/* ==========================================================================
   USDM Play — Knowledge Hub stylesheet
   Palette: ink #0B1220, navy #0B2545, teal #0EA5A5, amber #F5A623
   Type: Space Grotesk (display), Inter (body), JetBrains Mono (code)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@500;600;700&family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500;600&display=swap');

:root{
  --ink:#0B1220;
  --navy:#0B2545;
  --navy-2:#123163;
  --teal:#0EA5A5;
  --teal-light:#5EEAD4;
  --amber:#F5A623;
  --bg:#F6F8FB;
  --card:#FFFFFF;
  --line:#E3E9F2;
  --text:#1B2430;
  --muted:#57667A;
  --radius:14px;
  --maxw:1180px;
  --code-bg:#0B1220;
}

*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  font-family:'Inter',system-ui,-apple-system,Segoe UI,sans-serif;
  line-height:1.65;
  font-size:17px;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,h4{
  font-family:'Space Grotesk',system-ui,sans-serif;
  color:var(--navy);
  line-height:1.2;
  font-weight:600;
  letter-spacing:-0.01em;
}
h1{font-size:2.5rem;margin:0 0 .5rem;}
h2{font-size:1.65rem;margin:2.6rem 0 1rem;padding-top:.4rem;border-top:1px solid var(--line);}
h2:first-of-type{border-top:none;padding-top:0;}
h3{font-size:1.2rem;margin:1.8rem 0 .7rem;color:var(--navy-2);}
p{margin:0 0 1.1rem;}
a{color:var(--teal);text-decoration:none;}
a:hover{text-decoration:underline;}
code, pre, .mono{font-family:'JetBrains Mono',monospace;}
ul,ol{margin:0 0 1.2rem;padding-left:1.4rem;}
li{margin-bottom:.4rem;}
strong{color:var(--navy);}

.skip-link{position:absolute;left:-999px;top:0;background:var(--teal);color:#fff;padding:.5rem 1rem;z-index:100;}
.skip-link:focus{left:0;}

/* ---------- header ---------- */
header.site{
  background:var(--ink);
  color:#fff;
  position:sticky;top:0;z-index:50;
  border-bottom:1px solid rgba(255,255,255,.08);
}
.nav-wrap{
  max-width:var(--maxw);margin:0 auto;padding:.85rem 1.5rem;
  display:flex;align-items:center;justify-content:space-between;gap:1rem;flex-wrap:wrap;
}
.brand{display:flex;align-items:center;gap:.55rem;font-family:'Space Grotesk';font-weight:700;font-size:1.15rem;color:#fff;}
.brand:hover{text-decoration:none;}
.brand .node{width:11px;height:11px;border-radius:50%;background:var(--teal);box-shadow:0 0 0 4px rgba(14,165,165,.25);}
nav.primary{display:flex;gap:1.35rem;flex-wrap:wrap;font-size:.92rem;}
nav.primary a{color:#C8D3E6;font-weight:500;}
nav.primary a:hover{color:#fff;text-decoration:none;}
nav.primary details{position:relative;display:inline-block;}
nav.primary summary{cursor:pointer;color:#C8D3E6;list-style:none;}
nav.primary summary::-webkit-details-marker{display:none;}
nav.primary details[open] summary{color:#fff;}
.dropdown{
  position:absolute;left:0;top:1.6rem;background:#111a2e;border:1px solid rgba(255,255,255,.1);
  border-radius:10px;padding:.6rem;min-width:230px;box-shadow:0 20px 40px rgba(0,0,0,.35);
}
.dropdown a{display:block;padding:.4rem .6rem;border-radius:6px;font-size:.88rem;}
.dropdown a:hover{background:rgba(14,165,165,.15);text-decoration:none;}

/* ---------- breadcrumb ---------- */
.breadcrumb{max-width:var(--maxw);margin:1rem auto 0;padding:0 1.5rem;font-size:.85rem;color:var(--muted);}
.breadcrumb a{color:var(--muted);}
.breadcrumb a:hover{color:var(--teal);}

/* ---------- hero / backbone signature ---------- */
.hero{max-width:var(--maxw);margin:0 auto;padding:1.4rem 1.5rem 0;}
.eyebrow{
  display:inline-block;font-family:'Space Grotesk';font-size:.78rem;font-weight:600;
  letter-spacing:.08em;text-transform:uppercase;color:var(--teal);background:rgba(14,165,165,.1);
  padding:.3rem .7rem;border-radius:100px;margin-bottom:.9rem;
}
.subhead{font-size:1.15rem;color:var(--muted);max-width:62ch;margin:0 0 1.4rem;}

.backbone{
  display:flex;align-items:center;gap:0;flex-wrap:wrap;
  background:linear-gradient(135deg,var(--navy) 0%, var(--navy-2) 100%);
  border-radius:var(--radius);padding:1.3rem 1.4rem;margin:0 0 2rem;
  overflow-x:auto;
}
.backbone .bnode{
  display:flex;flex-direction:column;align-items:center;gap:.35rem;flex:0 0 auto;padding:0 .9rem;
}
.backbone .dot{width:14px;height:14px;border-radius:50%;background:var(--teal-light);box-shadow:0 0 0 6px rgba(94,234,212,.15);}
.backbone .lbl{color:#EAF1FF;font-size:.78rem;font-family:'JetBrains Mono';white-space:nowrap;}
.backbone .arrow{color:rgba(255,255,255,.35);flex:0 0 auto;font-size:1.1rem;}

/* ---------- layout ---------- */
main{max-width:var(--maxw);margin:0 auto;padding:0 1.5rem 4rem;}
.layout{display:grid;grid-template-columns:1fr 260px;gap:3rem;align-items:start;}
article{min-width:0;}
.toc{
  position:sticky;top:5.5rem;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:1.2rem 1.3rem;font-size:.88rem;
}
.toc h4{margin:0 0 .7rem;font-size:.8rem;text-transform:uppercase;letter-spacing:.06em;color:var(--muted);}
.toc ul{margin:0;padding:0;list-style:none;}
.toc li{margin-bottom:.5rem;}
.toc a{color:var(--text);}
.toc a:hover{color:var(--teal);}

/* ---------- callouts / boxes ---------- */
.callout{
  background:var(--card);border:1px solid var(--line);border-left:4px solid var(--teal);
  border-radius:10px;padding:1.1rem 1.3rem;margin:1.5rem 0;
}
.callout.amber{border-left-color:var(--amber);}
.callout h4{margin:0 0 .4rem;font-size:1rem;color:var(--navy);}

.tldr{
  background:#EAFBF8;border:1px solid #C7EFE9;border-radius:var(--radius);
  padding:1.2rem 1.4rem;margin:0 0 2rem;
}
.tldr h4{margin:0 0 .5rem;color:var(--navy);font-size:.95rem;text-transform:uppercase;letter-spacing:.05em;}
.tldr p{margin:0;}

.download-box{
  display:flex;justify-content:space-between;align-items:center;gap:1rem;flex-wrap:wrap;
  background:var(--navy);color:#fff;border-radius:var(--radius);padding:1.3rem 1.5rem;margin:1.8rem 0;
}
.download-box .file{font-family:'JetBrains Mono';font-size:.85rem;color:var(--teal-light);}
.download-box p{margin:0;color:#D7E2F5;}
.btn{
  display:inline-block;background:var(--teal);color:#032B2B;font-weight:700;padding:.65rem 1.1rem;
  border-radius:8px;font-size:.9rem;white-space:nowrap;
}
.btn:hover{background:var(--teal-light);text-decoration:none;}
.btn.ghost{background:transparent;border:1px solid rgba(255,255,255,.35);color:#fff;}
.btn.ghost:hover{background:rgba(255,255,255,.08);}

/* ---------- tables ---------- */
table{width:100%;border-collapse:collapse;margin:1.2rem 0 1.8rem;font-size:.94rem;}
th,td{text-align:left;padding:.65rem .8rem;border-bottom:1px solid var(--line);}
th{background:#EEF3FA;color:var(--navy);font-family:'Space Grotesk';font-weight:600;font-size:.85rem;text-transform:uppercase;letter-spacing:.03em;}
tr:last-child td{border-bottom:none;}

/* ---------- code ---------- */
pre{
  background:var(--code-bg);color:#DCE6F5;border-radius:10px;padding:1.1rem 1.3rem;overflow-x:auto;
  font-size:.86rem;line-height:1.55;margin:1.2rem 0 1.8rem;border:1px solid #1B2A45;
}
pre .k{color:var(--teal-light);}
pre .s{color:#F5A623;}
code.inline{background:#EEF3FA;color:var(--navy-2);padding:.15rem .4rem;border-radius:5px;font-size:.88em;}

/* ---------- cards / grid ---------- */
.grid-cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:1.1rem;margin:1.6rem 0 2rem;}
.grid-cards .card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:1.1rem 1.2rem;}
.grid-cards .card h4{margin:0 0 .4rem;font-size:1rem;color:var(--navy);}
.grid-cards .card p{margin:0;font-size:.9rem;color:var(--muted);}

/* ---------- hub index grid ---------- */
.hub-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(270px,1fr));gap:1.2rem;margin:1.6rem 0 2.5rem;}
.hub-card{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:1.4rem;
  transition:transform .15s ease, box-shadow .15s ease;
}
.hub-card:hover{transform:translateY(-3px);box-shadow:0 14px 30px rgba(11,37,69,.1);}
.hub-card .tag{font-size:.72rem;text-transform:uppercase;letter-spacing:.06em;color:var(--teal);font-weight:700;}
.hub-card h3{margin:.4rem 0 .5rem;font-size:1.05rem;}
.hub-card p{color:var(--muted);font-size:.9rem;margin:0 0 .8rem;}
.hub-card a.readmore{font-weight:600;font-size:.88rem;}

/* ---------- faq ---------- */
.faq details{
  background:var(--card);border:1px solid var(--line);border-radius:10px;padding:1rem 1.2rem;margin-bottom:.8rem;
}
.faq summary{font-weight:600;color:var(--navy);cursor:pointer;font-family:'Space Grotesk';}
.faq p{margin:.7rem 0 0;color:var(--muted);}

/* ---------- keyword chips ---------- */
.chips{display:flex;flex-wrap:wrap;gap:.5rem;margin:1rem 0 2rem;}
.chip{background:#EEF3FA;color:var(--navy-2);font-size:.8rem;padding:.35rem .75rem;border-radius:100px;font-family:'JetBrains Mono';}

/* ---------- related ---------- */
.related{background:#EEF3FA;border-radius:var(--radius);padding:1.4rem 1.6rem;margin:2.5rem 0;}
.related h4{margin:0 0 .8rem;}
.related ul{margin:0;padding:0;list-style:none;display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:.5rem .8rem;}
.related a{font-weight:600;}

/* ---------- svg diagram frame ---------- */
.diagram{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:1.2rem;margin:1.6rem 0 2rem;text-align:center;
}
.diagram svg{max-width:100%;height:auto;}
.diagram figcaption{font-size:.85rem;color:var(--muted);margin-top:.7rem;}

/* ---------- footer ---------- */
footer.site{background:var(--ink);color:#B9C4D8;margin-top:3rem;}
.footer-wrap{max-width:var(--maxw);margin:0 auto;padding:2.6rem 1.5rem;display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:2rem;}
footer.site h5{color:#fff;font-family:'Space Grotesk';font-size:.85rem;text-transform:uppercase;letter-spacing:.06em;margin:0 0 .8rem;}
footer.site ul{list-style:none;padding:0;margin:0;}
footer.site li{margin-bottom:.5rem;font-size:.88rem;}
footer.site a{color:#B9C4D8;}
footer.site a:hover{color:#fff;}
.footer-bottom{border-top:1px solid rgba(255,255,255,.08);text-align:center;padding:1.2rem;font-size:.8rem;color:#7C8AA3;}

@media (max-width:900px){
  .layout{grid-template-columns:1fr;}
  .toc{position:static;margin-bottom:1.5rem;}
  .footer-wrap{grid-template-columns:1fr 1fr;}
  h1{font-size:2rem;}
}
@media (max-width:560px){
  .footer-wrap{grid-template-columns:1fr;}
  nav.primary{display:none;}
}