/* ============================================================
   纸飞机 · zhifeijiguanwang.com.cn ——「现代对话 · 消息气泡」设计语言
   现代浅灰蓝白底 + 电光蓝 + 在线绿 + 深海军蓝页脚,系统 sans-serif。
   观感:一款现代即时通讯软件 —— 居中标题 + 真实聊天会话窗口(消息气泡左右对话、
   已读回执、输入框)+ 消息气泡飞行光轨招牌 + 功能 bento + 场景气泡 + 全平台下载卡。
   ============================================================ */

:root {
  --bg: #f6f8fb;           /* 现代浅灰蓝白底 */
  --bg-2: #eef2f7;         /* 交替区块底 */
  --panel: #ffffff;        /* 卡片白 */
  --ink: #1a2332;          /* 深墨蓝 */
  --ink-2: #3a4a5f;
  --muted: #6b7a90;
  --blue: #3b5bfd;         /* 电光靛蓝(主 CTA) */
  --blue-2: #2f48e6;
  --green: #12b76a;        /* 在线/已送达绿 */
  --cyan: #2ec5ce;         /* 辅助青 */
  --line: #e5eaf1;
  --line-2: #d4dce8;
  --foot-bg: #0f1b2d;      /* 深海军蓝页脚 */
  --sans: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  --mono: "SF Mono", "Cascadia Code", Consolas, "Courier New", monospace;
  --r: 14px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--sans); background: var(--bg); color: var(--ink);
  line-height: 1.75; -webkit-font-smoothing: antialiased; overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
ul { list-style: none; }
h1, h2, h3, h4 { line-height: 1.3; font-weight: 700; }

.wrap { width: min(1080px, 92%); margin: 0 auto; }
.sec { padding: 84px 0; }
.center { text-align: center; padding: 96px 0; }

/* 区块标题 */
.sec-head { max-width: 640px; margin: 0 auto 46px; text-align: center; }
.sec-head h2 { font-size: 34px; letter-spacing: .5px; }
.sec-head p { color: var(--muted); margin-top: 14px; font-size: 15.5px; }
.kicker {
  display: inline-block; font-family: var(--mono); font-size: 12px; letter-spacing: 2px;
  color: var(--blue); text-transform: uppercase; margin-bottom: 14px; font-weight: 700;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-weight: 700; border-radius: 10px; border: 1px solid transparent;
  cursor: pointer; transition: transform .15s ease, box-shadow .15s ease, background .15s;
  font-family: var(--sans);
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: linear-gradient(135deg, var(--blue), var(--cyan)); color: #fff; box-shadow: 0 10px 26px -12px rgba(59, 91, 253, .55); }
.btn-primary:hover { background: linear-gradient(135deg, var(--blue-2), #26aeb8); }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--line-2); }
.btn-ghost:hover { border-color: var(--blue); color: var(--blue); }
.btn-outline { background: transparent; color: var(--blue); border-color: var(--blue); }
.btn-outline:hover { background: rgba(59, 91, 253, .07); }
.btn-sm { padding: 8px 16px; font-size: 13px; }
.btn-lg { padding: 15px 30px; font-size: 16px; }

/* ---------- 顶部信息条 ---------- */
.topbar { background: var(--foot-bg); color: #c7d2e0; font-family: var(--mono); }
.topbar-inner { display: flex; align-items: center; justify-content: space-between; height: 38px; font-size: 12px; letter-spacing: 1px; }
.tb-msg { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.tb-link { color: #7fb3ff; font-weight: 700; flex-shrink: 0; margin-left: 20px; }
.tb-link:hover { color: #fff; }

/* ---------- 导航 ---------- */
.nav { position: sticky; top: 0; z-index: 50; background: rgba(255, 255, 255, .94); backdrop-filter: blur(12px); border-bottom: 1px solid var(--line); }
.nav-inner { display: flex; align-items: center; gap: 30px; height: 66px; }
.brand { display: flex; align-items: center; gap: 11px; }
.brand-ico { width: 32px; height: 32px; }
.brand-name { font-weight: 800; font-size: 20px; letter-spacing: .5px; }
.brand-sub { display: block; font-family: var(--mono); font-size: 10px; letter-spacing: 1.5px; color: var(--blue); margin-top: -3px; }
.nav-links { margin-left: auto; display: flex; align-items: center; gap: 2px; }
.nav-links a { padding: 8px 15px; border-radius: 8px; font-size: 14.5px; font-weight: 600; color: var(--ink-2); }
.nav-links a:hover, .nav-links a.on { color: var(--blue); background: var(--bg-2); }
.nav-cta { margin-left: 4px; }
.nav-toggle { display: none; background: none; border: none; color: var(--ink); font-size: 24px; cursor: pointer; }

.dd { position: relative; }
.dd > button { background: none; border: none; font-size: 14.5px; font-weight: 600; color: var(--ink-2); padding: 8px 15px; border-radius: 8px; cursor: pointer; font-family: var(--sans); }
.dd > button:hover, .dd > button.on { color: var(--blue); background: var(--bg-2); }
.dd-menu { position: absolute; top: calc(100% + 10px); left: 0; min-width: 200px; background: #fff; border: 1px solid var(--line); border-radius: 12px; box-shadow: 0 20px 44px -20px rgba(26, 35, 50, .30); padding: 8px; display: none; z-index: 60; }
.dd:hover .dd-menu, .dd:focus-within .dd-menu { display: block; }
.dd-menu a { display: block; padding: 9px 14px; border-radius: 8px; font-size: 14px; color: var(--ink-2); font-weight: 500; }
.dd-menu a:hover { background: var(--bg-2); color: var(--blue); }

/* ---------- hero:现代聊天台 ---------- */
.chat {
  position: relative; overflow: hidden; color: var(--ink);
  padding: 90px 0 80px;
  background:
    radial-gradient(820px 460px at 12% -8%, rgba(59, 91, 253, .13), transparent 60%),
    radial-gradient(640px 400px at 94% 10%, rgba(46, 197, 206, .12), transparent 60%),
    linear-gradient(180deg, #ffffff 0%, var(--bg) 100%);
}
.chat::before {
  content: ""; position: absolute; inset: 0; pointer-events: none; opacity: .4;
  background-image: radial-gradient(rgba(59, 91, 253, .07) 1px, transparent 1px);
  background-size: 26px 26px;
}
.chat-inner {
  position: relative; z-index: 1; display: grid; grid-template-columns: 1.02fr .98fr;
  gap: 44px; align-items: center; max-width: 1080px;
}
.chat-txt { display: flex; flex-direction: column; align-items: flex-start; }
.chat-kicker {
  display: inline-flex; align-items: center; gap: 9px;
  font-family: var(--mono); font-size: 12px; letter-spacing: 1.5px; color: var(--blue);
  border: 1px solid rgba(59, 91, 253, .35); border-radius: 999px; padding: 6px 16px; background: #fff;
}
.chat-kicker .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--green); box-shadow: 0 0 12px var(--green); animation: blink 1.6s infinite; }
@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: .3; } }
.chat-h1 { font-size: 48px; line-height: 1.16; letter-spacing: .5px; margin: 26px 0 18px; }
.chat-h1 em { font-style: normal; color: var(--blue); }
.chat-lede { font-size: 16.5px; color: var(--ink-2); max-width: 600px; margin: 0 0 30px; }
.chat-cta { display: flex; gap: 13px; justify-content: flex-start; flex-wrap: wrap; }
.chat-note { font-family: var(--mono); font-size: 12px; color: var(--muted); margin-top: 18px; }

/* 三张聊天会话卡错落(hero 招牌,三卡等大) */
.hero-visual { position: relative; z-index: 1; height: 500px; }
.plane-track { position: absolute; top: -36px; left: -32px; width: 210px; height: 140px; z-index: 6; pointer-events: none; }
.hero-visual .chat-window {
  position: absolute; width: 190px;
  text-align: left; background: #fff; border: 1px solid var(--line-2); border-radius: 16px;
  box-shadow: 0 40px 76px -40px rgba(26, 35, 50, .42); overflow: hidden;
}
.hero-visual .card-main { left: 50%; top: 52%; transform: translate(-50%, -50%) rotate(-2deg); z-index: 3; }
.hero-visual .card-mid  { left: 0;   top: 2%;  transform: rotate(4deg);  z-index: 2; }
.hero-visual .card-back { right: 0;  top: 4%;  transform: rotate(-6deg); z-index: 1; }
.hero-visual .chat-window:hover { z-index: 6; }
.hero-visual .card-mid .chat-avatar { background: linear-gradient(135deg, #2ec5ce, #12b76a); }
.hero-visual .card-mid .bubble.to { background: #2ec5ce; }
.hero-visual .card-mid .send { background: #2ec5ce; }
.hero-visual .card-back .chat-avatar { background: linear-gradient(135deg, #12b76a, #3b5bfd); }
.hero-visual .card-back .bubble.to { background: #12b76a; }
.hero-visual .card-back .send { background: #12b76a; }
.chat-head { display: flex; align-items: center; gap: 10px; padding: 11px 14px; background: #fafcff; border-bottom: 1px solid var(--line); }
.chat-avatar {
  width: 32px; height: 32px; border-radius: 50%; background: linear-gradient(135deg, var(--blue), var(--cyan));
  color: #fff; display: flex; align-items: center; justify-content: center; font-size: 16px; flex-shrink: 0;
}
.chat-peer { display: flex; flex-direction: column; line-height: 1.3; flex: 1; }
.chat-peer strong { font-size: 12px; }
.chat-status { font-size: 10px; color: var(--green); font-family: var(--mono); }
.chat-opt { color: var(--muted); font-size: 14px; }
.chat-body { padding: 17px 14px 11px; background: #f4f7fb; display: flex; flex-direction: column; gap: 11px; }
.bubble { max-width: 82%; padding: 9px 12px; border-radius: 12px; font-size: 11.5px; position: relative; line-height: 1.5; }
.bubble.from { align-self: flex-start; background: #fff; border: 1px solid var(--line); border-bottom-left-radius: 4px; }
.bubble.to { align-self: flex-end; background: var(--blue); color: #fff; border-bottom-right-radius: 4px; }
.bubble p { margin: 0; }
.bubble-time { display: block; font-size: 9px; color: var(--muted); text-align: right; margin-top: 3px; font-family: var(--mono); }
.bubble.to .bubble-time { color: rgba(255,255,255,.8); }
.read { font-style: normal; color: var(--green); }
.bubble.to .read { color: #bff0d9; }
.chat-input { display: flex; align-items: center; justify-content: space-between; padding: 11px 14px; border-top: 1px solid var(--line); }
.ph { color: var(--muted); font-size: 11px; }
.send { background: var(--blue); color: #fff; padding: 6px 12px; border-radius: 8px; font-size: 11px; font-weight: 700; }

/* ---------- 功能 bento ---------- */
.bento { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.bento-card { background: #fff; border: 1px solid var(--line); border-radius: 16px; padding: 26px 24px; transition: transform .18s ease, box-shadow .18s ease; }
.bento-card:hover { transform: translateY(-4px); box-shadow: 0 22px 44px -24px rgba(26, 35, 50, .28); border-color: var(--line-2); }
.bento-ico { display: inline-flex; width: 48px; height: 48px; border-radius: 12px; background: #eef4ff; align-items: center; justify-content: center; font-size: 24px; margin-bottom: 14px; }
.bento-h3 { font-size: 18px; margin-bottom: 6px; }
.bento-p { color: var(--muted); font-size: 14px; }
.bento-card.big { grid-column: span 2; }
.bento-cta { background: linear-gradient(135deg, var(--blue), var(--cyan)); border-radius: 16px; color: #fff; display: flex; flex-direction: column; justify-content: center; padding: 26px 24px; transition: filter .18s ease; }
.bento-cta:hover { filter: brightness(1.06); }
.bento-cta-t { font-size: 20px; font-weight: 800; }
.bento-cta-s { font-size: 13.5px; opacity: .92; margin-top: 8px; }

/* 全球节点 */
.global-svg { max-width: 880px; margin: 0 auto; }
.global-svg svg { width: 100%; height: auto; display: block; }
.tz-strip { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; margin-top: 26px; }
.tz-city { background: #fff; border: 1px solid var(--line); border-radius: 999px; padding: 9px 18px; display: flex; gap: 9px; align-items: baseline; }
.tz-city b { font-size: 15px; }
.tz-city span { font-family: var(--mono); font-size: 12px; color: var(--blue); }

/* ---------- 即时送达流程 ---------- */
.flow-grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: 48px; align-items: center; }
.flow-svg { border: 1px solid var(--line); border-radius: var(--r); background: #fff; padding: 20px 16px; }
.flow-svg svg { width: 100%; height: auto; display: block; }
.flow-cards { display: flex; flex-direction: column; gap: 14px; }
.flow-card { background: #fff; border: 1px solid var(--line); border-left: 3px solid var(--blue); border-radius: 10px; padding: 18px 20px; }
.flow-num { font-family: var(--mono); font-size: 22px; font-weight: 800; color: var(--blue); }
.flow-card h3 { font-size: 18px; margin: 6px 0 5px; }
.flow-card p { color: var(--muted); font-size: 14px; }

/* ---------- 使用场景 ---------- */
.scene { display: flex; flex-direction: column; max-width: 820px; margin: 0 auto; }
.scene-entry {
  display: grid; grid-template-columns: 96px 1fr 200px; gap: 26px; padding: 36px 0;
  border-top: 1px solid var(--line); position: relative; align-items: center;
}
.scene-entry:first-child { border-top: none; }
.scene-body { display: flex; flex-direction: column; }
.scene-visual img { border-radius: 12px; border: 1px solid var(--line-2); width: 100%; aspect-ratio: 4/3; object-fit: cover; }
.scene-num { font-family: var(--mono); font-size: 42px; font-weight: 800; color: var(--bg-2); -webkit-text-stroke: 1px var(--line-2); line-height: 1; }
.scene-tag { font-family: var(--mono); font-size: 12px; letter-spacing: 2px; color: var(--blue); font-weight: 700; }
.scene-h3 { font-size: 24px; margin: 8px 0 8px; }
.scene-p { color: var(--muted); }
.scene-bubbles { margin-top: 14px; display: flex; flex-direction: column; gap: 7px; }
.scene-bubbles .from, .scene-bubbles .to {
  font-size: 13.5px; border-radius: 10px; padding: 8px 13px; max-width: 88%; line-height: 1.5;
}
.scene-bubbles .from { align-self: flex-start; background: #fff; border: 1px solid var(--line); border-bottom-left-radius: 3px; }
.scene-bubbles .to { align-self: flex-end; background: #eaf2fe; border: 1px solid #cfe0f8; border-bottom-right-radius: 3px; }

/* ---------- 全平台下载卡 ---------- */
.dls { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.dl-card {
  background: #fff; border: 1px solid var(--line-2); border-radius: var(--r); padding: 26px 22px;
  text-align: center; transition: transform .18s ease, box-shadow .18s ease;
}
.dl-card:hover { transform: translateY(-4px); box-shadow: 0 22px 44px -24px rgba(26, 35, 50, .30); }
.dl-ico { font-size: 34px; margin-bottom: 10px; }
.dl-os { font-size: 19px; font-weight: 800; margin-bottom: 4px; }
.dl-sub { color: var(--muted); font-size: 13px; margin-bottom: 18px; }
.dl-code { font-family: var(--mono); font-size: 11px; color: var(--muted); letter-spacing: 1px; margin-top: 14px; padding-top: 14px; border-top: 1px dashed var(--line); }

/* ---------- 常见问题(首页 FAQ) ---------- */
.manual { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; max-width: 900px; margin: 0 auto; }
.manual-item { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 20px 22px; }
.manual-q { font-size: 16px; font-weight: 700; margin-bottom: 7px; display: flex; gap: 10px; }
.manual-q .ico { color: var(--blue); font-family: var(--mono); font-size: 14px; }
.manual-a { color: var(--muted); font-size: 14px; }

/* ---------- 内页头 ---------- */
.pagehead { padding: 60px 0 26px; text-align: center; border-bottom: 1px solid var(--line); background: var(--bg-2); }
.pagehead h1 { font-size: 40px; letter-spacing: .5px; margin: 16px 0 12px; }
.pagehead h1 em { font-style: normal; color: var(--blue); }
.lede { max-width: 680px; margin: 0 auto; color: var(--muted); font-size: 16px; }
.head-cta { display: flex; gap: 12px; justify-content: center; margin: 26px 0 8px; flex-wrap: wrap; }
.breadcrumb { font-family: var(--mono); font-size: 13px; color: var(--muted); }
.breadcrumb a { color: var(--blue); }
.breadcrumb .sep { margin: 0 8px; color: var(--line-2); }

/* ---------- 左右图文 ---------- */
.duo { display: grid; grid-template-columns: 1fr 1fr; gap: 50px; align-items: center; }
.duo-txt h2 { font-size: 28px; margin-bottom: 14px; }
.duo-txt p { color: var(--muted); margin-bottom: 8px; }
.duo-img img { border-radius: var(--r); border: 1px solid var(--line-2); }

/* ---------- 步骤 ---------- */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.step { background: #fff; border: 1px solid var(--line); border-top: 3px solid var(--blue); border-radius: 12px; padding: 24px; }
.step-num { font-family: var(--mono); font-size: 30px; font-weight: 800; color: var(--blue); }
.step h4 { font-size: 18px; margin: 10px 0 6px; }
.step p { color: var(--muted); font-size: 13.5px; }

/* ---------- 表格 / 提示 ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--r); }
.table-wrap table { width: 100%; border-collapse: collapse; min-width: 480px; }
.table-wrap th, .table-wrap td { padding: 14px 18px; text-align: left; font-size: 14px; }
.table-wrap thead th { background: var(--foot-bg); color: #fff; font-family: var(--mono); font-size: 12px; letter-spacing: 1px; }
.table-wrap tbody tr { border-top: 1px solid var(--line); }
.table-wrap tbody td:first-child { font-weight: 700; white-space: nowrap; }
.table-wrap tbody td:last-child { color: var(--muted); }
.tip, .callout { display: flex; gap: 12px; padding: 16px 18px; border-radius: 12px; font-size: 14px; }
.tip { background: #eef4ff; border: 1px solid #d4e3fb; }
.callout { background: #eafbf2; border: 1px solid #c4efd8; }
.tip .e, .callout .e { font-size: 18px; flex-shrink: 0; }
.tip .e { color: var(--blue); }
.callout .e { color: var(--green); }
.tip p, .callout p { color: var(--ink-2); }

/* ---------- CTA 带 ---------- */
.cta-band { background: linear-gradient(135deg, var(--blue-2), var(--blue)); border-radius: 18px; padding: 56px 40px; text-align: center; color: #fff; position: relative; overflow: hidden; }
.cta-band::before { content: ""; position: absolute; width: 280px; height: 280px; border-radius: 50%; background: var(--cyan); filter: blur(100px); opacity: .3; top: -90px; right: -40px; }
.cta-band h2 { font-size: 30px; margin-bottom: 10px; position: relative; z-index: 1; }
.cta-band p { opacity: .9; margin-bottom: 26px; font-size: 15.5px; position: relative; z-index: 1; }
.cta-band .btn { position: relative; z-index: 1; background: #fff; color: var(--blue); }

/* ---------- 折叠 FAQ(内页) ---------- */
.faq-group { display: flex; flex-direction: column; gap: 10px; }
.faq-group details { background: #fff; border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.faq-group summary { cursor: pointer; padding: 16px 20px; font-size: 16px; font-weight: 700; }
.faq-group summary::-webkit-details-marker { display: none; }
.faq-group .faq-a { padding: 0 20px 16px; color: var(--muted); font-size: 14px; }

/* ---------- 文章页 ---------- */
.article-head { padding: 56px 0 8px; }
.article-head h1 { font-size: 38px; letter-spacing: .5px; margin: 18px 0 16px; max-width: 840px; }
.article-head .meta { display: flex; gap: 22px; flex-wrap: wrap; font-size: 13px; color: var(--muted); margin-top: 14px; }
.article-head .meta b { color: var(--ink-2); font-weight: 600; }
.article-body { padding: 40px 0 60px; }
.article-cols { display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 48px; align-items: start; }
.toc { position: sticky; top: 88px; background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 20px; }
.toc h5 { font-family: var(--mono); font-size: 11px; letter-spacing: 2px; color: var(--muted); margin-bottom: 14px; }
.toc ol { display: flex; flex-direction: column; gap: 10px; }
.toc li { display: flex; gap: 10px; font-size: 14px; }
.toc .num { font-family: var(--mono); color: var(--blue); }
.toc a { color: var(--ink-2); }
.toc a:hover { color: var(--blue); }
.prose { max-width: 720px; color: var(--ink-2); }
.prose h2 { font-size: 28px; color: var(--ink); margin: 42px 0 16px; padding-top: 6px; border-top: 1px solid var(--line); }
.prose h3 { font-size: 20px; color: var(--ink); margin: 28px 0 12px; }
.prose p { margin: 0 0 16px; }
.prose a { color: var(--blue); border-bottom: 1px solid var(--blue); }
.prose ul, .prose ol { margin: 0 0 16px 22px; }
.prose ul li { list-style: disc; margin: 6px 0; }
.prose ol li { list-style: decimal; margin: 6px 0; }
.prose img { border-radius: 12px; border: 1px solid var(--line-2); margin: 8px 0; }
.prose figure { margin: 22px 0; }
.prose figcaption { font-size: 12px; color: var(--muted); text-align: center; margin-top: 8px; }
.prose blockquote { border-left: 3px solid var(--blue); background: #fff; padding: 14px 18px; border-radius: 0 12px 12px 0; color: var(--ink); margin: 18px 0; }

/* 相关阅读 */
.related { max-width: 860px; margin: 0 auto; }
.rel-list { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.rel-item { background: #fff; border: 1px solid var(--line); border-radius: 10px; overflow: hidden; transition: border-color .15s ease; }
.rel-item:hover { border-color: var(--blue); }
.rel-item a { padding: 18px; display: flex; flex-direction: column; gap: 8px; }
.rel-item .tag { font-family: var(--mono); font-size: 11px; color: var(--blue); }
.rel-item h4 { font-size: 15.5px; font-weight: 700; color: var(--ink); }
.rel-item .go { color: var(--muted); font-size: 20px; align-self: flex-end; }

/* 分享 */
.share { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-top: 40px; padding-top: 22px; border-top: 1px solid var(--line); }
.share-lbl { font-family: var(--mono); font-size: 12px; color: var(--muted); margin-right: 4px; }
.share a { font-size: 13px; color: var(--ink-2); border: 1px solid var(--line); border-radius: 9px; padding: 6px 12px; }
.share a:hover { color: var(--blue); border-color: var(--blue); }

/* ---------- 工具页 ---------- */
.search-box { display: flex; gap: 10px; justify-content: center; margin: 24px 0; }
.search-box input {
  width: min(440px, 70vw); background: #fff; border: 1px solid var(--line-2); border-radius: 12px;
  color: var(--ink); padding: 14px 18px; font-size: 15px; outline: none;
}
.search-box input:focus { border-color: var(--blue); }
.sitemap-list { display: flex; flex-direction: column; gap: 6px; }
.sitemap-list .grp { font-family: var(--mono); font-size: 12px; letter-spacing: 2px; color: var(--blue); margin: 18px 0 4px; }
.sitemap-list li a { color: var(--ink-2); font-size: 15px; }
.sitemap-list li a:hover { color: var(--blue); }

/* ---------- 页脚 ---------- */
.foot { background: var(--foot-bg); color: #c7d2e0; }
.foot-inner { padding: 44px 0 34px; text-align: center; }
.foot-line { font-family: var(--mono); font-size: 13px; letter-spacing: 1px; color: #8fa1b8; }
.foot-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 6px 20px; margin: 20px 0 4px; }
.foot-links a { font-size: 13px; color: #c7d2e0; }
.foot-links a:hover { color: #7fb3ff; }
.foot-cr { border-top: 1px solid rgba(255,255,255,.10); padding: 18px 0; text-align: center; color: #8fa1b8; font-size: 13px; }

/* ---------- 返回顶部 ---------- */
.backtop {
  position: fixed; right: 22px; bottom: 22px; width: 44px; height: 44px; border-radius: 10px;
  background: var(--blue); border: 1px solid var(--blue-2); color: #fff;
  font-size: 20px; cursor: pointer; opacity: 0; pointer-events: none; transition: opacity .2s;
}
.backtop.show { opacity: 1; pointer-events: auto; }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .nav-toggle { display: block; }
  .nav-links { position: absolute; top: 66px; left: 0; right: 0; background: #fff; flex-direction: column; align-items: stretch; padding: 12px; border-bottom: 1px solid var(--line); display: none; }
  .nav-links.open { display: flex; }
  .nav-cta { display: none; }
  .dd-menu { position: static; display: block; box-shadow: none; border: none; min-width: 0; padding-left: 14px; }
  .dd > button { display: none; }
  .chat-h1 { font-size: 40px; }
  .chat-inner { grid-template-columns: 1fr; }
  .hero-visual { margin: 0 auto; height: 400px; }
  .hero-visual .chat-window { width: 165px; }
  .flow-grid, .duo, .article-cols { grid-template-columns: 1fr; }
  .bento, .dls { grid-template-columns: 1fr 1fr; }
  .bento-card.big { grid-column: span 1; }
  .steps, .manual { grid-template-columns: 1fr; }
  .rel-list { grid-template-columns: 1fr; }
  .toc { position: static; }
}
@media (max-width: 560px) {
  .chat-h1 { font-size: 31px; }
  .bento, .dls { grid-template-columns: 1fr; }
  .scene-entry { grid-template-columns: 60px 1fr; }
  .scene-num { font-size: 32px; }
  .scene-visual { display: none; }
  .plane-track { width: 160px; height: 108px; }
  .hero-visual { height: 360px; }
  .hero-visual .chat-window { width: 140px; }
}