:root {
  --paper: #f3efe5;
  --paper-deep: #e9e1d1;
  --surface: #fffdf8;
  --ink: #171917;
  --muted: #65675f;
  --cinnabar: #c54f35;
  --cinnabar-dark: #9f3826;
  --teal: #285b5b;
  --teal-soft: #dce8e4;
  --line: #d8d0c0;
  --shadow: 0 18px 55px rgba(37, 35, 29, .09);
  --content: 1180px;
  --radius: 18px;
  --font-display: "Songti SC", "STSong", "Noto Serif CJK SC", Georgia, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --font-mono: "Cascadia Code", "SFMono-Regular", Consolas, monospace;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(rgba(40, 91, 91, .035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(40, 91, 91, .035) 1px, transparent 1px),
    var(--paper);
  background-size: 28px 28px;
  font: 16px/1.72 var(--font-body);
  text-rendering: optimizeLegibility;
}
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: -1;
  background: radial-gradient(circle at 82% 8%, rgba(197, 79, 53, .12), transparent 30%);
}
a { color: inherit; }
a, button, [role="button"] {
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}
img, svg { display: block; max-width: 100%; }
button, input { font: inherit; }
button { cursor: pointer; }
::selection { color: var(--surface); background: var(--cinnabar); }
.skip-link { position: fixed; left: 16px; top: -80px; z-index: 100; padding: 10px 14px; background: var(--ink); color: white; }
.skip-link:focus { top: 16px; }
.container { width: min(calc(100% - 40px), var(--content)); margin-inline: auto; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  border-bottom: 1px solid rgba(216, 208, 192, .85);
  background: rgba(243, 239, 229, .88);
  backdrop-filter: blur(16px);
}
.nav-shell { min-height: 72px; display: flex; align-items: center; gap: 26px; }
.brand { display: flex; align-items: center; gap: 11px; margin-right: auto; text-decoration: none; }
.brand-mark {
  width: 34px;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  border-radius: 50% 50% 50% 12%;
  color: white;
  background: var(--cinnabar);
  font: 700 16px var(--font-display);
  transform: rotate(-5deg);
}
.brand-text { font: 700 18px/1 var(--font-display); letter-spacing: -.02em; }
.site-nav { display: flex; align-items: center; gap: 4px; }
.site-nav a {
  padding: 8px 11px;
  color: var(--muted);
  border-radius: 999px;
  text-decoration: none;
  font-size: 14px;
}
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--ink); background: rgba(255, 253, 248, .78); }
.nav-actions { display: flex; gap: 8px; }
.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--surface);
}
.nav-toggle span, .nav-toggle::before, .nav-toggle::after {
  content: "";
  display: block;
  width: 18px;
  height: 1.5px;
  margin: 4px auto;
  background: currentColor;
}
.nav-toggle:active { transform: scale(.94); background: var(--paper-deep); }
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 10px 18px;
  border: 1px solid transparent;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 650;
  transition: transform .2s ease, box-shadow .2s ease, background .2s ease;
}
.button:hover { transform: translateY(-2px); }
.button:active { transform: translateY(0) scale(.98); transition-duration: .05s; }
.button-primary { color: white; background: var(--cinnabar); box-shadow: 0 10px 24px rgba(197, 79, 53, .22); }
.button-primary:hover { background: var(--cinnabar-dark); }
.button-secondary { border-color: var(--line); background: rgba(255, 253, 248, .7); }
.button-quiet { color: var(--teal); background: var(--teal-soft); }
.hero { padding: clamp(76px, 10vw, 132px) 0 72px; overflow: hidden; }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.08fr) minmax(360px, .92fr); align-items: center; gap: 70px; }
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin: 0 0 20px;
  color: var(--cinnabar);
  font: 700 12px var(--font-mono);
  letter-spacing: .1em;
  text-transform: uppercase;
}
.kicker::before { content: ""; width: 30px; height: 1px; background: currentColor; }
h1, h2, h3 { margin-top: 0; font-family: var(--font-display); line-height: 1.15; text-wrap: balance; }
h1 { margin-bottom: 24px; font-size: clamp(46px, 7.3vw, 90px); letter-spacing: -.055em; }
h2 { margin-bottom: 18px; font-size: clamp(32px, 4.5vw, 54px); letter-spacing: -.035em; }
h3 { margin-bottom: 10px; font-size: 23px; letter-spacing: -.018em; }
.lead { max-width: 680px; margin: 0; color: var(--muted); font-size: clamp(17px, 2vw, 20px); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }
.hero-note { margin-top: 22px; color: var(--muted); font-size: 13px; }
.formula-board {
  position: relative;
  min-height: 430px;
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: 34px;
  background: rgba(255, 253, 248, .83);
  box-shadow: var(--shadow);
  transform: rotate(1.2deg);
}
.formula-board::before, .formula-board::after { position: absolute; color: rgba(40, 91, 91, .15); font: 70px var(--font-display); }
.formula-board::before { content: "∫"; top: 14px; right: 28px; }
.formula-board::after { content: "Σ"; left: 25px; bottom: 4px; }
.board-label { color: var(--muted); font: 12px var(--font-mono); letter-spacing: .08em; }
.equation { margin: 58px 0 45px; text-align: center; font: italic clamp(28px, 4vw, 43px) var(--font-display); }
.mini-flow { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.mini-step { position: relative; padding: 14px 10px; border-top: 2px solid var(--cinnabar); background: var(--paper); font-size: 13px; }
.mini-step strong { display: block; margin-bottom: 3px; font-family: var(--font-display); }
.section { padding: clamp(72px, 9vw, 112px) 0; }
.section-paper { background: rgba(255, 253, 248, .72); border-block: 1px solid var(--line); }
.section-ink { color: var(--surface); background: var(--ink); }
.section-ink .lead, .section-ink .muted { color: #b8b7af; }
.section-ink .card { color: var(--ink); }
.section-ink .card p { color: #3e403b; }
.section-ink .button-secondary { color: var(--surface); border-color: #555750; background: transparent; }
.section-head { display: flex; justify-content: space-between; align-items: end; gap: 28px; margin-bottom: 44px; }
.section-head > * { margin-bottom: 0; }
.section-number { color: var(--cinnabar); font: 12px var(--font-mono); letter-spacing: .12em; }
.grid { display: grid; gap: 20px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.card {
  position: relative;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 253, 248, .84);
  box-shadow: 0 8px 26px rgba(37, 35, 29, .04);
}
.card-accent { border-top: 4px solid var(--cinnabar); }
.card-teal { border-top: 4px solid var(--teal); }
.card p:last-child { margin-bottom: 0; }
.card-index { display: block; margin-bottom: 42px; color: var(--cinnabar); font: 12px var(--font-mono); }
.icon {
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  margin-bottom: 18px;
  border-radius: 14px;
  color: var(--teal);
  background: var(--teal-soft);
  font: 700 18px var(--font-display);
}
.role-flow { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; counter-reset: roles; }
.role { min-height: 300px; }
.role::after { content: "→"; position: absolute; top: 46%; right: -19px; z-index: 2; color: var(--cinnabar); font-size: 27px; }
.role:last-child::after { display: none; }
.deliverable {
  margin-top: 24px;
  padding: 14px 16px;
  border-radius: 12px;
  background: var(--paper);
  color: var(--teal);
  font: 13px/1.6 var(--font-mono);
}
.tag-list { display: flex; flex-wrap: wrap; gap: 8px; }
.tag { padding: 6px 11px; border: 1px solid var(--line); border-radius: 999px; color: var(--muted); background: var(--surface); font-size: 13px; }
.metric { padding: 26px 22px; border-left: 1px solid var(--line); }
.metric:first-child { border-left: 0; }
.metric strong { display: block; color: var(--cinnabar); font: 700 clamp(34px, 5vw, 54px)/1 var(--font-display); }
.metric span { color: var(--muted); font-size: 13px; }
.check-list { display: grid; gap: 12px; padding: 0; list-style: none; }
.check-list li { position: relative; padding-left: 30px; }
.check-list li::before { content: "✓"; position: absolute; left: 0; top: 1px; color: var(--cinnabar); font-weight: 800; }
.case-showcase { display: grid; gap: 26px; margin-top: 38px; }
.case-study { display: grid; grid-template-columns: 240px minmax(0, 1fr); overflow: hidden; border: 1px solid var(--line); border-radius: 24px; background: rgba(255, 253, 248, .9); box-shadow: 0 12px 38px rgba(37, 35, 29, .06); }
.case-study-copy { padding: 28px 25px; color: var(--surface); background: var(--cinnabar); }
.case-study--teal .case-study-copy { background: var(--teal); }
.case-study-copy .case-label { display: block; margin-bottom: 48px; font: 700 11px var(--font-mono); letter-spacing: .12em; }
.case-study-copy h3 { font-size: 27px; }
.case-study-copy p { color: rgba(255, 255, 255, .78); font-size: 14px; }
.case-study-copy .tag { color: var(--surface); border-color: rgba(255, 255, 255, .35); background: rgba(255, 255, 255, .08); }
.case-media { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; padding: 18px; }
.case-media figure { margin: 0; overflow: hidden; border: 1px solid var(--line); border-radius: 15px; background: white; }
.case-media img { width: 100%; aspect-ratio: 16/10; object-fit: contain; background: #fff; }
.case-media figcaption { display: flex; justify-content: space-between; gap: 12px; padding: 11px 13px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }
.case-media figcaption strong { color: var(--ink); font-family: var(--font-display); }
.chart-wrap { display: block; padding: 18px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.chart-wrap img { width: 100%; }
.page-hero { padding: 76px 0 54px; border-bottom: 1px solid var(--line); }
.page-hero h1 { max-width: 900px; font-size: clamp(42px, 6vw, 72px); }
.page-layout { display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 56px; padding-block: 64px 100px; }
.toc { position: sticky; top: 100px; align-self: start; display: grid; gap: 6px; }
.toc a { padding: 8px 11px; color: var(--muted); border-left: 2px solid var(--line); text-decoration: none; font-size: 14px; }
.toc a:hover { color: var(--ink); border-color: var(--cinnabar); }
.prose { min-width: 0; max-width: 830px; }
.prose section { margin-bottom: 70px; scroll-margin-top: 100px; }
.prose h2 { font-size: clamp(29px, 4vw, 42px); }
.prose p, .prose li { color: #3e403b; }
.notice { padding: 18px 20px; border-left: 4px solid var(--cinnabar); background: rgba(197, 79, 53, .08); }
.notice-teal { border-color: var(--teal); background: var(--teal-soft); }
.code-block { position: relative; margin: 20px 0; border-radius: 16px; overflow: hidden; color: #efeee8; background: #1d211f; }
.code-block pre { margin: 0; padding: 24px; overflow: auto; font: 13px/1.75 var(--font-mono); }
.copy-button { position: absolute; top: 10px; right: 10px; padding: 6px 10px; border: 1px solid #4b504c; border-radius: 8px; color: #dddcd5; background: #2b302d; font-size: 12px; }
.table-scroll { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; background: rgba(255, 253, 248, .76); }
th, td { padding: 14px 16px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { color: var(--teal); font: 700 14px var(--font-display); }
.timeline { border-left: 2px solid var(--line); margin-left: 10px; padding-left: 28px; }
.timeline-item { position: relative; margin-bottom: 36px; }
.timeline-item::before { content: ""; position: absolute; left: -36px; top: 8px; width: 14px; height: 14px; border: 3px solid var(--paper); border-radius: 50%; background: var(--cinnabar); }
.cta-band { padding: 62px 0; color: var(--surface); background: var(--teal); }
.cta-inner { display: flex; align-items: center; justify-content: space-between; gap: 26px; }
.cta-inner h2 { margin-bottom: 8px; font-size: clamp(30px, 4vw, 46px); }
.site-footer { padding: 50px 0 34px; border-top: 1px solid var(--line); }
.footer-grid { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 34px; }
.footer-grid h3 { font-size: 17px; }
.footer-links { display: grid; gap: 7px; }
.footer-links a { color: var(--muted); text-decoration: none; font-size: 14px; }
.footer-bottom { display: flex; justify-content: space-between; gap: 20px; margin-top: 42px; padding-top: 22px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }
.reveal.is-visible { animation: reveal-rise .55s ease both; }
@keyframes reveal-rise {
  from { transform: translateY(14px); }
  to { transform: none; }
}
:focus-visible { outline: 3px solid rgba(197, 79, 53, .42); outline-offset: 3px; }
@media (max-width: 980px) {
  .hero-grid, .page-layout { grid-template-columns: minmax(0, 1fr); }
  .formula-board { max-width: 700px; min-height: 360px; }
  .toc { position: static; display: flex; flex-wrap: wrap; }
  .toc a { border: 1px solid var(--line); border-radius: 999px; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 780px) {
  .nav-actions .button { display: none; }
  .nav-toggle { display: block; }
  .site-nav {
    position: absolute;
    left: 20px;
    right: 20px;
    top: 78px;
    display: none;
    padding: 12px;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: var(--surface);
    box-shadow: var(--shadow);
  }
  .site-nav.is-open { display: grid; }
  .site-nav a { padding: 12px 14px; }
  .hero { padding-top: 60px; }
  .hero-grid { gap: 44px; }
  .grid-2, .grid-3, .role-flow { grid-template-columns: 1fr; }
  .case-study, .case-media { grid-template-columns: 1fr; }
  .case-study-copy .case-label { margin-bottom: 22px; }
  .role::after { content: "↓"; top: auto; right: 50%; bottom: -25px; }
  .section-head, .cta-inner { align-items: flex-start; flex-direction: column; }
  .metric { border-left: 0; border-top: 1px solid var(--line); }
  .metric:first-child { border-top: 0; }
  .page-hero { padding: 56px 0 40px; }
  .page-layout { gap: 38px; padding-block: 42px 76px; }
  .toc {
    flex-wrap: nowrap;
    gap: 8px;
    margin-inline: -20px;
    padding: 0 20px 8px;
    overflow-x: auto;
    scrollbar-width: none;
  }
  .toc::-webkit-scrollbar { display: none; }
  .toc a { flex: 0 0 auto; }
  .prose section { margin-bottom: 52px; }
}
@media (max-width: 520px) {
  .container { width: min(calc(100% - 28px), var(--content)); }
  .brand-text { font-size: 16px; }
  h1 { font-size: 46px; }
  .page-hero { padding: 46px 0 34px; }
  .page-hero h1 { font-size: 36px; letter-spacing: -.04em; }
  .page-hero .lead { font-size: 16px; }
  .page-layout { gap: 30px; padding-block: 34px 64px; }
  .toc { margin-inline: -14px; padding-inline: 14px; }
  .toc a { padding: 7px 12px; font-size: 13px; }
  .prose h2 { font-size: 30px; }
  .prose section { margin-bottom: 46px; }
  .prose .card { padding: 22px 20px; }
  .code-block { border-radius: 13px; }
  .code-block pre {
    padding: 52px 16px 18px;
    overflow-x: hidden;
    white-space: pre-wrap;
    overflow-wrap: anywhere;
    word-break: break-word;
    font-size: 11.5px;
    line-height: 1.7;
  }
  .mobile-stack-table,
  .mobile-stack-table tbody,
  .mobile-stack-table tr,
  .mobile-stack-table td { display: block; width: 100%; }
  .mobile-stack-table { background: transparent; }
  .mobile-stack-table thead { display: none; }
  .mobile-stack-table tr {
    margin-bottom: 12px;
    padding: 13px 15px;
    border: 1px solid var(--line);
    border-radius: 13px;
    background: rgba(255, 253, 248, .76);
  }
  .mobile-stack-table td { padding: 4px 0; border: 0; }
  .mobile-stack-table td::before {
    content: attr(data-label);
    display: inline-block;
    width: 58px;
    color: var(--muted);
    font-size: 12px;
  }
  .formula-board { min-height: 320px; padding: 22px; border-radius: 24px; }
  .equation { margin: 45px 0 34px; font-size: 27px; }
  .mini-flow { grid-template-columns: 1fr; }
  .grid-4, .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
  .reveal.is-visible { animation: none; }
}