/**
 * [INPUT]: 被 /index.html 与 /404.html 以 ?v= 版本号引用；衬线字体来自 /assets/fonts/serif-sc.woff2（按页面用字子集化）
 * [OUTPUT]: 全站样式：纸面 token、编辑式排版、导航、首屏摄影、实时驾驶舱（深墨块）、服务条目、方法标尺、作品设备框、级别表、问答、页脚
 * [POS]: assets/css 唯一样式表；设计立场「出版物式的工作室」：暖白纸、墨色、唯一强调色火星红，细线代替卡片，不用渐变、辉光与毛玻璃
 * [PROTOCOL]: 变更时更新此头部，然后检查 CLAUDE.md
 */

/* ============================================================
   字体与 token
   ============================================================ */
@font-face {
  font-family: "HX Serif";
  src: url("/assets/fonts/serif-sc.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}

:root {
  --paper: #f3f0e8;
  --paper-2: #ebe7dd;
  --ink: #151412;
  --ink-2: #57544d;
  --ink-3: #8a867c;
  --rule: rgba(21, 20, 18, 0.14);
  --rule-2: rgba(21, 20, 18, 0.28);
  --red: #c4381e;
  /* 驾驶舱深墨块 */
  --night: #121110;
  --night-2: #1b1a18;
  --night-rule: rgba(236, 233, 225, 0.12);
  --night-ink: #ece9e1;
  --night-ink-2: #9d998f;
  --serif: "HX Serif", "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", serif;
  --sans: -apple-system, "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", "Cascadia Mono", Menlo, Consolas, monospace;
  --wrap: 1240px;
  --gut: 40px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  color-scheme: light;
}

/* ============================================================
   基础
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 72px; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font-family: var(--sans); font-size: 17px; line-height: 1.75;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
img, video { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4, p, figure, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
button { font: inherit; color: inherit; }
::selection { background: var(--ink); color: var(--paper); }
:focus-visible { outline: 2px solid var(--red); outline-offset: 3px; }

.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 var(--gut); }
.skip-link { position: absolute; left: 12px; top: -60px; z-index: 100; padding: 8px 14px; background: var(--ink); color: var(--paper); }
.skip-link:focus { top: 12px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* 文字层级 */
.serif { font-family: var(--serif); font-weight: 400; }
.label { font-family: var(--mono); font-size: 12px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-3); }
.display { font-family: var(--serif); font-weight: 400; font-size: clamp(44px, 7.2vw, 104px); line-height: 1.08; letter-spacing: -0.01em; }
.h2 { font-family: var(--serif); font-weight: 400; font-size: clamp(28px, 4.4vw, 60px); line-height: 1.18; letter-spacing: -0.005em; }
.h3 { font-family: var(--serif); font-weight: 400; font-size: clamp(24px, 2.4vw, 32px); line-height: 1.3; }
.lede { font-size: clamp(18px, 1.5vw, 21px); line-height: 1.75; color: var(--ink-2); max-width: 36em; }
.muted { color: var(--ink-2); }
.small { font-size: 14px; line-height: 1.7; color: var(--ink-3); }
.num { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.red { color: var(--red); }

/* 章节 */
.sec { padding: 144px 0; position: relative; }
.sec-top { padding-top: 0; }
.sec-head { display: grid; grid-template-columns: 200px 1fr; gap: 0 48px; margin-bottom: 72px; }
.sec-head .label { padding-top: 14px; }
.sec-head .h2 { max-width: 15em; }
.sec-head .lede { margin-top: 24px; }
.rule { border: 0; border-top: 1px solid var(--rule); margin: 0; }

/* 链接与按钮 */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 12px;
  min-height: 52px; padding: 0 26px; border-radius: 2px;
  font-size: 16px; font-weight: 600; letter-spacing: 0.02em; line-height: 1.3;
  background: var(--ink); color: var(--paper); border: 1px solid var(--ink);
  transition: background .25s var(--ease), color .25s var(--ease);
}
.btn:hover { background: var(--red); border-color: var(--red); }
.btn .arr { font-family: var(--mono); font-weight: 400; transition: transform .25s var(--ease); }
.btn:hover .arr { transform: translateX(3px); }
.btn-line { background: transparent; color: var(--ink); border-color: var(--rule-2); }
.btn-line:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.tlink { display: inline-flex; gap: 8px; align-items: baseline; font-weight: 600; border-bottom: 1px solid var(--ink); padding-bottom: 2px; transition: color .2s, border-color .2s; }
.tlink:hover { color: var(--red); border-color: var(--red); }
.tlink .arr { font-family: var(--mono); font-weight: 400; }

/* ============================================================
   导航
   ============================================================ */
.nav { position: fixed; inset: 0 0 auto 0; z-index: 50; height: 64px; display: flex; align-items: center; transition: background .3s, border-color .3s, color .3s; border-bottom: 1px solid transparent; color: var(--ink); }
.nav.solid { background: rgba(243, 240, 232, 0.94); border-bottom-color: var(--rule); }
.nav-inner { display: flex; align-items: center; gap: 36px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-family: var(--serif); font-size: 20px; letter-spacing: 0.04em; }
.brand img { width: 36px; height: 24px; }
.nav-links { display: flex; gap: 28px; margin-left: auto; font-size: 15px; }
.nav-links a { color: var(--ink-2); transition: color .2s; }
.nav-links a:hover { color: var(--ink); }
.nav-cta { font-size: 15px; font-weight: 600; padding: 8px 16px; border: 1px solid var(--ink); border-radius: 2px; transition: background .2s, color .2s; }
.nav-cta:hover { background: var(--ink); color: var(--paper); }
.menu-toggle { display: none; margin-left: auto; width: 44px; height: 44px; border: 0; background: transparent; cursor: pointer; }
.menu-toggle span { display: block; width: 22px; height: 1.5px; background: currentColor; margin: 6px auto; }
.mobile-menu { display: none; }

/* ============================================================
   首屏：满版摄影 + 衬线大字
   ============================================================ */
.hero { position: relative; min-height: 100vh; min-height: 100svh; display: flex; flex-direction: column; overflow: hidden; }
.hero-art { position: absolute; inset: 0; z-index: 0; pointer-events: none; }
.hero-canvas { position: absolute; inset: 0; width: 100%; height: 100%; opacity: 0; transition: opacity 1.6s var(--ease); }
.hero-canvas.on { opacity: 1; }
.hero-still { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; object-position: 70% 50%; opacity: 0; }
.hero.still .hero-still { opacity: 1; }
.hero-body { position: relative; z-index: 1; padding-top: 148px; }
.hero .label { color: var(--ink-2); }
.hero h1 { margin-top: 28px; max-width: 10em; }
.hero .lede { margin-top: 32px; color: var(--ink); max-width: 30em; }
.hero-cta { margin-top: 40px; display: flex; gap: 28px; align-items: center; flex-wrap: wrap; }
.hero-foot { position: relative; z-index: 1; margin-top: auto; padding: 48px 0 28px; }
.hero-foot .wrap { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; border-top: 1px solid var(--rule); padding-top: 18px; }
.hero-terms { display: flex; gap: 10px 28px; flex-wrap: wrap; font-family: var(--mono); font-size: 13px; color: var(--ink-2); }
.hero-terms span::before { content: "— "; opacity: .5; }

/* ============================================================
   实时驾驶舱：全站唯一的深墨块
   ============================================================ */
.deck { background: var(--night); color: var(--night-ink); padding: 104px 0 96px; }
.deck .label { color: var(--night-ink-2); }
.deck-head { display: grid; grid-template-columns: 1fr auto; gap: 24px 48px; align-items: end; padding-bottom: 32px; border-bottom: 1px solid var(--night-rule); }
.deck-head .h2 { color: var(--night-ink); max-width: 13em; }
.deck-head p { margin-top: 18px; color: var(--night-ink-2); max-width: 34em; font-size: 16px; }
.deck-status { text-align: right; font-family: var(--mono); font-size: 13px; color: var(--night-ink-2); line-height: 1.9; }
.pulse { display: inline-block; width: 7px; height: 7px; background: var(--red); margin-right: 8px; vertical-align: 1px; animation: blink 2s steps(2, jump-none) infinite; }
.deck.standby .pulse { background: var(--night-ink-2); animation: none; }
@keyframes blink { 0% { opacity: 1; } 100% { opacity: .25; } }

/* 指标行 */
.deck-metrics { display: grid; grid-template-columns: repeat(4, 1fr); border-bottom: 1px solid var(--night-rule); }
.metric { padding: 32px 24px 28px 0; }
.metric + .metric { padding-left: 24px; border-left: 1px solid var(--night-rule); }
.metric .v { display: block; font-family: var(--mono); font-variant-numeric: tabular-nums; font-size: clamp(34px, 3.6vw, 52px); line-height: 1.1; letter-spacing: -0.02em; color: var(--night-ink); }
.metric .v small { font-size: 0.42em; letter-spacing: 0; margin-left: 6px; color: var(--night-ink-2); }
.metric .k { display: block; margin-top: 10px; font-size: 14px; color: var(--night-ink-2); }
.est { font-family: var(--mono); font-size: 11px; letter-spacing: .06em; border: 1px solid var(--night-rule); padding: 1px 6px; margin-left: 6px; color: var(--night-ink-2); vertical-align: 2px; }

/* 三栏：数字员工 / 项目 / 事件 */
.deck-grid { display: grid; grid-template-columns: 1fr 1.25fr 1fr; }
.deck-col { padding: 28px 28px 8px 0; min-width: 0; }
.deck-col + .deck-col { padding-left: 28px; border-left: 1px solid var(--night-rule); }
.deck-col h3 { font-family: var(--mono); font-size: 12px; font-weight: 400; letter-spacing: .08em; color: var(--night-ink-2); display: flex; justify-content: space-between; margin-bottom: 14px; }
.row { padding: 14px 0; border-top: 1px solid var(--night-rule); }
.row:first-of-type { border-top: 0; }

.agent-top { display: flex; align-items: center; gap: 10px; }
.state { width: 9px; height: 9px; flex: none; border: 1px solid var(--night-ink-2); }
.state.working { background: var(--red); border-color: var(--red); animation: blink 2.4s steps(2, jump-none) infinite; }
.state.reviewing { border-color: var(--red); box-shadow: inset 0 0 0 2px var(--night), inset 0 0 0 9px var(--red); }
.state.waiting { border-color: var(--night-ink); }
.state.idle { border-color: var(--night-rule); background: transparent; }
.agent-name { font-weight: 600; font-size: 15px; }
.agent-state { margin-left: auto; font-family: var(--mono); font-size: 12px; color: var(--night-ink-2); }
.agent-role { font-size: 13px; color: var(--night-ink-2); margin-top: 2px; padding-left: 19px; }
.agent-doing { font-family: var(--mono); font-size: 13px; margin-top: 8px; padding-left: 19px; color: var(--night-ink); word-break: break-all; }

.proj-top { display: flex; gap: 10px; align-items: baseline; }
.proj-code { font-family: var(--mono); font-size: 12px; color: var(--night-ink-2); }
.proj-title { font-weight: 600; font-size: 15px; }
.proj-name { font-size: 13px; color: var(--night-ink-2); margin-left: auto; white-space: nowrap; }
.stages { display: grid; grid-template-columns: repeat(7, 1fr); gap: 3px; margin-top: 12px; }
.stages i { display: block; height: 4px; background: var(--night-rule); }
.stages i.done { background: var(--night-ink-2); }
.stages i.now { background: var(--red); }
.stage-letters { display: grid; grid-template-columns: repeat(7, 1fr); gap: 3px; margin-top: 6px; font-family: var(--mono); font-size: 11px; color: var(--night-ink-2); }
.stage-letters b { font-weight: 400; color: var(--night-ink); }
.proj-step { font-family: var(--mono); font-size: 12px; color: var(--night-ink-2); margin-top: 8px; display: flex; justify-content: space-between; }

.feed { max-height: 420px; overflow: hidden; }
.feed li { display: grid; grid-template-columns: 48px 1fr; gap: 10px; padding: 9px 0; border-top: 1px solid var(--night-rule); font-family: var(--mono); font-size: 13px; line-height: 1.55; transition: background 1.6s var(--ease); }
.feed li:first-child { border-top: 0; }
.feed time { color: var(--night-ink-2); }
.feed li.fresh { background: rgba(196, 56, 30, 0.16); }
.feed span { word-break: break-all; }

.empty { font-family: var(--mono); font-size: 13px; color: var(--night-ink-2); padding: 14px 0; }

.deck-pipe { display: grid; grid-template-columns: repeat(7, 1fr); border-top: 1px solid var(--night-rule); margin-top: 20px; }
.deck-pipe div { padding: 16px 12px 0 0; font-family: var(--mono); font-size: 12px; color: var(--night-ink-2); }
.deck-pipe b { display: block; font-size: 22px; font-weight: 400; color: var(--night-ink); }

.assump { margin-top: 28px; font-size: 14px; color: var(--night-ink-2); }
.assump summary { cursor: pointer; list-style: none; font-family: var(--mono); font-size: 13px; color: var(--night-ink); display: inline-flex; gap: 8px; }
.assump summary::-webkit-details-marker { display: none; }
.assump summary::before { content: "+"; }
.assump[open] summary::before { content: "−"; }
.assump-body { margin-top: 16px; display: grid; grid-template-columns: 1fr 1.6fr; gap: 24px 48px; }
.assump-body p { max-width: 36em; }
.base-table { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 0 24px; font-family: var(--mono); font-size: 12px; }
.base-table div { display: flex; justify-content: space-between; border-top: 1px solid var(--night-rule); padding: 6px 0; }
.deck-note { margin-top: 18px; font-size: 13px; color: var(--night-ink-2); }

/* ============================================================
   主张：编辑式三段
   ============================================================ */
.thesis { display: grid; grid-template-columns: 200px 1fr; gap: 0 48px; }
.thesis .h2 { max-width: 14em; }
.points { margin-top: 72px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 48px; }
.points li { border-top: 1px solid var(--ink); padding-top: 20px; }
.points .num { font-size: 13px; color: var(--ink-3); }
.points h3 { margin-top: 14px; font-size: 20px; font-weight: 600; line-height: 1.45; }
.points p { margin-top: 10px; color: var(--ink-2); font-size: 16px; }

/* 图版 */
.plate { margin: 0; }
.plate img { width: 100%; }
.plate figcaption { margin-top: 12px; display: flex; justify-content: space-between; gap: 16px; }
.split { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 72px; align-items: end; }

/* ============================================================
   服务：目录式条目
   ============================================================ */
.svc { display: grid; grid-template-columns: 200px 1.1fr 0.9fr; gap: 0 48px; padding: 56px 0; border-top: 1px solid var(--ink); }
.svc:last-child { border-bottom: 1px solid var(--ink); }
.svc .idx { font-family: var(--mono); font-size: 13px; color: var(--ink-3); padding-top: 12px; }
.svc h3 { font-family: var(--serif); font-weight: 400; font-size: clamp(28px, 3vw, 40px); line-height: 1.25; }
.svc .for { margin-top: 18px; color: var(--ink-2); max-width: 30em; }
.svc dl { display: grid; grid-template-columns: 88px 1fr; gap: 12px 16px; font-size: 15px; }
.svc dt { font-family: var(--mono); font-size: 12px; letter-spacing: .06em; color: var(--ink-3); padding-top: 3px; }
.svc dd { color: var(--ink); }
.svc .act { margin-top: 28px; display: flex; gap: 24px; align-items: center; flex-wrap: wrap; }
.steps5 { display: flex; flex-wrap: wrap; gap: 4px 0; }
.steps5 span { white-space: nowrap; }
.steps5 span + span::before { content: "→"; font-family: var(--mono); color: var(--ink-3); margin: 0 8px; }

/* ============================================================
   方法：航拍横幅 + 标尺
   ============================================================ */
.band { position: relative; height: min(64vh, 620px); overflow: hidden; }
.band img { width: 100%; height: 118%; object-fit: cover; will-change: transform; }
.band-cap { position: absolute; left: 0; right: 0; bottom: 0; padding: 28px 0; color: #fff; }
.band-cap .wrap { display: flex; justify-content: space-between; align-items: end; gap: 24px; }
.band-cap p { font-family: var(--serif); font-size: clamp(26px, 3.2vw, 44px); line-height: 1.25; max-width: 16em; text-shadow: 0 2px 24px rgba(0,0,0,.35); }
.band::after { content: ""; position: absolute; inset: auto 0 0 0; height: 50%; background: linear-gradient(180deg, rgba(0,0,0,0), rgba(0,0,0,.42)); pointer-events: none; }
.band-cap { z-index: 1; }
.band-cap .label { color: rgba(255,255,255,.8); }

.ruler { display: grid; grid-template-columns: repeat(7, 1fr); border-top: 1px solid var(--ink); }
.st { padding: 20px 20px 28px 0; position: relative; }
.st + .st { padding-left: 20px; border-left: 1px solid var(--rule); }
.st .l { font-family: var(--mono); font-size: 13px; color: var(--ink-3); display: flex; justify-content: space-between; }
.st .l i { font-style: normal; }
.st.human .l i { color: var(--red); }
.st h3 { margin-top: 18px; font-family: var(--serif); font-weight: 400; font-size: 24px; }
.st p { margin-top: 10px; font-size: 14px; line-height: 1.7; color: var(--ink-2); }
.st.human::before { content: ""; position: absolute; top: -1px; left: 0; right: 0; height: 3px; background: var(--red); }
.st.human + .st::before, .st:not(.human)::before { content: none; }
.legend { margin-top: 24px; display: flex; gap: 28px; flex-wrap: wrap; font-size: 14px; color: var(--ink-2); }
.legend i { display: inline-block; width: 18px; height: 3px; vertical-align: 4px; margin-right: 8px; background: var(--red); }
.legend i.a { background: var(--ink); height: 1px; }

.rules3 { margin-top: 96px; display: grid; grid-template-columns: repeat(4, 1fr); gap: 32px; }
.rules3 li { border-top: 1px solid var(--rule-2); padding-top: 16px; font-size: 15px; color: var(--ink-2); }
.rules3 b { display: block; color: var(--ink); font-weight: 600; margin-bottom: 6px; }

/* 就绪度 */
.ready { margin-top: 120px; display: grid; grid-template-columns: 200px 1fr; gap: 0 48px; }
.scale { margin-top: 48px; display: grid; grid-template-columns: repeat(5, 1fr); }
.lv { border-left: 1px solid var(--ink); padding: 0 16px 0 14px; }
.lv:last-child { border-right: 1px solid var(--ink); }
.lv .big { font-family: var(--serif); font-size: clamp(40px, 4.4vw, 64px); line-height: 1; }
.lv .th { font-family: var(--mono); font-size: 13px; color: var(--ink-3); margin-top: 8px; display: block; }
.lv p { margin-top: 12px; font-size: 14px; color: var(--ink-2); line-height: 1.65; }
.lv.gate { background: var(--paper-2); }
.lv.gate .th { color: var(--red); }
.dims { margin-top: 56px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 0 48px; }
.dims li { display: flex; justify-content: space-between; padding: 12px 0; border-top: 1px solid var(--rule); font-size: 15px; }
.dims .num { color: var(--ink-3); }

/* ============================================================
   作品：设备框
   ============================================================ */
.work { display: grid; grid-template-columns: 200px 1fr; gap: 0 48px; padding: 72px 0; border-top: 1px solid var(--ink); }
.work-body { display: grid; grid-template-columns: 0.9fr 1.1fr; gap: 56px; align-items: start; }
.work h3 { font-family: var(--serif); font-weight: 400; font-size: clamp(30px, 3.2vw, 44px); line-height: 1.2; }
.work .kind { margin-top: 10px; }
.facts { margin-top: 28px; }
.facts li { padding: 12px 0; border-top: 1px solid var(--rule); font-size: 15px; display: grid; grid-template-columns: 120px 1fr; gap: 16px; }
.facts li span:first-child { font-family: var(--mono); font-size: 12px; color: var(--ink-3); padding-top: 3px; letter-spacing: .04em; }
.work .tlink { margin-top: 28px; }
.phones { display: flex; gap: 20px; justify-content: flex-end; align-items: flex-start; }
.phone { width: 44%; max-width: 260px; border-radius: 34px; padding: 9px; background: #1a1917; box-shadow: 0 30px 60px -30px rgba(21,20,18,.45); }
.phone img { border-radius: 26px; }
.phone:nth-child(2) { margin-top: 56px; }
.laptop { max-width: 720px; margin-left: auto; }
.laptop .screen { border-radius: 12px 12px 0 0; padding: 10px 10px 0; background: #1a1917; }
.laptop .screen img { border-radius: 4px 4px 0 0; }
.laptop .base { height: 14px; background: linear-gradient(#cfcac0, #b6b0a4); border-radius: 0 0 14px 14px; margin: 0 -4%; }

/* ============================================================
   火星CC
   ============================================================ */
.product { text-align: left; }
.product .h2 { max-width: 12em; }
.product-cta { margin-top: 36px; display: flex; gap: 28px; align-items: center; flex-wrap: wrap; }
.product-shot { margin-top: 80px; }

/* ============================================================
   级别与价格：细线表
   ============================================================ */
.tiers { border-top: 1px solid var(--ink); }
.tier { display: grid; grid-template-columns: 200px 1fr 1.2fr 150px; gap: 0 32px; padding: 28px 0; border-bottom: 1px solid var(--rule); align-items: baseline; }
.tier .grp { font-family: var(--mono); font-size: 12px; color: var(--ink-3); letter-spacing: .04em; }
.tier h3 { font-family: var(--serif); font-weight: 400; font-size: 24px; line-height: 1.3; }
.tier h3 small { display: block; font-family: var(--sans); font-size: 14px; color: var(--ink-3); margin-top: 4px; }
.tier .lvl { font-family: var(--serif); font-size: 22px; }
.tier .lvl.free { color: var(--red); }
.tier p { font-size: 15px; color: var(--ink-2); margin-top: 6px; }
.tier .go { justify-self: end; font-size: 15px; }
.tiers-note { margin-top: 24px; }

/* ============================================================
   对比表
   ============================================================ */
.cmp-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; margin-top: 16px; }
.cmp { width: 100%; min-width: 860px; border-collapse: collapse; font-size: 15px; }
.cmp th, .cmp td { text-align: left; vertical-align: top; padding: 16px 20px 16px 0; border-top: 1px solid var(--rule); }
.cmp thead th { border-top: 1px solid var(--ink); font-family: var(--mono); font-weight: 400; font-size: 12px; letter-spacing: .04em; color: var(--ink-3); }
.cmp tbody th { font-weight: 600; width: 150px; }
.cmp td { color: var(--ink-2); }
.cmp .us { color: var(--ink); }
.cmp thead .us { color: var(--red); }

/* ============================================================
   问答
   ============================================================ */
.faq { border-top: 1px solid var(--ink); }
.faq details { border-bottom: 1px solid var(--rule); }
.faq summary { list-style: none; cursor: pointer; display: grid; grid-template-columns: 1fr 24px; gap: 24px; padding: 26px 0; font-family: var(--serif); font-size: clamp(20px, 2vw, 24px); line-height: 1.4; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-family: var(--mono); font-size: 20px; color: var(--ink-3); text-align: right; }
.faq details[open] summary::after { content: "−"; }
.faq details p { padding: 0 48px 28px 0; color: var(--ink-2); max-width: 46em; }

/* ============================================================
   收尾与页脚
   ============================================================ */
.closing { position: relative; overflow: hidden; padding: 160px 0 0; border-top: 1px solid var(--ink); }
.closing-photo { position: relative; margin-top: 120px; height: min(72vh, 680px); overflow: hidden; }
.closing-photo img { width: 100%; height: 118%; object-fit: cover; object-position: 50% 60%; will-change: transform; }
.closing-photo::after { content: ""; position: absolute; inset: 0; background: linear-gradient(180deg, var(--paper) 0%, rgba(243,240,232,0) 38%); }
.closing .display { font-size: clamp(40px, 6vw, 88px); max-width: 11em; }
.closing .lede { margin-top: 28px; }
.closing .hero-cta { margin-top: 44px; }
.closing .small { margin-top: 20px; }

.footer { border-top: 1px solid var(--ink); padding: 56px 0 40px; font-size: 14px; color: var(--ink-2); }
.foot-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 32px; }
.footer h4 { font-family: var(--mono); font-weight: 400; font-size: 12px; letter-spacing: .06em; color: var(--ink-3); margin-bottom: 14px; }
.footer li { margin: 8px 0; }
.footer a:hover { color: var(--red); }
.footer .brand { color: var(--ink); }
.footer p { margin-top: 14px; max-width: 24em; }
.foot-bottom { margin-top: 56px; padding-top: 20px; border-top: 1px solid var(--rule); display: flex; justify-content: space-between; gap: 12px 24px; flex-wrap: wrap; font-family: var(--mono); font-size: 12px; color: var(--ink-3); }
.foot-bottom a:hover { color: var(--ink); }

/* 404 */
.notfound { min-height: 100vh; display: grid; place-items: center; text-align: left; padding: 40px 24px; }
.notfound p { margin: 16px 0 32px; color: var(--ink-2); }

/* ============================================================
   动效：只做出现与细微视差
   ============================================================ */
.js .rv { opacity: 0; transform: translateY(14px); transition: opacity .9s var(--ease), transform .9s var(--ease); }
.js .rv.in { opacity: 1; transform: none; }

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1100px) {
  :root { --gut: 32px; }
  .sec-head, .thesis, .ready, .work { grid-template-columns: 1fr; }
  .sec-head .label, .thesis > .label, .ready > .label, .work > .label { padding: 0 0 16px; }
  .svc { grid-template-columns: 1fr 1fr; }
  .svc .idx { grid-column: 1 / -1; padding: 0 0 12px; }
  .tier { grid-template-columns: 1fr 1.3fr 120px; }
  .tier .grp { grid-column: 1 / -1; margin-bottom: 8px; }
  .deck-grid { grid-template-columns: 1fr 1fr; }
  .deck-col.c-feed { grid-column: 1 / -1; padding-left: 0; border-left: 0; border-top: 1px solid var(--night-rule); margin-top: 8px; }
  .ruler { grid-template-columns: repeat(4, 1fr); }
  .st:nth-child(5) { padding-left: 0; border-left: 0; }
  .st:nth-child(n+5) { border-top: 1px solid var(--rule); }
  .rules3 { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 860px) {
  .nav-links, .nav-cta { display: none; }
  .menu-toggle { display: block; }
  .mobile-menu { position: fixed; inset: 64px 0 auto 0; z-index: 49; background: var(--paper); border-bottom: 1px solid var(--ink); padding: 8px var(--gut) 24px; }
  .mobile-menu:not([hidden]) { display: block; }
  .mobile-menu a:not(.btn) { display: block; padding: 14px 0; border-bottom: 1px solid var(--rule); font-size: 17px; }
  .mobile-menu .btn { margin-top: 20px; width: 100%; }
  .points { grid-template-columns: 1fr; gap: 36px; margin-top: 48px; }
  .split { grid-template-columns: 1fr; gap: 40px; }
  .work-body { grid-template-columns: 1fr; gap: 40px; }
  .phones { justify-content: flex-start; }
  .deck-metrics { grid-template-columns: 1fr 1fr; }
  .metric:nth-child(3) { padding-left: 0; border-left: 0; }
  .metric:nth-child(n+3) { border-top: 1px solid var(--night-rule); }
  .deck-grid { grid-template-columns: 1fr; }
  .deck-col + .deck-col { padding-left: 0; border-left: 0; border-top: 1px solid var(--night-rule); }
  .deck-head { grid-template-columns: 1fr; }
  .deck-status { text-align: left; }
  .assump-body { grid-template-columns: 1fr; }
  .scale { grid-template-columns: 1fr; }
  .lv { border-right: 1px solid var(--ink); border-left: 0; border-top: 1px solid var(--ink); padding: 18px 0; display: grid; grid-template-columns: 90px 1fr; column-gap: 16px; }
  .lv:last-child { border-bottom: 1px solid var(--ink); }
  .lv.gate { padding-left: 12px; }
  .lv .big { grid-row: span 2; }
  .lv p { margin-top: 4px; }
  .lv, .lv:last-child { border-right: 0; }
  .dims { grid-template-columns: 1fr; }
  .foot-grid { grid-template-columns: 1fr 1fr; }
  .foot-grid > div:first-child { grid-column: 1 / -1; }
}
@media (max-width: 600px) {
  :root { --gut: 20px; }
  body { font-size: 16px; }
  .sec { padding: 96px 0; }
  .sec-head { margin-bottom: 48px; }
  .hero-body { padding-top: 112px; }
  .closing { padding-top: 112px; }
  .closing-photo { margin-top: 72px; height: 48vh; }
  .hero-cta .btn { width: 100%; }
  .hero-terms { font-size: 12px; }
  .deck { padding: 80px 0 72px; }
  .metric { padding: 22px 12px 20px 0; }
  .metric + .metric { padding-left: 12px; }
  .svc { grid-template-columns: 1fr; padding: 44px 0; }
  .svc dl { margin-top: 28px; }
  .svc .act .btn { width: 100%; }
  .ruler { grid-template-columns: 1fr; }
  .st, .st + .st { padding: 18px 0; border-left: 0; border-top: 1px solid var(--rule); display: grid; grid-template-columns: 76px 1fr; column-gap: 12px; }
  .st:first-child { border-top: 0; }
  .st .l { flex-direction: column; gap: 4px; grid-row: span 2; }
  .st h3 { margin-top: 0; font-size: 21px; }
  .st p { margin-top: 4px; }
  .st.human::before { top: 0; bottom: 0; left: -10px; right: auto; width: 3px; height: auto; }
  .rules3 { grid-template-columns: 1fr; margin-top: 64px; }
  .band { height: 52vh; }
  .tier { grid-template-columns: 1fr; gap: 6px; }
  .tier .go { justify-self: start; margin-top: 10px; }
  .facts li { grid-template-columns: 96px 1fr; }
  .phone { border-radius: 26px; padding: 6px; }
  .phone img { border-radius: 21px; }
  .closing .btn { width: 100%; }
  .faq details p { padding-right: 0; }
  .foot-grid { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .rv { opacity: 1; transform: none; }
  .closing-photo img, .band img { transform: none !important; }
}

/* ============================================================
   第二轮补充：图版对、产品窗口
   ============================================================ */
.pair { margin-top: 120px; display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.pair .plate:nth-child(2) { margin-top: 96px; }
.panes { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; max-width: 900px; margin-left: auto; margin-right: auto; align-items: start; }
.pane { margin: 0; }
.pane img { border: 1px solid var(--rule-2); border-radius: 10px; background: #fff; box-shadow: 0 40px 80px -48px rgba(21,20,18,.5); }
.pane:nth-child(2) { margin-top: 72px; }
.pane figcaption { margin-top: 14px; }
@media (max-width: 860px) {
  .pair { grid-template-columns: 1fr; gap: 48px; margin-top: 80px; }
  .pair .plate:nth-child(2) { margin-top: 0; }
  .panes { gap: 16px; }
  .pane:nth-child(2) { margin-top: 40px; }
}
@media (max-width: 600px) {
  .band-cap p { font-size: 24px; }
  .band-cap .label { display: none; }
  .deck-head .h2 { font-size: 30px; }
}
/* 方法章节末尾的粒子短片：深色影像嵌在纸面里，保持与图版同样的留白与图注 */
.plate.film { margin-top: 96px; }
.plate.film video { display: block; width: 100%; height: auto; aspect-ratio: 16 / 9; background: #07080a; }