/* ============================================================
   红线 Hongxian · 产品介绍网站样式 v2
   ------------------------------------------------------------
   品牌宪法（《定位声明》§11）：graph/网络语言贯穿；禁渐变、禁投影；
   英文一律拼音 HONGXIAN。
   Logo 交付包规则 4：亮底用红线红 #C8102E，墨底用提亮红 #E8556A。
   —— v2 的核心手法：在不违反「禁渐变禁投影」的前提下，
      用「明暗版面的交替节奏」替代「光影装饰」制造视觉层次。

   设计令牌分层：
     纸面层  paper / paper-alt / paper-deep  —— 亮区，靠线与面差建立秩序
     墨底层  ink / ink-raised / ink-line     —— 深区，靠明度差建立秩序
     主色    red（亮底）/ red-bright（墨底）  —— 严格遵守 logo 规则 4
     点缀    orange（结点橙，整站严格克制）
   隐私自证：系统字体栈，无字体 CDN、无统计 SDK、无外部资源。
   ============================================================ */

:root {
  /* ---------- 品牌主色 ---------- */
  --red: #C8102E;           /* 红线红：亮底边线、主按钮 */
  --red-dark: #B02E35;      /* 绛红：亮底字标、强调文字 */
  --red-bright: #E8556A;    /* 提亮红：墨底专用（logo 规则 4） */
  --orange: #F08200;        /* 结点橙：唯一点缀 */
  --ink: #1F2937;           /* 墨：亮底主文字、节点 */
  --gray: #5F5E5A;          /* 亮底次级文字 */

  /* ---------- 纸面层（亮区） ---------- */
  --paper: #FDFBF7;         /* 纸白：页面底 */
  --paper-alt: #F7F3EC;     /* 次纸面：交替区 */
  --paper-card: #FFFFFF;    /* 卡片面 */
  --paper-line: #E7E0D5;    /* 纸面分隔线 */
  --paper-line-soft: #F0EAE0;
  --tint: #FCEBEB;          /* 红晕底 */
  --tint-line: #F09595;

  /* ---------- 墨底层（深区） ---------- */
  --deep: #141B25;          /* 墨底：深区背景（比 --ink 更深的底） */
  --deep-2: #1C2531;        /* 墨底卡片面 */
  --deep-3: #232E3C;        /* 墨底更高层 */
  --deep-line: #33404F;     /* 墨底分隔线 */
  --deep-line-soft: #28323F;
  --on-deep: #EDE9E2;      /* 墨底主文字 */
  --on-deep-2: #A9B2BE;    /* 墨底次级文字 */
  --on-deep-3: #6E7885;    /* 墨底弱文字 */

  /* ---------- 尺度 ---------- */
  --font: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
  --mono: Consolas, "SF Mono", "Courier New", monospace;
  --r-sm: 8px;
  --r: 12px;
  --r-lg: 18px;
  --container: 1160px;
  --header-h: 68px;
  --measure: 34em;
}

* { box-sizing: border-box; }

/* hidden 属性必须战胜一切作者 display 规则 */
[hidden] { display: none !important; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 20px);
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.78;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3 { line-height: 1.25; margin: 0; letter-spacing: -0.01em; }
p { margin: 0 0 1em; }
img { max-width: 100%; height: auto; display: block; }
strong { font-weight: 600; }

code {
  font-family: var(--mono);
  font-size: 0.9em;
  background: #F3EEE6;
  border: 1px solid var(--paper-line);
  border-radius: 5px;
  padding: 1px 6px;
}

.container { max-width: var(--container); margin: 0 auto; padding: 0 28px; }
.container-narrow { max-width: 820px; }

.skip-link {
  position: absolute; left: -9999px; top: 0;
  background: var(--red); color: var(--paper);
  padding: 10px 18px; z-index: 100; border-radius: 0 0 var(--r-sm) 0;
}
.skip-link:focus { left: 0; }

:focus-visible { outline: 2px solid var(--red); outline-offset: 3px; border-radius: 4px; }
.deep :focus-visible { outline-color: var(--red-bright); }

/* ============================================================
   ① 头部导航
   ============================================================ */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(253, 251, 247, 0.92);
  backdrop-filter: saturate(1.4) blur(12px);
  border-bottom: 1px solid var(--paper-line);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: var(--header-h); gap: 24px;
}
.brand {
  display: flex; align-items: center; gap: 11px;
  text-decoration: none; color: var(--ink); flex: none;
}
.brand-mark { flex: none; }
.brand-text { font-weight: 700; font-size: 19px; letter-spacing: 0.01em; }
.brand-en {
  display: inline-block; margin-left: 7px;
  font-size: 10.5px; font-weight: 500; letter-spacing: 0.24em;
  color: var(--red-dark);
}

.nav-links { display: flex; align-items: center; gap: 2px; list-style: none; margin: 0; padding: 0; }
.nav-links a {
  display: block; padding: 7px 13px; border-radius: var(--r-sm);
  color: #3D4753; text-decoration: none; font-size: 14.5px;
  transition: background-color .16s ease, color .16s ease;
}
.nav-links a:hover { background: #F3EEE6; color: var(--red-dark); }
.nav-github {
  border: 1px solid var(--red); color: var(--red-dark) !important;
  margin-left: 10px; font-weight: 500;
}
.nav-github:hover { background: var(--red); color: var(--paper) !important; }

.nav-toggle {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: 1px solid var(--paper-line);
  border-radius: var(--r-sm); padding: 9px 10px; cursor: pointer;
}
.nav-toggle-bar { width: 20px; height: 2px; background: var(--ink); }

/* ============================================================
   ② Hero 首屏 —— 「所有信号都通向你」
   ============================================================ */
.hero { padding: 84px 0 72px; position: relative; overflow: hidden; }

/* 背景：极淡的 graph 网格（禁渐变，改用实线细网格） */
.hero::before {
  content: ""; position: absolute; inset: 0; z-index: 0;
  background-image:
    linear-gradient(var(--paper-line-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--paper-line-soft) 1px, transparent 1px);
  background-size: 56px 56px;
  opacity: .55;
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 40%, #000 40%, transparent 100%);
          mask-image: radial-gradient(ellipse 70% 60% at 50% 40%, #000 40%, transparent 100%);
}

.hero-grid {
  position: relative; z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(360px, 480px);
  gap: 56px; align-items: center;
}

.hero-eyebrow {
  display: inline-flex; align-items: center; gap: 9px;
  font-size: 11.5px; font-weight: 500; letter-spacing: 0.2em;
  color: var(--red-dark);
  border: 1px solid var(--tint-line); background: var(--tint);
  border-radius: 999px; padding: 5px 14px 5px 11px; margin-bottom: 26px;
}
.hero-eyebrow-dot {
  width: 6px; height: 6px; border-radius: 50%; background: var(--orange); flex: none;
}

.hero-copy h1 {
  font-size: clamp(38px, 5.4vw, 64px);
  font-weight: 700; line-height: 1.14; letter-spacing: -0.02em;
  margin-bottom: 24px;
}
.hero-copy h1 .accent { color: var(--red); display: block; }

.hero-lead {
  font-size: 17.5px; line-height: 1.85; color: #3D4753;
  max-width: var(--measure); margin-bottom: 8px;
}
.hero-lead strong { color: var(--red-dark); }

.hero-cta { display: flex; flex-wrap: wrap; gap: 14px; margin: 32px 0 30px; }

/* 承诺带：细线分隔的一行，比胶囊标签更有编辑感 */
.badges {
  display: flex; flex-wrap: wrap; align-items: center; gap: 0;
  list-style: none; margin: 0; padding: 18px 0 0;
  border-top: 1px solid var(--paper-line);
  font-size: 13px; color: var(--gray);
}
.badges li { display: flex; align-items: center; }
.badges li + li::before {
  content: ""; width: 3px; height: 3px; border-radius: 50%;
  background: var(--orange); margin: 0 14px; flex: none;
}

/* 构图：信号汇聚 */
.hero-art { position: relative; display: flex; justify-content: center; }
.hero-art-frame {
  position: relative; width: 100%;
  border: 1px solid var(--paper-line);
  border-radius: var(--r-lg);
  background: rgba(255, 255, 255, 0.55);
  padding: 22px 20px 18px;
}
.hero-art-label {
  font-size: 10px; letter-spacing: 0.18em; color: var(--gray);
  display: flex; align-items: center; gap: 10px; margin-bottom: 6px;
}
.hero-art-label::after { content: ""; flex: 1; height: 1px; background: var(--paper-line); }
.hero-net { display: block; width: 100%; height: auto; }

/* 标志上的信号流动动画（logo 交付包规则 6） */
@media (prefers-reduced-motion: no-preference) {
  .hero-flow { animation: flow 7s linear infinite; }
  @keyframes flow { from { stroke-dashoffset: 200; } to { stroke-dashoffset: 0; } }
  .hero-pulse { animation: pulse 4.5s ease-in-out infinite; }
  @keyframes pulse { 0%, 100% { opacity: .35; } 50% { opacity: 1; } }
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-family: var(--font); font-size: 15.5px; font-weight: 500; line-height: 1.4;
  padding: 13px 28px; border-radius: var(--r-sm); cursor: pointer;
  text-decoration: none; border: 1px solid transparent;
  transition: background-color .16s ease, color .16s ease, border-color .16s ease;
}
.btn-primary { background: var(--red); color: var(--paper); border-color: var(--red); }
.btn-primary:hover { background: #A80D27; border-color: #A80D27; }
.btn-ghost { background: transparent; color: var(--red-dark); border-color: var(--red); }
.btn-ghost:hover { background: var(--tint); }
.btn-small { font-size: 13.5px; padding: 8px 16px; }
.btn[aria-disabled="true"] { opacity: .5; pointer-events: none; }

/* ---------- 三步安装面板 ---------- */
.install-panel {
  position: relative; z-index: 1;
  margin-top: 52px;
  border: 1px solid var(--paper-line);
  border-top: 3px solid var(--red);
  border-radius: var(--r);
  background: var(--paper-card);
  padding: 32px 32px 22px;
}
.install-steps {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px;
  list-style: none; margin: 0; padding: 0; counter-reset: step;
}
.install-steps li { counter-increment: step; position: relative; padding-top: 40px; }
.install-steps li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute; top: 0; left: 0;
  font-family: var(--mono); font-size: 13px; font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--paper); background: var(--red);
  border-radius: 6px; padding: 3px 9px;
}
.install-steps h3 { font-size: 16.5px; margin-bottom: 8px; }
.install-steps p { font-size: 14px; color: var(--gray); margin-bottom: 12px; }
.install-note {
  margin: 24px 0 0; padding-top: 18px;
  border-top: 1px dashed var(--paper-line);
  font-size: 13px; color: var(--gray);
}
.code-block {
  display: flex; align-items: center; gap: 10px;
  background: #F5F1EA; border: 1px solid var(--paper-line);
  border-radius: var(--r-sm); padding: 9px 9px 9px 14px;
}
.code-block code {
  background: none; border: none; padding: 0;
  font-size: 13px; color: var(--ink); flex: 1;
  white-space: nowrap; overflow-x: auto;
}
.copy-btn {
  flex: none; font-family: var(--font); font-size: 12.5px;
  color: var(--red-dark); background: var(--paper);
  border: 1px solid var(--tint-line); border-radius: 6px;
  padding: 5px 12px; cursor: pointer;
}
.copy-btn:hover { background: var(--tint); }

/* ============================================================
   ③ 通用区块骨架
   ============================================================ */
.section { padding: 96px 0; position: relative; }
.section-alt { background: var(--paper-alt); border-block: 1px solid var(--paper-line); }
.section-deep { background: var(--deep); color: var(--on-deep); }
.section-deep h1, .section-deep h2, .section-deep h3 { color: var(--on-deep); }
.section-deep p { color: var(--on-deep-2); }
.section-deep strong { color: var(--red-bright); }
.section-deep .eyebrow { color: var(--red-bright); }
.section-deep .lead { color: var(--on-deep-2); }
.section-deep strong { color: var(--red-bright); }

/* 区块编号：小字号的 graph 节点编号，取代平淡的 eyebrow */
.section-head { max-width: 52em; margin-bottom: 56px; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 10px;
  font-size: 11.5px; font-weight: 600; letter-spacing: 0.2em;
  color: var(--red-dark); margin-bottom: 16px;
}
.eyebrow::before {
  content: ""; width: 22px; height: 1px; background: currentColor; opacity: .5; flex: none;
}
.section-head h2 {
  font-size: clamp(27px, 3.6vw, 42px);
  font-weight: 700; letter-spacing: -0.02em; margin-bottom: 18px;
}
.lead { font-size: 17px; line-height: 1.85; color: #3D4753; max-width: 46em; }
.section-deep .lead { color: var(--on-deep-2); }

/* ---------- ④ 工作原理：三张「横向叙事卡」 ---------- */
.how-grid { display: grid; gap: 28px; }
.how-card {
  margin: 0;
  display: grid; grid-template-columns: minmax(0, 400px) minmax(0, 1fr);
  align-items: stretch; gap: 0;
  background: var(--paper-card);
  border: 1px solid var(--paper-line);
  border-radius: var(--r-lg);
  overflow: hidden;
}
.how-card figcaption {
  padding: 40px 32px 40px 38px;
  display: flex; flex-direction: column; justify-content: center;
}
.how-card h3 {
  font-size: 21px; font-weight: 700; margin-bottom: 14px;
  display: flex; align-items: center; gap: 11px;
}
.how-card h3 .num {
  font-family: var(--mono); font-size: 12px; font-weight: 700;
  color: var(--red); background: var(--tint);
  border-radius: 5px; padding: 3px 8px; letter-spacing: 0.04em; flex: none;
}
.how-card p { font-size: 15px; line-height: 1.8; color: #3D4753; margin-bottom: 10px; }
.how-card p strong { color: var(--red-dark); }
.how-card .illus-box {
  background: var(--paper-alt);
  border-left: 1px solid var(--paper-line);
  padding: 30px 30px 30px 24px;
  align-self: stretch; display: flex; align-items: center; justify-content: center;
}
.how-card .illus { display: block; width: 100%; height: auto; max-width: 620px; }

/* ============================================================
   ⑤ Demo 区 —— 墨底「深水区」
   ============================================================ */
#demo { border-top: 1px solid #0D131B; }
.demo-grid {
  display: grid;
  grid-template-columns: minmax(320px, 440px) minmax(0, 1fr);
  gap: 36px; align-items: start;
}

.chat {
  background: var(--deep-2);
  border: 1px solid var(--deep-line);
  border-radius: var(--r-lg);
  overflow: hidden;
}
.chat-head {
  display: flex; align-items: center; gap: 11px;
  padding: 14px 18px;
  border-bottom: 1px solid var(--deep-line);
  background: var(--deep-3);
}
.chat-head img { filter: brightness(1.45) saturate(0.75); }
.chat-name { font-weight: 600; font-size: 15px; color: var(--on-deep); }
.demo-tag {
  margin-left: auto; font-size: 11.5px; letter-spacing: 0.04em;
  color: var(--red-bright); background: rgba(232, 85, 106, 0.12);
  border: 1px solid rgba(232, 85, 106, 0.32);
  border-radius: 999px; padding: 2px 11px;
}
.chat-body {
  padding: 22px 18px;
  display: flex; flex-direction: column; gap: 14px;
  min-height: 320px; max-height: 440px; overflow-y: auto;
}
.msg {
  max-width: 90%;
  padding: 11px 15px; border-radius: 14px;
  font-size: 14.5px; line-height: 1.75;
  white-space: pre-line;
}
.msg-yuelao {
  align-self: flex-start;
  background: var(--deep-3);
  border: 1px solid var(--deep-line);
  border-bottom-left-radius: 4px;
  color: var(--on-deep);
}
.msg-user {
  align-self: flex-end;
  background: rgba(200, 16, 46, 0.22);
  border: 1px solid rgba(232, 85, 106, 0.4);
  border-bottom-right-radius: 4px;
  color: #F6DDDF;
}
.msg-typing { align-self: flex-start; color: var(--on-deep-3); font-size: 13px; padding: 4px 14px; }
/* 敏感题：替用户问出不好意思问的问题 —— 墨底上用提亮红强调（logo 规则 4） */
.msg-sensitive {
  background: rgba(232, 85, 106, 0.1);
  border: 1px solid rgba(232, 85, 106, 0.34);
  border-left: 3px solid var(--red-bright);
  color: var(--on-deep);
}
.chat-options { display: flex; flex-wrap: wrap; gap: 10px; padding: 0 18px 16px; }
.opt-btn {
  font-family: var(--font); font-size: 13.5px; text-align: left;
  color: var(--on-deep); background: var(--deep-3);
  border: 1px solid var(--deep-line);
  border-radius: 999px; padding: 8px 16px; cursor: pointer;
  transition: background-color .16s ease, border-color .16s ease, color .16s ease;
}
.opt-btn:hover {
  background: rgba(232, 85, 106, 0.16);
  border-color: var(--red-bright); color: #FFD9DD;
}
.opt-btn:disabled { opacity: .45; cursor: default; }
.chat-foot { display: flex; gap: 10px; flex-wrap: wrap; padding: 0 18px 18px; }
.chat-foot .btn[hidden] { display: none; }
.chat-foot .btn-ghost { color: var(--red-bright); border-color: rgba(232, 85, 106, 0.5); }
.chat-foot .btn-ghost:hover { background: rgba(232, 85, 106, 0.14); }

/* 样例报告：墨底上的一张「纸」—— 强反差，视线自然落在结论上 */
.report-wrap { display: flex; flex-direction: column; gap: 18px; }
.report {
  background: var(--paper);
  border: 1px solid var(--paper-line);
  border-top: 3px solid var(--red);
  border-radius: var(--r);
  padding: 26px 28px;
  color: var(--ink);
}
.report-head {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 8px; padding-bottom: 14px;
  border-bottom: 1px solid var(--paper-line);
}
.report-title { font-weight: 700; font-size: 15.5px; margin: 0; letter-spacing: 0.02em; }
.report-private {
  font-size: 11.5px; color: var(--red-dark);
  background: var(--tint); border: 1px solid var(--tint-line);
  border-radius: 999px; padding: 3px 11px;
}
.report-meta { font-size: 13px; color: var(--gray); }
.report-tier {
  background: var(--tint); border: 1px solid var(--tint-line);
  border-radius: var(--r-sm); padding: 13px 16px; margin-bottom: 18px;
}
.report-tier p { margin: 0; font-size: 14px; }
.tier-name { color: var(--red-dark); font-weight: 700; font-size: 16px; }
.tier-rank { color: var(--gray); font-size: 12px; margin-left: 9px; }
.tier-basis { font-size: 12.5px; color: #3D4753; margin-top: 6px !important; }
.report-label {
  font-size: 12px; font-weight: 600; letter-spacing: 0.1em;
  color: var(--red-dark); margin: 0 0 5px;
}
.report-label:not(:first-of-type) { margin-top: 16px; }
.report-text { font-size: 14px; color: #3D4753; line-height: 1.8; margin: 0; }
.report-foot {
  font-size: 12px; color: var(--gray);
  border-top: 1px solid var(--paper-line);
  padding-top: 12px; margin: 18px 0 0;
}
.tier-strip { display: flex; flex-wrap: wrap; gap: 8px; }
.tier {
  font-size: 12.5px; color: var(--on-deep-2);
  border: 1px solid var(--deep-line);
  border-radius: 999px; padding: 4px 13px;
  background: var(--deep-2);
}
.tier-on {
  color: var(--paper); background: var(--red);
  border-color: var(--red); font-weight: 600;
}
.report-note { font-size: 12.5px; color: var(--on-deep-3); margin: 0; }

/* ============================================================
   ⑥ 信任清单 —— 竖向 stepper（连通的 graph 节点）
   ============================================================ */
.trust-list {
  list-style: none; margin: 0; padding: 0;
  counter-reset: trust;
  max-width: 860px;
}
.trust-step {
  position: relative;
  display: flex; gap: 24px;
  padding: 0 0 32px 0;
}
.trust-step:last-child { padding-bottom: 0; }
/* 节点之间的连线 */
.trust-step:not(:last-child)::before {
  content: ""; position: absolute;
  left: 19px; top: 42px; bottom: 2px;
  width: 1px; background: var(--paper-line);
}
.trust-num {
  flex: none; position: relative; z-index: 1;
  width: 40px; height: 40px; border-radius: 50%;
  border: 1.5px solid var(--red);
  background: var(--paper);
  color: var(--red); font-family: var(--mono);
  font-weight: 700; font-size: 14px;
  display: flex; align-items: center; justify-content: center;
}
.trust-step h3 { font-size: 18.5px; margin-bottom: 8px; }
.trust-step p { font-size: 15px; line-height: 1.8; color: #3D4753; margin: 0; max-width: 46em; }
.trust-foot {
  margin-top: 40px; padding: 20px 24px;
  font-size: 15px; color: var(--red-dark);
  background: var(--tint);
  border: 1px solid var(--tint-line);
  border-radius: var(--r);
  max-width: 860px;
}

/* ============================================================
   ⑦ 透明数据区 —— 墨底数据面板
   ============================================================ */
#data { border-top: 1px solid #0D131B; }
.stats-grid {
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px;
}
.stat-card {
  background: var(--deep-2);
  border: 1px solid var(--deep-line);
  border-radius: var(--r);
  padding: 24px 24px 22px;
}
.stat-wide { grid-column: span 3; }
.stat-num {
  font-size: 42px; font-weight: 700;
  color: var(--red-bright);
  font-variant-numeric: tabular-nums;
  margin: 0 0 4px; line-height: 1.15;
  font-family: var(--mono); letter-spacing: -0.02em;
}
.stat-label {
  font-size: 12px; color: var(--on-deep-3);
  letter-spacing: 0.06em; margin: 0;
}
.stat-empty { font-size: 13px; color: var(--on-deep-3); margin: 10px 0 0; }

.bar {
  display: flex; height: 30px; border-radius: var(--r-sm);
  overflow: hidden; background: var(--deep-3);
  border: 1px solid var(--deep-line);
  margin-top: 12px;
}
.bar-seg {
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 600;
  min-width: 0; transition: width .6s ease;
}
.bar-f { background: var(--red-bright); color: #2A0A0E; }
.bar-m { background: var(--deep-line); color: var(--on-deep); }
.bar-stacked { height: 36px; }
.bar-stacked .bar-seg {
  background: var(--red-bright); color: #2A0A0E;
  border-right: 1px solid var(--deep);
}
.bar-stacked .bar-seg:last-child { border-right: none; }

.stats-empty-lead {
  margin-top: 22px; font-size: 15px; color: var(--on-deep);
  background: var(--deep-2); border: 1px solid var(--deep-line);
  border-left: 3px solid var(--red-bright);
  border-radius: var(--r-sm); padding: 14px 20px;
}
.stats-detail {
  margin-top: 20px;
  border: 1px solid var(--deep-line);
  border-radius: var(--r); background: var(--deep-2);
  padding: 16px 20px;
}
.stats-detail summary {
  cursor: pointer; font-size: 14.5px; font-weight: 500;
  color: var(--on-deep); list-style: none;
  display: flex; align-items: center; gap: 10px;
}
.stats-detail summary::-webkit-details-marker { display: none; }
.stats-detail summary::after { content: "+"; margin-left: auto; color: var(--red-bright); font-size: 18px; }
.stats-detail[open] summary::after { content: "−"; }
.stats-detail p { font-size: 14px; line-height: 1.8; margin: 14px 0 0; color: var(--on-deep-2); }

/* ============================================================
   ⑧ FAQ —— 双栏编辑版式（左栏 sticky 标题）
   ============================================================ */
.faq-layout {
  display: grid; grid-template-columns: minmax(0, 300px) minmax(0, 720px);
  gap: 72px; align-items: start; justify-content: start;
}
.faq-aside { position: sticky; top: calc(var(--header-h) + 40px); }
.faq-aside h2 {
  font-size: clamp(26px, 3vw, 36px); font-weight: 700;
  letter-spacing: -0.02em; margin: 0;
}
.faq-aside .eyebrow { margin-bottom: 16px; }
.faq-aside p { font-size: 14.5px; color: var(--gray); margin: 18px 0 0; }

.faq-list { display: grid; gap: 0; border-top: 1px solid var(--paper-line); }
.faq-item { border-bottom: 1px solid var(--paper-line); }
.faq-item summary {
  cursor: pointer; list-style: none;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 22px 0; font-size: 17px; font-weight: 600;
  transition: color .16s ease;
}
.faq-item summary:hover { color: var(--red-dark); }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; flex: none;
  font-size: 21px; font-weight: 300;
  color: var(--red); transition: transform .2s ease;
}
.faq-item[open] summary::after { content: "−"; }
.faq-item p {
  font-size: 15px; line-height: 1.85; color: #3D4753;
  margin: 0; padding: 0 0 24px;
  max-width: 44em;
}
.faq-item p strong { color: var(--red-dark); }

/* ============================================================
   ⑨ 页脚 —— 墨底收尾
   ============================================================ */
.site-footer {
  background: var(--deep);
  color: var(--on-deep);
  padding: 72px 0 34px;
  border-top: 1px solid #0D131B;
}
.footer-grid {
  display: grid; grid-template-columns: minmax(0, 1.6fr) repeat(3, minmax(0, 1fr));
  gap: 44px; padding-bottom: 44px;
}
.footer-brand img { margin-bottom: 20px; }
.footer-brand p { font-size: 13.5px; line-height: 1.8; color: var(--on-deep-2); max-width: 32em; }
.footer-col h2 {
  font-size: 11.5px; font-weight: 600; letter-spacing: 0.16em;
  color: var(--on-deep-3); margin-bottom: 16px;
}
.footer-col ul { list-style: none; margin: 0; padding: 0; }
.footer-col li { margin-bottom: 10px; }
.footer-col a, .footer-col li { font-size: 13.5px; color: var(--on-deep-2); text-decoration: none; }
.footer-col a:hover { color: var(--red-bright); }

/* 赞助区：与产品功能区物理隔离（措辞纪律） */
.sponsor {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 24px;
  border: 1px dashed var(--deep-line);
  border-radius: var(--r);
  background: var(--deep-2);
  padding: 26px 28px;
}
.sponsor h2 { font-size: 16.5px; margin-bottom: 8px; color: var(--on-deep); }
.sponsor p { font-size: 13.5px; line-height: 1.8; color: var(--on-deep-2); margin: 0; max-width: 48em; }
.sponsor p strong { color: var(--red-bright); }
.sponsor-links { display: flex; gap: 12px; flex-wrap: wrap; }
.sponsor .btn-ghost { color: var(--red-bright); border-color: rgba(232, 85, 106, 0.45); }
.sponsor .btn-ghost:hover { background: rgba(232, 85, 106, 0.14); }

.footer-bottom {
  margin-top: 40px; padding-top: 24px;
  border-top: 1px solid var(--deep-line-soft);
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: 10px;
}
.footer-bottom p { font-size: 12.5px; color: var(--on-deep-3); margin: 0; }

/* ============================================================
   ⑩ 滚动显现
   ============================================================ */
@media (prefers-reduced-motion: no-preference) {
  .reveal { opacity: 0; transform: translateY(20px); transition: opacity .6s ease, transform .6s ease; }
  .reveal.is-visible { opacity: 1; transform: none; }
}

/* ============================================================
   ⑪ 响应式
   ============================================================ */
@media (max-width: 1020px) {
  .hero-grid { grid-template-columns: 1fr; gap: 44px; }
  .hero-art-frame { max-width: 520px; }
  .how-card { grid-template-columns: 1fr; }
  .how-card .illus-box { border-left: none; border-top: 1px solid var(--paper-line); padding: 24px; }
  .demo-grid { grid-template-columns: 1fr; }
  .faq-layout { grid-template-columns: 1fr; gap: 36px; }
  .faq-aside { position: static; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 36px; }
}

@media (max-width: 720px) {
  body { font-size: 15px; }
  .section { padding: 62px 0; }
  .container { padding: 0 20px; }
  .hero { padding: 48px 0 44px; }
  .hero-copy h1 { font-size: clamp(31px, 8.6vw, 42px); }
  .hero-lead { font-size: 16px; }
  .nav-toggle { display: flex; }
  .nav {
    position: absolute; top: var(--header-h); left: 0; right: 0;
    background: var(--paper);
    border-bottom: 1px solid var(--paper-line);
    display: none;
  }
  .nav.is-open { display: block; }
  .nav-links { flex-direction: column; align-items: stretch; gap: 0; padding: 8px 20px 16px; }
  .nav-links a { padding: 12px 8px; }
  .nav-github { margin-left: 0; text-align: center; }
  .install-panel { padding: 24px 20px 18px; }
  .install-steps { grid-template-columns: 1fr; gap: 24px; }
  .stats-grid { grid-template-columns: 1fr; }
  .stat-wide { grid-column: span 1; }
  .stat-num { font-size: 34px; }
  .footer-grid { grid-template-columns: 1fr; gap: 30px; }
  .sponsor { padding: 22px 20px; }
  .chat-body { min-height: 280px; }
  .report { padding: 22px 20px; }
  .faq-item summary { font-size: 16px; }
  .trust-step { gap: 18px; }
}

/* ============================================================
   ⑫ 打印
   ============================================================ */
@media print {
  .site-header, .nav, .chat-options, .chat-foot, .demo-tag { display: none; }
  body { background: #FFFFFF; }
  .section-deep, .site-footer, .chat { background: #FFFFFF !important; color: #1F2937 !important; }
}