* { margin: 0; padding: 0; box-sizing: border-box; }
        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            background: #f6f8fa;
            color: #1e293b;
            line-height: 1.7;
            font-size: 16px;
            -webkit-font-smoothing: antialiased;
        }
        a { text-decoration: none; color: #2563eb; }
        a:hover { color: #1d4ed8; text-decoration: underline; }

        .page {
            display: flex;
            max-width: 1400px;
            margin: 0 auto;
            background: #ffffff;
            min-height: 100vh;
            box-shadow: 0 0 40px rgba(0,0,0,0.03);
        }

        .toc {
            width: 280px;
            min-width: 280px;
            background: #fafcff;
            padding: 2.5rem 1.5rem 3rem 2rem;
            border-right: 1px solid #e9edf2;
            position: sticky;
            top: 0;
            height: 100vh;
            overflow-y: auto;
            flex-shrink: 0;
        }
        .toc h2 {
            font-size: 0.9rem;
            text-transform: uppercase;
            letter-spacing: 0.06em;
            color: #64748b;
            font-weight: 600;
            padding-bottom: 0.75rem;
            border-bottom: 1.5px solid #e2e8f0;
            margin-bottom: 1.5rem;
        }
        .toc-list {
            list-style: none;
            padding: 0;
            margin: 0;
        }
        .toc-list li {
            margin-bottom: 0.15rem;
        }
        .toc-list a {
            display: block;
            padding: 0.3rem 0.5rem 0.3rem 0.8rem;
            font-size: 0.85rem;
            color: #334155;
            border-left: 3px solid transparent;
            border-radius: 0 4px 4px 0;
            transition: all 0.12s;
            font-weight: 450;
        }
        .toc-list a:hover {
            background: #f1f5f9;
            border-left-color: #2563eb;
            text-decoration: none;
        }
        .toc-list a.active {
            background: #eef2ff;
            border-left-color: #2563eb;
            font-weight: 500;
        }
        .toc-sub {
            padding-left: 1.2rem;
        }
        .toc-sub a {
            font-size: 0.78rem;
            font-weight: 400;
            color: #475569;
            padding: 0.2rem 0.5rem 0.2rem 0.8rem;
        }
        .toc-sub a:hover {
            color: #2563eb;
            background: #f1f5f9;
        }

        .toc::-webkit-scrollbar { width: 4px; }
        .toc::-webkit-scrollbar-track { background: #f1f5f9; }
        .toc::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 8px; }

        .content {
            flex: 1;
            padding: 2.5rem 3.5rem 4rem 3.5rem;
            max-width: 900px;
        }
        .content h1 {
            font-size: 2.4rem;
            font-weight: 700;
            color: #0f172a;
            letter-spacing: -0.02em;
            margin-bottom: 0.2rem;
        }
        .content .meta {
            font-size: 0.9rem;
            color: #64748b;
            margin-bottom: 2rem;
            padding-bottom: 1rem;
            border-bottom: 1px solid #e9edf2;
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            align-items: center;
        }
        .content .meta .badge {
            background: #eef2f6;
            padding: 0.15rem 1rem;
            border-radius: 20px;
            font-size: 0.75rem;
            color: #334155;
        }
        .content h2 {
            font-size: 1.7rem;
            font-weight: 600;
            color: #0f172a;
            margin-top: 2.8rem;
            margin-bottom: 0.8rem;
            padding-top: 0.2rem;
            border-bottom: 1px solid #e9edf2;
            padding-bottom: 0.4rem;
        }
        .content h3 {
            font-size: 1.2rem;
            font-weight: 600;
            color: #1e293b;
            margin-top: 1.8rem;
            margin-bottom: 0.4rem;
        }
        .content p {
            margin-bottom: 0.9rem;
            color: #1e293b;
        }
        .content ul, .content ol {
            margin: 0.5rem 0 1.2rem 1.8rem;
        }
        .content ul li, .content ol li {
            margin-bottom: 0.3rem;
        }
        .content .highlight {
            background: #f8fafc;
            border-left: 4px solid #2563eb;
            padding: 1rem 1.5rem;
            margin: 1.2rem 0;
            border-radius: 0 6px 6px 0;
            font-size: 0.95rem;
        }
        .content hr {
            border: 0;
            border-top: 1px solid #e9edf2;
            margin: 2.5rem 0;
        }

        @media (max-width: 992px) {
            .page { flex-direction: column; }
            .toc {
                width: 100%;
                min-width: auto;
                height: auto;
                max-height: 260px;
                position: relative;
                border-right: none;
                border-bottom: 1px solid #e9edf2;
                padding: 1.2rem 1.5rem;
                overflow-y: auto;
            }
            .content {
                padding: 1.8rem 1.5rem 3rem;
            }
            .content h1 { font-size: 2rem; }
            .toc-sub { padding-left: 1rem; }
        }
        @media (max-width: 480px) {
            .content { padding: 1.2rem 1rem 2rem; }
            .content h1 { font-size: 1.6rem; }
            .content h2 { font-size: 1.3rem; }
            .toc { padding: 0.8rem 1rem; max-height: 200px; }
        }
        @media print {
            .toc { display: none; }
            .page { display: block; }
            .content { padding: 1.5rem; }
        }