/* Box Advance — page components. Inner pages: a dark hero (void) over light paper content. */
:root {
  --ink: #15140f; --muted: #5d5b55; --rule: #dedbd2; --panel: #ffffff; --soft: #efede6;
  --gold-t: #8a5a00; --ok: #17694a; --ok-bg: #e3f2ea; --warn: #8a5a00; --warn-bg: #fbf0d9; --bad: #a23b1c; --bad-bg: #fbe5dd; --info-bg: #e9efff;
  --w-max: 1180px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body { margin: 0; background: var(--paper); color: var(--ink); font: 16.5px/1.62 var(--body); -webkit-font-smoothing: antialiased; }
img, svg { max-width: 100%; }
a { color: #3d2a86; text-underline-offset: 3px; }
a:hover { color: #241a5c; }
h1, h2, h3, h4 { font-family: var(--display); line-height: 1.05; letter-spacing: -.03em; margin: 0; text-wrap: balance; }
p, li, dd { max-width: 70ch; }
.wrap { max-width: var(--w-max); margin: 0 auto; padding: 0 var(--pad); }
.eyebrow { font: 500 12px/1.3 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--gold-t); margin: 0 0 14px; }
.hero-s .eyebrow, .is-dark .eyebrow, .err-page .eyebrow { color: var(--gold); }
.mono { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.text-gold { color: var(--gold-t); }
.svg-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.svg-scroll > svg { min-width: 820px; display: block; }
.svg-scroll > #lad-svg { min-width: 520px; width: 100%; } /* the ladder is drawn at 560 units: fit the card, scroll only on phones */
main { overflow-x: clip; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* buttons */
.btn { display: inline-flex; align-items: center; gap: 10px; font: 600 15px/1 var(--body); padding: 15px 22px; border-radius: 999px; text-decoration: none; border: 1px solid currentColor; background: transparent; color: inherit; cursor: pointer; transition: background .3s var(--e1), transform .5s var(--e2), color .3s; }
.btn-gold { background: var(--gold); border-color: var(--gold); color: var(--dark); }
.btn-gold:hover { background: #f0bf68; color: var(--dark); }
.btn-dark { background: var(--dark); border-color: var(--dark); color: #fff; }
.btn-dark:hover { background: #2a2620; color: #fff; }
.btn .ar { transition: transform .4s var(--e2); } .btn:hover .ar { transform: translateX(4px); }
.btn-row { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px; }

/* hero (dark) */
.hero-s { position: relative; overflow: hidden; background: radial-gradient(1200px 600px at 78% 40%, rgba(47,107,255,.16), transparent 60%), var(--void); color: var(--light); padding: 150px 0 76px; }
.hero-s .wrap { position: relative; z-index: 2; }
.hero-s h1 { font-weight: 800; font-size: clamp(38px, 5.6vw, 80px); line-height: .96; letter-spacing: -.045em; max-width: 15ch; }
.hero-s h1 em { font-style: normal; color: var(--gold); }
.hero-s .lede { font-size: clamp(17px, 1.4vw, 20px); color: var(--dim); max-width: 50ch; margin: 22px 0 0; }
.hero-s .btn:not(.btn-gold) { color: var(--light); }
.hero-s .crumbs { font: 500 12px var(--mono); letter-spacing: .06em; color: var(--dim); margin-bottom: 18px; }
.hero-s .crumbs a { color: var(--dim); text-decoration: none; } .hero-s .crumbs a:hover { color: #fff; }
.hero-s.is-compact { padding: 132px 0 52px; } .hero-s.is-compact h1 { font-size: clamp(32px, 4.2vw, 58px); }

/* big CSS 3D glass cube, used in heroes */
.cube3d { position: absolute; right: max(4vw, calc((100vw - var(--w-max)) / 2 + 20px)); top: 50%; width: var(--s, 210px); height: var(--s, 210px); margin-top: calc(var(--s, 210px) / -2 + 30px); perspective: 900px; z-index: 1; pointer-events: none; }
.cube3d .spin { position: absolute; inset: 0; transform-style: preserve-3d; animation: c3spin 26s var(--e1) infinite alternate; }
.cube3d .face { position: absolute; inset: 0; border: 1.5px solid rgba(140,205,255,.85); background: linear-gradient(140deg, rgba(60,140,255,.18), rgba(20,60,160,.06)); box-shadow: inset 0 0 40px rgba(70,160,255,.25), 0 0 24px rgba(70,160,255,.25); }
.cube3d .f1 { transform: translateZ(calc(var(--s, 210px) / 2)); } .cube3d .f2 { transform: rotateY(180deg) translateZ(calc(var(--s, 210px) / 2)); }
.cube3d .f3 { transform: rotateY(90deg) translateZ(calc(var(--s, 210px) / 2)); } .cube3d .f4 { transform: rotateY(-90deg) translateZ(calc(var(--s, 210px) / 2)); }
.cube3d .f5 { transform: rotateX(90deg) translateZ(calc(var(--s, 210px) / 2)); } .cube3d .f6 { transform: rotateX(-90deg) translateZ(calc(var(--s, 210px) / 2)); }
.cube3d .core { position: absolute; inset: 30%; transform-style: preserve-3d; animation: c3spin 26s var(--e1) infinite alternate-reverse; }
.cube3d .core .face { border-color: rgba(220,240,255,.95); background: rgba(150,210,255,.22); }
.cube3d .core .f1 { transform: translateZ(calc(var(--s, 210px) * .2)); } .cube3d .core .f2 { transform: rotateY(180deg) translateZ(calc(var(--s, 210px) * .2)); }
.cube3d .core .f3 { transform: rotateY(90deg) translateZ(calc(var(--s, 210px) * .2)); } .cube3d .core .f4 { transform: rotateY(-90deg) translateZ(calc(var(--s, 210px) * .2)); }
.cube3d .core .f5 { transform: rotateX(90deg) translateZ(calc(var(--s, 210px) * .2)); } .cube3d .core .f6 { transform: rotateX(-90deg) translateZ(calc(var(--s, 210px) * .2)); }
.cube3d::before { content: ""; position: absolute; inset: -60%; border-radius: 50%; background: radial-gradient(closest-side, rgba(70,160,255,.38), rgba(70,160,255,.08) 55%, transparent 72%); animation: c3glow 9s ease-in-out infinite; }
@keyframes c3spin { from { transform: rotateX(-22deg) rotateY(-28deg) rotateZ(-5deg); } to { transform: rotateX(-36deg) rotateY(62deg) rotateZ(7deg); } }
@keyframes c3glow { 50% { opacity: .65; } }
@media (max-width: 900px) { .cube3d { --s: 120px !important; top: 96px; right: 24px; margin-top: 0; opacity: .8; } .hero-s, .hero-s.is-compact { padding-top: 200px; } }
/* phones: a smaller mark tucked under the header, clear of the breadcrumb and headline */
@media (max-width: 620px) { .cube3d { --s: 92px !important; top: 80px; right: 22px; } .hero-s, .hero-s.is-compact { padding-top: 196px; } }

/* sections on paper */
.sec { --sec-pad: clamp(56px, 8vw, 104px); padding: var(--sec-pad) 0; border-bottom: 1px solid var(--rule); }
.sec[id] { scroll-margin-top: calc(28px - var(--sec-pad)); }   /* an anchored section lands with its heading just under the header, not its padding */
.sec:last-of-type { border-bottom: 0; }
.sec-head { max-width: 760px; margin-bottom: 36px; }
.sec h2 { font-weight: 800; font-size: clamp(28px, 3.4vw, 46px); }
.sec h2 + p, .sec-head p { color: var(--muted); font-size: 18px; margin: 14px 0 0; }
.sec h3 { font-weight: 700; font-size: 21px; letter-spacing: -.02em; margin: 0 0 8px; }
.sec.is-dark { background: var(--void); color: var(--light); border-bottom-color: transparent; }
.sec.is-dark .sec-head p, .sec.is-dark p { color: var(--dim); } .sec.is-dark a:not(.btn) { color: var(--cyan); }
.sec.is-dark .btn:not(.btn-gold) { color: var(--light); } .sec.is-dark .btn-gold { color: var(--dark); }
.sec.is-soft { background: var(--soft); }
.prose { max-width: 72ch; }
.prose p { margin: 0 0 14px; } .prose ul, .prose ol { padding-left: 22px; margin: 0 0 16px; } .prose li { margin-bottom: 7px; }
.prose h2 { font-size: clamp(24px, 2.6vw, 32px); margin: 44px 0 12px; } .prose h3 { font-size: 19px; margin: 26px 0 8px; }

/* grids and cards */
.grid { display: grid; gap: 20px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); } .grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); } .grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 900px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 620px) { .grid-2, .grid-3, .grid-4 { grid-template-columns: minmax(0, 1fr); } }
.card { background: var(--panel); border: 1px solid var(--rule); border-radius: 16px; padding: 24px; transition: transform .5s var(--e2), box-shadow .5s var(--e2); }
.card p { color: var(--muted); margin: 6px 0 0; }
.card .num { font: 500 12px var(--mono); color: var(--gold-t); letter-spacing: .08em; display: block; margin-bottom: 14px; }
a.card { display: block; text-decoration: none; color: inherit; } a.card:hover { transform: translateY(-3px); box-shadow: 0 20px 40px -24px rgba(30,20,0,.35); }
a.card .go { display: inline-block; margin-top: 14px; font: 600 14px var(--body); color: #3d2a86; }
.is-dark .card { background: rgba(255,255,255,.04); border-color: rgba(255,255,255,.1); } .is-dark .card p { color: var(--dim); }

/* key facts strip */
.facts { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 0; border-top: 1px solid rgba(255,255,255,.16); margin-top: 44px; }
.facts div { padding: 16px 18px 4px 0; }
.facts dt { font: 500 11px var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--dim); }
.facts dd { margin: 6px 0 0; font: 600 18px/1.25 var(--display); letter-spacing: -.01em; color: #fff; }
.paper .facts, .sec .facts { border-top-color: var(--rule); } .sec .facts dt { color: var(--muted); } .sec .facts dd { color: var(--ink); }

/* numbered steps */
.steps { list-style: none; margin: 0; padding: 0; counter-reset: st; display: grid; gap: 0; }
.steps > li { counter-increment: st; position: relative; padding: 22px 0 22px 64px; border-top: 1px solid var(--rule); max-width: none; }
.steps > li::before { content: counter(st, decimal-leading-zero); position: absolute; left: 0; top: 22px; font: 500 13px var(--mono); color: var(--gold-t); width: 44px; height: 44px; border-radius: 50%; border: 1px solid var(--rule); display: grid; place-items: center; background: var(--panel); }
.steps > li h3 { margin: 6px 0 4px; } .steps > li p { margin: 0; color: var(--muted); }
.is-dark .steps > li { border-top-color: rgba(255,255,255,.12); } .is-dark .steps > li::before { background: transparent; border-color: rgba(255,255,255,.2); color: var(--gold); }

/* level ladder list */
.levels { display: grid; gap: 8px; margin: 0; padding: 0; list-style: none; }
.levels li { display: grid; grid-template-columns: 92px 150px 1fr; gap: 14px; align-items: baseline; padding: 16px 18px; border-radius: 12px; background: var(--panel); border: 1px solid var(--rule); max-width: none; border-left: 4px solid var(--c, var(--rule)); }
.levels .pct { font: 600 22px var(--mono); } .levels .nm { font: 700 16px var(--display); } .levels p { margin: 0; color: var(--muted); }
@media (max-width: 700px) { .levels li { grid-template-columns: 70px 1fr; } .levels p { grid-column: 1 / -1; } }

/* callouts */
.callout { border-left: 3px solid var(--gold-d); background: var(--panel); padding: 18px 22px; border-radius: 0 12px 12px 0; margin: 24px 0; max-width: 78ch; }
.callout p { margin: 4px 0; } .callout strong { font-family: var(--display); }
.callout.is-warn { border-color: var(--warn); background: var(--warn-bg); } .callout.is-bad { border-color: var(--bad); background: var(--bad-bg); } .callout.is-info { border-color: #2f6bff; background: var(--info-bg); }

/* tables */
.tbl-wrap { overflow-x: auto; border: 1px solid var(--rule); border-radius: 14px; background: var(--panel); }
table.tbl { border-collapse: collapse; width: 100%; font-size: 15px; }
.tbl th, .tbl td { text-align: left; vertical-align: top; padding: 13px 16px; border-bottom: 1px solid var(--rule); }
.tbl tr:last-child td { border-bottom: 0; }
.tbl th { font: 500 11.5px var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); background: var(--soft); }
.tbl td.num, .tbl th.num { text-align: right; font-family: var(--mono); font-variant-numeric: tabular-nums; white-space: nowrap; }
.tbl caption { caption-side: bottom; text-align: left; padding: 10px 16px; font-size: 13px; color: var(--muted); }

/* legal layout with contents rail */
.legal-grid { display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 56px; align-items: start; }
.toc { position: sticky; top: 140px; font-size: 14px; }
.toc h2 { font: 500 11.5px var(--mono) !important; letter-spacing: .1em; text-transform: uppercase; color: var(--muted); margin: 0 0 12px !important; }
.toc ol { list-style: none; padding: 0; margin: 0; display: grid; gap: 2px; border-left: 1px solid var(--rule); }
.toc a { display: block; padding: 5px 0 5px 14px; color: var(--muted); text-decoration: none; margin-left: -1px; border-left: 2px solid transparent; }
.toc a:hover, .toc a.is-on { color: var(--ink); border-left-color: var(--gold-d); }
.summary-box { background: var(--panel); border: 1px solid var(--rule); border-radius: 16px; padding: 22px 24px; margin: 0 0 34px; }
.summary-box h2 { font-size: 15px !important; font-family: var(--mono) !important; letter-spacing: .08em !important; text-transform: uppercase; color: var(--gold-t); margin: 0 0 10px !important; }
.summary-box ul { margin: 0; padding-left: 20px; }
@media (max-width: 900px) { .legal-grid { grid-template-columns: minmax(0, 1fr); gap: 20px; } .toc { position: static; } }

/* FAQ accordions */
.faq { border-top: 1px solid var(--rule); }
.faq details { border-bottom: 1px solid var(--rule); }
.faq summary { cursor: pointer; list-style: none; padding: 20px 44px 20px 0; position: relative; font: 600 18px/1.35 var(--display); letter-spacing: -.01em; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; position: absolute; right: 6px; top: 16px; font: 400 26px var(--body); color: var(--gold-d); transition: transform .35s var(--e2); }
.faq details[open] summary::after { transform: rotate(45deg); }
.faq .a { padding: 0 0 22px; color: var(--muted); max-width: 72ch; } .faq .a p { margin: 0 0 10px; }
.faq-group { margin-top: 44px; } .faq-group > h2 { font-size: 15px !important; font-family: var(--mono) !important; letter-spacing: .1em !important; text-transform: uppercase; color: var(--gold-t); margin-bottom: 8px !important; }

/* glossary */
dl.gloss { display: grid; grid-template-columns: 240px 1fr; gap: 0; border-top: 1px solid var(--rule); margin: 0; }
dl.gloss dt, dl.gloss dd { padding: 16px 0; border-bottom: 1px solid var(--rule); margin: 0; }
dl.gloss dt { font: 700 17px var(--display); padding-right: 20px; } dl.gloss dd { color: var(--muted); }
@media (max-width: 700px) { dl.gloss { grid-template-columns: 1fr; } dl.gloss dt { border-bottom: 0; padding-bottom: 0; } }

/* forms */
.form { display: grid; gap: 18px; max-width: 640px; }
.field { display: grid; gap: 7px; }
.field label, .field legend { font: 600 14px var(--body); }
.field .hint { font-size: 13.5px; color: var(--muted); }
.field input, .field select, .field textarea { font: 16px var(--body); padding: 13px 14px; border: 1px solid #cfccc2; border-radius: 10px; background: #fff; color: var(--ink); width: 100%; }
.field textarea { min-height: 120px; resize: vertical; }
.field input:focus, .field select:focus, .field textarea:focus { outline: 2px solid var(--ink); outline-offset: 1px; border-color: var(--ink); }
.field [aria-invalid="true"] { border-color: var(--bad); }
.field .err { color: var(--bad); font-size: 13.5px; min-height: 1em; }
fieldset.field { border: 0; padding: 0; margin: 0; }
.choice { display: flex; gap: 10px; align-items: flex-start; padding: 12px 14px; border: 1px solid var(--rule); border-radius: 10px; background: #fff; cursor: pointer; }
.choice input { margin-top: 4px; accent-color: var(--gold-d); width: auto; }
.form-done { display: none; background: var(--ok-bg); color: var(--ok); border-radius: 12px; padding: 18px 20px; } .form-done.is-on { display: block; }
.form-note { font-size: 13.5px; color: var(--muted); }

/* tools: simulator, checker, chart */
.tool { background: var(--panel); border: 1px solid var(--rule); border-radius: 18px; padding: clamp(20px, 3vw, 34px); }
.tool-grid { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: 32px; }
@media (max-width: 900px) { .tool-grid { grid-template-columns: minmax(0, 1fr); } }
.readouts { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 12px; }
.readout { border: 1px solid var(--rule); border-radius: 12px; padding: 14px; }
.readout span { display: block; font: 500 11px var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.readout b { display: block; font: 500 24px/1.2 var(--mono); font-variant-numeric: tabular-nums; margin-top: 6px; overflow-wrap: anywhere; }
.state { margin-top: 18px; padding: 16px 18px; border-radius: 12px; background: var(--soft); font-size: 16px; }
.state.is-warn { background: var(--warn-bg); color: var(--warn); } .state.is-bad { background: var(--bad-bg); color: var(--bad); } .state.is-ok { background: var(--ok-bg); color: var(--ok); }
input[type="range"] { width: 100%; accent-color: var(--gold-d); }
.chart { width: 100%; height: auto; display: block; }
.chart text { font: 500 11px var(--mono); fill: var(--muted); }

/* sample documents */
.doc { background: #fff; border: 1px solid var(--rule); border-radius: 6px; box-shadow: 0 24px 50px -30px rgba(30,20,0,.4); padding: clamp(20px, 3vw, 40px); font-size: 14.5px; position: relative; }
.doc::before { content: "SAMPLE — ILLUSTRATIVE"; position: absolute; top: 16px; right: 18px; font: 500 11px var(--mono); letter-spacing: .1em; color: var(--bad); border: 1px solid var(--bad); border-radius: 4px; padding: 3px 7px; }
.doc h3 { font-family: var(--display); font-size: 20px; margin-bottom: 4px; }
.doc .meta { font: 12.5px var(--mono); color: var(--muted); margin-bottom: 18px; }

/* email previews */
.mail { background: #fff; border: 1px solid var(--rule); border-radius: 14px; overflow: hidden; }
.mail-head { background: var(--soft); padding: 12px 18px; font: 12.5px/1.6 var(--mono); color: var(--muted); border-bottom: 1px solid var(--rule); }
.mail-body { padding: 22px; font-size: 15px; } .mail-body p { margin: 0 0 12px; }

/* status */
.status-row { display: flex; justify-content: space-between; align-items: center; gap: 16px; padding: 18px 0; border-bottom: 1px solid var(--rule); }
.pill { font: 500 12px var(--mono); padding: 5px 10px; border-radius: 999px; background: var(--soft); color: var(--muted); white-space: nowrap; }
.pill.is-ok { background: var(--ok-bg); color: var(--ok); } .pill.is-warn { background: var(--warn-bg); color: var(--warn); }

/* error pages */
.err-page { min-height: 100vh; display: grid; place-items: center; text-align: center; background: var(--void); color: var(--light); padding: 120px var(--pad) 60px; }
.err-page .code { font: 800 clamp(90px, 18vw, 220px)/.9 var(--display); letter-spacing: -.04em; color: rgba(124,200,255,.14); text-shadow: 0 0 40px rgba(70,160,255,.45), 0 0 1px rgba(160,215,255,.9); margin-bottom: 22px; }
.err-page p { color: var(--dim); margin: 14px auto 0; max-width: 46ch; }

/* reveal */
.rv { opacity: 0; transform: translateY(22px); transition: opacity .9s var(--e1) var(--rd, 0s), transform 1.1s var(--e2) var(--rd, 0s); }
.rv.in { opacity: 1; transform: none; }
.no-js .rv { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .rv { opacity: 1 !important; transform: none !important; transition: none; } .cube3d .spin, .cube3d .core, .cube3d::before { animation: none; } }
@media print { .sh, .sf-top, .sf-base, .ck, .cube3d, .hero-gl, .btn, .btn-row, .sk-skip { display: none !important; } .sf { background: none !important; color: #000 !important; padding: 12px 0 0; } .sf a { color: #000 !important; } .hero-s { background: none; color: #000; padding: 20px 0; } .hero-s *, .facts dd, .facts dt, .sec.is-dark, .sec.is-dark *, .err-page, .err-page * { color: #000 !important; } .sec.is-dark, .err-page { background: none !important; } .hero-s::after { display: none; } .rv { opacity: 1 !important; transform: none !important; } body { background: #fff; } .tbl-wrap { overflow: visible; border: 0; } }
:focus-visible { outline-color: var(--ink); }
.hero-s :focus-visible, .is-dark :focus-visible, .err-page :focus-visible { outline-color: var(--gold); }
/* row headers in key/value tables read as normal text, not column headers */
.tbl th[scope="row"] { font: 600 15px/1.5 var(--body); letter-spacing: 0; text-transform: none; color: var(--ink); background: transparent; }
.tbl th[scope="rowgroup"] { background: var(--soft); }

/* ---------- hero motion (assets/hero-cube.js) ---------- */
.hero-gl { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 1; pointer-events: none; }
.hero-s.has-gl .cube3d { visibility: hidden; }       /* still measured for size and position */
/* liquid lower edge: the same language as the colour bands on the home page */
.hero-s::after { content: ""; position: absolute; left: 0; right: 0; bottom: -1px; height: 44px; z-index: 2; pointer-events: none;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 44' preserveAspectRatio='none'%3E%3Cpath d='M0 26 C150 6 300 6 450 26 S750 46 900 26 S1050 6 1200 26 V44 H0Z' fill='%23f6f5f1'/%3E%3C/svg%3E") 0 100% / 1200px 44px repeat-x;
  animation: heroWave 22s linear infinite; }
.hero-s:has(+ .sec.is-soft)::after { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 44' preserveAspectRatio='none'%3E%3Cpath d='M0 26 C150 6 300 6 450 26 S750 46 900 26 S1050 6 1200 26 V44 H0Z' fill='%23efede6'/%3E%3C/svg%3E"); }
.hero-s:has(+ .sec.is-dark)::after { display: none; }
@keyframes heroWave { to { background-position-x: -1200px; } }
@media (prefers-reduced-motion: reduce) { .hero-s::after { animation: none; } }

/* ---------- negative space: editorial layout on wide screens ----------
   Wide screens get a 12-column reading of the same markup, so the page uses its width instead of leaving it empty.
   1. Rail (.wrap.is-rail, set by build.py mark_layouts): text-led sections put the heading in a sticky left rail
      (4 of 12 columns) and the content in the right 8, so the heading stays in view while you read.
   2. Split head: a heading with one summary line sets the title left and the summary right on a shared baseline,
      and the cards or tool run full width underneath.
   Below 1100px both fall back to the stacked layout. */
@media (min-width: 1100px) {
  .wrap.is-rail { display: grid; grid-template-columns: minmax(0, 4fr) minmax(0, 8fr); column-gap: clamp(48px, 5vw, 88px); align-items: start; }
  .wrap.is-rail > * { grid-column: 2; }
  .wrap.is-rail > .sec-head { grid-column: 1; grid-row: 1 / span 20; position: sticky; top: 140px; margin-bottom: 0; }
  .wrap.is-rail > .sec-head h2 { font-size: clamp(28px, 2.7vw, 40px); }
  .wrap.is-rail > .sec-head p:not(.eyebrow) { font-size: 17px; }
  .wrap.is-rail > .steps { border-bottom: 1px solid var(--rule); }
  .wrap.is-rail > .callout:first-of-type { margin-top: 0; }

  .wrap:not(.is-rail) > .sec-head:has(> h2):has(> p:not(.eyebrow)):not(:has(> p:not(.eyebrow) ~ p:not(.eyebrow))) {
    max-width: none; display: grid; grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); column-gap: clamp(40px, 5vw, 88px); align-items: end; margin-bottom: 48px;
  }
  .wrap:not(.is-rail) > .sec-head > .eyebrow, .wrap:not(.is-rail) > .sec-head > h2 { grid-column: 1; }
  .wrap:not(.is-rail) > .sec-head:has(> h2):not(:has(> p:not(.eyebrow) ~ p:not(.eyebrow))) > p:not(.eyebrow) { grid-column: 2; grid-row: 1 / span 2; align-self: end; margin: 0; padding-bottom: 4px; }
}

/* ---------- wayfinding (markup from build.py add_navigation; one sitemap feeds all of it) ----------
   Header: the six places to go. Section tabs: the pages in this section (sections of two or more pages), current one
   marked; sticky under the header on wide screens. Page tabs (.is-page): on a long merged page, a second row of
   anchors to its own sections, the one in view marked by site.js and sticky instead of the section tabs. Previous/next:
   within the section only, at the end of the page. No breadcrumb: the layers above already say where a page sits. */
.subnav { position: relative; z-index: 4; background: var(--paper); border-bottom: 1px solid var(--rule); }
.subnav .wrap { display: flex; align-items: center; gap: 20px; }
.subnav-t { flex: none; font: 500 11.5px var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--gold-t); text-decoration: none; }
a.subnav-t:hover { text-decoration: underline; text-underline-offset: 3px; }
.subnav-tabs { display: flex; gap: 4px; list-style: none; margin: 0; padding: 0; overflow-x: auto; scrollbar-width: none; -webkit-overflow-scrolling: touch; min-width: 0;
  mask-image: linear-gradient(90deg, #000 calc(100% - 28px), transparent); -webkit-mask-image: linear-gradient(90deg, #000 calc(100% - 28px), transparent); }
.subnav-tabs::-webkit-scrollbar { display: none; }
.subnav li { max-width: none; flex: none; }
.subnav a { display: block; padding: 16px 12px 14px; font: 500 14px/1 var(--body); color: var(--muted); text-decoration: none; border-bottom: 2px solid transparent; white-space: nowrap; transition: color .3s var(--e1), border-color .3s var(--e1); }
.subnav a:hover { color: var(--ink); }
.subnav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--gold-d); }
.subnav-tabs li:last-child { padding-right: 12px; }
.subnav a[aria-current="location"] { color: var(--ink); border-bottom-color: var(--gold-d); }
/* page tabs (a long merged page): a second row that jumps to the page's own sections. On a wide screen the section tabs scroll
   away (is-static) and the page tabs stay under the header; the page then lands its anchors a little lower to clear them. */
.subnav.is-page .subnav-t { color: var(--muted); }
.subnav.is-static { border-bottom-color: transparent; }
@media (min-width: 1100px) {
  .subnav { position: sticky; top: 60px; }                 /* 60px = the solid header's height */
  .subnav.is-static { position: relative; top: auto; }
  html { scroll-padding-top: 124px; }                       /* header (60px) + tab row (about 46px) + breathing room */
}
@media (max-width: 620px) { .subnav-t { display: none; } .subnav .wrap { gap: 8px; } }
.hero-s:has(+ .subnav)::after { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 44' preserveAspectRatio='none'%3E%3Cpath d='M0 26 C150 6 300 6 450 26 S750 46 900 26 S1050 6 1200 26 V44 H0Z' fill='%23f6f5f1'/%3E%3C/svg%3E"); display: block; }

.pager { border-top: 1px solid var(--rule); background: var(--paper); }
.pager .wrap { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; padding-top: 28px; padding-bottom: 28px; }
.pager a { display: grid; gap: 6px; padding: 20px 22px; border: 1px solid var(--rule); border-radius: 14px; background: var(--panel); color: var(--ink); text-decoration: none; transition: border-color .3s var(--e1), transform .5s var(--e2); }
.pager a:hover { border-color: var(--gold-d); transform: translateY(-2px); }
.pager span { font: 500 11.5px var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.pager b { font: 700 19px/1.2 var(--display); letter-spacing: -.01em; }
.pager .pager-prev b::before { content: "← "; color: var(--gold-t); } .pager .pager-next b::after { content: " →"; color: var(--gold-t); }
.pager .pager-next { text-align: right; grid-column: 2; }
@media (max-width: 620px) { .pager .wrap { grid-template-columns: 1fr; } .pager .pager-next { grid-column: 1; } .pager .wrap > span:empty { display: none; } }
@media print { .subnav, .pager { display: none; } }

/* section-level two-column layouts need the room: they stack below the editorial breakpoint */
.wrap.grid-2 { gap: clamp(32px, 4vw, 56px); align-items: start; }
@media (max-width: 1099px) { .wrap.grid-2 { grid-template-columns: minmax(0, 1fr); } }
.wrap.grid-2.is-centred { align-items: center; }

/* a table is never put in a narrow column: a section that holds one (build.py mark_layouts) stacks, heading above and
   the table full width; a tool whose result is a table does the same */
.wrap.grid.is-stack { grid-template-columns: minmax(0, 1fr); }
.wrap.grid.is-stack > :not(.tbl-wrap) { max-width: 760px; }
.tool-grid:has(.tbl-wrap) { grid-template-columns: minmax(0, 1fr); }

/* calmer card grids: two across with room, not four small boxes */
.grid.is-calm { gap: clamp(20px, 3vw, 32px); }
.grid.is-calm > .card { padding: clamp(24px, 3vw, 36px); }
.grid.is-calm > .card p { max-width: 46ch; }

/* key facts: a short summary, then the full detail grouped in sections that open */
.kf-more { border-top: 1px solid var(--rule); }
.kf-more details { border-bottom: 1px solid var(--rule); }
.kf-more summary { cursor: pointer; list-style: none; padding: 22px 48px 22px 0; position: relative; font: 700 20px/1.3 var(--display); letter-spacing: -.01em; }
.kf-more summary::-webkit-details-marker { display: none; }
.kf-more summary small { display: block; margin-top: 4px; font: 400 15px/1.5 var(--body); letter-spacing: 0; color: var(--muted); }
.kf-more summary::after { content: "+"; position: absolute; right: 6px; top: 18px; font: 400 28px var(--body); color: var(--gold-d); transition: transform .35s var(--e2); }
.kf-more details[open] summary::after { transform: rotate(45deg); }
.kf-more details > .tbl-wrap { margin: 0 0 28px; }