:root {
            --bg-deep: #060b16;
            --bg-primary: #0b1120;
            --bg-card: rgba(255, 255, 255, 0.035);
            --bg-card-hover: rgba(255, 255, 255, 0.06);
            --border-glass: rgba(255, 255, 255, 0.07);
            --text-primary: #f0f4ff;
            --text-secondary: rgba(240, 244, 255, 0.7);
            --text-muted: rgba(240, 244, 255, 0.4);
            --accent-cyan: #06b6d4;
            --accent-teal: #34d399;
            --accent-gold: #fbbf24;
            --gradient-main: linear-gradient(135deg, #06b6d4, #34d399);
            --gradient-glow: linear-gradient(135deg, rgba(6, 182, 212, 0.2), rgba(52, 211, 153, 0.15));
            --shadow-glow: 0 0 80px rgba(6, 182, 212, 0.07), 0 0 160px rgba(52, 211, 153, 0.03);
            --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', Roboto, sans-serif;
            --radius-xl: 32px;
            --radius-lg: 24px;
            --radius-md: 16px;
            --radius-sm: 10px;
            --transition-smooth: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
        }
        * { margin:0; padding:0; box-sizing:border-box; }
        html { scroll-behavior:smooth; scroll-padding-top:90px; }
        body {
            font-family: var(--font-family);
            background: var(--bg-deep);
            color: var(--text-primary);
            line-height: 1.6;
            overflow-x: hidden;
            -webkit-font-smoothing: antialiased;
        }
        ::-webkit-scrollbar { width:5px; }
        ::-webkit-scrollbar-track { background:var(--bg-deep); }
        ::-webkit-scrollbar-thumb { background:var(--accent-cyan); border-radius:10px; }

        canvas#particles {
            position:fixed; top:0; left:0; width:100%; height:100%;
            z-index:0; pointer-events:none; opacity:0.28;
        }
        .app { position:relative; z-index:1; }
        .container { max-width:1240px; margin:0 auto; padding:0 28px; }
        @media (max-width:640px) { .container { padding:0 16px; } }

        /* HEADER 统一导航 */
        header {
            position:fixed; top:0; left:0; right:0; z-index:100; padding:12px 0;
            background: rgba(6, 11, 22, 0.55); backdrop-filter:blur(24px);
            -webkit-backdrop-filter:blur(24px); border-bottom:1px solid var(--border-glass);
            transition: all var(--transition-smooth);
        }
        header.scrolled {
            background: rgba(6, 11, 22, 0.94); box-shadow:0 4px 50px rgba(0,0,0,0.55); padding:8px 0;
        }
        .header-inner { display:flex; align-items:center; justify-content:space-between; flex-wrap:wrap; gap:10px; }
        .logo {
            display:flex; align-items:center; gap:10px; text-decoration:none;
            font-weight:800; font-size:20px; color:var(--text-primary); letter-spacing:-0.3px;
        }
        .logo-icon {
            width:34px; height:34px; border-radius:var(--radius-sm);
            background:var(--gradient-main); display:flex; align-items:center; justify-content:center;
            font-size:15px; font-weight:900; color:#fff; box-shadow:0 0 36px rgba(6,182,212,0.22);
            transition:transform var(--transition-smooth);
        }
        .logo:hover .logo-icon { transform:scale(1.06) rotate(-5deg); }
        .logo span {
            background:var(--gradient-main); -webkit-background-clip:text;
            -webkit-text-fill-color:transparent; background-clip:text;
        }
        nav { display:flex; align-items:center; gap:2px; flex-wrap:wrap; }
        nav a {
            color:var(--text-secondary); text-decoration:none; font-size:13.5px; font-weight:500;
            padding:7px 14px; border-radius:var(--radius-sm); transition:all 0.2s; white-space:nowrap;
        }
        nav a:hover { color:#fff; background:rgba(255,255,255,0.05); }
        nav a.active {
            color:#fff; background:rgba(6,182,212,0.13); box-shadow:0 0 18px rgba(6,182,212,0.04);
            font-weight:600;
        }
        nav a.active::after {
            content:''; position:absolute; bottom:3px; left:50%; transform:translateX(-50%);
            width:16px; height:2px; border-radius:2px; background:var(--gradient-main);
        }
        nav a.nav-letsvpn {
            color:var(--accent-gold); font-weight:700;
            border:1px solid rgba(245,158,11,0.25); background:rgba(245,158,11,0.06);
            animation:nav-pulse 3s ease-in-out infinite;
        }
        @keyframes nav-pulse { 0%,100%{box-shadow:0 0 6px rgba(245,158,11,0.06);} 50%{box-shadow:0 0 20px rgba(245,158,11,0.16);} }
        nav a.nav-letsvpn:hover { background:rgba(245,158,11,0.14); border-color:rgba(245,158,11,0.45); color:#fde68a; }
        .header-actions { display:flex; align-items:center; gap:8px; }
        .btn-header {
            padding:7px 18px; border-radius:var(--radius-sm); background:var(--gradient-main);
            color:#fff; font-size:13px; font-weight:600; text-decoration:none;
            transition:all var(--transition-smooth); box-shadow:0 0 28px rgba(6,182,212,0.14);
        }
        .btn-header:hover { transform:translateY(-2px); box-shadow:0 0 48px rgba(6,182,212,0.28); }
        .mobile-toggle { display:none; flex-direction:column; gap:4px; background:none; border:none; cursor:pointer; padding:6px; }
        .mobile-toggle span { display:block; width:24px; height:2px; background:var(--text-primary); border-radius:2px; transition:all 0.3s; }
        .mobile-toggle.active span:nth-child(1){ transform:rotate(45deg) translate(5px,5px); }
        .mobile-toggle.active span:nth-child(2){ opacity:0; }
        .mobile-toggle.active span:nth-child(3){ transform:rotate(-45deg) translate(5px,-5px); }
        @media (max-width:920px){
            .mobile-toggle{display:flex;}
            nav{display:none;width:100%;flex-direction:column;padding:12px 0 6px;gap:1px;order:10;}
            nav.open{display:flex;}
            nav a{padding:11px 16px;font-size:14px;text-align:center;}
            nav a.active::after{display:none;}
            .header-actions .btn-header{display:none;}
            .header-actions .btn-header.mobile-show{display:inline-flex;font-size:12px;padding:6px 14px;}
        }
        @media (min-width:921px){ .header-actions .btn-header.mobile-show{display:none;} }

        /* 页面头部 */
        .page-hero { padding:140px 0 50px; text-align:center; position:relative; }
        .page-hero::after {
            content:''; position:absolute; bottom:0; left:50%; transform:translateX(-50%);
            width:60%; height:1px; background:linear-gradient(90deg, transparent, var(--accent-cyan), transparent); opacity:0.1;
        }
        .section-label {
            display:inline-block; font-size:11px; font-weight:600; text-transform:uppercase; letter-spacing:2.8px;
            color:var(--accent-cyan); background:rgba(6,182,212,0.06); padding:4px 16px;
            border-radius:50px; border:1px solid rgba(6,182,212,0.06); margin-bottom:14px;
        }
        .page-hero h1 { font-size:clamp(38px,5.5vw,58px); font-weight:800; letter-spacing:-1.5px; }
        .page-hero h1 .highlight { background:var(--gradient-main); -webkit-background-clip:text; -webkit-text-fill-color:transparent; background-clip:text; }
        .page-hero .sub { font-size:clamp(15px,1.2vw,18px); color:var(--text-secondary); max-width:620px; margin:10px auto 0; line-height:1.75; }

        /* 分类过滤 */
        .faq-categories { display:flex; gap:8px; flex-wrap:wrap; justify-content:center; padding:20px 0 30px; }
        .faq-categories .cat {
            padding:6px 20px; border-radius:50px; background:var(--bg-card); border:1px solid var(--border-glass);
            color:var(--text-secondary); font-size:13px; font-weight:500; cursor:pointer; transition:all 0.3s; text-decoration:none;
        }
        .faq-categories .cat:hover { background:rgba(255,255,255,0.04); }
        .faq-categories .cat.active { background:rgba(6,182,212,0.08); border-color:rgba(6,182,212,0.12); color:var(--accent-cyan); }

        /* FAQ列表 */
        .faq-list { padding:10px 0 80px; }
        .faq-items { max-width:820px; margin:0 auto; display:flex; flex-direction:column; gap:12px; }
        .faq-item {
            background:var(--bg-card); border:1px solid var(--border-glass); border-radius:var(--radius-md);
            transition:all 0.3s; overflow:hidden;
        }
        .faq-item:hover { border-color:rgba(6,182,212,0.08); }
        .faq-item summary {
            padding:20px 28px; cursor:pointer; font-weight:600; font-size:16px;
            display:flex; align-items:center; justify-content:space-between; list-style:none; user-select:none;
        }
        .faq-item summary::-webkit-details-marker { display:none; }
        .faq-item summary::after {
            content:'+'; font-size:26px; font-weight:300; color:var(--text-muted); transition:transform 0.35s; flex-shrink:0; margin-left:16px;
        }
        .faq-item[open] summary::after { content:'−'; }
        .faq-item .answer {
            padding:0 28px 24px; color:var(--text-secondary); font-size:15px; line-height:1.8;
            border-top:1px solid var(--border-glass);
        }
        .faq-item .answer p { margin-top:16px; }
        .faq-item .answer p:first-child { margin-top:0; }
        .tag-group { display:flex; gap:8px; flex-wrap:wrap; margin-top:12px; }
        .tag-group span {
            font-size:11px; padding:2px 12px; border-radius:50px;
            background:rgba(6,182,212,0.04); border:1px solid rgba(6,182,212,0.04); color:var(--text-muted);
        }
        .no-result { text-align:center; padding:40px 0; color:var(--text-muted); font-size:16px; display:none; }
        .no-result.visible { display:block; }

        /* 创意版块：高速稳定秘诀 */
        .quick-tips { padding:30px 0 80px; border-top:1px solid var(--border-glass); }
        .tips-grid { display:grid; grid-template-columns:repeat(3,1fr); gap:22px; margin-top:30px; }
        @media (max-width:768px){ .tips-grid{grid-template-columns:1fr; max-width:400px; margin-left:auto; margin-right:auto;} }
        .tip-card {
            padding:24px 20px; border-radius:var(--radius-lg); background:var(--bg-card);
            border:1px solid var(--border-glass); text-align:center; transition:all var(--transition-smooth);
        }
        .tip-card:hover { transform:translateY(-4px); border-color:rgba(6,182,212,0.12); box-shadow:var(--shadow-glow); }
        .tip-card .tip-icon { font-size:34px; margin-bottom:10px; }
        .tip-card h4 { font-size:16px; font-weight:600; margin-bottom:6px; }
        .tip-card p { font-size:13px; color:var(--text-secondary); line-height:1.6; }

        /* 创意版块：自助排障工具箱 */
        .self-help { padding:30px 0 70px; border-top:1px solid var(--border-glass); }
        .self-help-steps { max-width:700px; margin:0 auto; display:flex; flex-direction:column; gap:14px; margin-top:24px; }
        .self-help-step {
            padding:16px 22px; border-radius:var(--radius-md); background:var(--bg-card);
            border:1px solid var(--border-glass); display:flex; align-items:flex-start; gap:14px; transition:all 0.3s;
        }
        .self-help-step:hover { border-color:rgba(6,182,212,0.1); background:var(--bg-card-hover); }
        .self-help-step .step-num {
            width:32px; height:32px; border-radius:50%; background:var(--gradient-main);
            color:#fff; font-weight:700; font-size:14px; display:flex; align-items:center; justify-content:center; flex-shrink:0;
        }
        .self-help-step .step-content h5 { font-size:15px; font-weight:600; margin-bottom:4px; }
        .self-help-step .step-content p { font-size:13px; color:var(--text-secondary); }

        /* 信任与页脚 */
        .trust { padding:30px 0 60px; border-top:1px solid var(--border-glass); }
        .trust-wrap {
            display:flex; align-items:center; justify-content:space-between; flex-wrap:wrap; gap:24px;
            padding:26px 34px; border-radius:var(--radius-xl); background:var(--bg-card); border:1px solid var(--border-glass);
        }
        .trust-wrap:hover { border-color:rgba(6,182,212,0.07); box-shadow:var(--shadow-glow); }
        .trust-left { display:flex; align-items:center; gap:16px; }
        .trust-left .badge-icon {
            width:48px; height:48px; border-radius:var(--radius-sm); background:var(--gradient-main);
            display:flex; align-items:center; justify-content:center; font-size:19px; color:#fff;
        }
        .trust-right { display:flex; gap:9px; flex-wrap:wrap; }
        .trust-right .tag {
            padding:5px 14px; border-radius:50px; font-size:11.5px; background:rgba(255,255,255,0.025);
            border:1px solid var(--border-glass); color:var(--text-secondary);
        }
        .trust-right .tag.verified { background:rgba(6,182,212,0.04); border-color:rgba(6,182,212,0.07); color:var(--accent-cyan); }
        footer { padding:32px 0 24px; border-top:1px solid var(--border-glass); }
        .footer-inner { display:flex; justify-content:space-between; align-items:center; flex-wrap:wrap; gap:16px; font-size:12.5px; }
        .footer-inner .copy { color:var(--text-muted); }
        .footer-links { display:flex; gap:20px; flex-wrap:wrap; }
        .footer-links a { color:var(--text-muted); text-decoration:none; transition:color 0.2s; }
        .footer-links a:hover { color:var(--text-primary); }
        .scroll-top {
            position:fixed; bottom:28px; right:28px; width:44px; height:44px; border-radius:50%;
            background:var(--bg-card); border:1px solid var(--border-glass); color:var(--text-secondary);
            font-size:17px; cursor:pointer; backdrop-filter:blur(10px); opacity:0; transform:translateY(20px);
            pointer-events:none; z-index:50; display:flex; align-items:center; justify-content:center;
            transition:all var(--transition-smooth);
        }
        .scroll-top.visible { opacity:1; transform:translateY(0); pointer-events:auto; }
        .scroll-top:hover { background:rgba(6,182,212,0.07); border-color:rgba(6,182,212,0.14); color:var(--accent-cyan); }
        .sr-only { position:absolute; width:1px; height:1px; overflow:hidden; clip:rect(0,0,0,0); }