/* Chenlun — site styles. Palette and type follow the original design export. */
:root {
  --bg: #F6F4EF;
  --bg-2: #EFEDE6;
  --ink: #14171A;
  --ink-2: #3A4045;
  --muted: #5B6167;
  --grey: #8A8F94;
  --grey-2: #A0A5AA;
  --line: #D8D3C8;
  --line-2: #E2DED4;
  --line-3: #C9C3B6;
  --accent: #A2402A;
  --accent-2: #D9825F;
  --dark: #14171A;
  --dark-line: #333A40;
  --dark-text: #C3C7CB;
  --dark-text-2: #F0EDE6;

  --serif: 'Spectral', 'Noto Serif SC', serif;
  --sans: 'IBM Plex Sans', 'Noto Sans SC', sans-serif;
  --mono: 'IBM Plex Mono', monospace;
  --gutter: 48px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: var(--sans); -webkit-font-smoothing: antialiased;
}
img { display: block; max-width: 100%; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--ink); text-decoration: underline; text-underline-offset: 3px; }

/* language switching */
[data-lang="en"] .zh, [data-lang="zh"] .en { display: none !important; }

.wrap { max-width: 1180px; margin: 0 auto; padding: 88px var(--gutter); }
.mono { font-family: var(--mono); }
.eyebrow { font-family: var(--mono); font-size: 12px; letter-spacing: 0.16em; color: var(--accent); }
.kicker { font-family: var(--mono); font-size: 11px; letter-spacing: 0.12em; color: var(--accent); margin-bottom: 12px; }
.band { border-top: 1px solid var(--line); }
.band.alt { background: var(--bg-2); }

/* header */
.site-header {
  position: sticky; top: 0; z-index: 20;
  display: flex; align-items: center; justify-content: space-between; gap: 32px;
  padding: 16px var(--gutter);
  background: rgba(246, 244, 239, 0.93); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: baseline; gap: 12px; color: var(--ink); }
.brand:hover { text-decoration: none; color: var(--ink); }
.brand b { font-family: var(--mono); font-size: 15px; letter-spacing: 0.14em; font-weight: 500; }
.brand small { font-family: var(--mono); font-size: 11px; letter-spacing: 0.1em; color: var(--grey-2); }
.site-nav { display: flex; align-items: center; gap: 26px; font-size: 13px; }
.site-nav a.link { color: var(--muted); }
.lang-btn {
  font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.1em; padding: 8px 12px; min-width: 58px;
  white-space: nowrap; line-height: 1.2; background: transparent; border: 1px solid var(--line-3);
  color: var(--muted); cursor: pointer;
}
.lang-btn:hover { border-color: var(--ink); color: var(--ink); }
.btn-outline {
  display: inline-block; padding: 8px 16px; border: 1px solid var(--ink); color: var(--ink);
  font-family: var(--mono); font-size: 12px; letter-spacing: 0.08em;
}
.btn {
  display: inline-block; padding: 14px 28px; font-family: var(--mono); font-size: 13px; letter-spacing: 0.08em;
}
.btn.primary { background: var(--ink); color: var(--bg); }
.btn.primary:hover { background: var(--accent); color: var(--bg); text-decoration: none; }
.btn.ghost { border: 1px solid var(--line); color: var(--ink); }
.btn.ghost:hover { border-color: var(--ink); text-decoration: none; }

/* hero */
.hero { max-width: 1180px; margin: 0 auto; padding: 116px var(--gutter) 84px; }
.hero .eyebrow { margin-bottom: 40px; }
.hero h1 {
  font-family: var(--serif); font-weight: 400; font-size: 66px; line-height: 1.14; letter-spacing: -0.015em;
  margin: 0 0 30px; max-width: 19ch; text-wrap: pretty;
}
[data-lang="zh"] .hero h1 { font-size: 62px; line-height: 1.2; max-width: 16ch; letter-spacing: 0; }
.hero p.lead { font-size: 18px; line-height: 1.75; color: var(--ink-2); margin: 0 0 48px; max-width: 62ch; text-wrap: pretty; }
[data-lang="zh"] .hero p.lead { line-height: 1.85; max-width: 44ch; }
.cta-row { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }

.proof {
  margin-top: 76px; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 1px solid var(--ink);
}
.proof a { display: block; padding: 20px 20px 4px 0; color: var(--ink); }
.proof a:hover { text-decoration: none; }
.proof a:hover .num { color: var(--accent); }
.proof .num { font-family: var(--serif); font-size: 34px; line-height: 1.1; margin-bottom: 8px; }
.proof .lbl { font-family: var(--mono); font-size: 10.5px; letter-spacing: 0.08em; color: var(--grey); line-height: 1.5; }

/* section headings */
.sec-head { display: flex; align-items: baseline; gap: 20px; margin-bottom: 10px; }
.sec-head .n { font-family: var(--mono); font-size: 12px; letter-spacing: 0.14em; color: var(--accent); }
.sec-head h2 { font-family: var(--serif); font-weight: 400; font-size: 38px; margin: 0; }
[data-lang="zh"] .sec-head h2 { font-size: 36px; }
.sec-sub { font-family: var(--mono); font-size: 12px; letter-spacing: 0.1em; color: var(--grey); margin: 0 0 52px; padding-left: 52px; }

p.body { font-size: 14.5px; line-height: 1.7; color: var(--ink-2); margin: 0; }
[data-lang="zh"] p.body { line-height: 1.8; }
p.note { font-size: 14.5px; line-height: 1.75; color: var(--muted); margin: 26px 0 0; max-width: 76ch; }

/* scales */
.scales { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); }
.scales > div { background: var(--bg); }
.scales .img { aspect-ratio: 376 / 210; border-bottom: 1px solid var(--line); overflow: hidden; }
.scales .img img { width: 100%; height: 100%; object-fit: contain; }
.scales .txt { padding: 26px 26px 32px; }
h3.card-title { font-family: var(--serif); font-weight: 600; font-size: 22px; margin: 0 0 12px; }

/* services */
.services { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); column-gap: 64px; }
.service { border-top: 1px solid var(--line); padding: 22px 0 26px; }
.service.first { border-top-color: var(--ink); }
.service .top { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 10px; gap: 16px; }
.service h3 { font-family: var(--serif); font-weight: 600; font-size: 20px; margin: 0; }
.service .code { font-family: var(--mono); font-size: 11px; color: var(--accent); white-space: nowrap; }
.service .code a { color: var(--accent); }

/* MCP */
.dark { background: var(--dark); color: var(--dark-text-2); border-top: 1px solid var(--line); }
.dark .sec-head .n { color: var(--accent-2); }
.dark .sec-head h2 { color: var(--bg); }
.dark .big {
  font-family: var(--serif); font-size: 27px; line-height: 1.5; color: var(--dark-text-2);
  margin: 0 0 64px; max-width: 44ch; text-wrap: pretty;
}
[data-lang="zh"] .dark .big { font-size: 26px; line-height: 1.6; max-width: 32ch; }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; margin-bottom: 64px; }
.dark-label {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.14em; color: var(--accent-2);
  margin-bottom: 16px; padding-bottom: 12px; border-bottom: 1px solid var(--dark-line);
}
.dark p.dbody { font-size: 15.5px; line-height: 1.8; color: var(--dark-text); margin: 0; }
[data-lang="zh"] .dark p.dbody { line-height: 1.9; }
.mcp-panel { border: 1px solid var(--dark-line); }
.mcp-panel .shot { border-bottom: 1px solid var(--dark-line); background: #1B1F23; }
.mcp-panel .shot img { width: 100%; height: auto; }
.mcp-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.mcp-grid > div { padding: 26px 26px 30px; border-right: 1px solid var(--dark-line); }
.mcp-grid > div:last-child { border-right: 0; }
.mcp-grid .lab { font-family: var(--mono); font-size: 11px; letter-spacing: 0.12em; color: var(--grey); margin-bottom: 12px; }
.mcp-grid p { font-size: 14.5px; line-height: 1.75; color: var(--dark-text); margin: 0; }
.mcp-grid .hi .lab { color: var(--accent-2); }
.mcp-grid .hi p { color: var(--dark-text-2); }
.dark a.more { color: var(--accent-2); font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.06em; }
.dark a.more:hover { color: var(--bg); }

/* validation */
.val-grid { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); gap: 56px; align-items: start; }
.val-fig { border: 1px solid var(--line); }
.val-fig img { width: 100%; height: auto; }
.val-fig figcaption, figure.fig figcaption {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.04em; line-height: 1.6; color: var(--grey);
  padding: 12px 14px; border-top: 1px solid var(--line); margin: 0;
}
.step { border-top: 1px solid var(--line); padding: 20px 0; }
.step:first-child { border-top-color: var(--ink); }
.step .kicker { margin-bottom: 10px; }
.step h3 { font-family: var(--serif); font-weight: 600; font-size: 19px; margin: 0 0 8px; }

/* case cards */
.cases { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 32px; }
.case-card { background: var(--bg); border: 1px solid var(--line); display: flex; flex-direction: column; color: inherit; transition: border-color .15s; }
.case-card:hover { border-color: var(--ink); text-decoration: none; color: inherit; }
.case-card .img { aspect-ratio: 372 / 196; border-bottom: 1px solid var(--line); overflow: hidden; }
.case-card .img img { width: 100%; height: 100%; object-fit: contain; }
.case-card .txt { padding: 24px 24px 24px; display: flex; flex-direction: column; flex: 1; }
.case-card h3 { font-family: var(--serif); font-weight: 600; font-size: 19px; line-height: 1.35; margin: 0 0 10px; color: var(--ink); }
.case-card p { font-size: 14px; line-height: 1.7; color: var(--muted); margin: 0 0 16px; }
[data-lang="zh"] .case-card p { line-height: 1.8; }
.case-card .metrics { margin-top: auto; }
.metrics { display: flex; gap: 28px; border-top: 1px solid var(--line-2); padding-top: 14px; flex-wrap: wrap; }
.metrics .v { font-family: var(--serif); font-size: 26px; line-height: 1.2; color: var(--ink); }
.metrics .v small { font-size: 15px; color: var(--muted); }
.metrics .k { font-family: var(--mono); font-size: 10.5px; color: var(--grey); letter-spacing: 0.08em; }
.case-card .read { font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.08em; color: var(--accent); margin-top: 16px; }

/* contact */
.contact { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 72px; align-items: start; }
.contact h2 { font-family: var(--serif); font-weight: 400; font-size: 42px; line-height: 1.2; margin: 0 0 22px; max-width: 22ch; }
[data-lang="zh"] .contact h2 { font-size: 40px; line-height: 1.3; max-width: 16ch; }
.contact p.lead { font-size: 16px; line-height: 1.75; color: var(--ink-2); margin: 0 0 32px; max-width: 52ch; }
.contact .box { border: 1px solid var(--line); background: var(--bg); padding: 28px; }
.contact .box .lab { font-family: var(--mono); font-size: 11px; letter-spacing: 0.14em; color: var(--grey); margin-bottom: 20px; }
.contact .item { display: flex; gap: 14px; font-size: 14.5px; line-height: 1.6; color: var(--ink-2); margin-bottom: 14px; }
.contact .item span:first-child { font-family: var(--mono); color: var(--accent); }
.mail { font-family: var(--mono); font-size: 19px; letter-spacing: 0.02em; }

.site-footer {
  border-top: 1px solid var(--line); padding: 32px var(--gutter);
  display: flex; justify-content: space-between; align-items: center; gap: 16px; flex-wrap: wrap;
  font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.08em; color: var(--grey);
}

/* ───────────── case pages ───────────── */
.case-hero { max-width: 1180px; margin: 0 auto; padding: 72px var(--gutter) 56px; }
.back { font-family: var(--mono); font-size: 12px; letter-spacing: 0.08em; color: var(--muted); display: inline-block; margin-bottom: 44px; }
.case-hero h1 {
  font-family: var(--serif); font-weight: 400; font-size: 52px; line-height: 1.16; letter-spacing: -0.01em;
  margin: 18px 0 26px; max-width: 22ch; text-wrap: pretty;
}
[data-lang="zh"] .case-hero h1 { font-size: 46px; line-height: 1.3; max-width: 20ch; letter-spacing: 0; }
.case-hero .lead { font-size: 18px; line-height: 1.75; color: var(--ink-2); max-width: 64ch; margin: 0; text-wrap: pretty; }
[data-lang="zh"] .case-hero .lead { line-height: 1.9; max-width: 46ch; }

.kpis { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); border-top: 1px solid var(--ink); border-bottom: 1px solid var(--line); margin-top: 52px; }
.kpis > div { padding: 22px 20px 22px 0; }
.kpis .v { font-family: var(--serif); font-size: 36px; line-height: 1.1; }
.kpis .v small { font-size: 18px; color: var(--muted); }
.kpis .k { font-family: var(--mono); font-size: 10.5px; letter-spacing: 0.08em; color: var(--grey); margin-top: 8px; line-height: 1.5; }

.case-body { max-width: 1180px; margin: 0 auto; padding: 64px var(--gutter) 88px; display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 72px; align-items: start; }
.facts { position: sticky; top: 90px; border-top: 1px solid var(--ink); }
.facts dl { margin: 0; }
.facts dt { font-family: var(--mono); font-size: 10.5px; letter-spacing: 0.12em; color: var(--grey); padding-top: 14px; }
.facts dd { margin: 4px 0 0; padding-bottom: 14px; border-bottom: 1px solid var(--line); font-size: 14px; line-height: 1.55; color: var(--ink-2); }

.article section { margin-bottom: 64px; }
.article section:last-child { margin-bottom: 0; }
.article h2 { font-family: var(--serif); font-weight: 400; font-size: 30px; margin: 0 0 20px; display: flex; gap: 16px; align-items: baseline; }
.article h2 .n { font-family: var(--mono); font-size: 12px; letter-spacing: 0.14em; color: var(--accent); }
.article p { font-size: 16px; line-height: 1.8; color: var(--ink-2); margin: 0 0 16px; max-width: 70ch; }
[data-lang="zh"] .article p { line-height: 1.95; }
.article ul.res { list-style: none; padding: 0; margin: 0 0 24px; max-width: 70ch; }
.article ul.res li { position: relative; padding: 10px 0 10px 26px; border-top: 1px solid var(--line-2); font-size: 15.5px; line-height: 1.7; color: var(--ink-2); }
.article ul.res li::before { content: '→'; position: absolute; left: 0; color: var(--accent); font-family: var(--mono); }
.article strong { font-weight: 500; color: var(--ink); }

.method { counter-reset: m; border-top: 1px solid var(--ink); margin-bottom: 8px; }
.method > div { display: grid; grid-template-columns: 56px minmax(0, 1fr); padding: 18px 0; border-bottom: 1px solid var(--line); }
.method > div::before { counter-increment: m; content: counter(m, decimal-leading-zero); font-family: var(--mono); font-size: 12px; color: var(--accent); padding-top: 3px; }
.method h3 { font-family: var(--serif); font-weight: 600; font-size: 18px; margin: 0 0 6px; }
.method p { font-size: 15px; line-height: 1.7; margin: 0; }

figure.fig { margin: 32px 0; border: 1px solid var(--line); background: var(--bg); }
figure.fig img { width: 100%; height: auto; }
figure.fig.dark-shot { background: #1B1F23; border-color: var(--dark-line); }
figure.fig.dark-shot figcaption { background: var(--bg); }
.fig-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin: 32px 0; }
.fig-pair figure.fig { margin: 0; }

.limits { background: var(--bg-2); border-left: 2px solid var(--accent); padding: 20px 24px; margin: 8px 0 0; max-width: 70ch; }
.limits p { font-size: 15px; margin: 0; }
.deliver { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 32px; border-top: 1px solid var(--ink); max-width: 76ch; }
.deliver > div { padding: 14px 0; border-bottom: 1px solid var(--line); font-size: 15px; line-height: 1.6; color: var(--ink-2); }

.next-case { border-top: 1px solid var(--line); background: var(--bg-2); }
.next-case .wrap { padding-top: 48px; padding-bottom: 48px; display: flex; justify-content: space-between; align-items: center; gap: 24px; flex-wrap: wrap; }
.next-case a.nx { font-family: var(--serif); font-size: 26px; color: var(--ink); }
.next-case a.nx:hover { color: var(--accent); }

/* ───────────── responsive ───────────── */
@media (max-width: 1000px) {
  :root { --gutter: 32px; }
  .site-nav a.link { display: none; }
  .cases { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .case-body { grid-template-columns: minmax(0, 1fr); gap: 40px; }
  .facts { position: static; }
  .facts dl { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); column-gap: 24px; }
  .proof, .kpis { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 720px) {
  :root { --gutter: 16px; }
  .wrap { padding-top: 64px; padding-bottom: 64px; }
  .site-header { gap: 12px; padding: 12px var(--gutter); }
  .brand small { display: none; }
  .hero { padding: 64px var(--gutter) 56px; }
  .hero h1, [data-lang="zh"] .hero h1 { font-size: 40px; }
  .case-hero h1, [data-lang="zh"] .case-hero h1 { font-size: 34px; }
  .sec-head h2, [data-lang="zh"] .sec-head h2 { font-size: 30px; }
  .sec-sub { padding-left: 0; margin-bottom: 36px; }
  .scales, .services, .two-col, .mcp-grid, .val-grid, .cases, .contact, .fig-pair, .deliver { grid-template-columns: minmax(0, 1fr); }
  .mcp-grid > div { border-right: 0; border-bottom: 1px solid var(--dark-line); }
  .mcp-panel .shot { overflow-x: auto; }
  .mcp-panel .shot img { min-width: 720px; }
  .two-col, .val-grid, .contact { gap: 40px; }
  .dark .big, [data-lang="zh"] .dark .big { font-size: 22px; margin-bottom: 44px; }
  .contact h2, [data-lang="zh"] .contact h2 { font-size: 32px; }
  .facts dl { grid-template-columns: minmax(0, 1fr); }
  .kpis .v, .proof .num { font-size: 24px; }
  .method > div { grid-template-columns: 40px minmax(0, 1fr); }
}