*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
:root{
    --blue:#1a73e8;--blue-dark:#1557b0;--blue-light:#e8f0fe;
    --green:#1e8e3e;--green-bg:#e6f4ea;
    --red:#d93025;--yellow:#f9ab00;
    --text:#202124;--text-2:#5f6368;--text-3:#80868b;
    --bg:#fff;--bg-2:#f8f9fa;--bg-3:#f1f3f4;
    --border:#dadce0;--border-2:#e8eaed;
    --radius:8px;--radius-lg:12px;--radius-xl:16px;
    --shadow-sm:0 1px 2px rgba(60,64,67,.3),0 1px 3px 1px rgba(60,64,67,.15);
    --shadow-md:0 1px 3px rgba(60,64,67,.3),0 4px 8px 3px rgba(60,64,67,.15);
    --shadow-lg:0 1px 3px rgba(60,64,67,.3),0 8px 16px 4px rgba(60,64,67,.15);
    --max-w:1140px;
    --transition:0.2s cubic-bezier(.4,0,.2,1);
}
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes fadeUp{from{opacity:0;transform:translateY(16px)}to{opacity:1;transform:none}}
body{font-family:"Google Sans",Roboto,-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif;line-height:1.6;color:var(--text);background:var(--bg);-webkit-font-smoothing:antialiased}
a{color:var(--blue);text-decoration:none}
img{max-width:100%;display:block}
.wrap{max-width:var(--max-w);margin:0 auto;padding:0 24px}

/* ===== NAV ===== */
.nav{position:sticky;top:0;z-index:100;background:var(--bg);border-bottom:1px solid var(--border-2)}
.nav-inner{display:flex;align-items:center;height:56px;max-width:var(--max-w);margin:0 auto;padding:0 24px}
.nav-brand{display:flex;align-items:center;gap:8px;font-size:18px;font-weight:500;color:var(--text);text-decoration:none;margin-right:auto}
.nav-brand svg{flex-shrink:0}
.nav-menu{display:flex;gap:4px;list-style:none}
.nav-menu a{display:flex;align-items:center;height:36px;padding:0 16px;font-size:14px;font-weight:500;color:var(--text-2);border-radius:18px;transition:background var(--transition),color var(--transition)}
.nav-menu a:hover{background:var(--bg-2);color:var(--text)}
.nav-menu a.active{background:var(--blue-light);color:var(--blue)}

/* ===== HERO (index) ===== */
.hero{padding:72px 0 80px;background:var(--bg);text-align:center}
.hero h1{font-size:52px;font-weight:400;letter-spacing:-.5px;line-height:1.15;color:var(--text);margin-bottom:16px}
.hero h1 strong{font-weight:600}
.hero-sub{font-size:18px;color:var(--text-2);max-width:600px;margin:0 auto 36px}
.hero-actions{display:flex;justify-content:center;gap:12px;flex-wrap:wrap;margin-bottom:48px}
.btn{display:inline-flex;align-items:center;gap:8px;height:48px;padding:0 28px;font-size:14px;font-weight:500;border:none;border-radius:24px;cursor:pointer;transition:background var(--transition),box-shadow var(--transition),transform var(--transition)}
.btn:disabled{opacity:.6;cursor:default;transform:none!important}
.btn-primary{background:var(--blue);color:#fff}
.btn-primary:hover:not(:disabled){background:var(--blue-dark);box-shadow:var(--shadow-sm)}
.btn-outline{background:transparent;color:var(--blue);border:1px solid var(--border)}
.btn-outline:hover{background:var(--blue-light);border-color:var(--blue-light)}
.hero-stats{display:flex;justify-content:center;gap:56px}
.hero-stat{text-align:center}
.hero-stat-num{font-size:36px;font-weight:600;color:var(--text)}
.hero-stat-label{font-size:13px;color:var(--text-3);margin-top:4px}

/* ===== SECTIONS ===== */
.section{padding:72px 0}
.section--alt{background:var(--bg-2)}
.section-head{text-align:center;margin-bottom:48px}
.section-head h2{font-size:32px;font-weight:400;color:var(--text);letter-spacing:-.3px}
.section-head p{font-size:16px;color:var(--text-2);margin-top:12px;max-width:560px;margin-left:auto;margin-right:auto}

/* ===== FEATURE CARDS (index) ===== */
.features{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.feat{padding:32px 28px;border-radius:var(--radius-lg);border:1px solid var(--border-2);background:var(--bg);transition:box-shadow var(--transition),border-color var(--transition)}
.feat:hover{box-shadow:var(--shadow-sm);border-color:var(--border)}
.feat-icon{width:40px;height:40px;margin-bottom:16px;color:var(--blue)}
.feat h3{font-size:16px;font-weight:600;color:var(--text);margin-bottom:8px}
.feat p{font-size:14px;color:var(--text-2);line-height:1.7}

/* ===== PLATFORMS (index) ===== */
.platforms{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.plat{border:1px solid var(--border-2);border-radius:var(--radius-lg);padding:28px 24px;text-align:center;background:var(--bg);transition:box-shadow var(--transition),border-color var(--transition)}
.plat:hover{box-shadow:var(--shadow-sm);border-color:var(--border)}
.plat.plat--win{border-color:var(--blue);background:var(--blue-light)}
.plat-icon{margin:0 auto 12px;color:var(--text-2);width:36px;height:36px}
.plat--win .plat-icon{color:var(--blue)}
.plat h3{font-size:15px;font-weight:600;margin-bottom:4px;color:var(--text)}
.plat span{font-size:13px;color:var(--text-3);display:block;margin-bottom:16px}
.plat .btn{width:100%;justify-content:center;height:40px;font-size:13px;border-radius:20px}

/* ===== REVIEWS ===== */
.reviews{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.rev{padding:24px;border:1px solid var(--border-2);border-radius:var(--radius-lg);background:var(--bg)}
.rev-stars{color:var(--yellow);font-size:14px;letter-spacing:2px;margin-bottom:12px}
.rev p{font-size:14px;color:var(--text-2);line-height:1.7;margin-bottom:16px}
.rev-author{display:flex;align-items:center;gap:10px}
.rev-avatar{width:32px;height:32px;border-radius:50%;background:var(--blue);color:#fff;display:flex;align-items:center;justify-content:center;font-size:13px;font-weight:600}
.rev-name{font-size:13px;font-weight:600;color:var(--text)}
.rev-role{font-size:12px;color:var(--text-3)}

/* ===== FAQ ===== */
.faq-list{max-width:720px;margin:0 auto}
.faq-item{border-bottom:1px solid var(--border-2)}
.faq-q{display:flex;justify-content:space-between;align-items:center;padding:18px 0;cursor:pointer;gap:16px}
.faq-q h3{font-size:15px;font-weight:500;color:var(--text)}
.faq-q svg{flex-shrink:0;transition:transform var(--transition);color:var(--text-3)}
.faq-item.open .faq-q svg{transform:rotate(180deg)}
.faq-a{max-height:0;overflow:hidden;transition:max-height .3s ease}
.faq-item.open .faq-a{max-height:400px}
.faq-a p{padding-bottom:18px;font-size:14px;color:var(--text-2);line-height:1.75}

/* ===== FOOTER ===== */
.footer{background:var(--bg-2);border-top:1px solid var(--border-2);padding:32px 0;text-align:center}
.footer p{font-size:13px;color:var(--text-3);margin-bottom:6px}
.footer p:last-child{margin-bottom:0}

/* ===== DOWNLOAD PAGE ===== */
.dl-hero{padding:56px 0 48px;background:var(--bg);text-align:center}
.dl-hero h1{font-size:40px;font-weight:400;color:var(--text);margin-bottom:12px}
.dl-hero p{font-size:16px;color:var(--text-2)}

.dl-layout{display:grid;grid-template-columns:1fr 340px;gap:32px;padding:0 0 72px}
.dl-main{border:1px solid var(--border-2);border-radius:var(--radius-xl);padding:36px;background:var(--bg)}
.dl-badge{display:inline-flex;align-items:center;gap:6px;padding:4px 14px;background:var(--blue-light);color:var(--blue);border-radius:16px;font-size:13px;font-weight:500;margin-bottom:20px}
.dl-main h2{font-size:26px;font-weight:500;color:var(--text);margin-bottom:8px}
.dl-main>p{font-size:14px;color:var(--text-2);margin-bottom:24px}
.dl-info{display:grid;grid-template-columns:repeat(4,1fr);gap:1px;background:var(--border-2);border-radius:var(--radius);overflow:hidden;margin-bottom:24px}
.dl-info-item{background:var(--bg-2);padding:16px;text-align:center}
.dl-info-label{font-size:12px;color:var(--text-3);margin-bottom:4px}
.dl-info-val{font-size:15px;font-weight:600;color:var(--text)}
.dl-main .btn{width:100%;justify-content:center;height:52px;font-size:16px;border-radius:26px;margin-bottom:24px}
.dl-checks{display:flex;flex-direction:column;gap:10px}
.dl-check{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--text-2)}
.dl-check svg{flex-shrink:0;color:var(--green)}

.dl-side{display:flex;flex-direction:column;gap:16px}
.dl-side-card{border:1px solid var(--border-2);border-radius:var(--radius-lg);padding:20px;background:var(--bg);display:flex;align-items:center;gap:16px;transition:border-color var(--transition),box-shadow var(--transition)}
.dl-side-card:hover{border-color:var(--border);box-shadow:var(--shadow-sm)}
.dl-side-icon{flex-shrink:0;width:40px;height:40px;color:var(--text-2)}
.dl-side-text{flex:1}
.dl-side-text h3{font-size:15px;font-weight:600;color:var(--text);margin-bottom:2px}
.dl-side-text p{font-size:13px;color:var(--text-3)}
.dl-side-card .btn{height:36px;padding:0 18px;font-size:13px;border-radius:18px;flex-shrink:0}

/* requirements tabs */
.req-tabs{max-width:720px;margin:0 auto}
.req-tab-btns{display:flex;gap:0;border-bottom:2px solid var(--border-2);margin-bottom:24px}
.req-tab-btn{padding:12px 20px;font-size:14px;font-weight:500;color:var(--text-3);background:none;border:none;cursor:pointer;border-bottom:2px solid transparent;margin-bottom:-2px;transition:color var(--transition),border-color var(--transition)}
.req-tab-btn:hover{color:var(--text-2)}
.req-tab-btn.active{color:var(--blue);border-bottom-color:var(--blue)}
.req-panel{display:none}
.req-panel.active{display:block}
.req-table{width:100%;border-collapse:collapse}
.req-table td{padding:12px 0;font-size:14px;color:var(--text-2);border-bottom:1px solid var(--border-2);vertical-align:top}
.req-table td:first-child{font-weight:500;color:var(--text);width:140px;padding-right:20px}

/* steps */
.steps{display:grid;grid-template-columns:repeat(5,1fr);gap:16px;counter-reset:step}
.step{border:1px solid var(--border-2);border-radius:var(--radius-lg);padding:24px 20px;background:var(--bg);counter-increment:step;position:relative}
.step::before{content:counter(step);display:flex;align-items:center;justify-content:center;width:32px;height:32px;border-radius:50%;background:var(--blue);color:#fff;font-size:14px;font-weight:600;margin-bottom:12px}
.step h3{font-size:14px;font-weight:600;color:var(--text);margin-bottom:6px}
.step p{font-size:13px;color:var(--text-2);line-height:1.6}

/* download faq cards */
.dl-faq-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
.dl-faq-card{border:1px solid var(--border-2);border-radius:var(--radius-lg);padding:24px;background:var(--bg)}
.dl-faq-card h3{font-size:15px;font-weight:600;color:var(--text);margin-bottom:8px}
.dl-faq-card p{font-size:14px;color:var(--text-2);line-height:1.7}

/* security strip */
.safe-strip{padding:48px 0;background:var(--green-bg)}
.safe-strip-inner{display:flex;align-items:center;gap:20px;max-width:720px;margin:0 auto}
.safe-strip-inner svg{flex-shrink:0;color:var(--green)}
.safe-strip-inner h3{font-size:18px;font-weight:500;color:var(--text);margin-bottom:4px}
.safe-strip-inner p{font-size:14px;color:var(--text-2)}

/* ===== ARTICLE PAGE (zh-cn) ===== */
.art{padding:0 0 48px}
.art-layout{display:grid;grid-template-columns:220px 1fr;gap:48px;padding:48px 0}
.art-aside{position:relative}
.toc-sticky{position:sticky;top:72px}
.toc-sticky h3{font-size:12px;font-weight:600;text-transform:uppercase;letter-spacing:.8px;color:var(--text-3);margin-bottom:12px}
.toc{display:flex;flex-direction:column;gap:2px}
.toc a{font-size:13px;padding:6px 12px;border-radius:6px;color:var(--text-2);border-left:2px solid transparent;transition:all var(--transition)}
.toc a:hover{color:var(--text);background:var(--bg-2)}
.toc a.active{color:var(--blue);border-left-color:var(--blue);background:var(--blue-light);font-weight:500}
.art-body{max-width:780px;min-width:0}
.art-header{margin-bottom:40px}
.art-header h1{font-size:36px;font-weight:400;color:var(--text);line-height:1.3;margin-bottom:16px}
.art-meta{display:flex;gap:16px;font-size:13px;color:var(--text-3)}
.art-meta svg{vertical-align:-3px;margin-right:4px}
.art-section{margin-bottom:48px}
.art-section h2{font-size:26px;font-weight:500;color:var(--text);margin-bottom:16px;padding-bottom:8px;border-bottom:1px solid var(--border-2)}
.art-section h3{font-size:18px;font-weight:600;color:var(--text);margin:24px 0 12px}
.art-section p{font-size:15px;color:var(--text-2);line-height:1.8;margin-bottom:14px}
.art-section ul,.art-section ol{margin:0 0 16px 20px}
.art-section li{font-size:15px;color:var(--text-2);line-height:1.8;margin-bottom:8px}
.art-section strong{color:var(--text)}

/* advantage cards in article */
.adv-list{display:flex;flex-direction:column;gap:16px}
.adv-item{display:flex;gap:16px;padding:20px;border:1px solid var(--border-2);border-radius:var(--radius-lg);background:var(--bg)}
.adv-icon{flex-shrink:0;width:32px;height:32px;color:var(--blue);margin-top:2px}
.adv-item h3{font-size:16px;font-weight:600;margin-bottom:6px}
.adv-item p{margin-bottom:0}

/* comparison table in article */
.table-wrap{overflow-x:auto;margin:20px 0;border:1px solid var(--border-2);border-radius:var(--radius-lg)}
.cmp-table{width:100%;border-collapse:collapse;font-size:14px}
.cmp-table thead{background:var(--bg-2)}
.cmp-table th{padding:12px 16px;text-align:left;font-weight:600;color:var(--text);border-bottom:1px solid var(--border-2)}
.cmp-table td{padding:12px 16px;border-bottom:1px solid var(--border-2);color:var(--text-2)}
.cmp-table tr:last-child td{border-bottom:none}
.cmp-table .hl{background:var(--blue-light);color:var(--blue);font-weight:600}

/* update timeline */
.ver-list{display:flex;flex-direction:column;gap:20px;margin-top:20px}
.ver-item{padding:20px 24px;border-left:3px solid var(--blue);border-radius:0 var(--radius-lg) var(--radius-lg) 0;background:var(--bg-2)}
.ver-tag{font-size:16px;font-weight:600;color:var(--blue)}
.ver-date{font-size:13px;color:var(--text-3);margin-bottom:10px}
.ver-item ul{margin:0 0 0 18px}
.ver-item li{font-size:14px;color:var(--text-2);margin-bottom:6px}

/* tips grid */
.tips-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;margin-top:16px}
.tip-card{padding:20px;border:1px solid var(--border-2);border-radius:var(--radius-lg);background:var(--bg)}
.tip-card h3{font-size:15px;font-weight:600;color:var(--text);margin-bottom:10px}
.tip-card ul{margin:0;padding:0;list-style:none}
.tip-card li{font-size:14px;color:var(--text-2);padding:4px 0 4px 16px;position:relative}
.tip-card li::before{content:"";position:absolute;left:0;top:12px;width:6px;height:6px;border-radius:50%;background:var(--blue)}
.tip-card p{font-size:14px;color:var(--text-2);margin-bottom:10px}

/* article CTA */
.art-cta{margin-top:56px;padding:48px;border-radius:var(--radius-xl);background:var(--blue);text-align:center;color:#fff}
.art-cta h2{font-size:28px;font-weight:400;margin-bottom:12px}
.art-cta p{font-size:15px;opacity:.9;margin-bottom:28px}
.art-cta a{display:inline-flex;align-items:center;gap:8px;height:48px;padding:0 32px;background:#fff;color:var(--blue);border-radius:24px;font-size:15px;font-weight:500;transition:box-shadow var(--transition)}
.art-cta a:hover{box-shadow:var(--shadow-md)}

/* feature list checkmarks */
.check-list{list-style:none;margin-left:0!important}
.check-list li{padding-left:24px;position:relative}
.check-list li::before{content:"";position:absolute;left:0;top:8px;width:16px;height:16px;background:var(--green);mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3'%3E%3Cpolyline points='20 6 9 17 4 12'/%3E%3C/svg%3E") center/contain no-repeat;-webkit-mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3'%3E%3Cpolyline points='20 6 9 17 4 12'/%3E%3C/svg%3E") center/contain no-repeat}

/* ===== RESPONSIVE ===== */
@media(max-width:1024px){
    .features{grid-template-columns:repeat(2,1fr)}
    .platforms{grid-template-columns:repeat(2,1fr)}
    .reviews{grid-template-columns:repeat(2,1fr)}
    .steps{grid-template-columns:repeat(3,1fr)}
    .dl-layout{grid-template-columns:1fr}
    .art-layout{grid-template-columns:1fr}
    .art-aside{display:none}
    .dl-faq-grid{grid-template-columns:1fr}
}
@media(max-width:768px){
    .hero h1{font-size:36px}
    .hero-stats{flex-direction:column;gap:20px;align-items:center}
    .features,.platforms,.reviews{grid-template-columns:1fr}
    .steps{grid-template-columns:1fr}
    .tips-grid{grid-template-columns:1fr}
    .dl-info{grid-template-columns:repeat(2,1fr)}
    .dl-hero h1{font-size:30px}
    .art-header h1{font-size:28px}
    .art-cta{padding:32px 20px}
    .safe-strip-inner{flex-direction:column;text-align:center}
    .nav-inner{flex-wrap:wrap;height:auto;padding:12px 16px;gap:8px}
    .nav-brand{margin-right:0;width:100%;justify-content:center}
    .nav-menu{width:100%;justify-content:center}
    .section-head h2{font-size:26px}
}