/* Functor Foundation — its own palette, deliberately unlike the exchange.
 * Institutional and calm: warm paper, deep ink, one green accent, with Functor
 * amber kept only for the mark and the links back to the exchange.
 * Fonts are the same free pair the main site uses, so the two read as one family. */
:root{
  --paper:#f6f3ec;--paper2:#efebe1;--ink:#16211c;--muted:#5d6661;
  --line:rgba(22,33,28,.12);--green:#0f6b4f;--green-d:#0a4f3b;--amber:#ffb020;
  --serif:"Instrument Serif",Georgia,serif;
  --sans:"Inter",system-ui,-apple-system,"Segoe UI",sans-serif;
  --mono:"IBM Plex Mono",ui-monospace,monospace;
  --wrap:1120px;--r:14px;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{background:var(--paper);color:var(--ink);font-family:var(--sans);font-size:16px;line-height:1.62;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
img,svg{display:block;max-width:100%}
.wrap{width:min(var(--wrap),calc(100% - 40px));margin:0 auto}
.display{font-family:var(--serif);font-weight:400;letter-spacing:-.015em;line-height:1.04}
h1.display{font-size:clamp(40px,5.6vw,72px)}
h2.display{font-size:clamp(28px,3.4vw,44px)}
h3{font-size:19px;font-weight:600;letter-spacing:-.01em}
.lead{font-size:clamp(17px,1.4vw,19px);color:var(--muted);max-width:66ch}
.eyebrow{display:inline-flex;align-items:center;gap:10px;font-size:.76rem;letter-spacing:.15em;text-transform:uppercase;color:var(--green);font-weight:600}
.eyebrow::before{content:"";width:18px;height:1px;background:currentColor;opacity:.7}

/* header */
.nav{position:sticky;top:0;z-index:40;background:rgba(246,243,236,.9);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}
.nav__in{display:flex;align-items:center;gap:26px;height:70px}
.brand{display:flex;align-items:center;gap:11px;font-weight:600;letter-spacing:.04em;font-size:14px}
.brand svg{width:30px;height:25px}
.brand .sep{width:1px;height:20px;background:var(--line)}
.brand .fdn{font-family:var(--serif);font-size:19px;letter-spacing:0;font-weight:400}
.nav__links{display:flex;gap:22px;margin-left:auto;font-size:.92rem;color:var(--muted)}
.nav__links a:hover{color:var(--ink)}
.nav__links a.back{color:var(--green);font-weight:500}
@media(max-width:860px){.nav__links{display:none}}

/* buttons */
.btn{display:inline-flex;align-items:center;height:44px;padding:0 20px;border-radius:999px;border:1px solid var(--line);font-size:.95rem;font-weight:500;transition:background .18s,border-color .18s}
.btn:hover{border-color:rgba(22,33,28,.34)}
.btn--green{background:var(--green);border-color:var(--green);color:#fff}
.btn--green:hover{background:var(--green-d);border-color:var(--green-d)}
.btns{display:flex;gap:12px;flex-wrap:wrap;margin-top:30px}

/* sections */
.hero{padding:clamp(64px,9vw,120px) 0 clamp(40px,6vw,70px)}
.hero h1{margin:16px 0 0;max-width:18ch}
.hero .lead{margin-top:22px}
.sec{padding:clamp(56px,7vw,96px) 0;border-top:1px solid var(--line)}
.sec--ink{background:var(--ink);color:var(--paper);border-top:0}
.sec--ink .lead,.sec--ink p{color:rgba(246,243,236,.72)}
.sec--ink .eyebrow{color:#7fd3b4}
.sec--ink .num{color:#fff}
.head{display:grid;grid-template-columns:1.1fr .9fr;gap:40px;align-items:end;margin-bottom:38px}
@media(max-width:820px){.head{grid-template-columns:1fr;gap:16px}}
.pill{display:inline-flex;align-items:center;gap:9px;padding:7px 14px;border:1px solid var(--line);border-radius:999px;font-size:.82rem;color:var(--muted);background:#fff}
.pill i{width:7px;height:7px;border-radius:50%;background:var(--green);display:block}

/* cards + lists */
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.cards--2{grid-template-columns:repeat(2,1fr)}
@media(max-width:860px){.cards,.cards--2{grid-template-columns:1fr}}
.card{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:26px;display:flex;flex-direction:column;gap:10px}
.card p{color:var(--muted);font-size:.97rem}
.card .n{font-family:var(--mono);font-size:.76rem;letter-spacing:.12em;text-transform:uppercase;color:var(--green)}
.steps{display:grid;gap:0;border-top:1px solid var(--line)}
.step{display:grid;grid-template-columns:150px 1fr;gap:28px;padding:22px 0;border-bottom:1px solid var(--line)}
.step b{font-family:var(--mono);font-size:.78rem;letter-spacing:.1em;text-transform:uppercase;color:var(--green);font-weight:500}
.step p{color:var(--muted)}
@media(max-width:700px){.step{grid-template-columns:1fr;gap:6px}}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:var(--line);border:1px solid var(--line);border-radius:var(--r);overflow:hidden;margin-top:34px}
.stats div{background:var(--ink);padding:24px 22px}
.stats .num{font-family:var(--serif);font-size:34px;line-height:1}
.stats .k{font-size:.82rem;color:rgba(246,243,236,.6);margin-top:8px}
@media(max-width:820px){.stats{grid-template-columns:1fr}}
.faq details{border-bottom:1px solid var(--line);padding:18px 0}
.faq summary{cursor:pointer;font-weight:500;list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";float:right;color:var(--green)}
.faq details[open] summary::after{content:"\2013"}
.faq p{margin-top:12px;color:var(--muted);max-width:76ch}
.note{font-size:.88rem;color:var(--muted);margin-top:22px}
.note a{color:var(--green);text-decoration:underline;text-underline-offset:3px}

/* footer */
.foot{border-top:1px solid var(--line);padding:44px 0 56px;font-size:.92rem;color:var(--muted)}
.foot__in{display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap}
.foot a:hover{color:var(--ink)}

/* ---- photographs (public domain; see assets/img/CREDITS.md) ---- */
.split{display:grid;grid-template-columns:1.05fr .95fr;gap:clamp(28px,4vw,56px);align-items:center}
@media(max-width:860px){.split{grid-template-columns:1fr}}
.fig{margin:0}
.fig img{width:100%;height:auto;border-radius:var(--r);border:1px solid var(--line);display:block;filter:saturate(.82)}
.fig figcaption{margin-top:10px;font-size:.8rem;color:var(--muted);font-family:var(--mono);letter-spacing:.02em}
.strip{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin-top:38px}
@media(max-width:860px){.strip{grid-template-columns:1fr}}
.strip .fig img{aspect-ratio:4/3;object-fit:cover}
.hero .fig img{aspect-ratio:4/3;object-fit:cover}

/* floating equations + Functor marks (js/mathfield.js): green on paper, cream on ink */
.mf{--mf:246,243,236;opacity:.62}
.mf--light{--mf:15,107,79}