:root {
  --paper: #fff;
  --ink: #0a0b0d;
  --muted: #71757e;
  --line: #dedfe3;
  --soft: #f5f5f7;
  --blue: #1d55ff;
  --blue-soft: #eef3ff;
  --green: #1f8a58;
  --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(--ink); background: var(--paper); font-family: var(--sans); line-height: 1.6; }
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(--ink); border-color: var(--ink); }
.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,.9fr) minmax(580px,1.1fr); 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; }
.status-line { display: flex; align-items: center; gap: 10px; margin-bottom: 20px; color: var(--green); font-size: 10px; letter-spacing: .15em; }
.status-line i, .live-label i { width: 7px; height: 7px; background: var(--green); border-radius: 50%; box-shadow: 0 0 0 5px rgba(31,138,88,.1); }
.project-name-en { margin: 0 0 18px; color: var(--muted); font-size: 11px; letter-spacing: .17em; }
.hero-copy h1 { margin: 0; font-family: var(--serif); font-size: clamp(96px,10vw,158px); line-height: .9; }
.hero-statement { margin: 32px 0 0; font-family: var(--serif); font-size: clamp(35px,3.4vw,56px); font-weight: 700; line-height: 1.22; }
.hero-statement span { display: block; white-space: nowrap; }
.hero-description { max-width: 580px; margin: 24px 0 34px; color: #3f4249; 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: 74px 1fr; gap: 18px; }
.project-facts dt { color: var(--muted); }
.project-facts dd { margin: 0; }

.course-map { position: relative; min-width: 0; overflow: hidden; background: #fbfbfc; border-left: 1px solid var(--line); }
.map-head { position: absolute; z-index: 3; top: 38px; right: 40px; left: 40px; display: flex; justify-content: space-between; padding-bottom: 14px; border-bottom: 1px solid var(--line); font-size: 10px; letter-spacing: .15em; }
.map-head small { color: var(--green); font-size: 10px; letter-spacing: 0; }
.map-core { position: absolute; z-index: 3; top: 50%; left: 50%; width: 230px; height: 230px; padding: 44px 34px; background: var(--ink); color: #fff; transform: translate(-50%,-50%); }
.map-core span { font-size: 11px; color: #b8bac0; }
.map-core strong { display: block; margin-top: 24px; font-family: var(--serif); font-size: 27px; line-height: 1.35; }
.map-core small { position: absolute; bottom: 22px; left: 34px; color: #989ba3; font-size: 8px; letter-spacing: .12em; }
.course-map ol { position: absolute; z-index: 3; inset: 100px 38px 40px; margin: 0; padding: 0; list-style: none; }
.course-map li { position: absolute; display: grid; grid-template-columns: 28px 1fr; width: 210px; padding: 16px; background: rgba(255,255,255,.92); border: 1px solid var(--line); }
.course-map li:nth-child(1) { top: 3%; left: 2%; }
.course-map li:nth-child(2) { top: 5%; right: 1%; }
.course-map li:nth-child(3) { right: 1%; bottom: 4%; }
.course-map li:nth-child(4) { bottom: 2%; left: 2%; }
.course-map li > span { grid-row: 1 / 3; color: var(--muted); font-size: 9px; }
.course-map li strong { font-family: var(--serif); font-size: 18px; }
.course-map li small { color: var(--muted); font-size: 9px; }
.course-map > svg { position: absolute; inset: 5%; width: 90%; height: 90%; color: #9fa3ab; }
.course-map > svg path { stroke-width: 1; }
.course-map > svg .accent { color: var(--blue); stroke-width: 1.4; }
.course-map > svg circle { fill: var(--blue); stroke: none; }

.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-statement, .system-heading, .principles-heading, .beta-heading { grid-column: 2 / 13; padding: 86px 5vw 54px; }
.problem-statement > p, .system-heading > div > p, .principles-heading > p, .scope-heading > p { margin: 0 0 14px; color: var(--muted); font-size: 11px; letter-spacing: .1em; }
.problem-statement h2, .system-heading h2, .principles-heading h2, .beta-heading h2, .scope-heading h2, .boundary-heading h2 {
  margin: 0; font-family: var(--serif); font-size: clamp(38px,4.6vw,68px); line-height: 1.22;
}
.problem-lines span, .principle-list span, .beta-grid article > span, .responsibility-map span { color: var(--muted); font-size: 10px; letter-spacing: .14em; }

.problem-statement { padding-bottom: 70px; }
.problem-lines { grid-column: 2 / 13; display: grid; grid-template-columns: repeat(3,1fr); border-top: 1px solid var(--line); }
.problem-lines article { min-height: 265px; padding: 34px 3vw; border-right: 1px solid var(--line); }
.problem-lines article:last-child { border-right: 0; }
.problem-lines strong { display: block; margin: 74px 0 10px; font-family: var(--serif); font-size: 23px; }
.problem-lines p { margin: 0; color: var(--muted); font-size: 14px; }

.system-heading { display: flex; justify-content: space-between; align-items: end; gap: 48px; }
.system-heading > p { max-width: 360px; margin: 0; color: var(--muted); }
.loop-interface { grid-column: 2 / 13; display: grid; grid-template-columns: minmax(330px,.38fr) minmax(0,.62fr); border-top: 1px solid var(--line); }
.loop-tabs { display: grid; border-right: 1px solid var(--line); }
.loop-tab { display: grid; grid-template-columns: 48px 1fr; align-items: center; min-height: 76px; padding: 0 32px; background: #fff; border: 0; border-bottom: 1px solid var(--line); cursor: pointer; text-align: left; transition: background .18s ease; }
.loop-tab span { color: var(--muted); font-size: 10px; }
.loop-tab:hover { background: var(--soft); }
.loop-tab.active { background: var(--ink); color: #fff; }
.loop-tab.active span { color: #aeb1b8; }
.loop-tab:focus { outline: none; }
.loop-tab:focus-visible { box-shadow: inset 0 0 0 1px #aaaeb7; }
.loop-detail { display: grid; grid-template-columns: .75fr 1.25fr; gap: 48px; min-height: 380px; padding: 58px; }
.loop-detail span { color: var(--blue); font-size: 10px; letter-spacing: .16em; }
.loop-detail h3 { max-width: 430px; margin: 16px 0 0; font-family: var(--serif); font-size: 34px; line-height: 1.35; }
.loop-detail > p { margin: 32px 0 0; color: #42454b; font-size: 16px; }
.loop-detail dl { grid-column: 1 / -1; display: grid; grid-template-columns: repeat(3,1fr); margin: 28px 0 0; border-top: 1px solid var(--line); }
.loop-detail dl div { padding: 18px 22px 0 0; }
.loop-detail dt { color: var(--muted); font-size: 10px; }
.loop-detail dd { margin: 6px 0 0; font-size: 13px; }

.principles-heading { grid-column: 2 / 7; padding-right: 4vw; }
.principle-list { grid-column: 7 / 13; display: grid; grid-template-columns: repeat(2,1fr); border-left: 1px solid var(--line); }
.principle-list article { min-height: 270px; padding: 34px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.principle-list article:nth-child(even) { border-right: 0; }
.principle-list article:nth-last-child(-n+2) { border-bottom: 0; }
.principle-list h3 { margin: 72px 0 8px; font-family: var(--serif); font-size: 26px; }
.principle-list p { margin: 0; color: var(--muted); font-size: 14px; }

.beta-heading { grid-column: 2 / 8; padding-right: 4vw; }
.live-label { display: flex; align-items: center; gap: 12px; margin-bottom: 28px; color: var(--green); font-size: 12px; }
.beta-grid { grid-column: 8 / 13; display: grid; grid-template-columns: 1fr 1fr; border-left: 1px solid var(--line); }
.beta-grid article { min-height: 280px; padding: 40px 32px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.beta-grid article:nth-child(2) { border-right: 0; }
.beta-grid article > strong { display: block; margin: 64px 0 10px; font-family: var(--serif); font-size: 27px; line-height: 1.35; }
.beta-grid article > p { margin: 0; color: var(--muted); font-size: 13px; }
.beta-grid .wide { grid-column: 1 / -1; min-height: 220px; border-right: 0; border-bottom: 0; }
.beta-grid .wide div { display: grid; grid-template-columns: 1fr 1fr; gap: 0 28px; margin-top: 30px; }
.beta-grid .wide p { margin: 0; padding: 10px 0; border-bottom: 1px solid var(--line); }

.scope-heading { grid-column: 2 / 8; padding: 82px 5vw; }
.scope-list { grid-column: 8 / 13; padding: 64px 4vw; border-left: 1px solid var(--line); }
.scope-list p { display: grid; grid-template-columns: 86px 1fr; gap: 16px; margin: 0; padding: 18px 0; border-bottom: 1px solid var(--line); }
.scope-list span { color: var(--muted); font-size: 11px; }

.boundary-heading { grid-column: 2 / 8; padding: 82px 5vw; }
.responsibility-map { grid-column: 8 / 13; display: grid; grid-template-columns: 1fr 1fr; border-left: 1px solid var(--line); }
.responsibility-map > div { padding: 74px 34px; }
.responsibility-map > div + div { border-left: 1px solid var(--line); }
.responsibility-map p { margin: 16px 0 0; padding-bottom: 9px; border-bottom: 1px solid var(--line); }
.responsibility-map .human { background: var(--blue-soft); }
.responsibility-map .human span { color: var(--blue); }

.case-cta { display: grid; place-items: center; min-height: 620px; padding: 100px 28px; text-align: center; }
.case-cta > p:first-child { color: var(--muted); font-size: 10px; letter-spacing: .2em; }
.case-cta h2 { margin: 18px 0; font-family: var(--serif); font-size: clamp(42px,6vw,80px); }
.cta-note { max-width: 620px; margin: 0; color: var(--muted); }
.cta-actions { display: flex; align-items: center; gap: 30px; margin-top: 42px; }
.primary-action { display: inline-flex; align-items: center; justify-content: center; gap: 38px; min-width: 224px; min-height: 58px; padding: 0 24px; background: var(--ink); color: #fff; }
.primary-action svg { width: 18px; stroke-width: 1.7; }
.text-action { padding: 12px 0; border-bottom: 1px solid var(--ink); }
.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; }
  .course-map { grid-column: 2; min-height: 700px; 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; }
  .system-heading { display: block; }
  .system-heading > p { margin-top: 22px; }
  .principles-heading, .beta-heading, .scope-heading, .boundary-heading { grid-column: 2 / 13; }
  .principle-list, .beta-grid, .scope-list, .responsibility-map { 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: 34px; }
  .hero-statement span { white-space: normal; }
  .hero-description { font-size: 15px; }
  .project-facts div { grid-template-columns: 70px 1fr; }
  .hero-description, .project-facts dd { min-width: 0; overflow-wrap: anywhere; }
  .course-map { min-height: 700px; }
  .map-head { right: 20px; left: 20px; }
  .map-core { width: 190px; height: 190px; padding: 32px 26px; }
  .map-core strong { margin-top: 18px; font-size: 23px; }
  .map-core small { left: 26px; bottom: 16px; }
  .course-map ol { inset: 92px 14px 26px; }
  .course-map li { width: 158px; padding: 12px; }
  .course-map li strong { font-size: 15px; }
  .course-map li small { font-size: 8px; }
  .problem-statement, .system-heading, .principles-heading, .beta-heading, .scope-heading, .boundary-heading { padding: 72px 20px 40px; }
  .problem-statement h2, .system-heading h2, .principles-heading h2, .beta-heading h2, .scope-heading h2, .boundary-heading h2 { font-size: 36px; }
  .problem-lines, .principle-list, .beta-grid, .responsibility-map { display: block; }
  .problem-lines article, .principle-list article, .beta-grid article { min-height: 230px; padding: 30px 20px; border-right: 0; border-bottom: 1px solid var(--line); }
  .problem-lines strong, .principle-list h3 { margin-top: 52px; }
  .loop-interface { display: block; }
  .loop-tabs { grid-template-columns: repeat(5,minmax(132px,1fr)); overflow-x: auto; border-right: 0; }
  .loop-tab { display: block; min-height: 78px; padding: 12px; white-space: nowrap; }
  .loop-tab span { display: block; margin-bottom: 4px; }
  .loop-detail { display: block; min-height: 520px; padding: 38px 20px; }
  .loop-detail > p { margin-top: 28px; }
  .loop-detail dl { grid-template-columns: 1fr; }
  .loop-detail dl div { padding: 14px 0; border-bottom: 1px solid var(--line); }
  .beta-grid article > strong { margin-top: 48px; }
  .beta-grid .wide div { grid-template-columns: 1fr; }
  .scope-list { padding: 30px 20px 66px; }
  .scope-list p { grid-template-columns: 72px 1fr; }
  .responsibility-map > div { padding: 54px 20px; }
  .responsibility-map > div + div { border-top: 1px solid var(--line); border-left: 0; }
  .case-cta { min-height: 540px; padding: 80px 20px; }
  .case-cta h2 { font-size: 43px; }
  .cta-actions { flex-direction: column; }
  .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; }
}