:first-child { margin-top: 0; }

    .sidebar-link {
      display: flex;
      align-items: center;
      gap: 7px;
      padding: 6px 20px;
      font-size: 13px;
      font-weight: 500;
      color: var(--text-muted);
      border-radius: 0;
      transition: color var(--t-fast), background var(--t-fast);
      cursor: pointer;
      position: relative;
    }
    .sidebar-link:hover {
      color: var(--brand);
      background: var(--accent-dim);
    }
    .sidebar-link--active {
      color: var(--brand);
      font-weight: 600;
      background: var(--accent-dim);
    }
    .sidebar-link--active::before {
      content: '';
      position: absolute;
      left: 0;
      top: 4px; bottom: 4px;
      width: 2.5px;
      background: var(--brand);
      border-radius: 0 2px 2px 0;
    }
    .sidebar-link svg {
      flex-shrink: 0;
      color: var(--text-dim);
    }
    .sidebar-link--active svg { color: var(--brand); }

    /* Sub-links (indented) */
    .sidebar-sublink {
      display: flex;
      align-items: center;
      gap: 7px;
      padding: 5px 20px 5px 36px;
      font-size: 12.5px;
      font-weight: 500;
      color: var(--text-muted);
      transition: color var(--t-fast), background var(--t-fast);
      cursor: pointer;
    }
    .sidebar-sublink:hover {
      color: var(--brand);
      background: var(--accent-dim);
    }
    .sidebar-sublink--active {
      color: var(--brand);
      font-weight: 600;
    }

    /* ── Main content ── */
    .docs-content {
      flex: 1;
      min-width: 0;
      padding: 40px 44px 100px 44px;
      max-width: 740px;
    }

    /* Breadcrumbs */
    .docs-breadcrumb {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 12px;
      color: var(--text-dim);
      margin-bottom: 28px;
    }
    .docs-breadcrumb a {
      color: var(--text-muted);
      transition: color var(--t-fast);
    }
    .docs-breadcrumb a:hover { color: var(--brand); }
    .docs-breadcrumb__sep { color: var(--text-dim); }

    /* Page heading */
    .docs-page-title {
      font-size: 26px;
      font-weight: 800;
      color: var(--text);
      letter-spacing: -0.5px;
      line-height: 1.25;
      margin-bottom: 10px;
    }
    .docs-page-subtitle {
      font-size: 14.5px;
      color: var(--text-muted);
      line-height: 1.65;
      margin-bottom: 36px;
      padding-bottom: 28px;
      border-bottom: 1px solid var(--border);
    }

    /* Section headings */
    .docs-h2 {
      font-size: 18px;
      font-weight: 700;
      color: var(--text);
      letter-spacing: -0.3px;
      margin: 40px 0 12px;
      scroll-margin-top: calc(var(--header-h) + 20px);
    }
    .docs-h3 {
      font-size: 14px;
      font-weight: 700;
      color: var(--text);
      margin: 24px 0 8px;
      scroll-margin-top: calc(var(--header-h) + 20px);
    }

    /* Body prose */
    .docs-p {
      font-size: 14.5px;
      color: var(--text-muted);
      line-height: 1.8;
      margin-bottom: 16px;
    }
    .docs-p code {
      font-family: 'JetBrains Mono', 'Fira Code', monospace;
      font-size: 12.5px;
      background: var(--surface-active);
      border: 1px solid var(--border);
      padding: 1px 5px;
      border-radius: 4px;
      color: var(--brand);
    }

    /* Formula / code block */
    .formula-block {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--card-radius);
      padding: 16px 20px;
      margin: 20px 0;
      font-family: 'JetBrains Mono', 'Fira Code', monospace;
      font-size: 13px;
      line-height: 2;
      color: var(--text);
    }
    .formula-block .formula-comment { color: var(--text-dim); }
    .formula-block .formula-var     { color: #4878c0; }
    .formula-block .formula-fn      { color: var(--brand); font-weight: 600; }
    .formula-block .formula-num     { color: #b88414; }

    /* Divider */
    .docs-divider {
      border: none;
      border-top: 1px solid var(--border);
      margin: 40px 0;
    }

    /* Page nav (prev / next) */
    .docs-page-nav {
      display: flex;
      justify-content: space-between;
      gap: 14px;
      margin-top: 52px;
      padding-top: 24px;
      border-top: 1px solid var(--border);
    }
    .docs-page-nav__btn {
      flex: 1;
      display: flex;
      flex-direction: column;
      gap: 3px;
      padding: 14px 16px;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--card-radius);
      cursor: pointer;
      transition: border-color var(--t-fast), background var(--t-fast);
      text-decoration: none;
    }
    .docs-page-nav__btn:hover {
      border-color: var(--border-strong);
      background: var(--surface-hover);
    }
    .docs-page-nav__btn--next { text-align: right; }
    .docs-page-nav__direction {
      font-size: 11px;
      font-weight: 600;
      color: var(--text-dim);
      text-transform: uppercase;
      letter-spacing: 0.06em;
    }
    .docs-page-nav__label {
      font-size: 13.5px;
      font-weight: 700;
      color: var(--brand);
    }

    /* ── Right ToC ── */
    .docs-toc {
      position: sticky;
      top: calc(var(--header-h) + 32px);
      width: 196px;
      min-width: 196px;
      padding: 0 0 60px 28px;
      height: fit-content;
      max-height: calc(100vh - var(--header-h) - 40px);
      overflow-y: auto;
    }
    .toc-label {
      font-size: 10.5px;
      font-weight: 700;
      letter-spacing: 0.09em;
      text-transform: uppercase;
      color: var(--text-dim);
      margin-bottom: 10px;
    }
    .toc-link {
      display: block;
      padding: 4px 0;
      font-size: 12.5px;
      color: var(--text-muted);
      transition: color var(--t-fast);
      line-height: 1.4;
    }
    .toc-link:hover { color: var(--brand); }
    .toc-link--active { color: var(--brand); font-weight: 600; }
    .toc-sublink {
      display: block;
      padding: 3px 0 3px 12px;
      font-size: 12px;
      color: var(--text-dim);
      border-left: 1px solid var(--border);
      margin-left: 2px;
      transition: color var(--t-fast), border-color var(--t-fast);
    }
    .toc-sublink:hover { color: var(--brand); border-color: var(--brand); }
    .toc-sublink--active { color: var(--brand); border-color: var(--brand); font-weight: 600; }

    /* ── Responsive ── */
    @media (max-width: 1200px) {
      .docs-toc { display: none; }
      .docs-content { max-width: none; }
    }
    @media (max-width: 900px) {
      .docs-sidebar { display: none; }
      .docs-content { padding: 28px 20px 80px; }
    }
    @media (max-width: 520px) {
      .docs-content { padding: 20px 14px 60px; }
      .docs-page-title { font-size: 22px; }
      .docs-h2 { font-size: 17px; }
      .formula-block { font-size: 12px; padding: 12px 14px; }
    }