/* ═══════════════════════════════════════════════════════════════
   微信AI助手 — 营销网站样式
   优化：响应式 / 移动优先 / SEO语义化 / 性能
   ═══════════════════════════════════════════════════════════════ */

/* ── CSS 变量 ───────────────────────────────────────────────── */
:root {
  --primary: #4263eb;
  --primary-hover: #3b5de7;
  --success: #2f9e44;
  --warning: #e8590c;
  --danger: #e03131;
  --dark: #1a1d23;
  --gray-900: #212529;
  --gray-700: #495057;
  --gray-500: #6c757d;
  --gray-300: #adbac5;
  --gray-200: #dee2e6;
  --gray-100: #f1f3f5;
  --gray-50: #f8f9fa;
  --white: #ffffff;
  --radius: 10px;
  --shadow: 0 2px 16px rgba(0,0,0,.08);
  --shadow-lg: 0 8px 40px rgba(0,0,0,.12);
  --max-w: 1140px;
}

/* ── Reset ──────────────────────────────────────────────────── */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:"Microsoft YaHei","PingFang SC","Noto Sans SC",system-ui,-apple-system,sans-serif;color:var(--gray-900);line-height:1.7;background:var(--white)}
img{max-width:100%;height:auto}
a{color:var(--primary);text-decoration:none}
a:hover{text-decoration:underline}
ul{list-style:none}
.container{max-width:var(--max-w);margin:0 auto;padding:0 20px}
.section{padding:80px 0}
.section-alt{background:var(--gray-50)}
.section-title{font-size:32px;text-align:center;margin-bottom:8px}
.section-sub{text-align:center;color:var(--gray-500);font-size:16px;margin-bottom:48px;max-width:640px;margin-left:auto;margin-right:auto}
.text-center{text-align:center}

/* ── 导航栏 ─────────────────────────────────────────────────── */
.navbar{position:fixed;top:0;left:0;right:0;z-index:1000;background:rgba(255,255,255,.95);backdrop-filter:blur(10px);transition:box-shadow .3s}
.navbar.scrolled{box-shadow:var(--shadow)}
.nav-inner{display:flex;align-items:center;justify-content:space-between;height:64px}
.logo{font-size:20px;font-weight:bold;color:var(--gray-900)}
.logo:hover{text-decoration:none}
.nav-links{display:flex;align-items:center;gap:8px}
.nav-links a{color:var(--gray-700);font-size:14px;padding:8px 14px;border-radius:6px;transition:background .2s}
.nav-links a:hover{background:var(--gray-100);text-decoration:none}
.btn-nav{background:var(--primary)!important;color:var(--white)!important;font-weight:bold}
.btn-nav:hover{background:var(--primary-hover)!important}
.mobile-toggle{display:none;background:none;border:none;font-size:24px;cursor:pointer;color:var(--gray-900)}

/* ── Hero ───────────────────────────────────────────────────── */
.hero{padding:140px 0 80px;background:linear-gradient(135deg,#f8f9fa 0%,#e8f0fe 50%,#dbe4ff 100%)}
.hero-grid{display:flex;align-items:center;gap:60px}
.hero-text{flex:1}
.hero-text h1{font-size:40px;line-height:1.3;margin-bottom:20px}
.highlight{color:var(--primary)}
.hero-sub{font-size:18px;color:var(--gray-500);margin-bottom:32px;line-height:1.8}
.hero-cta{display:flex;gap:12px;margin-bottom:24px;flex-wrap:wrap}
.hero-stats{display:flex;gap:20px;flex-wrap:wrap;font-size:14px;color:var(--gray-500)}
.hero-stats strong{color:var(--gray-900)}
.hero-img{flex:1;max-width:440px}

/* Mockup */
.mockup-window{background:var(--white);border-radius:12px;box-shadow:var(--shadow-lg);overflow:hidden}
.mockup-titlebar{background:var(--gray-100);padding:12px 16px;font-size:13px;font-weight:bold;color:var(--gray-700);border-bottom:1px solid var(--gray-200)}
.mockup-body{padding:16px}
.chat-msg{padding:10px 14px;border-radius:8px;margin-bottom:8px;font-size:13px;max-width:85%;line-height:1.6}
.chat-msg.other{background:var(--gray-100);color:var(--gray-900)}
.chat-msg.self{background:var(--primary);color:var(--white);margin-left:auto}
.chat-msg.ai-label{background:var(--success);font-size:12px;text-align:center;max-width:100%}

/* ── Buttons ────────────────────────────────────────────────── */
.btn{display:inline-block;padding:12px 28px;border-radius:8px;font-size:15px;font-weight:bold;cursor:pointer;border:none;transition:all .2s;text-align:center}
.btn:hover{text-decoration:none;transform:translateY(-1px)}
.btn-primary{background:var(--primary);color:var(--white)}
.btn-primary:hover{background:var(--primary-hover)}
.btn-outline{border:2px solid var(--primary);color:var(--primary);background:transparent}
.btn-outline:hover{background:var(--primary);color:var(--white)}
.btn-block{display:block;width:100%}
.btn-lg{padding:16px 36px;font-size:17px;border-radius:10px}

/* ── 功能卡片 ───────────────────────────────────────────────── */
.features-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.feature-card{background:var(--white);padding:32px 24px;border-radius:var(--radius);border:1px solid var(--gray-200);transition:box-shadow .3s,transform .3s}
.feature-card:hover{box-shadow:var(--shadow-lg);transform:translateY(-4px)}
.feature-icon{font-size:36px;margin-bottom:12px}
.feature-card h3{font-size:18px;margin-bottom:8px}
.feature-card p{color:var(--gray-500);font-size:14px;line-height:1.8}

/* ── 工作原理 ────────────────────────────────────────────────── */
.steps{display:flex;align-items:center;justify-content:center;gap:16px;flex-wrap:wrap}
.step{background:var(--white);padding:24px 20px;border-radius:var(--radius);text-align:center;width:200px;box-shadow:var(--shadow)}
.step-num{width:40px;height:40px;border-radius:50%;background:var(--primary);color:var(--white);font-size:20px;font-weight:bold;display:flex;align-items:center;justify-content:center;margin:0 auto 12px}
.step h4{font-size:15px;margin-bottom:8px}
.step p{font-size:13px;color:var(--gray-500);line-height:1.6}
.step-arrow{font-size:24px;color:var(--gray-300)}
.safety-note{text-align:center;margin-top:40px;padding:16px 24px;background:var(--white);border-radius:var(--radius);border-left:4px solid var(--success);font-size:14px;color:var(--gray-700);max-width:720px;margin-left:auto;margin-right:auto}

/* ── 定价 ───────────────────────────────────────────────────── */
.pricing-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;align-items:start}
.pricing-card{background:var(--white);border-radius:var(--radius);border:1px solid var(--gray-200);overflow:hidden;transition:box-shadow .3s,transform .3s}
.pricing-card:hover{box-shadow:var(--shadow-lg);transform:translateY(-4px)}
.pricing-card.popular{border:2px solid var(--primary);position:relative;transform:scale(1.04)}
.pricing-card.popular:hover{transform:scale(1.04) translateY(-4px)}
.popular-badge{background:var(--primary);color:var(--white);text-align:center;font-size:12px;font-weight:bold;padding:6px}
.pricing-header{padding:28px 24px 20px;text-align:center}
.pricing-header h3{font-size:22px;margin-bottom:12px}
.pricing-price{font-size:40px;font-weight:bold;color:var(--gray-900)}
.pricing-price span{font-size:16px;color:var(--gray-500);font-weight:normal}
.pricing-yearly{font-size:13px;color:var(--success);margin-top:4px}
.pricing-options{display:flex;flex-direction:column;gap:6px;margin-top:8px;padding:8px 12px;background:var(--gray-50);border-radius:8px}
.pricing-option{display:flex;align-items:center;gap:6px}
.po-label{font-size:10px;font-weight:bold;color:var(--gray-500);min-width:28px}
.po-price{font-size:14px;font-weight:bold;color:var(--gray-900)}
.po-price span{font-size:11px;color:var(--gray-500);font-weight:normal}
.po-sub{font-size:10px;color:var(--success)}
.pricing-option.highlight{background:#fff9db;border-radius:4px;padding:3px 6px;margin:2px -6px}
.pricing-features{padding:0 24px 20px}
.pricing-features li{padding:8px 0;font-size:14px;color:var(--gray-700);border-bottom:1px solid var(--gray-100)}
.pricing-features li:last-child{border-bottom:none}
.pricing-features li::before{content:"✅ ";font-size:12px}
.pricing-card .btn{margin:0 24px 24px}

/* ── FAQ ────────────────────────────────────────────────────── */
.faq-list{max-width:760px;margin:0 auto}
.faq-item{background:var(--white);border-radius:var(--radius);margin-bottom:12px;box-shadow:var(--shadow);overflow:hidden}
.faq-item summary{padding:18px 24px;font-size:16px;font-weight:bold;cursor:pointer;list-style:none;display:flex;justify-content:space-between;align-items:center}
.faq-item summary::-webkit-details-marker{display:none}
.faq-item summary::after{content:"▸";font-size:14px;transition:transform .3s;color:var(--gray-500)}
.faq-item[open] summary::after{transform:rotate(90deg)}
.faq-answer{padding:0 24px 20px;font-size:14px;color:var(--gray-700);line-height:1.9}
.faq-answer ul{margin:8px 0 8px 20px;list-style:disc}

/* ── 下载 ───────────────────────────────────────────────────── */
.download-card{max-width:520px;margin:0 auto;background:var(--white);border-radius:var(--radius);padding:40px;box-shadow:var(--shadow-lg);text-align:center}
.download-version{font-size:28px;font-weight:bold;margin-bottom:8px}
.download-size,.download-system{font-size:14px;color:var(--gray-500);margin-bottom:4px}
.download-note{font-size:13px;color:var(--gray-500);margin-top:16px;line-height:1.8}

/* ── 联系 ───────────────────────────────────────────────────── */
.contact-card{display:flex;justify-content:center;gap:40px;flex-wrap:wrap;max-width:700px;margin:0 auto}
.contact-item{text-align:center;padding:24px;background:var(--white);border-radius:var(--radius);box-shadow:var(--shadow);width:200px}
.contact-icon{font-size:32px;margin-bottom:8px}
.contact-item h4{font-size:15px;margin-bottom:8px}
.contact-value{font-size:18px;font-weight:bold;color:var(--primary)}
.contact-note{font-size:12px;color:var(--gray-500);margin-top:4px}

/* ── Footer ─────────────────────────────────────────────────── */
.footer{background:var(--dark);color:var(--gray-300);padding:60px 0 30px}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 2fr;gap:40px}
.footer-col h4{color:var(--white);margin-bottom:16px;font-size:16px}
.footer-col p,.footer-col a{font-size:13px;line-height:2;display:block}
.footer-col a{color:var(--gray-300)}
.footer-col a:hover{color:var(--white);text-decoration:none}
.footer-disclaimer{font-size:12px!important;line-height:1.8!important;color:var(--gray-500)!important}
.footer-bottom{border-top:1px solid rgba(255,255,255,.1);margin-top:40px;padding-top:20px;text-align:center;font-size:12px;color:var(--gray-500)}

/* ── 响应式 ─────────────────────────────────────────────────── */
@media(max-width:900px){
  .hero-grid{flex-direction:column;text-align:center}
  .hero-text h1{font-size:30px}
  .hero-cta{justify-content:center}
  .hero-stats{justify-content:center}
  .hero-img{max-width:100%}
  .features-grid{grid-template-columns:1fr 1fr}
  .pricing-grid{grid-template-columns:1fr;max-width:400px;margin:0 auto}
  .pricing-card.popular{transform:none}
  .pricing-card.popular:hover{transform:translateY(-4px)}
  .steps{flex-direction:column}
  .step-arrow{transform:rotate(90deg)}
  .footer-grid{grid-template-columns:1fr 1fr}
  .nav-links{display:none;position:absolute;top:64px;left:0;right:0;background:var(--white);flex-direction:column;padding:16px;box-shadow:var(--shadow)}
  .nav-links.show{display:flex}
  .mobile-toggle{display:block}
}

@media(max-width:600px){
  .section{padding:48px 0}
  .section-title{font-size:26px}
  .hero{padding:120px 0 48px}
  .hero-text h1{font-size:24px}
  .features-grid{grid-template-columns:1fr}
  .contact-card{flex-direction:column;align-items:center}
  .footer-grid{grid-template-columns:1fr}
  .pricing-grid{max-width:100%}
}