:root {
            --bg-deep: #05050A;
            --bg-card: rgba(15, 23, 42, 0.55);
            --border-subtle: rgba(255, 255, 255, 0.06);
            --border-glow: rgba(59, 130, 246, 0.25);
            --blue-400: #60A5FA;
            --blue-500: #3B82F6;
            --blue-600: #2563EB;
            --text-primary: #EDEDF0;
            --text-secondary: #9CA3AF;
            --text-muted: #6B7280;
            --amber: #FBBF24;
            --emerald: #10B981;
            --red-400: #F87171;
            --radius-xl: 32px;
            --transition-fast: 0.2s;
            --transition-smooth: 0.25s;
        }
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        body {
            font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background: var(--bg-deep);
            color: var(--text-primary);
            overflow-x: hidden;
            line-height: 1.6;
            -webkit-font-smoothing: antialiased;
        }
        .glow-bg {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            pointer-events: none;
            z-index: 0;
            background: radial-gradient(circle at 20% 30%, rgba(37,99,235,0.07) 0%, rgba(5,5,10,0) 60%),
                        radial-gradient(circle at 75% 60%, rgba(6,182,212,0.04) 0%, rgba(5,5,10,0) 50%);
        }
        .container {
            max-width: 1280px;
            margin: 0 auto;
            padding: 0 32px;
            position: relative;
            z-index: 2;
        }

        /* 导航 */
        header {
            background: rgba(5, 5, 10, 0.85);
            backdrop-filter: blur(16px);
            -webkit-backdrop-filter: blur(16px);
            border-bottom: 1px solid var(--border-subtle);
            position: sticky;
            top: 0;
            z-index: 100;
        }
        nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 18px 0;
            flex-wrap: wrap;
        }
        .logo {
            font-size: 1.6rem;
            font-weight: 700;
            letter-spacing: -0.02em;
            background: linear-gradient(125deg, #FFFFFF, #3B82F6);
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
            text-decoration: none;
            white-space: nowrap;
        }
        .logo .icon-rocket {
            display: inline-block;
            margin-right: 2px;
        }
        .nav-links {
            display: flex;
            gap: 32px;
            align-items: center;
            flex-wrap: wrap;
        }
        .nav-links a {
            text-decoration: none;
            font-weight: 500;
            color: #A1A1AA;
            transition: var(--transition-fast);
            font-size: 0.9rem;
            white-space: nowrap;
        }
        .nav-links a:hover,
        .nav-links a.active {
            color: var(--blue-500);
        }

        /* 标题区 */
        .page-hero {
            padding: 70px 0 40px;
            text-align: center;
        }
        .page-hero h1 {
            font-size: 2.8rem;
            font-weight: 800;
            letter-spacing: -0.02em;
            margin-bottom: 16px;
            background: linear-gradient(135deg, #FFFFFF, #60A5FA);
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
        }
        .page-hero .sub {
            font-size: 1.1rem;
            color: var(--text-secondary);
            max-width: 720px;
            margin: 0 auto;
        }
        .highlight {
            background: linear-gradient(135deg, #60A5FA, #3B82F6);
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
        }

        /* 问题分类大按钮 */
        .categories-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
            gap: 16px;
            margin: 40px 0;
        }
        .cat-btn {
            background: rgba(15, 23, 42, 0.5);
            border: 1px solid rgba(255, 255, 255, 0.05);
            border-radius: 24px;
            padding: 24px 12px;
            text-align: center;
            text-decoration: none;
            color: var(--text-primary);
            transition: var(--transition-smooth);
            display: block;
            font-size: 0.9rem;
            font-weight: 600;
        }
        .cat-btn:hover {
            border-color: var(--blue-500);
            background: rgba(30, 41, 59, 0.6);
            transform: translateY(-2px);
        }
        .cat-btn .cat-emoji {
            font-size: 2rem;
            display: block;
            margin-bottom: 8px;
        }

        /* 故障自检向导 */
        .wizard {
            background: rgba(15, 23, 42, 0.4);
            border-radius: 40px;
            padding: 36px 28px;
            margin: 50px 0;
            border: 1px solid rgba(255, 255, 255, 0.06);
        }
        .wizard h2 {
            text-align: center;
            margin-bottom: 30px;
        }
        .wizard-steps {
            display: flex;
            flex-wrap: wrap;
            gap: 20px;
            justify-content: center;
        }
        .step-col {
            flex: 1 1 220px;
            background: rgba(15, 23, 42, 0.5);
            border-radius: 28px;
            padding: 28px 20px;
            border: 1px solid rgba(255, 255, 255, 0.05);
            text-align: center;
        }
        .step-num {
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background: linear-gradient(135deg, #3B82F6, #2563EB);
            display: inline-flex;
            align-items: center;
            justify-content: center;
            font-weight: 700;
            margin-bottom: 12px;
        }
        select, .fake-select {
            background: #1E293B;
            border: 1px solid rgba(255,255,255,0.1);
            color: #EDEDF0;
            padding: 10px 16px;
            border-radius: 20px;
            width: 100%;
            margin: 10px 0;
            font-size: 0.9rem;
        }
        .solution-box {
            background: rgba(0,0,0,0.3);
            border-radius: 16px;
            padding: 14px;
            margin-top: 14px;
            font-size: 0.8rem;
            color: var(--text-secondary);
        }

        /* FAQ 折叠面板 */
        .faq-section {
            margin: 50px 0;
        }
        .faq-group {
    margin-bottom: 40px;
    max-width: 860px;
    margin-left: 360px;
    margin-right: auto;
        }
        .faq-group h3 {
            font-size: 1.5rem;
            margin-bottom: 20px;
            color: #E2E8F0;
        }
        details.faq-item {
            background: rgba(15, 23, 42, 0.5);
            border: 1px solid rgba(255,255,255,0.05);
            border-radius: 20px;
            padding: 20px 24px;
            margin-bottom: 12px;
            transition: var(--transition-smooth);
        }
        details.faq-item[open] {
            border-color: var(--blue-500);
            background: rgba(30,41,59,0.6);
        }
        details.faq-item summary {
            font-weight: 700;
            font-size: 1rem;
            list-style: none;
            display: flex;
            justify-content: space-between;
            align-items: center;
            cursor: pointer;
            color: #E2E8F0;
        }
        details.faq-item summary::after {
            content: "➕";
            font-size: 0.8rem;
            color: var(--blue-400);
            margin-left: 12px;
        }
        details.faq-item[open] summary::after {
            content: "➖";
        }
        details.faq-item .faq-answer {
            margin-top: 14px;
            font-size: 0.92rem;
            color: #B0B7C3;
            line-height: 1.7;
            border-top: 1px solid rgba(255,255,255,0.05);
            padding-top: 14px;
        }

        /* 真实案例库 */
        .cases-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 24px;
            margin: 40px 0;
        }
        .case-card {
            background: rgba(15, 23, 42, 0.5);
            border-radius: 28px;
            padding: 30px 24px;
            border: 1px solid rgba(255,255,255,0.05);
            transition: var(--transition-smooth);
        }
        .case-card:hover {
            border-color: var(--blue-500);
            background: rgba(30,41,59,0.55);
        }
        .case-card h4 {
            font-size: 1.2rem;
            margin-bottom: 10px;
        }
        .case-card .analysis {
            font-size: 0.85rem;
            color: var(--text-secondary);
            margin: 12px 0;
        }
        .case-card .solution {
            background: rgba(59,130,246,0.1);
            border-left: 3px solid var(--blue-500);
            padding: 10px 14px;
            border-radius: 12px;
            font-size: 0.85rem;
            color: #CBD5E1;
        }

        /* 修复工具推荐 (下载入口) */
        .toolbox {
            background: linear-gradient(115deg, #0F172A, #1E293B);
            border-radius: 48px;
            padding: 40px 28px;
            margin: 50px 0;
            border: 1px solid rgba(59,130,246,0.3);
            text-align: center;
        }
        .toolbox h3 {
            font-size: 1.8rem;
            margin-bottom: 12px;
        }
        .toolbox p {
            color: var(--text-secondary);
            margin-bottom: 28px;
        }
        .tool-row {
            display: flex;
            flex-wrap: wrap;
            gap: 16px;
            justify-content: center;
        }
        .tool-item {
            background: rgba(15, 23, 42, 0.6);
            border-radius: 24px;
            padding: 20px 16px;
            flex: 1 1 140px;
            border: 1px solid rgba(255,255,255,0.06);
            transition: var(--transition-smooth);
            text-decoration: none;
            color: var(--text-primary);
        }
        .tool-item:hover {
            border-color: var(--blue-500);
            transform: translateY(-3px);
        }
        .tool-item .tool-icon {
            font-size: 2rem;
            margin-bottom: 8px;
        }
        .tool-item h5 {
            font-size: 0.9rem;
            margin-bottom: 4px;
        }
        .tool-item span {
            font-size: 0.75rem;
            color: var(--text-muted);
        }

        /* 页脚 */
        footer {
            background: #020308;
            padding: 50px 0 28px;
            border-top: 1px solid rgba(255, 255, 255, 0.03);
            font-size: 0.85rem;
            color: #6B7280;
        }
        .footer-grid {
            display: flex;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 36px;
            margin-bottom: 40px;
        }
        .footer-col h4 {
            color: #CBD5E1;
            margin-bottom: 12px;
            font-size: 0.9rem;
            font-weight: 600;
        }
        .footer-col a {
            display: block;
            color: #6B7280;
            text-decoration: none;
            margin-bottom: 6px;
            transition: var(--transition-fast);
            font-size: 0.82rem;
        }
        .footer-col a:hover {
            color: var(--blue-400);
        }
        .footer-bottom {
            text-align: center;
            border-top: 1px solid rgba(255, 255, 255, 0.04);
            padding-top: 20px;
            font-size: 0.78rem;
            color: #4B5563;
        }

        @media (max-width: 900px) {
            .page-hero h1 {
                font-size: 2.2rem;
            }
            .nav-links {
                gap: 20px;
                margin-top: 10px;
                width: 100%;
                justify-content: center;
            }
            nav {
                flex-direction: column;
            }
        }
        @media (max-width: 500px) {
            .container {
                padding: 0 16px;
            }
            .page-hero h1 {
                font-size: 1.8rem;
            }
            .categories-grid {
                grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
            }
        }