.layout {
            display: grid;
            grid-template-columns: 260px 1fr;
            height: calc(100vh - 60px);
            overflow-y: auto;
        }

        /* Right sidebar for overflow panel */
        .right-sidebar {
            display: none;
            position: fixed;
            top: 60px;
            right: 0;
            bottom: 0;
            width: 360px;
            background: var(--surface-high);
            border-left: 1px solid var(--border-ghost);
            z-index: 40;
            flex-direction: column;
            box-shadow: -8px 0 32px rgba(0,0,0,0.4);
        }
        .right-sidebar.open { display: flex; }
        .right-sidebar-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0.85rem 1rem;
            border-bottom: 1px solid var(--border-ghost);
            background: var(--surface-low);
            flex-shrink: 0;
        }
        .right-sidebar-body {
            flex: 1;
            overflow-y: auto;
            padding: 1rem;
        }

        /* ==================== HELP SYSTEM ==================== */
        .content {
            padding: 2.5rem 3rem;
            overflow: visible;
            height: auto;
        }

        .help-header {
            display: flex;
            justify-content: space-between;
            align-items: flex-end;
            margin-bottom: 2.5rem;
            border-bottom: 1px solid var(--border-ghost);
            padding-bottom: 1.25rem;
        }

        .help-header h1 {
            font-size: 2rem;
            color: var(--text-primary);
            font-family: var(--font-headline);
            letter-spacing: -0.03em;
        }

        .help-header p {
            color: var(--text-secondary);
            font-size: 0.9rem;
            margin-top: 0.25rem;
        }

        /* Chapter Navigation (Left Index) */
        .help-layout {
            display: grid;
            grid-template-columns: 240px 1fr;
            gap: 2rem;
        }

        .chapter-index {
            position: sticky;
            top: 2rem;
            align-self: start;
            background: var(--surface-low);
            border: 1px solid var(--border-ghost);
            border-radius: var(--radius-md);
            padding: 1.25rem;
            backdrop-filter: blur(20px);
        }

        .chapter-index h3 {
            color: var(--text-primary);
            font-size: 0.85rem;
            text-transform: uppercase;
            letter-spacing: 0.06em;
            margin-bottom: 1rem;
            padding-bottom: 0.5rem;
            border-bottom: 1px solid var(--border-ghost);
        }

        .chapter-link {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            padding: 0.6rem 0.75rem;
            color: var(--text-secondary);
            font-size: 0.85rem;
            border-radius: var(--radius-sm);
            cursor: pointer;
            transition: all 0.2s;
            margin-bottom: 0.25rem;
            font-weight: 500;
        }

        .chapter-link:hover {
            background: rgba(255,255,255,0.04);
            color: var(--text-primary);
        }

        .chapter-link.active {
            background: rgba(0, 209, 255, 0.12);
            color: var(--primary);
            border-left: 2px solid var(--primary-container);
            font-weight: 600;
        }

        /* Chapter Content Area */
        .chapter-content {
            background: var(--surface-low);
            border: 1px solid var(--border-ghost);
            border-radius: var(--radius-md);
            padding: 2.5rem;
            backdrop-filter: blur(20px);
            min-height: 60vh;
        }

        .chapter-content h2 {
            color: var(--text-primary);
            font-family: var(--font-headline);
            font-size: 1.6rem;
            margin-bottom: 1.5rem;
            letter-spacing: -0.02em;
        }

        .chapter-content h3 {
            color: var(--primary);
            font-size: 1.15rem;
            margin: 2rem 0 1rem 0;
        }

        .chapter-content p, .chapter-content li {
            color: var(--text-secondary);
            font-size: 0.95rem;
            line-height: 1.75;
            margin-bottom: 0.75rem;
        }

        .chapter-content ul, .chapter-content ol {
            padding-left: 1.5rem;
            margin-bottom: 1rem;
        }

        .chapter-content code {
            background: rgba(0,209,255,0.08);
            color: var(--primary);
            padding: 0.15em 0.4em;
            border-radius: 4px;
            font-family: var(--font-mono);
            font-size: 0.88em;
        }

        .chapter-content pre {
            background: rgba(0,0,0,0.5);
            border: 1px solid var(--border-ghost);
            border-radius: var(--radius-sm);
            padding: 1.25rem;
            overflow-x: auto;
            margin: 1rem 0;
            font-family: var(--font-mono);
            font-size: 0.85rem;
            color: var(--text-primary);
            line-height: 1.6;
        }

        .chapter-content pre code {
            background: none;
            padding: 0;
            color: inherit;
        }

        .chapter-content blockquote {
            border-left: 3px solid var(--primary-container);
            padding: 0.75rem 1.25rem;
            margin: 1.25rem 0;
            background: rgba(0, 209, 255, 0.04);
            border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
            color: var(--text-secondary);
            font-style: italic;
        }

        .chapter-content table {
            width: 100%;
            border-collapse: collapse;
            margin: 1rem 0;
        }
        .chapter-content th, .chapter-content td {
            padding: 0.65rem 1rem;
            text-align: left;
            border: 1px solid var(--border-ghost);
            font-size: 0.88rem;
            color: var(--text-secondary);
        }
        .chapter-content th {
            background: rgba(0,209,255,0.06);
            color: var(--primary);
            font-weight: 600;
        }

        .chapter-content img {
            max-width: 100%;
            border-radius: var(--radius-sm);
        }

        /* Mermaid diagram style adjustments */
        .chapter-content .mermaid {
            background: rgba(0,0,0,0.3);
            border: 1px solid var(--border-ghost);
            border-radius: var(--radius-sm);
            padding: 1.5rem;
            margin: 1.25rem 0;
            text-align: center;
        }

        /* Nav Footer */
        .chapter-nav {
            display: flex;
            justify-content: space-between;
            margin-top: 2.5rem;
            padding-top: 1.25rem;
            border-top: 1px solid var(--border-ghost);
        }

        .chapter-nav button {
            padding: 0.6rem 1.5rem;
            border-radius: var(--radius-sm);
            font-size: 0.9rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            border: 1px solid var(--border-ghost);
            background: transparent;
            color: var(--text-secondary);
        }

        .chapter-nav button:hover {
            background: rgba(0,209,255,0.1);
            color: var(--primary);
            border-color: var(--primary-container);
        }

        .chapter-nav button:disabled {
            opacity: 0.3;
            cursor: not-allowed;
        }

        @media (max-width: 1024px) {
            .help-layout {
                grid-template-columns: 1fr !important;
            }
            .chapter-index {
                position: relative !important;
                top: 0 !important;
            }
            .content { padding: 1.5rem 1rem !important; }
        }
        .nav-avatar { width:36px; height:36px; border-radius:50%; background:linear-gradient(135deg,var(--cyan),var(--amber)); display:flex; align-items:center; justify-content:center; font-weight:700; font-size:0.9rem; cursor:pointer; box-shadow:0 0 16px rgba(0,245,212,0.3); }
    .nav-avatar:hover { filter: brightness(1.1); }
    .avatar-dropdown { position:absolute; top:50px; right:20px; background:var(--surface-high); border:1px solid var(--border-ghost); border-radius:10px; padding:6px; width:200px; box-shadow:0 8px 24px rgba(0,0,0,0.5); z-index:1000; opacity:0; visibility:hidden; transform:translateY(-8px); transition:all 0.2s; }
    .avatar-dropdown.show { opacity:1; visibility:visible; transform:translateY(0); }
    .avatar-dropdown::before { content:''; position:absolute; top:-6px; right:12px; width:12px; height:12px; background:var(--surface-high); border-left:1px solid var(--border-ghost); border-top:1px solid var(--border-ghost); transform:rotate(45deg); }
    .dd-item { display:flex; align-items:center; justify-content:flex-start; gap:10px; padding:9px 12px; border-radius:6px; cursor:pointer; color:var(--text-primary); font-size:0.85rem; transition:background 0.15s; }
    .dd-item:hover { background:rgba(255,255,255,0.06); }
    .dd-item.danger { color:var(--error); }
    .dd-item.danger:hover { background:rgba(255,115,115,0.1); }
    .dd-divider { height:1px; background:var(--border-ghost); margin:4px 8px; }