/* ==========================================================================
   LINE官网 — 即时通讯应用工具
   主色：LINE 品牌蓝 #02B1D4，时间轴架构（差异化于 ie 绿左右图文 / in 绿卡片网格）
   ========================================================================== */

:root {
  --primary: #02b1d4;
  --primary-dark: #0198b8;
  --primary-darker: #017d99;
  --primary-light: #e0f6fc;
  --primary-border: #a8e6f5;
  --accent: #02b1d4;
  --bg: #f6fbfd;
  --card: #ffffff;
  --border: #e2e8f0;
  --title: #0f172a;
  --body: #334155;
  --muted: #64748b;
  --radius: 16px;
  --shadow: 0 2px 12px rgba(15,23,42,.06);
  --shadow-lg: 0 12px 32px rgba(2,177,212,.18);
  --maxw: 1160px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg); color: var(--body); font-size: 16px; line-height: 1.7;
}
a { color: var(--primary-dark); text-decoration: none; transition: color .2s; }
a:hover { color: var(--primary-darker); }
img { max-width: 100%; height: auto; display: block; }
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

/* ---------- 导航 ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100; background: rgba(255,255,255,.9);
  backdrop-filter: blur(10px); border-bottom: 1px solid var(--border);
}
.nav { display: flex; align-items: center; gap: 26px; height: 66px; }
.logo { display: flex; align-items: center; gap: 10px; font-size: 20px; font-weight: 700; color: var(--title); letter-spacing: 2px; }
.logo img, .f-logo img { flex: none; border-radius: 8px; }
.logo em { font-style: normal; color: var(--primary-dark); }
.nav-links { display: flex; gap: 4px; }
.nav-links a { padding: 7px 14px; border-radius: 8px; color: var(--body); font-size: 15px; font-weight: 500; }
.nav-links a:hover { background: var(--primary-light); color: var(--primary-darker); }
.nav-links a.active { color: var(--primary-dark); background: var(--primary-light); }
.nav-actions { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.nav-login { color: var(--body); font-size: 15px; font-weight: 500; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 12px 28px; border-radius: 10px; font-size: 15px; font-weight: 700;
  cursor: pointer; border: 1px solid transparent; transition: all .2s; white-space: nowrap; letter-spacing: .5px;
}
.btn-primary { background: var(--primary); color: #fff; box-shadow: 0 4px 14px rgba(2,177,212,.32); }
.btn-primary:hover { background: var(--primary-dark); color: #fff; transform: translateY(-1px); }
.btn-outline { background: #fff; color: var(--primary-dark); border: 1px solid var(--primary); }
.btn-outline:hover { background: var(--primary-light); color: var(--primary-darker); }
.btn-lg { padding: 14px 34px; font-size: 16px; }
.btn-block { width: 100%; }

/* ---------- 居中 Hero（时间轴风） ---------- */
.hero { text-align: center; padding: 80px 5%; background: linear-gradient(180deg, #e0f6fc 0%, var(--bg) 100%); }
.hero-badge {
  display: inline-block; border: 1px solid var(--primary); color: var(--primary-dark);
  padding: 6px 20px; font-size: 11px; letter-spacing: 3px; margin-bottom: 20px; border-radius: 999px;
}
.hero h1 { font-size: 46px; font-weight: 300; line-height: 1.3; margin-bottom: 16px; letter-spacing: 2px; color: var(--title); }
.hero h1 .hl { font-weight: 700; color: var(--primary-dark); }
.hero .sub { color: var(--muted); font-size: 17px; max-width: 540px; margin: 0 auto 32px; }
.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

/* ---------- 时间轴 ---------- */
.timeline { max-width: 820px; margin: 0 auto 60px; padding: 0 5%; }
.timeline h2 { text-align: center; font-weight: 700; font-size: 28px; letter-spacing: 2px; margin-bottom: 40px; color: var(--title); }
.tl-item { display: flex; gap: 24px; margin-bottom: 32px; align-items: flex-start; position: relative; }
.tl-item::before { content: ""; position: absolute; left: 5px; top: 16px; bottom: -32px; width: 2px; background: var(--primary-border); }
.tl-item:last-child::before { display: none; }
.tl-item .tl-dot { flex-shrink: 0; width: 12px; height: 12px; border-radius: 50%; background: var(--primary); margin-top: 6px; position: relative; z-index: 1; box-shadow: 0 0 0 4px var(--primary-light); }
.tl-item .tl-content { flex: 1; background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 22px 24px; }
.tl-item .tl-content h4 { font-size: 17px; margin-bottom: 6px; color: var(--primary-dark); }
.tl-item .tl-content p { font-size: 14px; color: var(--muted); }

/* ---------- 通用 section ---------- */
.section { padding: 60px 0; }
.section.soft { background: #fff; border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.sec-head { text-align: center; max-width: 640px; margin: 0 auto 40px; }
.sec-head h2 { font-size: 28px; font-weight: 700; color: var(--title); letter-spacing: 1px; }
.sec-head p { margin-top: 12px; color: var(--muted); font-size: 16px; }
.sec-head.left { text-align: left; margin-left: 0; }

/* ---------- 功能卡 ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.feature-card {
  background: #fff; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 26px; transition: all .25s;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--primary-border); }
.feature-card .ic { width: 52px; height: 52px; border-radius: 14px; display: flex; align-items: center; justify-content: center; background: var(--primary-light); margin-bottom: 16px; }
.feature-card h3 { font-size: 18px; color: var(--title); margin-bottom: 8px; }
.feature-card p { font-size: 14px; color: var(--muted); }

/* ---------- 下载矩阵 ---------- */
.dl-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.dl-card {
  background: #fff; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 26px; text-align: center; transition: all .25s;
}
.dl-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--primary-border); }
.dl-card .ic { width: 60px; height: 60px; margin: 0 auto 16px; border-radius: 16px; background: var(--primary-light); display: flex; align-items: center; justify-content: center; }
.dl-card h3 { font-size: 17px; color: var(--title); }
.dl-card p { font-size: 13px; color: var(--muted); margin: 8px 0 16px; }
.dl-card .badge { display: inline-block; font-size: 12px; color: var(--primary-dark); background: var(--primary-light); padding: 3px 10px; border-radius: 99px; margin-bottom: 14px; }

/* ---------- 场景卡 ---------- */
.scene-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
.scene-card { display: flex; gap: 18px; background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; align-items: flex-start; }
.scene-card .ic { flex: none; width: 48px; height: 48px; border-radius: 12px; background: var(--primary-light); display: flex; align-items: center; justify-content: center; }
.scene-card h3 { font-size: 17px; color: var(--title); }
.scene-card p { font-size: 14px; color: var(--muted); margin-top: 6px; }

/* ---------- 订阅套餐 ---------- */
.plan-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; align-items: stretch; }
.plan {
  background: #fff; border: 1px solid var(--border); border-radius: 18px; padding: 30px;
  display: flex; flex-direction: column; position: relative; transition: all .25s;
}
.plan:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.plan.hot { border: 2px solid var(--primary); box-shadow: 0 10px 30px rgba(2,177,212,.14); }
.plan .tag { position: absolute; top: -13px; left: 50%; transform: translateX(-50%); background: var(--primary); color: #fff; font-size: 12px; font-weight: 700; padding: 4px 14px; border-radius: 99px; }
.plan h3 { font-size: 18px; color: var(--title); }
.plan .price { margin: 16px 0 4px; font-size: 40px; font-weight: 800; color: var(--title); line-height: 1; }
.plan .price small { font-size: 15px; color: var(--muted); }
.plan .price-unit { font-size: 14px; color: var(--muted); }
.plan ul { list-style: none; margin: 22px 0 26px; flex: 1; }
.plan ul li { padding: 8px 0; font-size: 14px; color: var(--body); display: flex; gap: 9px; align-items: flex-start; }
.plan ul li::before { content: "✓"; color: var(--primary-dark); font-weight: 700; flex: none; }

/* ---------- FAQ ---------- */
.faq-list { max-width: 820px; margin: 0 auto; }
.faq-item { background: #fff; border: 1px solid var(--border); border-radius: 12px; margin-bottom: 14px; overflow: hidden; }
.faq-item details summary { padding: 18px 22px; cursor: pointer; font-weight: 600; color: var(--title); font-size: 16px; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq-item details summary::-webkit-details-marker { display: none; }
.faq-item details summary::after { content: "+"; font-size: 22px; color: var(--primary-dark); font-weight: 400; }
.faq-item details[open] summary::after { content: "−"; }
.faq-item details .faq-a { padding: 0 22px 20px; font-size: 15px; color: var(--body); }

/* ---------- 正文 SEO 段 ---------- */
.seo-content { font-size: 15px; color: var(--body); text-align: justify; }
.seo-content p { margin-bottom: 14px; text-indent: 2em; }
.seo-content h2, .seo-content h3 { text-indent: 0; color: var(--title); margin: 22px 0 12px; }
.seo-content strong { color: var(--primary-darker); }

/* ---------- 文章页 ---------- */
.article { max-width: 820px; margin: 0 auto; }
.article-meta { color: var(--muted); font-size: 13px; margin: 14px 0 26px; display: flex; gap: 16px; flex-wrap: wrap; }
.article h2 { font-size: 22px; color: var(--title); margin: 28px 0 12px; }
.article h3 { font-size: 18px; color: var(--title); margin: 22px 0 10px; }
.article p { margin-bottom: 14px; text-align: justify; }
.article ul, .article ol { margin: 0 0 16px 22px; }
.article li { margin-bottom: 8px; }
.article strong { color: var(--primary-darker); }
.article .tip { background: var(--primary-light); border-left: 4px solid var(--primary); padding: 16px 18px; border-radius: 8px; margin: 18px 0; }

/* ---------- 面包屑 ---------- */
.breadcrumb { font-size: 13px; color: var(--muted); padding: 18px 0 0; }
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--primary-dark); }
.breadcrumb span { margin: 0 6px; color: var(--border); }

/* ---------- 页脚 ---------- */
.site-footer { background: #015a70; color: #a8e6f5; padding: 54px 0 0; margin-top: 40px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1fr; gap: 32px; }
.footer-col .f-logo { display: flex; align-items: center; gap: 8px; color: #fff; font-size: 17px; font-weight: 700; margin-bottom: 14px; }
.footer-col .f-logo img { border-radius: 8px; }
.footer-col p { font-size: 13px; color: #7fd9e8; line-height: 1.8; }
.footer-col h4 { color: #fff; font-size: 15px; margin-bottom: 16px; }
.footer-col a { display: block; color: #7fd9e8; font-size: 13px; padding: 5px 0; }
.footer-col a:hover { color: #02b1d4; }
.footer-bottom { border-top: 1px solid #017d99; margin-top: 40px; padding: 20px 0; font-size: 12px; color: #4aa8b8; text-align: center; }

/* ---------- 404 ---------- */
.error-404 { text-align: center; padding: 90px 0 70px; }
.error-404 .code { font-size: 100px; font-weight: 800; color: var(--primary); line-height: 1; }
.error-404 h1 { font-size: 26px; color: var(--title); margin: 18px 0 10px; }
.error-404 p { color: var(--muted); margin-bottom: 28px; }

/* ---------- 响应式 ---------- */
@media (max-width: 768px) {
  .nav { gap: 14px; flex-wrap: wrap; height: auto; padding: 12px 0; }
  .nav-links { order: 3; width: 100%; overflow-x: auto; gap: 2px; }
  .nav-links a { white-space: nowrap; }
  .hero { padding: 48px 5%; }
  .hero h1 { font-size: 30px; }
  .feature-grid, .dl-grid, .plan-grid { grid-template-columns: 1fr 1fr; }
  .scene-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .sec-head h2 { font-size: 25px; }
}
@media (max-width: 480px) {
  .feature-grid, .dl-grid, .plan-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .hero h1 { font-size: 26px; }
  .hero-cta { flex-direction: column; }
  .hero-cta .btn { width: 100%; }
  body { font-size: 15px; }
}