/* Polar concept — site.css: tokens + every component used on two or more pages (rules/site.md S1/S2).
   Every length is rem (1rem = 16 design px) so the whole page scales as one unit — RULE 1s. */
:root{
  --gutter:2.5rem; --gutter-m:1.25rem; --section-m:2.5rem; --nav-h:4.5rem;
  --space-2xs:.5rem; --space-xs:1rem; --space-sm:1.5rem; --space-md:2.5rem; --space-lg:3.5rem; --space-xl:5rem; --space-2xl:6.25rem;
  --section-pad-tight:var(--space-lg); --section-pad:var(--space-xl); --section-pad-open:var(--space-2xl);

  --ink:#0b0b0c; --lift:#151517; --lift-2:#1d1d20;
  --paper:#ededea; --paper-2:#e2e2de;
  --on-ink:#f4f3ef; --muted-d:#8e8e93; --line-d:rgba(255,255,255,.12);
  --on-paper:#131316; --muted:#66666b; --line:rgba(19,19,22,.14);
  --loss:#e5484d;                       /* semantic only: a negative margin */
  --font:'Geist','Inter',system-ui,sans-serif;
  --mono:'Geist Mono',ui-monospace,monospace;
  --ease:cubic-bezier(.2,.8,.2,1);
}
*,*::before,*::after{box-sizing:border-box}
html,body{margin:0}
body{background:var(--ink);color:var(--on-ink);font:400 1rem/1.45 var(--font);-webkit-font-smoothing:antialiased;overflow-x:hidden}
img{max-width:100%;height:auto;display:block}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit}
h1,h2,h3{font-weight:400;margin:0;text-wrap:balance}
p{margin:0;text-wrap:pretty}
.ph{display:inline-block;flex:none;fill:currentColor;vertical-align:-.125em}
.sr-only{position:absolute;left:var(--gutter);width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
:focus-visible{outline:2px solid currentColor;outline-offset:.1875rem}
.num{font-variant-numeric:tabular-nums}

/* SCREEN SCALE — the page is drawn on a 1440×800 canvas in rem (1rem = 16 design px). From 1440 up the root grows
   with the screen (width, limited by height so an 800 band never outgrows the viewport), capped at 1.667×. */
@media (min-width:1025px){html{font-size:clamp(100%,min(1.1111vw,2vh),166.667%)}}
.ph[width="16"]{width:1rem;height:1rem}.ph[width="18"]{width:1.125rem;height:1.125rem}.ph[width="20"]{width:1.25rem;height:1.25rem}.ph[width="24"]{width:1.5rem;height:1.5rem}.ph[width="32"]{width:2rem;height:2rem}
.container{box-sizing:border-box;width:100%;padding:0 var(--gutter)}

/* ── shared type ── */
.h2{font-size:clamp(1.875rem,3.3vw,2.875rem);line-height:1.08;letter-spacing:-.02em;max-width:18ch}
.mute{color:var(--muted-d)}
.light .mute{color:var(--muted)}
.lead{font-size:1.25rem;line-height:1.4;color:var(--muted-d);max-width:40ch}
.light .lead{color:var(--muted)}
.mono{font-family:var(--mono);font-size:.75rem;letter-spacing:.02em}
.word-mask{display:inline-block;overflow:hidden;vertical-align:top;padding-bottom:.08em;margin-bottom:-.08em}
.word{display:inline-block}

/* ── grounds ── */
.dark{background:var(--ink);color:var(--on-ink)}
.light{background:var(--paper);color:var(--on-paper)}
.band{min-height:50rem;padding:var(--section-pad) 0;display:flex;flex-direction:column;justify-content:center;position:relative}

/* ── buttons: Type 1 solid pill + Type 2 ghost, hover E arrow relay (the disc of Type 3 was retired 2026-09-30) ── */
.btn{display:inline-flex;align-items:center;gap:.75rem;height:3.25rem;padding:0 1.5rem;border-radius:18.75rem;border:0;cursor:pointer;
  background:var(--on-ink);color:var(--ink);font-size:.9375rem;font-weight:500;white-space:nowrap;transition:background .3s ease}
.btn:hover{background:#fff}
.light .btn{background:var(--on-paper);color:var(--paper)}
.light .btn:hover{background:#000}
.relay{position:relative;display:block;width:1.125rem;height:1.125rem;overflow:hidden}
.relay .ph{position:absolute;inset:0;transition:transform .42s var(--ease)}
.relay .ph:nth-child(2){transform:translateX(-140%)}
.btn:hover .relay .ph:nth-child(1),.btn:focus-visible .relay .ph:nth-child(1){transform:translateX(140%)}
.btn:hover .relay .ph:nth-child(2),.btn:focus-visible .relay .ph:nth-child(2){transform:translateX(0)}
.btn-sm{height:2.5rem;padding:0 1.125rem;gap:.625rem;font-size:.875rem}
.btn[disabled]{opacity:.45;cursor:not-allowed}
.ghost{display:inline-flex;align-items:center;gap:.5rem;height:3.25rem;padding:0 1.5rem;border-radius:18.75rem;font-size:.9375rem;font-weight:500;
  border:1px solid rgba(255,255,255,.3);transition:border-color .3s ease}
.ghost:hover{border-color:var(--on-ink)}
button.ghost{background:transparent;color:inherit;cursor:pointer;font-family:inherit}
.btn[hidden],.ghost[hidden]{display:none}
.light .ghost{border-color:rgba(19,19,22,.3)}
.light .ghost:hover{border-color:var(--on-paper)}
.actions{display:flex;gap:.75rem;flex-wrap:wrap;align-items:center}

/* ── NAV ── */
.nav{position:fixed;inset:0 0 auto 0;z-index:50;height:var(--nav-h);color:var(--on-ink);border-bottom:1px solid transparent;
  transition:transform .45s var(--ease),background .35s ease,border-color .35s ease,color .35s ease}
.nav.solid{background:rgba(11,11,12,.86);backdrop-filter:blur(.875rem);-webkit-backdrop-filter:blur(.875rem);border-color:var(--line-d)}
/* RULE 3c — hide on scroll down, return on scroll up */
.nav.hide{transform:translateY(-101%)}
/* RULE 3d — re-tone to the ground under the nav */
.nav[data-tone="light"]{color:var(--on-paper)}
.nav.solid[data-tone="light"]{background:rgba(237,237,234,.86);border-color:var(--line)}
.nav[data-tone="light"] .nav-links a{color:var(--muted)}
.nav[data-tone="light"] .nav-links a:hover,.nav[data-tone="light"] .nav-links a:focus-visible{color:var(--on-paper)}
.nav[data-tone="light"] .nav-links a::before{background:var(--paper-2)}
.nav-links a[aria-current="page"]{color:var(--on-ink)}
.nav[data-tone="light"] .nav-links a[aria-current="page"]{color:var(--on-paper)}
.nav[data-tone="light"] .btn{background:var(--on-paper);color:var(--paper)}
@media (prefers-reduced-motion:reduce){.nav{transition:none}}
.nav-inner{padding:0 var(--gutter);height:100%;display:flex;align-items:center;gap:2.5rem}
.nav-links .ph{margin-left:.25rem;opacity:.6}
.logo{display:flex;align-items:center;gap:.625rem;font-size:1.25rem;letter-spacing:-.01em}
.logo svg{width:1.75rem;height:1.75rem}
.nav-links{display:flex;gap:.25rem;list-style:none;margin:0;padding:0}
.nav-links a{position:relative;display:block;padding:.5rem .875rem;font-size:.9375rem;color:var(--muted-d);transition:color .3s ease;isolation:isolate}
.nav-links a::before{content:'';position:absolute;inset:0;border-radius:18.75rem;background:var(--lift-2);z-index:-1;transform:scale(.4);opacity:0;transition:transform .35s var(--ease),opacity .25s ease}
.nav-links a:hover,.nav-links a:focus-visible{color:var(--on-ink)}
.nav-links a:hover::before,.nav-links a:focus-visible::before{transform:scale(1);opacity:1}
.nav-right{margin-left:auto;display:flex;align-items:center;gap:1.5rem}
.nav-right .signin{font-size:.9375rem}
.burger{display:none}
.overlay{position:fixed;inset:0;z-index:45;background:var(--ink);padding:calc(var(--nav-h) + 1.5rem) var(--gutter-m) var(--gutter-m);flex-direction:column;justify-content:space-between}
.overlay:not([hidden]){display:flex}
.overlay[hidden]{display:none}
.overlay ul{list-style:none;margin:0;padding:0}
.overlay ul a{display:block;font-size:2.125rem;padding:.625rem 0;border-bottom:1px solid var(--line-d)}
.overlay .btn{justify-content:space-between;width:100%}

/* ── shared pieces (used on two or more pages) ── */
@view-transition{navigation:auto}
.skip{position:absolute;left:var(--gutter);top:-4rem;z-index:60;background:var(--on-ink);color:var(--ink);padding:.625rem 1rem;border-radius:18.75rem;font-size:.875rem}
.skip:focus{top:.75rem}
.split-head{display:grid;grid-template-columns:58% 1fr;gap:var(--space-lg);align-items:start}
.body{font-size:1.125rem;color:var(--muted-d);max-width:38ch}
.light .body{color:var(--muted)}
.avatar-l{width:1.75rem;height:1.75rem;border-radius:.4375rem;background:var(--on-paper);color:var(--paper);display:grid;place-items:center;font:500 .8125rem var(--mono)}
.chips{display:flex;gap:.5rem;flex-wrap:wrap}
.chip{display:inline-flex;align-items:center;gap:.5rem;height:2.5rem;padding:0 1.125rem;border-radius:18.75rem;border:1px solid rgba(19,19,22,.28);background:transparent;cursor:pointer;font-size:.875rem;color:var(--muted);transition:background .3s ease,color .3s ease,border-color .3s ease}
.chip .ph{width:1rem;height:1rem;opacity:0;margin-left:-1.5rem;transition:opacity .25s ease,margin .3s var(--ease)}
.chip[aria-pressed="true"],.chip[aria-selected="true"]{background:var(--on-paper);border-color:var(--on-paper);color:var(--paper)}
.chip[aria-pressed="true"] .ph{opacity:1;margin-left:0}
.dark .chip{border-color:rgba(255,255,255,.3);color:var(--muted-d)}
.dark .chip[aria-pressed="true"],.dark .chip[aria-selected="true"]{background:var(--on-ink);border-color:var(--on-ink);color:var(--ink)}
.seg{display:inline-flex;padding:.25rem;border-radius:18.75rem;background:var(--paper)}
.seg button{border:0;background:transparent;height:2.25rem;padding:0 1.125rem;border-radius:18.75rem;cursor:pointer;font-size:.875rem;color:var(--muted);transition:background .3s ease,color .3s ease;white-space:nowrap}
.seg button[aria-selected="true"]{background:var(--on-paper);color:var(--paper)}
.dark .seg{background:var(--lift-2)}
.dark .seg button{color:var(--muted-d)}
.dark .seg button[aria-selected="true"]{background:var(--on-ink);color:var(--ink)}
.facts{list-style:none;margin:0;padding:0;border-top:1px solid rgba(255,255,255,.18)}
.facts li{display:flex;justify-content:space-between;gap:1rem;padding:.75rem 0;border-bottom:1px solid rgba(255,255,255,.18);font-size:.9375rem}
.facts li span:first-child{color:#b3b3b8}
.light .facts,.light .facts li{border-color:var(--line)}
.light .facts li span:first-child{color:var(--muted)}
.textlink{display:inline-flex;align-items:center;gap:.5rem;font-weight:500;border-bottom:1px solid currentColor;padding-bottom:.125rem;align-self:flex-start}
.textlink .ph{transition:transform .35s var(--ease)}
.textlink:hover .ph{transform:translate(.125rem,-.125rem)}
.panel,.panel-d{min-width:0}
/* surfaces: a card is a tonal step + hairline, never a shadow */
.panel{background:#fff;border:1px solid var(--line);border-radius:.875rem;overflow:hidden;color:var(--on-paper)}
.panel-d{background:var(--lift);border:1px solid var(--line-d);border-radius:.875rem;overflow:hidden;color:var(--on-ink)}
/* code — tokens are functional colour, one grey ramp, namespaced (never a layout class) */
.code{margin:0;font:400 .875rem/1.7 var(--mono);color:#d8d7d2;white-space:pre;overflow-x:auto;tab-size:2}
.code .c-k{color:#f4f3ef}.code .c-s{color:#a5a5aa}.code .c-c{color:#6e6e73}.code .c-p{color:#8e8e93}

/* ── PAGE HEADER (inner pages, site S5): 45–80vh, clears the nav, content on the page frame ── */
.page-head{min-height:68svh;padding:calc(var(--nav-h) + var(--space-md)) 0 var(--space-md);display:flex;flex-direction:column;justify-content:flex-end;position:relative}
.h1{font-size:clamp(3.25rem,7.4vw,7rem);line-height:.95;letter-spacing:-.04em}
.h1.long{font-size:clamp(2.5rem,5vw,4.75rem);line-height:1;letter-spacing:-.035em;max-width:17ch}

/* ── CLOSING BAND — the same last section on every page (RULE 6, dark utility close) ── */
.s-close{justify-content:space-between;padding:var(--section-pad-open) 0}
.s-close .container{flex:1;display:flex;flex-direction:column;justify-content:space-between;gap:var(--space-lg)}
.close-h{font-size:clamp(2.875rem,8.2vw,7.75rem);line-height:.94;letter-spacing:-.045em;max-width:12ch}
.close-h .mute{display:block}
.close-foot{display:grid;grid-template-columns:1fr auto;gap:var(--space-md);align-items:end;border-top:1px solid var(--line-d);padding-top:var(--space-sm)}
.close-foot p{color:var(--muted-d);max-width:44ch}

/* ── FOOTER ── */
.footer{background:var(--ink);padding:var(--space-xl) 0 var(--space-md);border-top:1px solid var(--line-d)}
.foot-grid{display:grid;grid-template-columns:2fr 2fr 2fr 2fr 3fr;gap:var(--space-md)}
.foot-col h4{font-weight:400;font-size:.875rem;color:var(--muted-d);margin:0 0 .875rem}
.foot-col ul{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:.5rem}
.foot-col a{font-size:.9375rem;transition:color .25s ease}
.foot-col a:hover{color:#fff;text-decoration:underline;text-underline-offset:.25rem}
.foot-mark{display:flex;justify-content:flex-end;align-items:flex-start;gap:.75rem}
.social{width:2.75rem;height:2.75rem;border-radius:50%;border:1px solid rgba(255,255,255,.3);display:grid;place-items:center;transition:border-color .3s ease}
.social:hover{border-color:var(--on-ink)}
.foot-bar{margin-top:var(--space-xl);padding-top:var(--space-sm);border-top:1px solid var(--line-d);display:flex;justify-content:space-between;gap:1.5rem;flex-wrap:wrap;color:var(--muted-d);font-size:.8125rem}

/* ── CURSOR (Tier B · tech crosshair, lerp .24, bracket snap) ── */
.cur{display:none}
html.has-cur,html.has-cur *{cursor:none!important}
html.has-cur .cur{display:block;opacity:0;position:fixed;top:0;left:0;pointer-events:none;z-index:9999;mix-blend-mode:difference}
.cur-core{width:.375rem;height:.375rem;background:#fff;margin:-.1875rem 0 0 -.1875rem}
.cur-x{width:1.375rem;height:1.375rem;margin:-.6875rem 0 0 -.6875rem}
.cur-x::before,.cur-x::after{content:'';position:absolute;background:#fff;opacity:.85}
.cur-x::before{left:50%;top:0;bottom:0;width:1.5px;margin-left:-.75px;clip-path:polygon(0 0,100% 0,100% 30%,0 30%,0 70%,100% 70%,100% 100%,0 100%)}
.cur-x::after{top:50%;left:0;right:0;height:1.5px;margin-top:-.75px;clip-path:polygon(0 0,30% 0,30% 100%,0 100%,0 0,70% 0,100% 0,100% 100%,70% 100%)}
.cur-br{width:2rem;height:2rem;opacity:0;transition:opacity .2s ease}
.cur-br.on{opacity:1}
.cur-br i{position:absolute;width:.5rem;height:.5rem;border:1.5px solid #fff}
.cur-br i:nth-child(1){left:0;top:0;border-right:0;border-bottom:0}
.cur-br i:nth-child(2){right:0;top:0;border-left:0;border-bottom:0}
.cur-br i:nth-child(3){left:0;bottom:0;border-right:0;border-top:0}
.cur-br i:nth-child(4){right:0;bottom:0;border-left:0;border-top:0}
html.cur-live .cur{opacity:1}
html.cur-live .cur-br{opacity:0}
html.cur-live .cur-br.on{opacity:1}
html.cur-live.snap .cur-x{opacity:0}
@media (hover:none),(pointer:coarse),(prefers-reduced-motion:reduce){html.has-cur,html.has-cur *{cursor:auto!important}html.has-cur .cur{display:none}}
/* ── ≤1024: content height ── */
@media (max-width:1024px){
  .band{min-height:0}
  .page-head{min-height:0;padding-top:calc(var(--nav-h) + var(--space-lg))}
  .foot-grid{grid-template-columns:repeat(3,1fr)}
  .nav-inner{gap:1.25rem}
}

/* ═══ MOBILE GLOBAL RULES — ≤768px. Last block in the file. ═══ */
@media (max-width:768px){
  .container,.nav-inner{padding-left:var(--gutter-m);padding-right:var(--gutter-m)}
  .band,[class^="s-"]{padding-top:var(--section-m);padding-bottom:var(--section-m)}
  .page-head{padding-top:6.5rem;padding-bottom:var(--section-m)}
  .nav-links,.nav-right .signin,.nav-right .btn{display:none}
  .burger{display:flex;flex-direction:column;justify-content:center;align-items:stretch;width:2.75rem;height:2.75rem;padding:.75rem .625rem;gap:.375rem;border:0;background:none;cursor:pointer}
  .burger span{display:block;width:100%;height:1.5px;background:currentColor;transition:transform .34s var(--ease)}
  .burger[aria-expanded="true"] span:nth-child(1){transform:translateY(.2344rem) rotate(45deg)}
  .burger[aria-expanded="true"] span:nth-child(2){transform:translateY(-.2344rem) rotate(-45deg)}
  .split-head{grid-template-columns:1fr;gap:var(--space-sm)}
  .h1{font-size:clamp(2.75rem,13vw,3.5rem)}
  .h1.long{font-size:clamp(2.125rem,9vw,2.75rem)}
  .close-h{font-size:clamp(2.75rem,13vw,3.5rem)}
  .s-close .container{gap:var(--space-md)}
  .close-foot{grid-template-columns:1fr;gap:var(--space-sm)}
  .foot-grid{grid-template-columns:1fr 1fr;gap:1.5rem 1rem}
  .foot-col a{display:block;padding:.25rem 0;font-size:.875rem}
  .foot-mark{grid-column:1/-1;justify-content:flex-start}
  .foot-bar{margin-top:var(--space-md);flex-direction:column;gap:.5rem}
  .footer{padding:var(--section-m) 0}
}