/* ===== CSS Reset & Variables ===== */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --primary:#2B6CB0;
  --primary-dark:#1a4f8b;
  --primary-light:#4299E1;
  --secondary:#38B2AC;
  --accent:#ED8936;
  --bg:#FFFFFF;
  --bg-alt:#F7FAFC;
  --bg-dark:#1A202C;
  --text:#2D3748;
  --text-light:#718096;
  --text-white:#FFFFFF;
  --border:#E2E8F0;
  --shadow:0 4px 6px -1px rgba(0,0,0,.1),0 2px 4px -1px rgba(0,0,0,.06);
  --shadow-lg:0 10px 25px -5px rgba(0,0,0,.1),0 10px 10px -5px rgba(0,0,0,.04);
  --radius:12px;
  --radius-sm:8px;
  --radius-lg:16px;
  --max-w:1200px;
  --transition:all .3s ease;
}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;color:var(--text);line-height:1.7;background:var(--bg);-webkit-font-smoothing:antialiased}
a{text-decoration:none;color:inherit;transition:var(--transition)}
ul{list-style:none}
img{max-width:100%;display:block}
h1,h2,h3,h4{line-height:1.3}
.container{max-width:var(--max-w);margin:0 auto;padding:0 24px}

/* ===== Header ===== */
.header{position:fixed;top:0;left:0;right:0;z-index:1000;background:rgba(255,255,255,.95);backdrop-filter:blur(20px);border-bottom:1px solid var(--border);transition:var(--transition)}
.header.scrolled{box-shadow:var(--shadow)}
.nav{display:flex;align-items:center;justify-content:space-between;height:64px}
.logo{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.1rem;color:var(--primary)}
.nav-links{display:flex;gap:28px}
.nav-links a{font-size:.95rem;color:var(--text-light);font-weight:500;position:relative}
.nav-links a:hover{color:var(--primary)}
.nav-links a::after{content:'';position:absolute;bottom:-4px;left:0;width:0;height:2px;background:var(--primary);transition:var(--transition)}
.nav-links a:hover::after{width:100%}
.nav-cta{background:var(--primary);color:#fff;padding:8px 20px;border-radius:var(--radius-sm);font-size:.9rem;font-weight:600;transition:var(--transition)}
.nav-cta:hover{background:var(--primary-dark);transform:translateY(-1px)}
.mobile-toggle{display:none;flex-direction:column;gap:5px;background:none;border:none;cursor:pointer;padding:4px}
.mobile-toggle span{display:block;width:24px;height:2px;background:var(--text);transition:var(--transition)}

/* ===== Buttons ===== */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 28px;border-radius:var(--radius-sm);font-weight:600;font-size:1rem;transition:var(--transition);cursor:pointer;border:2px solid transparent}
.btn-primary{background:var(--primary);color:#fff;border-color:var(--primary)}
.btn-primary:hover{background:var(--primary-dark);border-color:var(--primary-dark);transform:translateY(-2px);box-shadow:0 8px 25px rgba(43,108,176,.3)}
.btn-outline{background:transparent;color:var(--primary);border-color:var(--primary)}
.btn-outline:hover{background:var(--primary);color:#fff;transform:translateY(-2px)}
.btn-large{padding:16px 36px;font-size:1.1rem;border-radius:var(--radius)}
.btn-sm{padding:8px 20px;font-size:.875rem}

/* ===== Hero ===== */
.hero{padding:120px 0 80px;background:linear-gradient(135deg,#EBF4FF 0%,#F0FFF4 50%,#FFF5F5 100%);overflow:hidden}
.hero .container{display:grid;grid-template-columns:1fr 1fr;gap:60px;align-items:center}
.hero-badge{display:inline-block;background:linear-gradient(135deg,var(--primary),var(--secondary));color:#fff;padding:6px 16px;border-radius:20px;font-size:.85rem;font-weight:600;margin-bottom:20px}
.hero h1{font-size:2.5rem;font-weight:800;color:var(--bg-dark);margin-bottom:20px;line-height:1.25}
.hero-desc{font-size:1.1rem;color:var(--text-light);margin-bottom:28px;max-width:560px}
.hero-desc strong{color:var(--text)}
.hero-stats{display:flex;gap:32px;margin-bottom:32px}
.stat{text-align:center}
.stat-num{display:block;font-size:1.5rem;font-weight:800;color:var(--primary)}
.stat-label{font-size:.8rem;color:var(--text-light)}
.hero-buttons{display:flex;gap:16px;margin-bottom:16px;flex-wrap:wrap}
.hero-meta{display:flex;gap:12px;font-size:.82rem;color:var(--text-light);flex-wrap:wrap}

/* App Preview */
.app-preview{background:#fff;border-radius:var(--radius-lg);box-shadow:var(--shadow-lg);overflow:hidden;border:1px solid var(--border)}
.app-titlebar{display:flex;align-items:center;gap:12px;padding:12px 16px;background:#f8f9fa;border-bottom:1px solid var(--border)}
.dots{display:flex;gap:6px}
.dots i{width:12px;height:12px;border-radius:50%;display:block}
.dots i:nth-child(1){background:#FF5F56}
.dots i:nth-child(2){background:#FFBD2E}
.dots i:nth-child(3){background:#27C93F}
.app-titlebar span{font-size:.82rem;color:var(--text-light);font-weight:500}
.app-body{display:flex;min-height:300px}
.app-sidebar{width:80px;background:#f1f5f9;padding:16px 8px;display:flex;flex-direction:column;gap:8px;border-right:1px solid var(--border)}
.sidebar-item{display:flex;flex-direction:column;align-items:center;gap:4px;padding:10px 4px;border-radius:var(--radius-sm);font-size:.7rem;color:var(--text-light);cursor:pointer;transition:var(--transition)}
.sidebar-item.active{background:#fff;color:var(--primary);box-shadow:0 1px 3px rgba(0,0,0,.1)}
.sidebar-item.ai-item{color:var(--accent);margin-top:auto}
.app-content{flex:1;padding:24px;display:flex;flex-direction:column;gap:12px}
.doc-line{height:10px;border-radius:4px;background:#e2e8f0}
.doc-line.w100{width:100%}.doc-line.w90{width:90%}.doc-line.w80{width:80%}.doc-line.w70{width:70%}.doc-line.w60{width:60%}
.ai-bubble{display:inline-flex;align-items:center;gap:8px;background:linear-gradient(135deg,#EBF4FF,#E9D8FD);padding:10px 16px;border-radius:var(--radius-sm);margin-top:auto;font-size:.82rem;color:#553C9A}
.ai-icon{background:linear-gradient(135deg,#667EEA,#764BA2);color:#fff;padding:2px 8px;border-radius:4px;font-size:.75rem;font-weight:700}

/* ===== Platforms ===== */
.platforms{padding:80px 0;background:var(--bg)}
.platforms h2,.features h2,.versions h2,.guide h2,.reviews h2,.faq h2,.bottom-cta h2{text-align:center;font-size:2rem;margin-bottom:12px}
.platforms h2 strong,.features h2 strong,.versions h2 strong,.guide h2 strong,.reviews h2 strong,.faq h2 strong,.bottom-cta h2 strong{color:var(--primary)}
.section-desc{text-align:center;color:var(--text-light);margin-bottom:48px;font-size:1.05rem}
.platform-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:20px}
.platform-card{text-align:center;padding:32px 20px;border-radius:var(--radius);border:1px solid var(--border);transition:var(--transition);background:#fff}
.platform-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--primary-light)}
.platform-icon{margin-bottom:16px}
.platform-card h3{font-size:1rem;margin-bottom:8px}
.platform-card p{font-size:.85rem;color:var(--text-light);margin-bottom:16px;line-height:1.5}

/* ===== Features ===== */
.features{padding:80px 0;background:var(--bg-alt)}
.feature-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.feature-card{background:#fff;padding:32px;border-radius:var(--radius);border:1px solid var(--border);transition:var(--transition)}
.feature-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg)}
.feature-icon{width:56px;height:56px;border-radius:var(--radius-sm);display:flex;align-items:center;justify-content:center;margin-bottom:16px}
.feature-icon.blue{background:#EBF4FF;color:var(--primary)}
.feature-icon.green{background:#F0FFF4;color:#38A169}
.feature-icon.purple{background:#FAF5FF;color:#805AD5}
.feature-icon.orange{background:#FFFAF0;color:#DD6B20}
.feature-icon.red{background:#FFF5F5;color:#E53E3E}
.feature-icon.teal{background:#E6FFFA;color:#319795}
.feature-card h3{font-size:1.1rem;margin-bottom:10px}
.feature-card p{font-size:.9rem;color:var(--text-light);line-height:1.7}

/* ===== Version Table ===== */
.versions{padding:80px 0;background:var(--bg)}
.version-table-wrap{overflow-x:auto}
.version-table{width:100%;border-collapse:collapse;background:#fff;border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.version-table th,.version-table td{padding:16px 24px;text-align:center;border-bottom:1px solid var(--border)}
.version-table th{background:var(--bg-alt);font-weight:600;font-size:.95rem}
.version-table td:first-child{text-align:left;font-weight:500}
.version-table .highlight{background:#EBF4FF}
.version-table th.highlight{background:var(--primary);color:#fff}

/* ===== Guide ===== */
.guide{padding:80px 0;background:var(--bg-alt)}
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:32px}
.step{text-align:center;padding:40px 24px;background:#fff;border-radius:var(--radius);border:1px solid var(--border)}
.step-num{width:56px;height:56px;border-radius:50%;background:var(--primary);color:#fff;font-size:1.5rem;font-weight:700;display:flex;align-items:center;justify-content:center;margin:0 auto 20px}
.step h3{margin-bottom:12px;font-size:1.1rem}
.step p{font-size:.9rem;color:var(--text-light)}

/* ===== Reviews ===== */
.reviews{padding:80px 0;background:var(--bg)}
.review-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.review-card{background:#fff;padding:32px;border-radius:var(--radius);border:1px solid var(--border);transition:var(--transition)}
.review-card:hover{box-shadow:var(--shadow-lg)}
.review-stars{color:#F6AD55;font-size:1.2rem;margin-bottom:16px;letter-spacing:2px}
.review-card>p{font-size:.95rem;color:var(--text);margin-bottom:20px;font-style:italic;line-height:1.7}
.reviewer{display:flex;align-items:center;gap:12px}
.reviewer-avatar{width:40px;height:40px;border-radius:50%;background:var(--primary);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:600;font-size:.9rem}
.reviewer small{color:var(--text-light)}

/* ===== FAQ ===== */
.faq{padding:80px 0;background:var(--bg-alt)}
.faq-list{max-width:800px;margin:0 auto}
.faq-item{border:1px solid var(--border);border-radius:var(--radius-sm);margin-bottom:12px;background:#fff;overflow:hidden}
.faq-item summary{padding:18px 24px;cursor:pointer;font-weight:600;font-size:1rem;display:flex;align-items:center;justify-content:space-between;transition:var(--transition);list-style:none}
.faq-item summary::-webkit-details-marker{display:none}
.faq-item summary::after{content:'+';font-size:1.3rem;color:var(--primary);font-weight:300;transition:var(--transition)}
.faq-item[open] summary::after{transform:rotate(45deg)}
.faq-item[open] summary{border-bottom:1px solid var(--border);color:var(--primary)}
.faq-item p{padding:18px 24px;font-size:.95rem;color:var(--text-light);line-height:1.8}

/* ===== Bottom CTA ===== */
.bottom-cta{padding:80px 0;background:linear-gradient(135deg,var(--primary) 0%,#1a365d 100%);text-align:center;color:#fff}
.bottom-cta h2{color:#fff}
.bottom-cta h2 strong{color:#BEE3F8}
.bottom-cta p{color:rgba(255,255,255,.8);margin-bottom:32px;font-size:1.1rem}
.bottom-cta .btn-primary{background:#fff;color:var(--primary);border-color:#fff}
.bottom-cta .btn-primary:hover{background:#EBF4FF;box-shadow:0 8px 25px rgba(0,0,0,.2)}

/* ===== Friend Links ===== */
.friend-links{padding:32px 0;background:var(--bg-alt);border-top:1px solid var(--border)}
.friend-links h3{font-size:.9rem;color:var(--text-light);margin-bottom:12px}
.links-wrap{display:flex;flex-wrap:wrap;gap:16px}
.links-wrap a{font-size:.85rem;color:var(--text-light);transition:var(--transition);padding:4px 8px;border-radius:4px}
.links-wrap a:hover{color:var(--primary);background:#EBF4FF}

/* ===== Footer ===== */
.footer{background:var(--bg-dark);color:rgba(255,255,255,.7);padding:60px 0 30px}
.footer-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:40px;margin-bottom:40px}
.footer-col h4{color:#fff;margin-bottom:16px;font-size:1rem}
.footer-col li{margin-bottom:8px}
.footer-col a{font-size:.9rem;transition:var(--transition)}
.footer-col a:hover{color:#fff}
.footer-bottom{border-top:1px solid rgba(255,255,255,.1);padding-top:24px;text-align:center;font-size:.82rem}

/* ===== Responsive ===== */
@media(max-width:1024px){
  .hero .container{grid-template-columns:1fr;text-align:center}
  .hero-desc{margin-left:auto;margin-right:auto}
  .hero-stats{justify-content:center}
  .hero-buttons{justify-content:center}
  .hero-meta{justify-content:center}
  .hero-visual{max-width:600px;margin:0 auto}
  .platform-grid{grid-template-columns:repeat(3,1fr)}
  .feature-grid{grid-template-columns:repeat(2,1fr)}
  .footer-grid{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:768px){
  .nav-links,.nav-cta{display:none}
  .mobile-toggle{display:flex}
  .hero h1{font-size:1.8rem}
  .hero{padding:100px 0 60px}
  .platforms h2,.features h2,.versions h2,.guide h2,.reviews h2,.faq h2,.bottom-cta h2{font-size:1.6rem}
  .platform-grid{grid-template-columns:repeat(2,1fr)}
  .feature-grid{grid-template-columns:1fr}
  .steps{grid-template-columns:1fr}
  .review-grid{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr;gap:24px}
  .hero-stats{flex-wrap:wrap;gap:16px}
  .stat{min-width:70px}
  .version-table th,.version-table td{padding:10px 12px;font-size:.85rem}
}
@media(max-width:480px){
  .hero h1{font-size:1.5rem}
  .hero-buttons{flex-direction:column;align-items:center}
  .btn-large{width:100%}
  .platform-grid{grid-template-columns:1fr}
}

/* ===== Animations ===== */
@keyframes fadeInUp{from{opacity:0;transform:translateY(30px)}to{opacity:1;transform:translateY(0)}}
.hero-content{animation:fadeInUp .8s ease}
.hero-visual{animation:fadeInUp .8s ease .2s both}
.fade-in{opacity:0;transform:translateY(20px);transition:opacity .6s ease,transform .6s ease}
.fade-in.visible{opacity:1;transform:translateY(0)}