/* ============================================================
   LUYA TECH — article / insights stylesheet
   Shared by all /articles/*.html pages.
   Light theme, print-friendly, chunk-friendly for AI extraction.
   ============================================================ */

:root{
  --ink:#0B1116;--ink-80:#1A242C;--ink-60:#4A5763;--ink-40:#7A8792;--ink-25:#A9B3BC;
  --line:#E4E2DE;--line-soft:#EFEDE9;--paper:#FFFFFF;--paper-2:#FAF9F7;--paper-3:#F2F0EC;
  --copper:#9C6B33;--copper-lt:#C89B62;--dark:#0B1116;--dark-2:#121A21;
  --max:1240px;--read:740px;--gut:32px;
  --ease:cubic-bezier(.22,.61,.36,1);
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  font-family:"Helvetica Neue",Helvetica,Arial,"Segoe UI",Roboto,"PingFang SC","Microsoft YaHei",sans-serif;
  background:var(--paper);color:var(--ink-60);font-size:17px;line-height:1.75;
  -webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;
  font-feature-settings:"kern" 1,"liga" 1;
}
a{color:inherit;text-decoration:none}
svg{display:block}
img{max-width:100%}
::selection{background:var(--ink);color:#fff}

.wrap{max-width:var(--max);margin:0 auto;padding:0 var(--gut)}
.read{max-width:var(--read);margin:0 auto;padding:0 var(--gut)}

h1,h2,h3,h4,h5{color:var(--ink);font-weight:500;letter-spacing:-0.028em;line-height:1.15}

/* ---------- nav ---------- */
header.site{
  position:sticky;top:0;z-index:100;background:rgba(255,255,255,.92);
  backdrop-filter:saturate(180%) blur(16px);-webkit-backdrop-filter:saturate(180%) blur(16px);
  border-bottom:1px solid var(--line);
}
.nav{display:flex;align-items:center;justify-content:space-between;height:72px}
.brand{display:flex;align-items:center;gap:12px}
.brand-mark{width:26px;height:26px;flex:none}
.brand-name{display:block;font-size:14.5px;font-weight:600;letter-spacing:.1em;color:var(--ink);line-height:1.1}
.brand-sub{display:block;font-size:9px;font-weight:500;letter-spacing:.2em;color:var(--ink-40);text-transform:uppercase;margin-top:4px}
.nav-right{display:flex;align-items:center;gap:32px}
.nav-link{font-size:13.5px;color:var(--ink-80);transition:color .25s}
.nav-link:hover{color:var(--copper)}
.btn{display:inline-flex;align-items:center;gap:9px;padding:11px 20px;font-size:13px;
  font-weight:550;border:1px solid var(--ink);background:var(--ink);color:#fff;
  transition:all .25s var(--ease);cursor:pointer;font-family:inherit;white-space:nowrap}
.btn:hover{background:var(--copper);border-color:var(--copper)}

/* ---------- breadcrumb ---------- */
.crumb{font-size:11.5px;color:var(--ink-40);padding:26px 0 0;letter-spacing:.01em}
.crumb a:hover{color:var(--copper)}
.crumb .sep{margin:0 8px;color:var(--ink-25)}
.crumb .cur{color:var(--ink-80)}

/* ---------- article header ---------- */
.ahead{padding:34px 0 0}
.ahead .kicker{
  display:inline-flex;align-items:center;gap:9px;font-size:10.5px;font-weight:600;
  letter-spacing:.16em;text-transform:uppercase;color:var(--copper);margin-bottom:22px;
}
.ahead .kicker::before{content:"";width:20px;height:1px;background:var(--copper)}
.ahead h1{
  font-size:clamp(30px,4vw,46px);line-height:1.08;letter-spacing:-0.038em;
  margin-bottom:26px;max-width:900px;
}
.standfirst{
  font-size:19px;line-height:1.62;color:var(--ink-80);max-width:760px;
  margin-bottom:32px;font-weight:400;
}
.byline{
  display:flex;flex-wrap:wrap;align-items:center;gap:10px 22px;
  padding:18px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);
  font-size:12.5px;color:var(--ink-40);max-width:900px;
}
.byline b{color:var(--ink-80);font-weight:600}
.byline .dot{width:3px;height:3px;border-radius:50%;background:var(--ink-25)}

/* ---------- answer box (GEO: extractable summary) ---------- */
.answer{
  border-left:3px solid var(--copper);background:var(--paper-2);
  padding:26px 30px;margin:40px 0 44px;
}
.answer .lbl{
  font-size:10px;font-weight:700;letter-spacing:.16em;text-transform:uppercase;
  color:var(--copper);margin-bottom:12px;
}
.answer p{font-size:16.5px;line-height:1.72;color:var(--ink-80);margin:0}
.answer p + p{margin-top:14px}
.answer strong{color:var(--ink);font-weight:600}

/* ---------- body prose ---------- */
.prose{padding:8px 0 40px}
.prose p{margin:0 0 22px;line-height:1.78}
.prose p.lead-in{font-size:18px;color:var(--ink-80);line-height:1.7}
.prose h2{
  font-size:clamp(24px,2.6vw,31px);line-height:1.16;letter-spacing:-0.03em;
  margin:64px 0 20px;scroll-margin-top:90px;
}
.prose h2:first-of-type{margin-top:12px}
.prose h3{
  font-size:19.5px;line-height:1.3;letter-spacing:-0.02em;
  margin:40px 0 14px;scroll-margin-top:90px;
}
.prose h4{font-size:16px;margin:28px 0 10px;letter-spacing:-0.012em}
.prose strong{color:var(--ink);font-weight:600}
.prose em{color:var(--ink-80)}
.prose a{
  color:var(--ink);border-bottom:1px solid var(--ink-25);
  transition:all .2s;
}
.prose a:hover{color:var(--copper);border-bottom-color:var(--copper)}
.prose ul,.prose ol{margin:0 0 24px;padding-left:22px}
.prose li{margin-bottom:10px;line-height:1.72}
.prose li::marker{color:var(--copper)}
.prose ul.plain{list-style:none;padding-left:0}
.prose ul.plain li{padding-left:20px;position:relative}
.prose ul.plain li::before{
  content:"";position:absolute;left:0;top:11px;width:7px;height:1px;background:var(--copper);
}
.prose blockquote{
  margin:32px 0;padding:4px 0 4px 26px;border-left:2px solid var(--ink-25);
  font-size:17.5px;line-height:1.7;color:var(--ink-80);font-style:italic;
}
.prose hr{border:none;border-top:1px solid var(--line);margin:48px 0}

/* ---------- tables ---------- */
.tw{overflow-x:auto;margin:32px 0;border:1px solid var(--line);-webkit-overflow-scrolling:touch}
table{width:100%;border-collapse:collapse;font-size:14px;min-width:560px}
thead th{
  background:var(--paper-2);text-align:left;padding:13px 16px;
  font-size:10.5px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;
  color:var(--ink);border-bottom:1px solid var(--line);white-space:nowrap;
}
tbody td{padding:13px 16px;border-bottom:1px solid var(--line-soft);vertical-align:top;line-height:1.6}
tbody tr:last-child td{border-bottom:none}
tbody tr:hover{background:var(--paper-2)}
tbody td:first-child{font-weight:600;color:var(--ink);white-space:nowrap}
td.num{font-variant-numeric:tabular-nums}

/* ---------- callout ---------- */
.note{
  border:1px solid var(--line);background:var(--paper-2);
  padding:24px 26px;margin:32px 0;
}
.note .note-lbl{
  font-size:10px;font-weight:700;letter-spacing:.15em;text-transform:uppercase;
  color:var(--copper);margin-bottom:10px;
}
.note p{font-size:15px;line-height:1.7;margin:0;color:var(--ink-60)}
.note p + p{margin-top:12px}
.note strong{color:var(--ink);font-weight:600}
.note.warn{border-left:3px solid #A8452B}
.note.warn .note-lbl{color:#A8452B}

/* ---------- key facts strip ---------- */
.facts{
  display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:var(--line);
  border:1px solid var(--line);margin:32px 0;
}
.facts div{background:#fff;padding:22px 20px}
.facts b{
  display:block;font-size:22px;font-weight:500;color:var(--ink);
  letter-spacing:-0.03em;line-height:1.1;margin-bottom:6px;font-variant-numeric:tabular-nums;
}
.facts span{font-size:11.5px;color:var(--ink-40);line-height:1.45;display:block}

/* ---------- FAQ ---------- */
.faq{margin:56px 0 0}
.faq h2{margin-top:0}
details{border-bottom:1px solid var(--line);border-top:1px solid var(--line);margin-bottom:-1px}
summary{
  list-style:none;cursor:pointer;padding:20px 0;display:flex;justify-content:space-between;
  align-items:center;gap:20px;font-size:16px;font-weight:550;color:var(--ink);
  letter-spacing:-0.018em;transition:color .25s;
}
summary::-webkit-details-marker{display:none}
summary:hover{color:var(--copper)}
summary .plus{width:14px;height:14px;flex:none;position:relative}
summary .plus::before,summary .plus::after{
  content:"";position:absolute;background:var(--ink-40);transition:all .25s;
}
summary .plus::before{left:0;top:6.5px;width:14px;height:1px}
summary .plus::after{left:6.5px;top:0;width:1px;height:14px}
details[open] summary .plus::after{transform:rotate(90deg);opacity:0}
details[open] summary{color:var(--copper)}
details .ans{font-size:15.5px;line-height:1.76;color:var(--ink-60);padding:0 30px 22px 0}
details .ans strong{color:var(--ink);font-weight:600}

/* ---------- author / sources ---------- */
.sources{margin:52px 0 0;padding:26px 0 0;border-top:1px solid var(--line)}
.sources h3{font-size:14px;margin-bottom:14px;letter-spacing:0}
.sources ol{padding-left:20px;margin:0}
.sources li{font-size:13px;line-height:1.6;color:var(--ink-40);margin-bottom:8px}

/* ---------- related ---------- */
.related{background:var(--paper-2);border-top:1px solid var(--line);margin-top:72px;padding:64px 0}
.related h2{font-size:22px;margin-bottom:28px;letter-spacing:-0.025em}
.rel-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}
.rel-item{
  background:#fff;border:1px solid var(--line);padding:26px 24px;
  transition:all .3s var(--ease);display:flex;flex-direction:column;
}
.rel-item:hover{border-color:var(--ink-25);box-shadow:0 12px 30px rgba(11,17,22,.06)}
.rel-item .tag{
  font-size:9.5px;font-weight:700;letter-spacing:.14em;text-transform:uppercase;
  color:var(--copper);margin-bottom:12px;
}
.rel-item h3{font-size:15.5px;line-height:1.35;letter-spacing:-0.018em;margin-bottom:10px}
.rel-item p{font-size:12.8px;line-height:1.6;color:var(--ink-40);margin:0}

/* ---------- article CTA ---------- */
.acta{background:var(--dark);color:#fff;padding:64px 0;margin-top:0}
.acta-inner{display:grid;grid-template-columns:1.2fr .8fr;gap:56px;align-items:center}
.acta h2{color:#fff;font-size:clamp(24px,2.8vw,32px);line-height:1.14;margin-bottom:14px;letter-spacing:-0.03em}
.acta p{font-size:14.5px;line-height:1.7;color:rgba(255,255,255,.6);margin:0}
.acta .btn{background:#fff;color:var(--ink);border-color:#fff;justify-self:end;padding:15px 28px}
.acta .btn:hover{background:var(--copper-lt);border-color:var(--copper-lt);color:#fff}

/* ---------- footer ---------- */
footer.site{background:#060A0E;color:rgba(255,255,255,.42);padding:56px 0 30px;font-size:12.5px}
.foot-top{
  display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:44px;
  padding-bottom:40px;border-bottom:1px solid rgba(255,255,255,.09);
}
.foot-brand .brand-name{color:#fff}
.foot-brand .brand-sub{color:rgba(255,255,255,.36)}
.foot-brand p{max-width:290px;line-height:1.7;font-size:12.2px;margin-top:18px;color:rgba(255,255,255,.4)}
.fc h5{color:#fff;font-size:10px;letter-spacing:.15em;text-transform:uppercase;margin-bottom:16px;font-weight:600}
.fc ul{list-style:none;display:grid;gap:10px}
.fc a:hover{color:#fff}
.fc li{font-size:12.2px;line-height:1.5}
.foot-bot{
  display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px;
  padding-top:24px;font-size:11px;color:rgba(255,255,255,.28);
}

/* ---------- responsive ---------- */
@media(max-width:980px){
  .acta-inner{grid-template-columns:1fr;gap:28px}
  .acta .btn{justify-self:start}
  .rel-grid{grid-template-columns:1fr 1fr}
  .foot-top{grid-template-columns:1fr 1fr;gap:32px}
  .facts{grid-template-columns:1fr}
}
@media(max-width:720px){
  :root{--gut:22px}
  body{font-size:16px}
  .nav-right .nav-link{display:none}
  .ahead h1{font-size:29px}
  .standfirst{font-size:17px}
  .answer{padding:22px 20px;margin:32px 0}
  .answer p{font-size:15.5px}
  .prose h2{font-size:23px;margin-top:48px}
  .prose h3{font-size:17.5px}
  .rel-grid{grid-template-columns:1fr}
  .foot-top{grid-template-columns:1fr}
  .prose{padding-bottom:24px}
}

@media print{
  header.site,.acta,.related,footer.site,.crumb{display:none}
  body{font-size:11pt;color:#000}
  .prose a{border-bottom:none;color:#000}
  .answer{background:#f5f5f5}
}