:root{
  --bg:#0a0f16;
  --bg-soft:#111823;
  --panel:#121b27;
  --panel-2:#172230;
  --text:#e8edf3;
  --muted:#9eabb9;
  --line:#263344;
  --accent:#77b9ff;
  --accent-2:#b5d7ff;
  --shadow:0 18px 60px rgba(0,0,0,.28);
  --radius:20px;
  --max:1180px;
}
html[data-theme="light"]{
  --bg:#f7f9fc;
  --bg-soft:#edf2f8;
  --panel:#ffffff;
  --panel-2:#f4f7fb;
  --text:#122033;
  --muted:#5d6c7d;
  --line:#d8e0ea;
  --accent:#1769aa;
  --accent-2:#0f4f86;
  --shadow:0 18px 48px rgba(28,51,77,.10);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);font:17px/1.68 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%}
.container{width:min(calc(100% - 36px),var(--max));margin:auto}
.narrow{max-width:880px}
.skip-link{position:absolute;left:-10000px;top:auto}
.skip-link:focus{left:16px;top:16px;z-index:1000;background:var(--panel);padding:10px 14px;border-radius:8px}
.site-header{position:sticky;top:0;z-index:100;background:color-mix(in srgb,var(--bg) 88%, transparent);backdrop-filter:blur(18px);border-bottom:1px solid var(--line)}
.nav-wrap{min-height:76px;display:flex;align-items:center;gap:18px}
.brand{display:flex;align-items:center;gap:11px;color:var(--text);min-width:250px}
.brand:hover{text-decoration:none}
.brand-mark{width:38px;height:38px;border:1px solid var(--line);border-radius:12px;display:grid;place-items:center;background:var(--panel);font-weight:800;letter-spacing:-.04em}
.brand-text{display:flex;flex-direction:column;line-height:1.08}
.brand-text small{color:var(--muted);font-size:.70rem;margin-top:4px}
.nav{margin-left:auto;display:flex;gap:7px;align-items:center;flex-wrap:wrap;justify-content:flex-end}
.nav a{color:var(--muted);font-size:.78rem;padding:7px 8px;border-radius:8px}
.nav a:hover,.nav a.active{color:var(--text);background:var(--panel);text-decoration:none}
.theme-toggle,.menu-toggle{border:1px solid var(--line);background:var(--panel);color:var(--text);border-radius:10px;padding:8px 10px;cursor:pointer}
.menu-toggle{display:none}
.hero{padding:86px 0 64px;border-bottom:1px solid var(--line);background:radial-gradient(circle at 75% 35%,rgba(119,185,255,.10),transparent 35%)}
.hero-grid{display:grid;grid-template-columns:1.08fr .92fr;gap:56px;align-items:center}
.hero h1,.page-hero h1{font-size:clamp(2.8rem,7vw,6.2rem);letter-spacing:-.055em;line-height:.92;margin:.18em 0}
.hero .lead,.page-hero .lead{font-size:clamp(1.25rem,2.2vw,1.75rem);color:var(--accent-2);max-width:760px}
.hero-copy>p:not(.eyebrow):not(.lead){max-width:720px;color:var(--muted)}
.eyebrow{text-transform:uppercase;letter-spacing:.18em;font-size:.72rem;font-weight:800;color:var(--accent)}
.hero-panel{background:linear-gradient(160deg,var(--panel),var(--panel-2));border:1px solid var(--line);border-radius:var(--radius);padding:30px;box-shadow:var(--shadow)}
.equation-flow{display:grid;gap:14px}
.equation-flow>div{display:grid;grid-template-columns:1fr auto 1fr;gap:12px;align-items:center}
.equation-flow span{border:1px solid var(--line);background:var(--bg-soft);padding:15px;border-radius:12px;text-align:center}
.equation-flow .arrow{display:block;text-align:center;color:var(--accent);font-size:1.4rem}
.cta-row{display:flex;flex-wrap:wrap;gap:10px;margin-top:28px}
.button{display:inline-flex;align-items:center;justify-content:center;border:1px solid var(--line);padding:11px 16px;border-radius:11px;color:var(--text);background:var(--panel);font-weight:700;font-size:.92rem}
.button:hover{text-decoration:none;transform:translateY(-1px)}
.button.primary{background:var(--accent);border-color:var(--accent);color:#07111d}
.button.ghost{background:transparent}
.button.small{padding:8px 12px;font-size:.82rem}
.section{padding:76px 0}
.section.alt{background:var(--bg-soft);border-block:1px solid var(--line)}
.section-head{max-width:760px;margin-bottom:30px}
.section-head h2,.prose h2,.table-title{font-size:clamp(1.7rem,3vw,2.7rem);letter-spacing:-.035em;line-height:1.12;margin:.25em 0 .55em}
.cards{display:grid;gap:18px}
.cards.four{grid-template-columns:repeat(4,1fr)}
.cards.two{grid-template-columns:repeat(2,1fr)}
.card,.callout,.publication{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:24px;box-shadow:0 8px 30px rgba(0,0,0,.05)}
.card h2,.card h3{margin:.5em 0 .4em}
.card p,.callout p{color:var(--muted)}
.num{font-size:.74rem;color:var(--accent);font-weight:800}
.mini-eq{font-family:ui-monospace,SFMono-Regular,Consolas,monospace;background:var(--bg-soft);border-radius:10px;padding:10px 12px;margin-top:14px}
.badge{display:inline-flex;align-items:center;border-radius:999px;padding:5px 9px;font-size:.63rem;font-weight:900;letter-spacing:.08em;border:1px solid var(--line)}
.badge.core{background:rgba(70,190,130,.13)}
.badge.derived{background:rgba(85,155,255,.13)}
.badge.effective{background:rgba(109,219,214,.13)}
.badge.candidate{background:rgba(244,181,65,.13)}
.badge.calibration{background:rgba(180,132,255,.13)}
.badge.open{background:rgba(240,96,96,.13)}
.two-col{display:grid;grid-template-columns:1.2fr .8fr;gap:36px;align-items:start}
.clean-list{padding-left:18px}
.quote-section blockquote{font-size:clamp(1.7rem,3vw,3rem);line-height:1.2;letter-spacing:-.03em;margin:20px 0 28px;max-width:1000px}
.status-legend{display:flex;gap:8px;flex-wrap:wrap}
.status-legend.big{margin-bottom:24px}
.page-hero{padding:74px 0 42px;border-bottom:1px solid var(--line);background:linear-gradient(180deg,var(--bg-soft),transparent)}
.page-hero h1{font-size:clamp(2.6rem,6vw,5rem)}
.prose>p,.prose>ul{color:var(--muted)}
.prose h2{margin-top:1.7em}
.math{overflow:auto;padding:8px 0}
.formula-stack{display:grid;gap:10px;margin:28px 0}
.formula-card{display:flex;justify-content:space-between;gap:20px;border:1px solid var(--line);border-radius:13px;padding:14px 16px;background:var(--panel)}
.formula-card span{color:var(--muted)}
.grid-list{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin:20px 0}
.grid-list>div{border:1px solid var(--line);border-radius:12px;padding:13px;background:var(--panel)}
.flow-diagram{display:grid;gap:10px;margin:28px 0}
.flow-diagram.compact{grid-template-columns:repeat(7,auto);align-items:center}
.flow-diagram.vertical{grid-template-columns:1fr}
.flow-node{border:1px solid var(--line);background:var(--panel);border-radius:12px;padding:14px;text-align:center}
.flow-arrow{text-align:center;color:var(--accent);font-weight:900}
.split{display:grid;grid-template-columns:1fr 1fr;gap:14px}
.large-gap{gap:20px}
.audit-row{display:flex;align-items:center;gap:12px;margin-top:46px}
.audit-row h2{margin:0}
.legend-table{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.legend-table>div{border:1px solid var(--line);border-radius:12px;padding:14px;background:var(--panel)}
.legend-table p{margin:8px 0 0;color:var(--muted)}
.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:16px}
table{width:100%;border-collapse:collapse;background:var(--panel);min-width:760px}
th,td{text-align:left;padding:14px 15px;border-bottom:1px solid var(--line);vertical-align:top}
th{font-size:.74rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);background:var(--panel-2)}
tbody tr:last-child td{border-bottom:0}
.top-space{margin-top:54px}
.problem{display:grid;grid-template-columns:70px 1fr;gap:18px;padding:28px 0;border-bottom:1px solid var(--line)}
.problem-n{font-size:1.6rem;font-weight:900;color:var(--accent)}
.problem h2{margin-top:0}
.publication{display:flex;align-items:center;justify-content:space-between;gap:20px}
.pub-label{font-size:.7rem;text-transform:uppercase;letter-spacing:.12em;color:var(--accent);font-weight:900}
.timeline{display:grid;gap:0}
.timeline-item{display:grid;grid-template-columns:70px 1fr;gap:20px;padding:24px 0;border-bottom:1px solid var(--line)}
.timeline-item>span{width:48px;height:48px;border-radius:50%;display:grid;place-items:center;border:1px solid var(--line);background:var(--panel);font-weight:900;color:var(--accent)}
.timeline-item.current>span{background:var(--accent);color:#07111d}
.timeline-item h2{margin:0 0 6px}
.timeline-item p{margin:0;color:var(--muted)}
.glossary{display:grid;grid-template-columns:220px 1fr;border-top:1px solid var(--line)}
.glossary dt,.glossary dd{padding:16px 0;border-bottom:1px solid var(--line);margin:0}
.glossary dt{font-weight:800}
.glossary dd{color:var(--muted)}
.faq details{border-bottom:1px solid var(--line);padding:16px 0}
.faq summary{cursor:pointer;font-weight:800;font-size:1.05rem}
.faq p{color:var(--muted)}
.site-footer{border-top:1px solid var(--line);padding:56px 0 26px;background:var(--bg-soft)}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr;gap:40px}
.footer-grid p{color:var(--muted)}
.footer-grid a{display:block;margin:6px 0;color:var(--muted)}
.footer-bottom{display:flex;justify-content:space-between;gap:24px;border-top:1px solid var(--line);padding-top:22px;margin-top:36px;color:var(--muted);font-size:.82rem}
.text-link{font-weight:800}
@media (max-width:980px){
  .menu-toggle{display:block;margin-left:auto}
  .nav{display:none;position:absolute;top:76px;left:18px;right:18px;background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:12px;box-shadow:var(--shadow);flex-direction:column;align-items:stretch}
  .nav.open{display:flex}
  .nav a{font-size:.92rem;padding:10px 12px}
  .theme-toggle{margin-left:0}
  .hero-grid,.two-col{grid-template-columns:1fr}
  .cards.four{grid-template-columns:repeat(2,1fr)}
  .flow-diagram.compact{grid-template-columns:1fr}
}
@media (max-width:680px){
  body{font-size:16px}
  .brand{min-width:0}
  .brand-text small{display:none}
  .hero{padding-top:56px}
  .cards.four,.cards.two,.grid-list,.legend-table,.split,.footer-grid{grid-template-columns:1fr}
  .publication,.footer-bottom{flex-direction:column;align-items:flex-start}
  .glossary{grid-template-columns:1fr}
  .glossary dt{padding-bottom:4px;border-bottom:0}
  .glossary dd{padding-top:0}
  .formula-card{flex-direction:column;gap:4px}
  .problem,.timeline-item{grid-template-columns:52px 1fr}
}