:root {
  --paper: #fff;
  --ink: #14251f;
  --text: #111513;
  --muted: #6f746f;
  --line: #dcdedb;
  --soft: #f4f6f4;
  --red: #963228;
  --red-soft: #f7efed;
  --teal: #12737b;
  --gold: #c49b3e;
  --serif: "Songti SC", "STSong", "Noto Serif CJK SC", Georgia, serif;
  --sans: Inter, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { max-width: 100%; overflow-x: hidden; scroll-behavior: smooth; }
body { max-width: 100%; margin: 0; overflow-x: hidden; color: var(--text); background: var(--paper); font-family: var(--sans); line-height: 1.62; }
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
button { color: inherit; font: inherit; }
svg { fill: none; stroke: currentColor; stroke-linecap: round; stroke-linejoin: round; }

.case-header { position: sticky; top: 0; z-index: 40; display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; min-height: 64px; padding: 0 42px; background: rgba(255,255,255,.94); border-bottom: 1px solid var(--line); backdrop-filter: blur(16px); }
.case-brand { display: flex; align-items: center; gap: 16px; font-size: 13px; letter-spacing: .05em; }
.case-brand span { width: 74px; height: 1px; background: var(--ink); }
.case-header nav { display: flex; gap: 32px; color: var(--muted); font-size: 13px; }
.case-header nav a { padding: 21px 0 18px; border-bottom: 2px solid transparent; }
.case-header nav a:hover { color: var(--red); border-color: var(--red); }
.back-link { display: flex; justify-content: flex-end; align-items: center; gap: 9px; font-size: 13px; }
.back-link svg { width: 17px; stroke-width: 1.7; }

.case-hero { display: grid; grid-template-columns: 132px minmax(520px,.88fr) minmax(580px,1.12fr); min-height: calc(100svh - 64px); border-bottom: 1px solid var(--line); }
.index-rail { padding: 62px 28px; border-right: 1px solid var(--line); }
.index-rail span, .section-index p { color: var(--muted); font-size: 9px; letter-spacing: .17em; }
.index-rail strong { display: block; margin-top: 12px; font-size: 26px; font-weight: 500; }
.index-rail i, .section-index::after { display: block; width: 22px; height: 1px; margin: 18px 0; content: ""; background: var(--ink); }
.index-rail small { color: var(--muted); font-size: 9px; letter-spacing: .13em; line-height: 1.7; }
.hero-copy { min-width: 0; align-self: center; padding: 72px 48px 72px 5vw; }
.project-name-en { margin: 0 0 18px; color: var(--red); font-size: 11px; font-weight: 600; letter-spacing: .18em; }
.hero-copy h1 { margin: 0; color: var(--ink); font-family: var(--serif); font-size: clamp(96px,10vw,158px); line-height: .9; }
.hero-statement { margin: 34px 0 0; font-family: var(--serif); font-size: clamp(40px,4vw,62px); font-weight: 700; line-height: 1.18; }
.hero-statement span { display: block; }
.hero-statement span:last-child { color: var(--red); }
.hero-description { max-width: 580px; margin: 26px 0 34px; color: #444945; font-size: 16px; }
.project-facts { display: grid; gap: 10px; margin: 0; padding-top: 24px; border-top: 1px solid var(--line); font-size: 12px; }
.project-facts div { display: grid; grid-template-columns: 72px 1fr; gap: 18px; }
.project-facts dt { color: var(--muted); }
.project-facts dd { min-width: 0; margin: 0; }

.trace-visual { position: relative; min-width: 0; overflow: hidden; background: #f7f8f7; border-left: 1px solid var(--line); transform: translate3d(var(--mx,0),var(--my,0),0); transition: transform .3s ease-out; }
.trace-mark { position: absolute; z-index: 1; top: 50%; left: 50%; width: min(42vw,540px); opacity: .08; transform: translate(-50%,-50%); }
.trace-title { position: absolute; z-index: 3; top: 44px; right: 44px; left: 44px; display: flex; justify-content: space-between; align-items: baseline; padding-bottom: 14px; border-bottom: 1px solid var(--line); }
.trace-title span { color: var(--red); font-size: 10px; letter-spacing: .16em; }
.trace-title strong { color: var(--ink); font-family: var(--serif); font-size: 17px; font-weight: 500; }
.trace-visual ol { position: absolute; z-index: 4; inset: 132px 40px 42px; margin: 0; padding: 0; list-style: none; }
.trace-visual li { position: absolute; display: grid; grid-template-columns: 32px 1fr auto; align-items: center; width: 270px; min-height: 64px; padding: 0 16px; background: rgba(255,255,255,.92); border: 1px solid var(--line); }
.trace-visual li:nth-child(1) { top: 5%; left: 1%; }
.trace-visual li:nth-child(2) { top: 26%; right: 0; }
.trace-visual li:nth-child(3) { right: 4%; bottom: 22%; }
.trace-visual li:nth-child(4) { bottom: 2%; left: 4%; }
.trace-visual li > span { color: var(--muted); font-size: 9px; }
.trace-visual li strong { font-family: var(--serif); font-size: 18px; }
.trace-visual li small { color: var(--red); font-size: 8px; letter-spacing: .1em; }
.trace-visual > svg { position: absolute; inset: 6%; width: 88%; height: 88%; }
.trace-visual .orbit { color: var(--red); stroke-width: 5; }
.trace-visual .axis { color: var(--teal); stroke-width: 1.5; }
.trace-visual circle { fill: #fff; stroke: var(--red); stroke-width: 4; }

.ruled-section { display: grid; grid-template-columns: 132px repeat(11,minmax(0,1fr)); border-bottom: 1px solid var(--line); }
.section-index { grid-column: 1; grid-row: 1 / span 4; padding: 72px 28px; border-right: 1px solid var(--line); }
.section-index span { font-size: 18px; }
.section-index p { margin: 10px 0 0; line-height: 1.55; }
.problem-heading, .framework-heading, .capability-heading, .loop-heading, .architecture-heading, .proof-heading { grid-column: 2 / 13; padding: 86px 5vw 54px; }
.problem-heading > p, .framework-heading > p, .capability-heading > p, .loop-heading > p, .architecture-heading > p, .proof-heading > p, .boundary-heading > p { margin: 0 0 14px; color: var(--muted); font-size: 11px; letter-spacing: .08em; }
.problem-heading h2, .framework-heading h2, .capability-heading h2, .loop-heading h2, .architecture-heading h2, .proof-heading h2, .boundary-heading h2 { margin: 0; color: var(--ink); font-family: var(--serif); font-size: clamp(38px,4.6vw,68px); line-height: 1.22; }

.problem-contrast { grid-column: 2 / 13; display: grid; grid-template-columns: 1fr 100px 1fr; padding: 0 5vw 84px; }
.problem-contrast article { min-height: 270px; padding: 34px; border: 1px solid var(--line); }
.problem-contrast article > span, .capability-list article > span, .architecture-stack span, .boundary-list span { color: var(--muted); font-size: 10px; letter-spacing: .14em; }
.problem-contrast strong { display: block; margin: 78px 0 10px; font-family: var(--serif); font-size: 26px; }
.problem-contrast p { margin: 0; color: var(--muted); }
.problem-contrast > i { align-self: center; height: 1px; background: var(--ink); }
.problem-contrast .target { background: var(--red-soft); border-top: 3px solid var(--red); }
.problem-contrast .target > span { color: var(--red); }

.framework-interface { grid-column: 2 / 13; display: grid; grid-template-columns: minmax(300px,.34fr) minmax(0,.66fr); border-top: 1px solid var(--line); }
.framework-tabs { display: grid; border-right: 1px solid var(--line); }
.framework-tab { display: grid; grid-template-columns: 50px 1fr; align-items: center; min-height: 82px; padding: 0 32px; background: #fff; border: 0; border-bottom: 1px solid var(--line); cursor: pointer; text-align: left; transition: background .18s ease; }
.framework-tab span { color: var(--muted); font-size: 10px; }
.framework-tab:hover { background: var(--soft); }
.framework-tab.active { color: #fff; background: var(--ink); }
.framework-tab.active span { color: #b8c1bd; }
.framework-tab:focus { outline: none; }
.framework-tab:focus-visible { box-shadow: inset 0 0 0 1px #aeb5b1; }
.framework-detail { display: grid; grid-template-columns: .7fr 1.3fr; gap: 44px; min-height: 410px; padding: 58px; }
.framework-detail > span { grid-column: 1 / -1; color: var(--red); font-size: 10px; letter-spacing: .16em; }
.framework-detail h3 { margin: 0; color: var(--ink); font-family: var(--serif); font-size: 36px; line-height: 1.35; }
.framework-detail > p { margin: 0; color: #424743; font-size: 16px; }
.framework-detail dl { grid-column: 1 / -1; display: grid; grid-template-columns: repeat(3,1fr); margin: 22px 0 0; border-top: 1px solid var(--line); }
.framework-detail dl div { padding: 18px 24px 0 0; }
.framework-detail dt { color: var(--muted); font-size: 10px; }
.framework-detail dd { margin: 6px 0 0; font-size: 13px; }

.capability-list { grid-column: 2 / 13; display: grid; grid-template-columns: repeat(3,1fr); border-top: 1px solid var(--line); }
.capability-list article { position: relative; min-height: 440px; padding: 38px 3vw; overflow: hidden; border-right: 1px solid var(--line); }
.capability-list article:last-child { border-right: 0; }
.capability-list img { width: 150px; height: 150px; margin-bottom: 28px; object-fit: contain; }
.capability-list article:nth-child(2) img { width: 170px; }
.capability-list h3 { margin: 34px 0 12px; color: var(--ink); font-family: var(--serif); font-size: 28px; line-height: 1.4; }
.capability-list p { margin: 0; color: var(--muted); }

.calibration-path { grid-column: 2 / 13; display: grid; grid-template-columns: 1fr 66px 1fr 66px 1fr 66px 1fr; padding: 0 5vw 88px; }
.calibration-path article { min-height: 210px; padding: 26px; border: 1px solid var(--line); }
.calibration-path article > span { color: var(--muted); font-size: 10px; letter-spacing: .12em; }
.calibration-path strong { display: block; margin: 54px 0 8px; color: var(--ink); font-family: var(--serif); font-size: 24px; }
.calibration-path small { color: var(--muted); }
.calibration-path > i { align-self: center; height: 1px; background: var(--ink); }
.calibration-path .update { background: var(--red-soft); border-top: 3px solid var(--red); }

.architecture-stack { grid-column: 2 / 13; display: grid; grid-template-columns: repeat(4,1fr); border-top: 1px solid var(--line); }
.architecture-stack article { min-height: 260px; padding: 34px 2.5vw; border-right: 1px solid var(--line); }
.architecture-stack article:last-child { border-right: 0; }
.architecture-stack strong { display: block; margin: 72px 0 8px; color: var(--ink); font-family: var(--serif); font-size: 25px; }
.architecture-stack p { margin: 0; color: var(--muted); font-size: 14px; }

.proof-heading { grid-column: 2 / 8; }
.proof-grid { grid-column: 8 / 13; display: grid; grid-template-columns: 1fr 1fr; border-left: 1px solid var(--line); }
.proof-grid article { min-height: 180px; padding: 34px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.proof-grid article:nth-child(even) { border-right: 0; }
.proof-grid article:nth-last-child(-n+2) { border-bottom: 0; }
.proof-grid strong { display: block; color: var(--red); font-family: var(--serif); font-size: 62px; line-height: 1; }
.proof-grid span { display: block; margin-top: 18px; font-size: 13px; }
.proof-note { grid-column: 2 / 13; margin: 0; padding: 28px 5vw; color: var(--muted); border-top: 1px solid var(--line); font-size: 13px; }

.boundary-heading { grid-column: 2 / 8; padding: 86px 5vw; }
.boundary-list { grid-column: 8 / 13; border-left: 1px solid var(--line); }
.boundary-list article { min-height: 170px; padding: 34px 3vw; border-bottom: 1px solid var(--line); }
.boundary-list article:last-child { border-bottom: 0; }
.boundary-list p { margin: 34px 0 0; color: #454a46; }

.case-cta { position: relative; display: grid; place-items: center; min-height: 650px; padding: 100px 28px; overflow: hidden; text-align: center; }
.case-cta > img { position: absolute; width: 520px; opacity: .05; }
.case-cta > p { position: relative; margin: 0; color: var(--red); font-size: 10px; font-weight: 600; letter-spacing: .22em; }
.case-cta h2 { position: relative; margin: 18px 0 42px; color: var(--ink); font-family: var(--serif); font-size: clamp(44px,6vw,84px); line-height: 1.25; }
.primary-action { position: relative; display: inline-flex; align-items: center; justify-content: center; gap: 38px; min-width: 224px; min-height: 58px; padding: 0 24px; color: #fff; background: var(--ink); }
.primary-action svg { width: 18px; stroke-width: 1.7; }
.case-footer { display: grid; grid-template-columns: 1fr auto 1fr; gap: 24px; padding: 26px 42px; border-top: 1px solid var(--line); font-size: 11px; }
.case-footer span { color: var(--muted); letter-spacing: .1em; }
.case-footer a { text-align: right; }

.reveal { opacity: 0; transform: translateY(20px); transition: opacity .65s ease, transform .65s ease; }
.reveal.visible { opacity: 1; transform: none; }

@media (max-width: 1180px) {
  .case-header { grid-template-columns: 1fr auto; padding: 0 24px; }
  .case-header nav { display: none; }
  .case-hero { grid-template-columns: 88px 1fr; }
  .index-rail { grid-row: 1 / span 2; padding: 48px 18px; }
  .hero-copy { padding: 64px 6vw; }
  .trace-visual { grid-column: 2; min-height: 720px; border-top: 1px solid var(--line); border-left: 0; }
  .ruled-section { grid-template-columns: 88px repeat(11,minmax(0,1fr)); }
  .section-index { padding: 58px 18px; }
  .problem-contrast { grid-template-columns: 1fr 60px 1fr; }
  .proof-heading, .boundary-heading { grid-column: 2 / 13; }
  .proof-grid, .boundary-list { grid-column: 2 / 13; border-top: 1px solid var(--line); border-left: 0; }
}

@media (max-width: 720px) {
  .case-header { min-height: 58px; padding: 0 20px; }
  .case-brand span { width: 34px; }
  .back-link { font-size: 0; }
  .case-hero, .ruled-section { display: block; }
  .index-rail, .section-index { display: none; }
  .hero-copy { padding: 58px 20px 64px; }
  .hero-copy h1 { font-size: 82px; }
  .hero-statement { font-size: 44px; }
  .hero-description { font-size: 15px; }
  .project-facts div { grid-template-columns: 70px 1fr; }
  .project-facts dd, .hero-description { overflow-wrap: anywhere; }
  .trace-visual { min-height: 700px; }
  .trace-title { right: 20px; left: 20px; }
  .trace-title strong { font-size: 13px; }
  .trace-mark { width: 430px; }
  .trace-visual ol { inset: 110px 14px 28px; }
  .trace-visual li { width: 185px; grid-template-columns: 26px 1fr; padding: 10px; }
  .trace-visual li small { display: none; }
  .trace-visual li strong { font-size: 15px; }
  .problem-heading, .framework-heading, .capability-heading, .loop-heading, .architecture-heading, .proof-heading, .boundary-heading { padding: 72px 20px 40px; }
  .problem-heading h2, .framework-heading h2, .capability-heading h2, .loop-heading h2, .architecture-heading h2, .proof-heading h2, .boundary-heading h2 { font-size: 36px; }
  .problem-contrast { display: block; padding: 0 20px 70px; }
  .problem-contrast > i { display: block; width: 1px; height: 28px; margin-left: 22px; }
  .problem-contrast article { min-height: 230px; }
  .problem-contrast strong { margin-top: 54px; }
  .framework-interface { display: block; }
  .framework-tabs { grid-template-columns: repeat(4,minmax(112px,1fr)); overflow-x: auto; border-right: 0; }
  .framework-tab { display: block; min-height: 76px; padding: 12px; white-space: nowrap; }
  .framework-tab span { display: block; margin-bottom: 4px; }
  .framework-detail { display: block; min-height: 570px; padding: 38px 20px; }
  .framework-detail h3 { margin-top: 22px; font-size: 31px; }
  .framework-detail > p { margin-top: 24px; }
  .framework-detail dl { grid-template-columns: 1fr; }
  .framework-detail dl div { padding: 14px 0; border-bottom: 1px solid var(--line); }
  .capability-list, .architecture-stack, .proof-grid { display: block; }
  .capability-list article { min-height: 410px; padding: 36px 20px; border-right: 0; border-bottom: 1px solid var(--line); }
  .capability-list img { width: 132px; height: 132px; }
  .calibration-path { display: block; padding: 0 20px 70px; }
  .calibration-path article { min-height: 180px; }
  .calibration-path > i { display: block; width: 1px; height: 26px; margin-left: 22px; }
  .architecture-stack article, .proof-grid article { min-height: 220px; padding: 32px 20px; border-right: 0; border-bottom: 1px solid var(--line); }
  .proof-note { padding: 26px 20px; }
  .boundary-list article { padding: 34px 20px; }
  .case-cta { min-height: 550px; padding: 80px 20px; }
  .case-cta h2 { font-size: 44px; }
  .case-footer { grid-template-columns: 1fr auto; padding: 24px 20px; }
  .case-footer span { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .trace-visual { transition: none; }
}