/* ==========================================================================
   RhoStone — v41 "Computed"
   One stylesheet, every page. Built on the v39 dark field and the v40 mark,
   re-centred on one idea: make complexity look understandable.

   What v41 changed, and why, is in other/V41_CHANGELOG.md. In short:
   - Ink and warm off-white instead of navy and cool white; one accent (blue)
     for anything active, changed or interactive, and one data state
     (--breach) used only when a computed rule is broken.
   - Inter Display for headlines, IBM Plex Mono for data and labels, EB
     Garamond for the editorial voice. Type does the work decoration did.
   - A 12-column editorial grid and one row idiom (hairline, key, title,
     text) instead of repeated card grids.
   - The recurring motif is STATE → EVENT → NEW STATE → CONSEQUENCE, drawn
     as nodes on a line. Motion is one-shot and reads as computation.

     01  Tokens and fonts
     02  Reset and base type
     03  Primitives — wrap, labels, buttons, links, evidence marks
     04  Header, nav, footer
     05  Sections — heads, rows, ledgers, splits, final band
     06  The engine (the interactive covenant model)
     07  The chain motif
     08  Home — hero, feature, proof
     09  Registers — work and notes indexes, filters
     10  Page heroes, investigations (case studies)
     11  Systems, about, contact
     12  Notes (articles), legal, 404
     13  Motion
     14  Responsive
   ========================================================================== */

/* 01 — Tokens and fonts =================================================== */

@font-face{font-family:InterDisplayLocal;src:url('assets/fonts/InterDisplay-Regular.woff') format('woff');font-weight:400;font-display:swap}
@font-face{font-family:InterDisplayLocal;src:url('assets/fonts/InterDisplay-Medium.woff') format('woff');font-weight:500;font-display:swap}
@font-face{font-family:InterLocal;src:url('assets/fonts/Inter-Regular.woff') format('woff');font-weight:400;font-display:swap}
@font-face{font-family:InterLocal;src:url('assets/fonts/Inter-Medium.woff') format('woff');font-weight:500;font-display:swap}
@font-face{font-family:InterLocal;src:url('assets/fonts/Inter-SemiBold.woff') format('woff');font-weight:600;font-display:swap}
@font-face{font-family:EBGaramondLocal;src:url('assets/fonts/EBGaramond-Regular.woff') format('woff');font-style:normal;font-display:swap}
@font-face{font-family:EBGaramondLocal;src:url('assets/fonts/EBGaramond-Italic.woff') format('woff');font-style:italic;font-display:swap}
@font-face{font-family:PlexMonoLocal;src:url('assets/fonts/IBMPlexMono-Regular.woff') format('woff');font-weight:400;font-display:swap}
@font-face{font-family:PlexMonoLocal;src:url('assets/fonts/IBMPlexMono-Medium.woff') format('woff');font-weight:500;font-display:swap}

:root{
  /* Ink, not navy. Every neutral keeps a trace of cool under a warm
     off-white type colour, so nothing is pure black or pure white. */
  --bg:#0A0B0F;
  --soft:#0D0F13;
  --s1:#111318;
  --s2:#171A20;
  --deep:#08090C;
  --ink:#ECE9E2;
  /* 7.8:1 on --bg */
  --ink-2:#A6A39B;
  /* 5.5:1 on --bg, 4.9:1 on --s2: the floor for 12px mono labels */
  --ink-3:#8A877F;
  --line:rgba(236,233,226,.09);
  --line-2:rgba(236,233,226,.18);

  /* The one accent. Fills and lines use --accent; text uses --accent-text
     (9.5:1). Solid buttons use --btn because white on --accent is 3.89:1. */
  --accent:#2E7BFF;
  --accent-text:#8FB4FF;
  --accent-soft:rgba(46,123,255,.12);
  --btn:#1E63E8;
  --btn-hover:#1A56CC;

  /* A data state, not a second accent: only a broken rule is drawn in it. */
  --breach:#F08A6C;
  --breach-soft:rgba(240,138,108,.1);

  --elev:inset 0 1px 0 rgba(255,255,255,.04),0 1px 1px rgba(0,0,0,.3),0 4px 10px rgba(0,0,0,.22),0 18px 40px rgba(0,0,0,.32);

  --display:InterDisplayLocal,InterLocal,-apple-system,'Segoe UI',Arial,sans-serif;
  --sans:InterLocal,-apple-system,'Segoe UI',Arial,sans-serif;
  --serif:EBGaramondLocal,Georgia,'Times New Roman',serif;
  --mono:PlexMonoLocal,ui-monospace,SFMono-Regular,Consolas,monospace;

  --fs-hero:clamp(2.6rem,4.9vw,4.75rem);
  --fs-h1:clamp(2.5rem,5vw,4.5rem);
  --fs-h2:clamp(2rem,3.4vw,3.25rem);
  --fs-h3:clamp(1.15rem,1.4vw,1.375rem);
  --fs-lead:clamp(1.125rem,1.3vw,1.3125rem);
  --fs-body:1rem;
  --fs-sm:.9375rem;
  --fs-label:.75rem;

  --max:1280px;
  --gutter:clamp(20px,4vw,48px);
  --col-gap:clamp(16px,2.2vw,32px);
  --band:clamp(64px,9vw,136px);
  /* 100%, not 100vw: vw includes the scrollbar. */
  --bleed:max(var(--gutter),calc((100% - var(--max)) / 2 + var(--gutter)));

  --ease:cubic-bezier(.16,1,.3,1);
}

/* 02 — Reset and base type ================================================ */

*,*::before,*::after{box-sizing:border-box}
html{color-scheme:dark;scroll-behavior:smooth;-webkit-text-size-adjust:100%;scroll-padding-top:96px} /* anchors and focus land clear of the sticky header (WCAG 2.4.11) */
body{
  margin:0;background:var(--bg);color:var(--ink);
  font:400 var(--fs-body)/1.6 var(--sans);
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
/* height:auto: without it an <img> keeps its height attribute as it shrinks. */
img{max-width:100%;height:auto;display:block}
a{color:inherit}
h1,h2,h3{margin:0;text-wrap:balance}
h1,h2{font-family:var(--display);font-weight:400;letter-spacing:-.035em;line-height:1.02}
h1{font-size:var(--fs-h1)}
h2{font-size:var(--fs-h2)}
h3{font-size:var(--fs-h3);font-weight:500;letter-spacing:-.018em;line-height:1.25}
p{margin:0 0 1.1em;text-wrap:pretty}
p:last-child{margin-bottom:0}
/* EB Garamond italic is the editorial voice: the word that carries the
   meaning in a headline, and pull quotes. Never decorative. */
h1 i,h1 em,h2 i,h2 em,h3 i{
  font-family:var(--serif);font-style:italic;font-weight:400;letter-spacing:-.01em;
}
b,strong{font-weight:600}
::selection{background:var(--accent);color:#fff}
:focus-visible{outline:2px solid var(--accent-text);outline-offset:3px;border-radius:1px}
.skip-link{position:absolute;left:-9999px}
.skip-link:focus{left:var(--gutter);top:14px;z-index:100;background:var(--ink);color:var(--bg);padding:11px 16px}
.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap}

/* 03 — Primitives ========================================================= */

.wrap{max-width:var(--max);margin-inline:auto;padding-inline:var(--gutter)}

/* The engineering voice: mono caps. A <b> inside is the index numeral. */
.label,.breadcrumbs,.article-kicker,.article-meta{
  font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;
  text-transform:uppercase;color:var(--ink-3);
}
.label b{font-weight:500;color:var(--accent-text);margin-right:.9em}
.lead{font-size:var(--fs-lead);line-height:1.5;color:var(--ink-2);max-width:34em}
.muted{color:var(--ink-2);font-size:var(--fs-sm)}

.actions{display:flex;flex-wrap:wrap;align-items:center;gap:16px 30px}

.btn{
  display:inline-flex;align-items:center;gap:16px;
  background:var(--btn);color:#fff;text-decoration:none;
  padding:15px 20px;font:500 var(--fs-sm)/1 var(--sans);
  transition:background .2s;
}
.btn:hover{background:var(--btn-hover)}
.btn span{transition:transform .25s var(--ease)}
.btn:hover span{transform:translateX(3px)}
.btn--quiet{background:none;color:var(--ink);box-shadow:inset 0 0 0 1px var(--line-2)}
.btn--quiet:hover{background:var(--s2)}
/* Faceted, like the stone. corner-shape does not clip focus rings; browsers
   without it keep square corners. */
@supports (corner-shape: bevel){
  .btn,.site-header .nav-cta{border-radius:0 10px 0 10px;corner-shape:bevel}
  .fit{border-radius:0 22px 0 22px;corner-shape:bevel}
}

.text-link{
  display:inline-flex;align-items:center;gap:9px;text-decoration:none;
  font:500 var(--fs-sm)/1 var(--sans);color:var(--ink);
  padding-bottom:6px;border-bottom:1px solid var(--line-2);
  transition:border-color .2s;
}
.text-link span{color:var(--accent-text);transition:transform .25s var(--ease)}
.text-link:hover{border-bottom-color:var(--accent-text)}
.text-link:hover span{transform:translateX(3px)}

/* Evidence marks. Applied is a filled node, prototype half, research a
   ring: the level reads before the word does. */
.ev{display:inline-flex;align-items:center;gap:8px;white-space:nowrap}
.ev::before{
  content:'';width:9px;height:9px;border-radius:50%;flex:0 0 9px;
  border:1.5px solid var(--accent-text);
}
.ev-applied::before{background:var(--accent-text)}
.ev-prototype::before{background:linear-gradient(90deg,var(--accent-text) 50%,transparent 50%)}
/* In lists the mark is boxed and the level sets its weight: applied reads
   first, research last. */
.label.ev{padding:4px 8px 4px 7px;border:1px solid var(--line-2);align-self:flex-start}
.label.ev-applied{color:var(--accent-text);border-color:var(--accent)}
.label.ev-prototype{color:var(--ink)}
.legend .label.ev{border:0;padding:0;white-space:normal}
.ev--lg{font:500 .8125rem/1 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink)}
.ev--lg::before{width:13px;height:13px;flex-basis:13px;border-width:2px}
.ev--lg.ev-applied{color:var(--accent-text)}
.sec-head > .ev{justify-self:start;align-self:start;margin-top:.5em;padding-top:6px}

.tags{display:flex;flex-wrap:wrap;gap:6px;margin:22px 0 0;padding:0;list-style:none}
.tags span,.tags li{
  border:1px solid var(--line-2);padding:6px 10px;
  font:400 var(--fs-label)/1 var(--mono);letter-spacing:.04em;color:var(--ink-2);
}

/* 04 — Header, nav, footer ================================================ */

.site-header{
  /* Solid, never backdrop-filter: a blurred sticky header repaints the
     viewport on every scroll frame and froze the renderer on the homepage. */
  position:sticky;top:0;z-index:20;background:var(--bg);
  border-bottom:1px solid var(--line);
  display:flex;align-items:center;justify-content:space-between;
  height:68px;padding-inline:var(--bleed);transition:box-shadow .25s;
}
.site-header.scrolled{box-shadow:0 12px 30px rgba(0,0,0,.45)}
.brand-lockup{display:inline-flex;align-items:center;gap:12px;text-decoration:none}
.brand-lockup img{width:36px;height:36px}
.brand-lockup span{font:600 .8125rem/1 var(--sans);letter-spacing:.26em;color:var(--ink)}
.site-header nav{display:flex;align-items:center;gap:clamp(18px,2.6vw,38px)}
.site-header nav a{
  position:relative;text-decoration:none;font-size:var(--fs-sm);
  color:var(--ink-2);padding-block:6px;transition:color .2s;
}
.site-header nav a:hover,.site-header nav a[aria-current]{color:var(--ink)}
.site-header nav a::after{
  content:'';position:absolute;left:0;right:100%;bottom:0;height:1px;
  background:var(--accent-text);transition:right .3s var(--ease);
}
.site-header nav a:hover::after,.site-header nav a[aria-current]::after{right:0}
.site-header .nav-cta{padding:9px 15px;border:1px solid var(--line-2);color:var(--ink)}
.site-header .nav-cta::after{display:none}
.site-header .nav-cta:hover{border-color:var(--accent-text)}

.menu-toggle{display:none}
.mobile-nav{display:none}
.mobile-nav[aria-hidden="true"]{visibility:hidden;pointer-events:none}
.mobile-nav.open[aria-hidden="false"]{visibility:visible;pointer-events:auto}

.site-footer{border-top:1px solid var(--line);background:var(--bg);padding:clamp(48px,6vw,80px) var(--bleed) 28px}
.footer-top{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:32px;
  padding-bottom:clamp(40px,5vw,64px);
}
.footer-brand{grid-column:1 / 6}
.footer-brand p{margin:18px 0 0;max-width:30ch;color:var(--ink-2);font-size:var(--fs-sm)}
.site-footer nav{grid-column:7 / 10;display:flex;flex-direction:column;gap:10px}
.site-footer nav a,.footer-contact a{text-decoration:none;font-size:var(--fs-sm);color:var(--ink)}
/* What each section is for: work is the evidence, systems the method... */
.site-footer nav a span,.mobile-nav a span{margin-left:.8em;font:400 var(--fs-label)/1 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}
.site-footer nav a:hover,.footer-contact a:hover{color:var(--accent-text)}
.footer-contact{grid-column:10 / 13;display:flex;flex-direction:column;gap:10px;font-size:var(--fs-sm);color:var(--ink-2)}
.footer-base{
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:10px 28px;
  border-top:1px solid var(--line);padding-top:22px;
  font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3);
}
.footer-base a{text-decoration:none}
.footer-base a:hover{color:var(--accent-text)}

/* 05 — Sections =========================================================== */

.sec{border-top:1px solid var(--line);padding-block:var(--band)}
.sec-soft{background:var(--soft)}

/* Section head: the label hangs in the left margin, the argument starts on
   column 4. The asymmetry is the page's architecture, used everywhere. */
.sec-head{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));
  column-gap:var(--col-gap);row-gap:20px;margin-bottom:clamp(40px,5.5vw,72px);
}
.sec-head > .label{grid-column:1 / 4;padding-top:.7em}
.sec-head h2{grid-column:4 / 13;max-width:19ch}
.sec-head > p{grid-column:4 / 11;margin:4px 0 0;font-size:var(--fs-lead);line-height:1.5;color:var(--ink-2);max-width:46ch}
.sec-head > .text-link{grid-column:4 / 13;justify-self:start;margin-top:8px}

/* Rows — one idiom for sequential and comparative content: hairline, key,
   title, text. It replaces the v38-v40 hairline card grids. */
.rows{border-top:1px solid var(--line-2);margin:0;padding:0;list-style:none}
.row{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));
  column-gap:var(--col-gap);row-gap:8px;padding:clamp(22px,2.6vw,32px) 0;
  border-bottom:1px solid var(--line);
}
.row-k{grid-column:1 / 4}
.row-k .sci{color:var(--accent-text)}
/* Small schematic under a row's key (homepage buyer problems) */
.opt-bar{display:block;margin-bottom:16px}
.row-fig{display:block;width:100%;max-width:180px;height:auto;margin-top:20px}
.row-t{grid-column:4 / 8}
.row-t h3{font-family:var(--display);font-weight:400;font-size:clamp(1.4rem,2vw,1.85rem);letter-spacing:-.025em;line-height:1.1}

.row-t p{color:var(--ink-2);font-size:var(--fs-sm);margin:12px 0 0;max-width:38ch}
.label a{text-decoration:none}
.label a:hover{color:var(--accent-text)}

/* Body copy that starts on column 4, under a section head. */
.grid12{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:32px}
.col-body{grid-column:4 / 11}
.col-body > p{color:var(--ink-2);max-width:64ch}

/* Ledger — key/value facts. */
.ledger{margin:0;border-top:1px solid var(--line-2)}
.ledger > div{
  display:grid;grid-template-columns:minmax(0,.85fr) minmax(0,1.6fr);gap:var(--col-gap);
  padding:15px 0;border-bottom:1px solid var(--line);
}
.ledger dt{font-weight:500;font-size:var(--fs-sm)}
.ledger dd{margin:0;color:var(--ink-2);font-size:var(--fs-sm)}

/* Split — a statement on the left, its qualification on the right. */
.split{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:22px;align-items:start}
.split > div{grid-column:1 / 8}
.split > div .label{display:block;margin-bottom:20px}
.split h2{max-width:18ch}
.split > p{grid-column:8 / 13;color:var(--ink-2);margin:0}
.split > .split-body{grid-column:8 / 13;color:var(--ink-2);font-size:var(--fs-lead);line-height:1.5}
.split-body .text-link{margin-top:14px}

/* Options — a small number of ways in, side by side. */
.options{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));column-gap:var(--col-gap);row-gap:48px;border-top:1px solid var(--line-2)}
.options > div{padding-top:22px}
.options h3{font-family:var(--display);font-weight:400;font-size:clamp(1.9rem,3vw,2.75rem);letter-spacing:-.035em;margin:8px 0 14px}
.options p{color:var(--ink-2);font-size:var(--fs-sm);max-width:38ch}
.options p.label{color:var(--ink-3);margin-top:18px}
/* What the client has at the end of that stage. */
.opt-eg{list-style:none;margin:10px 0 0;padding:0}
.opt-eg li{position:relative;padding:10px 0 10px 18px;border-top:1px solid var(--line);color:var(--ink-2);font-size:var(--fs-sm);line-height:1.5;max-width:38ch}
.opt-eg li::before{content:"";position:absolute;left:0;top:1.3em;width:7px;height:1.5px;background:var(--accent)}
.options .opt-out{margin-top:18px;padding-top:14px;border-top:1px solid var(--line);color:var(--ink)}
.opt-out b{display:block;margin-bottom:4px;font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--accent-text)}
/* What an engagement includes: length, scope, deliverables, next step. */
.opt-terms{margin:18px 0 0;border-top:1px solid var(--line)}
.opt-terms > div{padding:10px 0;border-bottom:1px solid var(--line)}
.opt-terms dt{font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}
.opt-terms dd{margin:4px 0 0;color:var(--ink-2);font-size:var(--fs-sm);max-width:38ch}

/* Fit — two panels in one faceted frame. Bullets are a connector ending in a
   leaf node, as in the mark: filled where it fits, open for how it runs. */
.fit{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));background:var(--s1);border:1px solid var(--line-2);overflow:hidden}
.fit-col{padding:clamp(28px,3.6vw,52px)}
.fit-col + .fit-col{border-left:1px solid var(--line-2)}
.fit-col--lead{box-shadow:inset 0 2px 0 var(--accent)}
.fit h3{font-family:var(--display);font-weight:400;font-size:clamp(1.7rem,2.6vw,2.3rem);letter-spacing:-.032em;line-height:1.08;margin:12px 0 28px;max-width:16ch}
.fit ul{list-style:none;margin:0;padding:0;border-bottom:1px solid var(--line)}
.fit li{position:relative;padding:20px 0 20px 34px;border-top:1px solid var(--line);color:var(--ink);font-size:clamp(1rem,1.2vw,1.125rem);line-height:1.5}
.fit li::before{content:'';position:absolute;left:0;top:calc(20px + .75em);width:14px;height:1px;background:var(--line-2)}
.fit li::after{content:'';position:absolute;left:14px;top:calc(20px + .75em - 4px);width:9px;height:9px;box-sizing:border-box;border-radius:50%;border:1.5px solid var(--accent)}
.fit-col--lead li::after{background:var(--accent)}

.faq-list{border-top:1px solid var(--line-2)}
.faq-list details{border-bottom:1px solid var(--line)}
.faq-list summary{
  list-style:none;cursor:pointer;display:flex;justify-content:space-between;align-items:center;
  gap:20px;padding:22px 0;font-size:var(--fs-h3);font-weight:500;letter-spacing:-.018em;
}
.faq-list summary::-webkit-details-marker{display:none}
.faq-list summary::after{content:'+';font:400 1.4rem/1 var(--mono);color:var(--accent-text)}
.faq-list details[open] summary::after{content:'−'}
.faq-list details p{max-width:70ch;margin:-4px 0 24px;font-size:var(--fs-sm);color:var(--ink-2)}

/* Final band — the closing call to action, on the pages that need one. */
.final{background:var(--deep);border-top:1px solid var(--line);padding:clamp(72px,11vw,160px) var(--bleed)}
.final h2{font-size:clamp(2.4rem,5.4vw,4.75rem);line-height:1;letter-spacing:-.045em;margin:0 0 26px;max-width:16ch}
.final p{font-size:var(--fs-lead);color:var(--ink-2);max-width:44ch;margin-bottom:38px}

/* Statement — one large paragraph where a section needs a voice, not a layout. */
.statement{font:400 clamp(1.7rem,3.2vw,2.75rem)/1.18 var(--display);letter-spacing:-.028em;color:var(--ink);max-width:26ch;margin:0}
.statement + p{margin-top:28px}

/* Letter — first-person prose in the editorial serif. */
.letter p{font-size:var(--fs-lead);line-height:1.6;color:var(--ink);max-width:36em;margin-bottom:1.1em}
.letter .sign{font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3);margin-top:28px}

.split > .pair--wide{grid-column:1 / -1;display:grid;grid-template-columns:repeat(4,minmax(0,1fr));margin-top:clamp(48px,6vw,80px)}
.pair--wide p{max-width:32ch}
/* The legal boundary, stated once in plain words. */
.boundary{margin-top:40px;padding:18px 20px;border:1px solid var(--line-2);color:var(--ink-2);font-size:var(--fs-sm);max-width:64ch}
.boundary b{color:var(--ink);font-weight:500}
.grid12 > .boundary{grid-column:4 / 11;margin-top:8px}

/* Quotes — what people say when they call, set as speech. */
.quotes{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:56px var(--col-gap)}
.quotes blockquote{margin:0;border-top:1px solid var(--line-2);padding-top:22px}
.quotes blockquote p{font-family:var(--serif);font-style:italic;font-size:clamp(1.45rem,2.3vw,2rem);line-height:1.2;color:var(--ink);max-width:20ch;margin-bottom:18px}
.quotes blockquote footer{color:var(--ink-2);font-size:var(--fs-sm);max-width:40ch}

/* The founder portrait hangs in the label margin beside the About letter. */
.portrait{grid-column:1 / 4;margin:0;max-width:220px}
.portrait img{width:100%;aspect-ratio:4 / 5;object-fit:cover;border:1px solid var(--line-2);filter:grayscale(1) contrast(1.05)}
.portrait figcaption{margin-top:10px}

/* 06 — The engine ========================================================= */

/* An interactive model in the site's four steps: state, event (the slider),
   new state, consequence. The headline states the answer for the current
   value. Everything it shows is produced by covenantModel() in script.js. */
.engine{margin:0 0 28px;background:var(--s1);border:1px solid var(--line-2);box-shadow:var(--elev)}
.engine-head{padding:14px 18px 16px;border-bottom:1px solid var(--line)}
.engine-meta{display:flex;flex-wrap:wrap;justify-content:space-between;gap:4px 14px}
/* two lines reserved so the panel does not jump as the sentence rewraps */
.engine-read{margin:12px 0 0;min-height:2.5em;font:400 clamp(1.25rem,1.7vw,1.5rem)/1.25 var(--display);letter-spacing:-.02em;color:var(--ink);text-wrap:balance}

.engine-shock{font-size:1.25rem}
.engine-slider{grid-column:2 / -1;position:relative;margin-top:14px;padding-top:10px;--fill:.75;--zero:.75}
.engine input[type=range]{
  -webkit-appearance:none;appearance:none;width:100%;height:24px;margin:0;background:transparent;cursor:pointer;position:relative;z-index:2;
}
/* The track shows the shock as a bar growing from zero, not from the left end. */
.engine input[type=range]::-webkit-slider-runnable-track{height:2px;background:var(--line-2)}
.engine input[type=range]::-moz-range-track{height:2px;background:var(--line-2)}
.engine input[type=range]::-webkit-slider-thumb{
  -webkit-appearance:none;width:16px;height:16px;margin-top:-7px;border-radius:50%;
  background:var(--bg);border:2px solid var(--accent-text);
}
.engine input[type=range]::-moz-range-thumb{width:12px;height:12px;border-radius:50%;background:var(--bg);border:2px solid var(--accent-text)}
.engine-bar{
  position:absolute;top:21px;height:2px;z-index:1;pointer-events:none;background:var(--accent);
  left:calc(min(var(--fill),var(--zero)) * (100% - 16px) + 8px);
  width:calc(max(var(--fill) - var(--zero),var(--zero) - var(--fill)) * (100% - 16px));
}
.engine[data-state="breach"] .engine-bar{background:var(--breach)}
.engine-marks i{
  position:absolute;top:14px;width:1px;height:16px;background:var(--ink-3);z-index:1;
  left:calc(var(--at,0) * (100% - 16px) + 8px);
}
.engine-marks i::after{
  content:attr(data-label);position:absolute;bottom:18px;left:50%;translate:-50% 0;white-space:nowrap;
  font:400 .6875rem/1 var(--mono);letter-spacing:.04em;color:var(--ink-3);
}
.engine-marks i.is-past{background:var(--breach)}
.engine-marks i.is-past::after{color:var(--breach)}
.engine-scale{display:flex;justify-content:space-between;margin-top:4px}

.engine-nodes{list-style:none;margin:0;padding:4px 18px}
.node{
  display:grid;grid-template-columns:14px minmax(0,1fr) auto;column-gap:14px;
  padding:12px 0;position:relative;
}
.node + .node{border-top:1px solid var(--line)}
/* The connector runs through every node; it turns accent as the change
   propagates, and --breach where a rule has been broken. */
.node::before{content:'';position:absolute;left:3px;top:0;bottom:0;width:1px;background:var(--line-2)}
.node:first-child::before{top:19px}
.node:last-child::before{bottom:calc(100% - 19px)}
.node-dot{width:7px;height:7px;margin-top:8px;border-radius:50%;background:var(--ink-3);position:relative;z-index:1;box-shadow:0 0 0 4px var(--s1);transition:background .3s}
.node-name{display:block;font-weight:500;font-size:var(--fs-sm);line-height:1.4}
.node-note{display:block;font-size:.875rem;line-height:1.4;color:var(--ink-2)}
.node-note b{font:500 .6875rem/1 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3);margin-right:6px}
.node-val{text-align:right;font:500 1rem/1.4 var(--mono);font-variant-numeric:tabular-nums;white-space:nowrap}
.node-delta{display:block;font:400 .8125rem/1.4 var(--mono);color:var(--ink-3);transition:color .3s}
.node-rights{grid-column:2 / -1;display:flex;flex-wrap:wrap;gap:6px;list-style:none;margin:10px 0 0;padding:0}
.node-rights li{
  padding:5px 8px;border:1px solid var(--line);color:var(--ink-3);
  font:400 .75rem/1.2 var(--mono);transition:color .3s,border-color .3s,background .3s;
}
.node-rights li.is-on{border-color:var(--accent);color:var(--accent-text);background:var(--accent-soft)}
.node-rights li.is-on[data-level="default"]{border-color:var(--breach);color:var(--breach);background:var(--breach-soft)}
.node--out .node-val > span:first-child{font-size:1.25rem}

.node.is-changed .node-dot{background:var(--accent)}
.node.is-changed::before{background:var(--accent)}
.node.is-changed .node-delta{color:var(--accent-text)}
.node.is-breach .node-dot{background:var(--breach)}
.node.is-breach::before{background:var(--breach)}
.node.is-breach .node-delta{color:var(--breach)}
/* the connector above the first node that did not change stays neutral */
.node:not(.is-changed):not(.is-breach)::before{background:var(--line-2)}

.engine-foot{border-top:1px solid var(--line);padding:12px 18px}

/* Scenario presets and reset: buttons, so the model works from a keyboard
   without dragging. */
.engine-presets{display:flex;flex-wrap:wrap;align-items:center;gap:6px;margin-top:14px}
.engine-presets .label{margin-right:8px}
.engine-presets button{
  font:400 var(--fs-label)/1 var(--mono);letter-spacing:.04em;color:var(--ink-2);
  background:transparent;border:1px solid var(--line-2);padding:9px 11px;cursor:pointer;min-height:36px;
  transition:color .2s,border-color .2s,background .2s;
}
.engine-presets button:hover{color:var(--ink);border-color:var(--ink-3)}
.engine-presets button[aria-pressed="true"]{color:var(--ink);border-color:var(--accent);background:var(--accent-soft)}
.engine-presets button[data-reset]{margin-left:auto}
/* Typed value for the revenue change, kept in step with the slider. */
.engine-num{display:inline-flex;align-items:baseline;gap:2px;font:500 1.25rem/1.2 var(--mono)}
.engine-num input{
  width:4.6em;padding:2px 4px;text-align:right;font:inherit;font-variant-numeric:tabular-nums;color:var(--ink);
  background:var(--bg);border:1px solid var(--line-2);border-radius:0;-moz-appearance:textfield;
}
.engine-num input::-webkit-inner-spin-button{opacity:.5}
/* Leverage against the three thresholds: a fill from 2.5x to 5x, with a
   tick where each clause bites. */
.engine-gauge{grid-column:2 / -1;position:relative;display:block;height:6px;margin:12px 0 2px;background:var(--line);--lev:.12}
.engine-gauge b{position:absolute;left:0;top:0;bottom:0;width:calc(var(--lev) * 100%);background:var(--accent);transition:width .15s}
.engine[data-state="breach"] .engine-gauge b{background:var(--breach)}
.engine-gauge i{position:absolute;top:-4px;width:1px;height:14px;background:var(--ink-3);left:calc(var(--at) * 100%)}
.engine-gauge i:last-of-type{background:var(--ink)}
.engine-gauge-scale{grid-column:2 / -1;display:flex;justify-content:space-between;margin-top:4px}

/* Base against scenario, row by row. */
.engine-table{width:100%;border-collapse:collapse;font-size:var(--fs-sm);border-top:1px solid var(--line-2)}
.engine-table th,.engine-table td{padding:9px 18px 9px 0;border-bottom:1px solid var(--line);text-align:right;font:400 .875rem/1.35 var(--mono);font-variant-numeric:tabular-nums}
.engine-table th:first-child{padding-left:18px;text-align:left;font:400 var(--fs-sm)/1.35 var(--sans);color:var(--ink-2)}
.engine-table thead th{font:400 var(--fs-label)/1.4 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}
.engine-table thead th:first-child{font:inherit;font:400 var(--fs-label)/1.4 var(--mono)}
.engine-table td.is-changed{color:var(--accent-text)}
.engine-table td.is-breach{color:var(--breach)}
.engine-table td:last-child{color:var(--ink-3)}
.engine-notes{border-top:1px solid var(--line);padding:0 18px}
.engine-notes summary{cursor:pointer;padding:12px 0;font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-2)}
.engine-notes summary:hover{color:var(--ink)}
.engine-notes ul{margin:0 0 14px;padding-left:1.1em;color:var(--ink-2);font-size:var(--fs-sm)}
.engine-notes li{margin-bottom:6px}

/* 07 — The chain motif ==================================================== */

/* STATE → EVENT → NEW STATE → CONSEQUENCE. Cells sit on one hairline with
   a node where each begins; the last node is the consequence. */
.chain{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));list-style:none;margin:0;padding:0;counter-reset:chain}
.chain > li{position:relative;padding:28px var(--col-gap) 0 0;border-top:1px solid var(--line-2)}
.chain > li::before{
  content:'';position:absolute;left:0;top:-4px;width:7px;height:7px;border-radius:50%;
  background:var(--ink-3);box-shadow:0 0 0 4px var(--bg);
}
.chain > li:last-child::before{background:var(--accent)}
/* the drawn path — see 13 Motion */
.chain > li::after{
  content:'';position:absolute;left:0;right:0;top:-1px;height:1px;
  background:var(--accent);opacity:.7;transform-origin:left;
}
.chain-step{display:flex;justify-content:space-between;gap:10px}
.chain-step span{color:var(--accent-text)}
.chain h3{font-family:var(--display);font-weight:400;font-size:clamp(1.6rem,2.3vw,2.2rem);letter-spacing:-.03em;margin:14px 0 12px}
.chain p{color:var(--ink-2);font-size:var(--fs-sm);max-width:30ch}

/* Compact chain — the per-investigation version in a case hero. */
.chain--compact > li{padding-top:18px}
.chain--compact .label{display:block;margin-bottom:6px}
.chain--compact p{color:var(--ink);font-size:var(--fs-sm);max-width:26ch}
.chain--compact > li:last-child p{color:var(--accent-text)}

.sec-soft .chain > li::before{box-shadow:0 0 0 4px var(--soft)}

/* Five steps: the method (understand to build), or a contract followed
   from its clause to its cost. */
.chain--five{grid-template-columns:repeat(5,minmax(0,1fr))}
.chain--five h3{font-size:clamp(1.35rem,1.9vw,1.85rem)}
.chain--five p{max-width:24ch}
.chain--compact.chain--five p{font-size:var(--fs-sm)}
.chain + .legend,.chain + .under{margin-top:clamp(28px,3.5vw,44px)}
/* The model underneath the method: one line, set as a note beneath it. */
.under{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);padding-top:18px;border-top:1px solid var(--line)}
.under > .label{grid-column:1 / 4}
.under > p{grid-column:4 / 11;margin:0;color:var(--ink-2)}
.under b{font:500 var(--fs-sm)/1 var(--mono);letter-spacing:.02em;color:var(--ink)}
.under a{color:var(--accent-text);text-underline-offset:3px}
.under + .options{margin-top:clamp(48px,6vw,80px)}
/* Example problems on the homepage: label hangs in columns 1–3 like a sec-head. */
.chain--compact.chain--five{margin-bottom:clamp(44px,5vw,64px)}
/* The stage a method rule belongs to, after its text. */
.index-list-row p .label{margin-left:.6em;white-space:nowrap}

/* 08 — Home =============================================================== */

.hero-grid{
  display:grid;grid-template-columns:minmax(0,1fr) minmax(0,.9fr);
  gap:clamp(36px,5vw,96px);align-items:center;
  min-height:calc(100svh - 68px);padding-block:clamp(48px,6vw,88px);
}
.hero-copy > .label{display:block;margin-bottom:24px}
.hero h1{font-size:var(--fs-hero);line-height:1;letter-spacing:-.045em;margin:0 0 30px;text-wrap:balance}
.hero .lead{margin-bottom:40px}
/* The mark as a system schematic: the homepage hero, and a per-page variant
   in every other page's page-hero-side, all inlined by
   other/tools/build_mark_assets.py. Its one-shot assembly is in 13 Motion. */
.hero-mark{margin:0;justify-self:center;width:100%;max-width:min(512px,40.5vw)}
.hero-mark svg{display:block;width:100%;height:auto}
/* Inlined diagrams carry a system-mono font-family attribute for when the
   file is opened on its own; on the page they use the site's mono. */
.hero-mark text,.system-figure text,.feature-fig text,.row-fig text,.ex-chart text,.chart text{font-family:var(--mono);letter-spacing:0}
/* Feature investigation — figure seven columns, argument five. */
.feature{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:28px;
  text-decoration:none;color:inherit;margin-bottom:clamp(40px,5vw,64px);
}
.feature-fig{grid-column:1 / 8;margin:0;background:var(--deep);border:1px solid var(--line);position:relative;overflow:hidden}
.feature-fig img,.feature-fig svg{display:block;width:100%;height:auto;aspect-ratio:1200 / 620;object-fit:contain;padding:36px 24px 20px}
.feature-fig .label{position:absolute;top:14px;left:16px}
.feature-body{grid-column:8 / 13;display:flex;flex-direction:column;align-items:flex-start}
.feature-body h3{font-family:var(--display);font-weight:400;font-size:clamp(1.75rem,2.6vw,2.5rem);letter-spacing:-.035em;line-height:1.05;margin:14px 0 14px}
.feature-body > p{color:var(--ink-2)}
.feature:hover h3{color:var(--accent-text)}
.feature-body > .text-link{margin-top:22px}
.legend{display:flex;flex-wrap:wrap;gap:10px 24px;margin-top:22px}

/* Explainer — one job as three columns: what comes in, what we build, what
   goes back. Plain HTML so it reflows on a phone and uses the site's type. */
.explainer{
  display:grid;grid-template-columns:repeat(3,minmax(0,1fr));column-gap:var(--col-gap);
  margin:0 0 clamp(56px,7vw,96px);border-top:1px solid var(--line-2);
}
.ex-col{position:relative;padding:22px 0 0}
.ex-col + .ex-col::before{
  content:'→';position:absolute;top:18px;left:calc(var(--col-gap) / -2);translate:-50% 0;
  font:400 1rem/1 var(--mono);color:var(--accent-text);background:var(--bg);padding:4px 2px;
}
.ex-model{background:var(--s1);border:1px solid var(--line-2);border-top:0;padding:22px 20px 20px}
.ex-col ul{list-style:none;margin:16px 0 0;padding:0}
.ex-col li{padding:12px 0;border-bottom:1px solid var(--line)}
.ex-col li:last-child{border-bottom:0}
.ex-col li b{display:block;font-weight:500;font-size:var(--fs-sm)}
.ex-col li span{display:block;color:var(--ink-2);font-size:var(--fs-sm);line-height:1.45}
.ex-model li b{font:500 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--accent-text)}
.ex-out li b{font:500 clamp(1.4rem,2vw,1.75rem)/1.2 var(--mono);font-variant-numeric:tabular-nums;letter-spacing:-.01em}
.ex-chart{display:block;width:100%;max-width:360px;height:auto;margin:18px 0 4px}
.ex-out li:last-child b{font-family:var(--display);letter-spacing:-.02em} /* words, not a figure */
.explainer figcaption{grid-column:1 / -1;margin-top:18px;font-size:var(--fs-sm);color:var(--ink-3)}
.explainer figcaption a{color:var(--accent-text);text-underline-offset:3px}


/* 09 — Registers ========================================================== */

.register{list-style:none;margin:0;padding:0;border-top:1px solid var(--line-2)}
.register > li{border-bottom:1px solid var(--line)}
.register > li > a{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:6px;
  align-items:baseline;padding:24px 0;text-decoration:none;color:inherit;
}
.reg-n{grid-column:1 / 2;font:400 var(--fs-label)/1.5 var(--mono);color:var(--ink-3)}
.reg-t{grid-column:2 / 6;font-family:var(--display);font-size:clamp(1.2rem,1.6vw,1.5rem);letter-spacing:-.02em;line-height:1.2;transition:color .2s}
.reg-d{grid-column:6 / 9;color:var(--ink-2);font-size:var(--fs-sm)}
.reg-m{grid-column:9 / 12;display:flex;flex-direction:column;gap:6px}
.reg-go{grid-column:12 / 13;justify-self:end;color:var(--accent-text);transition:transform .25s var(--ease)}
.register > li > a:hover .reg-t{color:var(--accent-text)}
.register > li > a:hover .reg-go{transform:translateX(4px)}

.filters{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin-bottom:26px}
.filters .label{margin-right:10px}
.filters button{
  font:400 var(--fs-label)/1 var(--mono);letter-spacing:.06em;text-transform:uppercase;
  color:var(--ink-2);background:transparent;border:1px solid var(--line-2);padding:8px 12px;cursor:pointer;
  transition:color .2s,border-color .2s,background .2s;
}
.filters button:hover{color:var(--ink);border-color:var(--ink-3)}
.filters button[aria-pressed="true"]{color:var(--ink);border-color:var(--accent);background:var(--accent-soft)}
.filters output{margin-left:auto}

/* 10 — Page heroes and investigations ===================================== */

.page-hero{padding-block:clamp(64px,9vw,128px) clamp(48px,6vw,88px)}
.page-hero .wrap{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:26px;align-items:start}
.page-hero .wrap > *{grid-column:1 / 10}
.page-hero h1{max-width:18ch}
.page-hero .page-hero-copy{display:flex;flex-direction:column;align-items:flex-start;gap:26px}
/* A page hero with the page's mark on the right. */
.page-hero--aside .page-hero-copy{grid-column:1 / 7}
.page-hero--aside .page-hero-side{grid-column:7 / 13;align-self:center}

.breadcrumbs{max-width:var(--max);margin-inline:auto;padding:24px var(--gutter) 0;display:flex;flex-wrap:wrap;gap:10px}
.breadcrumbs a{text-decoration:none}
.breadcrumbs a:hover{color:var(--accent-text)}

/* Case dossier — the facts a buyer checks first. */
.dossier{
  grid-column:1 / 13 !important;display:grid;grid-template-columns:repeat(4,minmax(0,1fr));
  column-gap:var(--col-gap);margin:clamp(20px,3vw,40px) 0 0;border-top:1px solid var(--line-2);
}
.dossier > div{padding:16px 0 0}
.dossier dt{margin-bottom:6px}
.dossier dd{margin:0;font-size:var(--fs-sm)}
.dossier dd a{color:var(--accent-text);text-underline-offset:3px}
.dossier > .dossier-result{grid-column:1 / -1;padding-bottom:16px;border-bottom:1px solid var(--line)}
.dossier-result dd{font-size:1.125rem;color:var(--ink);max-width:62ch}
.case-chain{grid-column:1 / 13 !important;margin-top:clamp(24px,3vw,36px)}
.case-chain > .label{display:block;margin-bottom:22px}

.inv{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:20px;
  padding-block:clamp(56px,7vw,104px);border-top:1px solid var(--line);
}
/* Sticky within its own grid row: the question stays beside the answer. */
.inv-label{grid-column:1 / 4;align-self:start;position:sticky;top:96px}
.inv-label .label{display:block}
.inv-body{grid-column:4 / 12}
.inv-body h2{font-size:clamp(1.75rem,2.8vw,2.6rem);letter-spacing:-.03em;line-height:1.08;max-width:22ch;margin-bottom:24px}
.inv-body > p{color:var(--ink-2);max-width:66ch;font-size:1.0625rem}
.inv-body p a{color:var(--accent-text);text-decoration:underline;text-decoration-color:var(--line-2);text-underline-offset:3px}
.inv-body p a:hover{text-decoration-color:currentColor}
.inv-body em{font-style:italic;color:var(--ink)}

.system-figure{margin:34px 0;border:1px solid var(--line);background:var(--deep)}
.system-figure img,.system-figure svg{display:block;width:100%;height:auto}
.system-figure svg.fig-tall{display:none}
.system-figure figcaption{border-top:1px solid var(--line);padding:12px 16px;font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}

.state-table{width:100%;border-collapse:collapse;margin:30px 0;font-size:var(--fs-sm)}
.state-table th,.state-table td{text-align:left;padding:13px 14px 13px 0;border-bottom:1px solid var(--line);vertical-align:top}
.state-table thead th{border-bottom-color:var(--line-2);font:400 var(--fs-label)/1.4 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}
.state-table td{color:var(--ink-2)}
.state-table td:first-child{color:var(--ink);font-weight:500}

/* Exhibits — artefacts from the work: a contract extract, a code listing, a
   record as a reviewer saw it. The caption says what it is and how real. */
.exhibit{margin:36px 0 40px}
.exhibit > figcaption{
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:4px 18px;margin-bottom:10px;
  font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3);
}
.exhibit > figcaption span:first-child{color:var(--ink-2)}
.exhibit-note{margin:12px 0 0;font-size:var(--fs-sm);color:var(--ink-2);max-width:60ch}
/* Charts in notes, drawn by hand from the note's own numbers. */
.article-body .exhibit:has(.chart){max-width:560px}
.chart{display:block;width:100%;height:auto;padding:14px;background:var(--deep);border:1px solid var(--line)}

/* A page from a document. Paper is the one light surface on the site, so
   the extract reads as a thing someone handed over, not a UI panel. */
.doc{
  --doc-ink:#1B1C20;--doc-mark:#1648B8;
  background:var(--ink);color:var(--doc-ink);box-shadow:var(--elev);
  padding:clamp(26px,4vw,52px) clamp(22px,4.5vw,60px);max-width:44rem;
  font:400 1.125rem/1.6 var(--serif);
}
.doc h3{margin:0 0 14px;font:500 .8125rem/1.4 var(--sans);letter-spacing:.08em;text-transform:uppercase}
.doc h3:not(:first-child){margin-top:28px}
.doc p{position:relative;padding-left:3.6em;margin:0 0 .9em;color:var(--doc-ink);font-size:inherit}
.doc .cl{position:absolute;left:0;font-variant-numeric:tabular-nums}
.doc mark{background:rgba(30,99,232,.12);color:inherit;border-bottom:1.5px solid var(--doc-mark);padding:0 .12em}
.doc mark[data-k]::after{
  content:attr(data-k);margin-left:.3em;vertical-align:.45em;
  font:500 .625rem/1 var(--mono);letter-spacing:.06em;text-transform:uppercase;color:var(--doc-mark);
}
.doc .doc-foot{margin:22px 0 0;padding:12px 0 0;border-top:1px solid rgba(27,28,32,.2);font:400 .75rem/1.5 var(--mono);color:#55534D}

.listing{
  margin:0;overflow-x:auto;background:var(--deep);border:1px solid var(--line);
  padding:20px 24px;font:400 .8125rem/1.7 var(--mono);color:var(--ink);tab-size:2;
}
/* <code> otherwise falls back to the browser's monospace, not Plex Mono. */
.listing code{font:inherit}
.listing .c{color:var(--ink-3)}
.listing .s{color:var(--accent-text)}
.listing .x{color:var(--breach)}

/* A record as a reviewer saw it: headline values, then what moved them. */
.record{background:var(--s1);border:1px solid var(--line-2)}
.record-head{display:grid;grid-template-columns:repeat(auto-fit,minmax(130px,1fr));border-bottom:1px solid var(--line)}
.record-head > div{padding:14px 18px;border-right:1px solid var(--line)}
.record-head > div:last-child{border-right:0}
.record-head .label{display:block;margin-bottom:4px}
.record-head b{font:500 1.25rem/1.3 var(--mono);font-variant-numeric:tabular-nums}
.record-head s{font:400 .8125rem/1 var(--mono);color:var(--ink-3);margin-left:6px}
.record-head .is-breach{color:var(--breach);font-family:var(--sans);font-size:1rem}
.drivers{width:100%;border-collapse:collapse;font-size:var(--fs-sm)}
.drivers th,.drivers td{padding:11px 18px;border-bottom:1px solid var(--line);text-align:left;font-weight:400}
.drivers tr:last-child > *{border-bottom:0}
.drivers th{color:var(--ink-2)}
.drivers td{width:34%}
.drivers td:last-child{width:5.5rem;text-align:right;font:400 .875rem/1 var(--mono);font-variant-numeric:tabular-nums}
.bar{display:block;width:100%;height:6px}
.bar rect{fill:var(--accent)}
.bar .neg{fill:var(--ink-3)}

/* Footnotes and asides in notes. */
sup.fn a{font:500 .68em/1 var(--mono);color:var(--accent-text);text-decoration:none;margin-left:1px}
.article-body .footnotes{margin:2.6em 0 0;padding:18px 0 0 1.2em;border-top:1px solid var(--line);font:400 var(--fs-sm)/1.6 var(--sans);color:var(--ink-2)}
.article-body .footnotes li{margin-bottom:.7em}
.article-body .footnotes a{text-decoration:none}
.article-body p.aside{font:400 var(--fs-sm)/1.65 var(--sans);color:var(--ink-2);border-left:1px solid var(--line-2);padding-left:18px;max-width:46ch;margin:1.6em 0}

.index-list{border-top:1px solid var(--line-2);margin-top:28px}
.index-list-row{display:grid;grid-template-columns:3rem minmax(0,1fr);gap:var(--col-gap);padding:22px 0;border-bottom:1px solid var(--line)}
.index-list-row .idx{font:500 var(--fs-label)/1.9 var(--mono);color:var(--accent-text)}
.index-list-row h3{margin-bottom:6px}
.index-list-row p{font-size:var(--fs-sm);color:var(--ink-2);margin:0}

/* What became possible — outcome statements, each on its own line. */
.outcomes{list-style:none;margin:28px 0;padding:0;border-top:1px solid var(--line-2)}
.outcomes li{display:grid;grid-template-columns:2rem minmax(0,1fr);gap:12px;padding:15px 0;border-bottom:1px solid var(--line);color:var(--ink)}
.outcomes li::before{content:'→';color:var(--accent-text);font-family:var(--mono)}

.related-reading-links{display:flex;flex-direction:column;border-top:1px solid var(--line-2);margin-top:28px}
.related-reading-links a{
  display:flex;justify-content:space-between;gap:16px;align-items:center;padding:16px 0;
  text-decoration:none;border-bottom:1px solid var(--line);
}
.related-reading-links a span{color:var(--accent-text);transition:transform .25s var(--ease)}
.related-reading-links a:hover{color:var(--accent-text)}
.related-reading-links a:hover span{transform:translateX(3px)}

.case-nav{
  margin-inline:var(--bleed);padding:24px 0;border-top:1px solid var(--line);
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:16px;
}
.case-nav a{font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;text-decoration:none;color:var(--ink-2)}
.case-nav a:hover{color:var(--accent-text)}

/* 11 — Systems, about, contact ============================================ */

.stage-artefacts{grid-column:8 / 13}
.stage-artefacts .label{display:block;margin-bottom:4px}
.stage-artefacts .label.ev{display:inline-flex;margin:14px 0 0 12px;vertical-align:middle}
.stage-artefacts .nodes{margin-top:10px}

/* Contact prompts: each opens an email with that sentence already in it. */
.prompts{list-style:none;margin:16px 0 14px;padding:0;border-top:1px solid var(--line-2)}
.prompts a{
  display:flex;justify-content:space-between;align-items:baseline;gap:16px;padding:14px 0;
  border-bottom:1px solid var(--line);text-decoration:none;
  font:400 var(--fs-lead)/1.35 var(--sans);color:var(--ink);
}
.prompts a span{font:400 var(--fs-sm)/1 var(--sans);color:var(--accent-text);transition:transform .25s var(--ease)}
.prompts a:hover{color:var(--accent-text)}
.prompts a:hover span{transform:translate(2px,-2px)}

/* Sectors: where the same kind of system shows up. */
.sectors{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:48px var(--col-gap)}
.sectors > div{border-top:1px solid var(--line-2);padding-top:20px}
.sectors h3{font-family:var(--display);font-weight:400;font-size:clamp(1.4rem,2vw,1.85rem);letter-spacing:-.025em;line-height:1.1;margin-bottom:12px}
.sectors p{color:var(--ink-2);font-size:var(--fs-sm);max-width:44ch}
.sectors .nodes{margin-top:12px}

.contact-grid{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);row-gap:48px}
.contact-grid > div:first-child{grid-column:1 / 7}
.contact-grid > div:last-child{grid-column:8 / 13}
.contact-grid > div > .label{display:block;margin-top:36px}
.contact-grid > div > .label:first-child{margin-top:0}
.brief{
  font-family:var(--serif);font-style:italic;font-size:clamp(1.6rem,2.8vw,2.5rem);line-height:1.2;
  color:var(--ink);margin:16px 0 18px;max-width:22ch;
}
.brief u{text-decoration:none;border-bottom:1px solid var(--accent-text);color:var(--accent-text);padding-inline:.4em}
.contact-email{font:400 clamp(1.25rem,2vw,1.6rem)/1.2 var(--display);letter-spacing:-.02em;text-decoration:none;border-bottom:1px solid var(--line-2);padding-bottom:6px}
.contact-email:hover{border-color:var(--accent-text)}
.contact-card{border-top:1px solid var(--line-2);padding-top:22px}
.contact-card .actions{margin:22px 0 26px}

/* 12 — Notes (articles), legal, 404 ======================================= */

/* An article is laid on the same 12 columns: the headline runs wide, the
   meta hangs in the margin beside a narrow reading column. */
.article{
  max-width:var(--max);margin-inline:auto;padding:clamp(48px,6vw,88px) var(--gutter) clamp(72px,9vw,128px);
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));column-gap:var(--col-gap);
}
.article > *{grid-column:4 / 11}
.article-kicker{grid-column:1 / 9;color:var(--accent-text)}
.article h1{grid-column:1 / 9;font-size:clamp(2.4rem,4.6vw,4.25rem);letter-spacing:-.04em;line-height:1.02;margin:22px 0 28px;max-width:20ch}
.article-dek{grid-column:1 / 9;font-family:var(--display);font-size:clamp(1.25rem,1.8vw,1.6rem);line-height:1.35;letter-spacing:-.01em;color:var(--ink-2);margin-bottom:clamp(40px,5vw,72px)}
.article-meta{grid-column:1 / 4;grid-row:4;align-self:start;position:sticky;top:96px;display:flex;flex-direction:column;gap:6px;border-top:1px solid var(--line-2);padding-top:14px}
.article-meta strong{font-weight:500;color:var(--ink)}
.article-body{grid-row:4;border-top:1px solid var(--line-2);padding-top:10px}
/* Long-form reads in EB Garamond: the law-and-finance half of the voice. */
.article-body p{font-size:var(--fs-lead);line-height:1.6;margin:0 0 1.2em;color:var(--ink)}
.article-body p:first-child{margin-top:18px}
.article-body h2{font-size:clamp(1.5rem,2.2vw,2rem);letter-spacing:-.025em;margin:2.2em 0 .7em}
.article-body a{color:var(--accent-text);text-underline-offset:3px;text-decoration-color:var(--line-2)}
.article-body blockquote{margin:2em 0;padding-left:24px;border-left:1px solid var(--accent);font-family:var(--serif);font-style:italic;font-size:1.6rem;line-height:1.3}
.article-body ul,.article-body ol{font-size:var(--fs-lead);line-height:1.6;padding-left:1.2em}
.article .chain{margin:36px 0 44px}
.article-body .chain p{font-size:var(--fs-sm);line-height:1.6}
.article .chain > li::before{box-shadow:0 0 0 4px var(--bg)}
.related-reading{display:grid;grid-template-columns:minmax(0,.7fr) minmax(0,1.3fr);gap:var(--col-gap);margin-top:72px;padding-top:28px;border-top:1px solid var(--line-2)}
.related-reading .label{display:block;margin-bottom:10px}
.related-reading h2{font-size:var(--fs-h3);letter-spacing:-.02em}
.related-reading .related-reading-links{margin-top:0}
.related-reading{row-gap:28px}
/* The close of a note: one line and the site's one call to action. */
.note-cta{
  margin-top:56px;padding:26px 28px;background:var(--s1);border:1px solid var(--line-2);
  display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:18px 28px;
}
.note-cta p{margin:0;font:400 clamp(1.25rem,1.9vw,1.55rem)/1.25 var(--display);letter-spacing:-.02em;max-width:30ch}
.article-nav{
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:16px;margin-top:48px;padding-top:22px;border-top:1px solid var(--line);
  font:400 var(--fs-label)/1.5 var(--mono);letter-spacing:.06em;text-transform:uppercase;
}
.article-nav a{text-decoration:none;color:var(--ink-2)}
.article-nav a:hover{color:var(--accent-text)}

.legal-copy > *{max-width:70ch}
.legal-copy h2{font-size:clamp(1.5rem,2.2vw,2rem);letter-spacing:-.025em;margin:44px 0 10px}
.legal-copy h2:first-child{margin-top:0}
.legal-copy p{color:var(--ink-2)}
.legal-copy a{color:var(--accent-text);text-underline-offset:3px}

.notfound-main{max-width:var(--max);margin-inline:auto;padding:clamp(80px,14vh,180px) var(--gutter)}
.notfound-main h1{margin:18px 0 30px;max-width:16ch}

/* Analytics consent: one bar, pinned to the bottom, until answered. No
   backdrop-filter (see the performance note in CLAUDE.md). */
.consent{
  position:fixed;left:var(--gutter);right:var(--gutter);bottom:var(--gutter);z-index:30;max-width:40rem;
  display:flex;flex-wrap:wrap;align-items:center;gap:16px 24px;padding:18px 20px;
  background:var(--s1);border:1px solid var(--line-2);box-shadow:var(--elev);font-size:var(--fs-sm);
}
.consent p{flex:1 1 20rem;margin:0;color:var(--ink-2)}
.consent a{color:var(--accent-text);text-underline-offset:3px}
.consent-actions{display:flex;gap:12px}
.consent .btn{border:0;cursor:pointer;padding:12px 18px}

/* 13 — Motion ============================================================= */

/* One-shot only. The homepage is ~7,000px tall and continuous animation or
   heavy compositing froze the renderer there. Motion should read as
   something being computed: paths drawing, values settling. */

/* script.js marks each main section after the first with .reveal */
.reveal{opacity:0;transform:translateY(14px);transition:opacity .6s var(--ease),transform .6s var(--ease)}
.reveal.is-visible{opacity:1;transform:none}

/* The hero mark assembles once on load: orbit, crow, connections, then the
   four disciplines in the chain's order. Every stroke has pathLength="1", so
   a dasharray of 1 draws it at any length. With motion reduced the
   animations are removed and it simply shows. */
@keyframes mk-draw{from{stroke-dashoffset:1}}
@keyframes mk-fade{from{opacity:0}}
@keyframes mk-rise{from{opacity:0;transform:translateY(16px)}}
.mk-orbit path,.mk-inner,.mk-span,.mk-links path{stroke-dasharray:1}
.mk-orbit path,.mk-inner{animation:mk-draw 1.5s var(--ease) .1s both}
.mk-crow{animation:mk-rise 1s var(--ease) .4s both}
.mk-links path{animation:mk-draw .7s var(--ease) 1s both}
.mk-span{animation:mk-draw 1s var(--ease) 1.4s both}
.mk-nodes{animation:mk-fade .6s var(--ease) 1.1s both}
.mk-steps > g{animation:mk-fade .5s var(--ease) both}
.mk-steps > g:nth-child(1){animation-delay:1.4s}
.mk-steps > g:nth-child(2){animation-delay:1.65s}
.mk-steps > g:nth-child(3){animation-delay:1.9s}
.mk-steps > g:nth-child(4){animation-delay:2.15s}

/* The accent path draws along the chain, node by node. The
   hidden state is keyed on .reveal:not(.is-visible), so with no script or
   reduced motion the path is simply drawn. */
.chain > li::after{transition:transform .7s var(--ease)}
.reveal:not(.is-visible) .chain > li::after{transform:scaleX(0)}
.chain > li:nth-child(2)::after{transition-delay:.25s}
.chain > li:nth-child(3)::after{transition-delay:.5s}
.chain > li:nth-child(4)::after{transition-delay:.75s}
.chain > li:nth-child(5)::after{transition-delay:1s}

@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none !important;transition:none !important}
  .reveal{opacity:1;transform:none}
}

/* 14 — Responsive ========================================================= */

/* Wide screens: the supporting text in rows and registers reads at body
   size rather than small. */
@media(min-width:1200px){
  .row-t p,.reg-d{font-size:var(--fs-body)}
  .row-t p{max-width:40ch}
}

@media(max-width:1080px){
  .hero-grid{grid-template-columns:1fr;min-height:0;gap:56px}
  .hero .lead{max-width:40em}
  .hero-mark{order:-1;max-width:340px}
  .reg-d{grid-column:6 / 9}
  .reg-m{grid-column:9 / 13}
  .reg-go{display:none}
}

@media(max-width:900px){
  .fit{grid-template-columns:1fr}
  .fit-col + .fit-col{border-left:0;border-top:1px solid var(--line-2)}
  .site-header nav{display:none}
  .menu-toggle{display:flex;flex-direction:column;justify-content:center;gap:5px;background:none;border:0;padding:10px;cursor:pointer}
  .menu-toggle span{display:block;width:22px;height:1.5px;background:var(--ink)}
  .mobile-nav{
    display:flex;flex-direction:column;gap:18px;position:fixed;inset:68px 0 auto 0;z-index:19;
    background:var(--bg);border-bottom:1px solid var(--line);padding:26px var(--gutter);
    transform:translateY(-120%);transition:transform .3s var(--ease);
  }
  .mobile-nav.open{transform:translateY(0)}
  .mobile-nav a{text-decoration:none;font:400 1.5rem/1.2 var(--display);letter-spacing:-.02em}

  .sec-head > *,.sec-head > .label,.sec-head h2,.sec-head > p,.sec-head > .text-link{grid-column:1 / -1}
  .sec-head > .label{padding-top:0}
  .row-k,.row-t,.stage-artefacts,.col-body,.split > .split-body,.portrait,.grid12 > .boundary{grid-column:1 / -1}
  .portrait{max-width:180px}
  .options{grid-template-columns:1fr}
  .row-t{margin-top:4px}
  .split > div,.split > p{grid-column:1 / -1}
  .chain{grid-template-columns:repeat(2,minmax(0,1fr));row-gap:40px}
  .chain--five{grid-template-columns:repeat(3,minmax(0,1fr))}
  .split > .pair--wide,.sectors{grid-template-columns:repeat(2,minmax(0,1fr))}
  .under > .label,.under > p{grid-column:1 / -1}
  .under > p{margin-top:8px}
  .explainer{grid-template-columns:1fr;row-gap:28px}
  .ex-col + .ex-col::before{content:'↓';top:-26px;left:0;translate:none}
  .feature-fig,.feature-body{grid-column:1 / -1}
  .footer-brand{grid-column:1 / -1}
  .site-footer nav{grid-column:1 / 7}
  .footer-contact{grid-column:7 / 13}

  .register > li > a{grid-template-columns:3rem minmax(0,1fr);row-gap:8px}
  .register .reg-n{grid-column:1;grid-row:1 / span 3}
  .register .reg-t,.register .reg-d,.register .reg-m{grid-column:2}
  .register .reg-m{flex-direction:row;flex-wrap:wrap;gap:6px 18px}

  .page-hero .wrap > *,.page-hero .lead{grid-column:1 / -1}
  .page-hero--aside .page-hero-side{order:-1;width:100%;max-width:340px;justify-self:center}
  .quotes{grid-template-columns:1fr}
  .dossier{grid-template-columns:repeat(2,minmax(0,1fr))}
  .inv-label,.inv-body{grid-column:1 / -1}
  .inv-label{position:static}
  .contact-grid > div:first-child,.contact-grid > div:last-child{grid-column:1 / -1}

  .article > *,.article h1,.article-dek,.article-meta,.article-body{grid-column:1 / -1}
  .article-meta{grid-row:auto;position:static;flex-direction:row;flex-wrap:wrap;gap:6px 20px;margin-bottom:10px}
  .article-body{grid-row:auto}
  .related-reading{grid-template-columns:1fr}
}

@media(max-width:600px){
  .breadcrumbs [aria-current],.breadcrumbs > span:has(+ [aria-current]){display:none}
  .hero-mark{max-width:220px}
  .hero-grid{gap:40px;padding-top:36px}
  .doc p{padding-left:2.8em}
  .drivers th,.drivers td{padding-inline:12px}
  .drivers td:first-of-type{width:28%}
  .actions{flex-direction:column;align-items:flex-start}
  .chain,.chain--five{grid-template-columns:1fr}
  .chain > li{padding-right:0}
  .split > .pair--wide,.sectors{grid-template-columns:1fr}
  .engine-presets button[data-reset]{margin-left:0}
  .engine-table th,.engine-table td{padding-right:10px}
  .engine-table th:first-child{padding-left:14px}
  .site-footer nav a span{display:none}
  .dossier{grid-template-columns:1fr}
  .engine-meta{flex-direction:column}
  .engine-nodes,.engine-head,.engine-foot{padding-inline:14px}
  .node{grid-template-columns:14px minmax(0,1fr);row-gap:4px}
  .node-val{grid-column:2;text-align:left;white-space:normal}
  .node-delta{display:inline;margin-left:10px}
  .node-rights{grid-column:2}
  .site-footer nav,.footer-contact{grid-column:1 / -1}
  .ledger > div{grid-template-columns:1fr;gap:4px}
  .state-table,.state-table thead,.state-table tbody,.state-table tr,.state-table th,.state-table td{display:block;width:100%}
  .state-table thead{display:none}
  .state-table tr{border-bottom:1px solid var(--line);padding:8px 0}
  .state-table td{border:0;padding:4px 0}
  .filters output{margin-left:0;flex-basis:100%}
  /* Thumb-sized targets for the small mono and footer links. */
  .breadcrumbs a,.page-hero .label a,.case-nav a,.article-nav a,.site-footer nav a,.footer-contact a,.footer-base a{display:inline-block;padding-block:6px}
  .site-footer nav,.footer-contact{gap:2px}
  .footer-base a{margin-block:-6px}
  /* Diagrams are drawn 800–1200 wide; scaled to a phone their labels drop
     under 5px. Where a figure has a phone version (.fig-tall) show that;
     otherwise keep them legible and let them scroll sideways. */
  .system-figure{overflow-x:auto}
  .system-figure img,.system-figure svg{width:800px;max-width:none}
  .system-figure svg.fig-wide{display:none}
  .system-figure svg.fig-tall{display:block;width:100%}
  .system-figure figcaption{position:sticky;left:0}
  .feature-fig{display:none}
}