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

        :root {
            --primary: #6366F1;
            --primary-deep: #4F46E5;
            --accent: #14B8A6;
            --bg: #F9FAFB;
            --surface: #FFFFFF;
            --text: #1E293B;
            --text-secondary: #64748B;
            --text-muted: #94A3B8;
            --border: #E2E8F0;
            --border-light: #F1F5F9;
            --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
            --shadow: 0 4px 12px rgba(0,0,0,0.06), 0 1px 3px rgba(0,0,0,0.04);
            --shadow-lg: 0 12px 32px rgba(0,0,0,0.08);
            --radius-sm: 8px;
            --radius: 12px;
            --radius-lg: 16px;
            --radius-xl: 20px;
            --transition: 0.2s cubic-bezier(0.4,0,0.2,1);
            --font-mono: 'SF Mono', 'Cascadia Code', 'Consolas', monospace;
        }

        html {
            scroll-behavior: smooth;
            font-size: 16px;
            -webkit-font-smoothing: antialiased;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Noto Sans SC', sans-serif;
            background: var(--bg);
            color: var(--text);
            line-height: 1.7;
        }

        header {
            background: rgba(255,255,255,0.88);
            backdrop-filter: blur(12px);
            border-bottom: 1px solid var(--border);
            position: sticky;
            top: 0;
            z-index: 100;
            box-shadow: var(--shadow-sm);
        }
        .header-box {
            max-width: 1280px;
            margin: 0 auto;
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0 24px;
            height: 60px;
            gap: 20px;
        }
        .brand-logo {
            display: flex;
            align-items: center;
            gap: 10px;
            text-decoration: none;
            color: var(--text);
            font-weight: 700;
            font-size: 1.1rem;
            transition: var(--transition);
        }
        .brand-logo:hover { color: var(--primary); }
        .brand-logo img {
            width: 34px;
            height: 34px;
            border-radius: 8px;
            object-fit: contain;
        }
        .brand-dot {
            width: 7px;
            height: 7px;
            background: var(--accent);
            border-radius: 50%;
            margin: 0 2px;
            animation: pulse-dot 2s infinite;
            display: inline-block;
        }
        @keyframes pulse-dot {
            0%,100% { opacity:1; transform:scale(1); }
            50% { opacity:0.4; transform:scale(1.6); }
        }
        nav { display: flex; gap: 4px; flex-wrap: wrap; }
        nav a {
            text-decoration: none;
            color: var(--text-secondary);
            font-weight: 500;
            font-size: 0.9rem;
            padding: 8px 14px;
            border-radius: 8px;
            transition: var(--transition);
            white-space: nowrap;
        }
        nav a:hover { color: var(--primary); background: #EEF2FF; }
        nav a.current-tab { color: var(--primary); background: #EEF2FF; font-weight: 600; }
        .nav-accent { background: linear-gradient(135deg, #EEF2FF, #E0F2FE); color: var(--primary-deep) !important; font-weight: 600 !important; }

        main { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
        .section-inner { max-width: 1100px; margin: 0 auto; padding: 60px 0; }
        section h2 {
            font-size: 2rem;
            font-weight: 800;
            letter-spacing: -0.5px;
            text-align: center;
            margin-bottom: 12px;
        }
        .section-lead {
            text-align: center;
            color: var(--text-secondary);
            font-size: 1.05rem;
            max-width: 700px;
            margin: 0 auto 40px;
            line-height: 1.8;
        }

        .page-hero {
            padding: 48px 0 40px;
            text-align: center;
            max-width: 800px;
            margin: 0 auto;
        }
        .badge {
            display: inline-block;
            background: #EEF2FF;
            color: var(--primary-deep);
            font-weight: 600;
            font-size: 0.85rem;
            padding: 6px 16px;
            border-radius: 20px;
            margin-bottom: 16px;
            border: 1px solid #C7D2FE;
        }
        .gradient-text {
            background: linear-gradient(135deg, #6366F1, #14B8A6);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        .page-hero h1 {
            font-size: 2.6rem;
            font-weight: 900;
            letter-spacing: -1px;
            line-height: 1.25;
            margin-bottom: 16px;
        }
        .desc {
            font-size: 1.05rem;
            color: var(--text-secondary);
            line-height: 1.8;
            margin-bottom: 24px;
        }
        .quick-jump {
            display: flex;
            gap: 12px;
            justify-content: center;
            flex-wrap: wrap;
        }
        .quick-jump a {
            background: var(--surface);
            border: 1px solid var(--border);
            padding: 8px 18px;
            border-radius: 20px;
            text-decoration: none;
            color: var(--text-secondary);
            font-weight: 500;
            font-size: 0.9rem;
            transition: var(--transition);
        }
        .quick-jump a:hover {
            border-color: var(--primary);
            color: var(--primary);
            background: #EEF2FF;
        }

        /* 诊断决策树 */
        .decision-tree {
            background: var(--surface);
            border-radius: var(--radius-xl);
            padding: 32px 24px;
            box-shadow: var(--shadow);
        }
        .tree-step {
            display: flex;
            flex-wrap: wrap;
            gap: 20px;
            margin-bottom: 28px;
            position: relative;
        }
        .tree-step:not(:last-child)::after {
            content: '';
            position: absolute;
            left: 20px;
            top: 40px;
            bottom: -28px;
            width: 2px;
            background: #C7D2FE;
        }
        .tree-question {
            background: #EEF2FF;
            border-radius: 28px;
            padding: 8px 20px;
            font-weight: 600;
            color: var(--primary-deep);
            display: inline-block;
            margin-bottom: 8px;
            position: relative;
            z-index: 1;
        }
        .tree-answer {
            flex: 1;
            background: #F8FAFC;
            border-radius: var(--radius);
            padding: 16px;
            border-left: 4px solid var(--primary);
        }

        /* 错误码卡片 */
        .error-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
            gap: 18px;
            margin-top: 24px;
        }
        .error-card {
            background: var(--surface);
            border-radius: var(--radius);
            padding: 20px;
            border: 1px solid var(--border-light);
            transition: var(--transition);
            box-shadow: var(--shadow-sm);
        }
        .error-card:hover {
            box-shadow: var(--shadow-lg);
            border-color: #C7D2FE;
        }
        .error-code {
            font-family: var(--font-mono);
            font-weight: 800;
            color: #EF4444;
            font-size: 1.1rem;
            margin-bottom: 6px;
        }
        .error-desc {
            color: var(--text-secondary);
            font-size: 0.9rem;
            margin-bottom: 10px;
        }
        .error-fix {
            font-size: 0.85rem;
            color: var(--primary-deep);
            font-weight: 500;
        }

        /* 系统自检清单 */
        .checklist {
            background: var(--surface);
            border-radius: var(--radius-xl);
            padding: 32px;
            box-shadow: var(--shadow);
        }
        .checklist-item {
            display: flex;
            align-items: flex-start;
            gap: 16px;
            padding: 14px 0;
            border-bottom: 1px solid var(--border-light);
        }
        .checklist-item:last-child {
            border-bottom: none;
        }
        .check-icon {
            font-size: 1.5rem;
            width: 32px;
            text-align: center;
        }
        .check-content h4 {
            font-weight: 700;
            margin-bottom: 4px;
        }
        .check-content p {
            color: var(--text-secondary);
            font-size: 0.9rem;
        }

        /* 日志解读 */
        .log-viewer {
            background: #1E293B;
            color: #E2E8F0;
            border-radius: var(--radius-lg);
            padding: 24px;
            font-family: var(--font-mono);
            font-size: 0.8rem;
            overflow-x: auto;
            white-space: pre-wrap;
            margin-top: 24px;
        }
        .log-highlight {
            color: #F87171;
        }

        /* 常见问题手风琴 */
        .faq-accordion {
            max-width: 860px;
            margin: 24px auto 0;
        }
        .faq-item {
            background: var(--surface);
            border: 1px solid var(--border-light);
            border-radius: var(--radius);
            margin-bottom: 12px;
            box-shadow: var(--shadow-sm);
            transition: var(--transition);
        }
        .faq-item:hover {
            border-color: #C7D2FE;
        }
        .faq-item summary {
            padding: 18px 24px;
            font-weight: 600;
            font-size: 1rem;
            cursor: pointer;
            list-style: none;
            display: flex;
            justify-content: space-between;
            align-items: center;
            color: var(--text);
            transition: var(--transition);
        }
        .faq-item summary::-webkit-details-marker {
            display: none;
        }
        .faq-item summary::after {
            content: '+';
            font-size: 1.5rem;
            color: var(--primary);
            font-weight: 400;
            transition: transform 0.2s;
        }
        .faq-item[open] summary::after {
            content: '−';
            transform: rotate(180deg);
        }
        .faq-item[open] summary {
            color: var(--primary-deep);
            background: #EEF2FF;
            border-radius: var(--radius) var(--radius) 0 0;
        }
        .faq-answer {
            padding: 0 24px 20px;
            color: var(--text-secondary);
            font-size: 0.95rem;
            line-height: 1.8;
            border-top: 1px solid var(--border-light);
        }
        .faq-answer p {
            margin-bottom: 10px;
        }
        .faq-answer code {
            background: #F1F5F9;
            padding: 2px 6px;
            border-radius: 4px;
            font-family: var(--font-mono);
            font-size: 0.85rem;
        }

        footer {
            background: #1E293B;
            color: #CBD5E1;
            margin-top: 32px;
            padding: 48px 24px 32px;
        }
        .footer-wrapper {
            max-width: 1280px;
            margin: 0 auto;
        }
        .footer-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
            gap: 28px;
            margin-bottom: 32px;
        }
        .footer-section h5 {
            font-size: 0.95rem;
            font-weight: 700;
            color: #F1F5F9;
            margin-bottom: 12px;
        }
        .footer-section ul { list-style: none; }
        .footer-section ul li { margin-bottom: 6px; }
        .footer-section ul li a {
            color: #94A3B8;
            text-decoration: none;
            font-size: 0.85rem;
        }
        .footer-section ul li a:hover {
            color: #E2E8F0;
            text-decoration: underline;
        }
        .footer-legal {
            border-top: 1px solid #334155;
            padding-top: 20px;
            text-align: center;
            font-size: 0.8rem;
            color: #64748B;
            line-height: 1.8;
        }

        @media (max-width: 768px) {
            .header-box {
                flex-direction: column;
                height: auto;
                padding: 12px 16px;
            }
            .page-hero h1 { font-size: 1.9rem; }
            section h2 { font-size: 1.5rem; }
            .section-inner { padding: 36px 16px; }
        }