/* Endstop — shared design system
   Identity: engineering specification document.
   Ground = graphite/paper, accent = signal amber (indicator lamp),
   oxide red reserved semantically for refusal & not-claimed states. */

:root {
  --ground:      #ECEEEF;
  --ground-sunk: #E2E6E8;
  --ink:         #13171A;
  --ink-muted:   #525A61;
  --ink-faint:   #7F878E;
  --rule:        #CDD3D6;
  --rule-strong: #A7AFB4;
  --accent:      #946412;
  --accent-soft: #EBE3D4;
  --stop:        #973520;

  --f-display: ui-sans-serif, -apple-system, "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  --f-body:    Georgia, "Iowan Old Style", "Times New Roman", serif;
  --f-mono:    ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;

  --measure: 36rem;
  --rail:    5.5rem;
  --gutter:  2.5rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ground:      #15171A;
    --ground-sunk: #1B1E22;
    --ink:         #E6E4DF;
    --ink-muted:   #9CA1A9;
    --ink-faint:   #6C727B;
    --rule:        #2A2E34;
    --rule-strong: #3C4148;
    --accent:      #E8A33D;
    --accent-soft: #2C2416;
    --stop:        #D2604A;
  }
}
:root[data-theme="dark"] {
  --ground:      #15171A;
  --ground-sunk: #1B1E22;
  --ink:         #E6E4DF;
  --ink-muted:   #9CA1A9;
  --ink-faint:   #6C727B;
  --rule:        #2A2E34;
  --rule-strong: #3C4148;
  --accent:      #E8A33D;
  --accent-soft: #2C2416;
  --stop:        #D2604A;
}
:root[data-theme="light"] {
  --ground:      #ECEEEF;
  --ground-sunk: #E2E6E8;
  --ink:         #13171A;
  --ink-muted:   #525A61;
  --ink-faint:   #7F878E;
  --rule:        #CDD3D6;
  --rule-strong: #A7AFB4;
  --accent:      #946412;
  --accent-soft: #EBE3D4;
  --stop:        #973520;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font-family: var(--f-body);
  font-size: 1.0625rem;
  line-height: 1.68;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.wrap { max-width: 60rem; margin: 0 auto; padding: 0 1.75rem; }

a { color: var(--accent); text-underline-offset: 0.18em; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
a:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 1px; }

/* ---------- masthead & navigation ---------- */

.masthead { border-bottom: 2px solid var(--ink); }
.masthead-inner {
  display: flex; flex-wrap: wrap; align-items: baseline; gap: 0.6rem 1.4rem;
  padding: 2rem 0 1.1rem;
}
.wordmark {
  font-family: var(--f-display); font-weight: 800; font-size: 1.35rem;
  letter-spacing: -0.02em; text-transform: uppercase; margin: 0;
}
.wordmark a { color: inherit; text-decoration: none; }
.byline {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.1em;
  text-transform: uppercase; color: var(--ink-muted);
}
.stamp {
  margin-left: auto; font-family: var(--f-mono); font-size: 0.66rem;
  letter-spacing: 0.12em; text-transform: uppercase; color: var(--accent);
  border: 1px solid currentColor; padding: 0.2rem 0.5rem; white-space: nowrap;
}
.sitenav { border-bottom: 1px solid var(--rule); }
.sitenav ul {
  list-style: none; margin: 0; padding: 0.85rem 0;
  display: flex; flex-wrap: wrap; gap: 0.35rem 1.6rem;
  font-family: var(--f-mono); font-size: 0.735rem;
  letter-spacing: 0.06em; text-transform: uppercase;
}
.sitenav a { color: var(--ink-muted); text-decoration: none; padding-bottom: 2px; }
.sitenav a:hover { color: var(--ink); }
.sitenav a[aria-current="page"] {
  color: var(--ink); border-bottom: 2px solid var(--accent);
}

/* ---------- page head ---------- */

.pagehead { padding: 3.5rem 0 2.75rem; border-bottom: 1px solid var(--rule); }
.eyebrow {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.13em;
  text-transform: uppercase; color: var(--ink-faint); margin: 0 0 1rem;
}
.pagehead h1 {
  font-family: var(--f-display); font-weight: 800;
  font-size: clamp(1.9rem, 4.6vw, 2.85rem); line-height: 1.1;
  letter-spacing: -0.03em; text-wrap: balance; margin: 0 0 1.25rem; max-width: 24ch;
}
.pagehead .standfirst {
  margin: 0; max-width: var(--measure); font-size: 1.16rem; color: var(--ink-muted);
}
.pagehead .standfirst strong { color: var(--ink); font-weight: 400; }

/* hero variant, home only */
.pagehead.hero { padding: 4.5rem 0 4rem; }
.pagehead.hero h1 { font-size: clamp(2rem, 5.4vw, 3.15rem); max-width: 21ch; }
.pagehead.hero .standfirst { font-size: 1.22rem; }

/* ---------- clause blocks ---------- */

.clause {
  display: grid; grid-template-columns: var(--rail) minmax(0, 1fr);
  gap: 0 var(--gutter); padding: 3rem 0;
  border-bottom: 1px solid var(--rule); position: relative;
}
.clause::before {
  content: ""; position: absolute; left: calc(var(--rail) - var(--gutter));
  top: 0; bottom: 0; width: 1px; background: var(--rule);
}
.clause::after {
  content: ""; position: absolute; left: calc(var(--rail) - var(--gutter) - 0.4rem);
  top: 3.65rem; width: 0.85rem; height: 1px; background: var(--rule-strong);
}
.clause.no-rail::before, .clause.no-rail::after { display: none; }
.marker {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.09em;
  color: var(--ink-faint); padding-top: 0.3rem;
}
.clause h2 {
  font-family: var(--f-display); font-weight: 700; font-size: 1.55rem;
  letter-spacing: -0.02em; line-height: 1.2; text-wrap: balance;
  margin: 0 0 1.15rem; max-width: 26ch;
}
.clause h3 {
  font-family: var(--f-display); font-weight: 700; font-size: 1.08rem;
  letter-spacing: -0.01em; margin: 2rem 0 0.75rem; max-width: 32ch;
}
.clause p { margin: 0 0 1.05rem; max-width: var(--measure); }
.clause p:last-child { margin-bottom: 0; }
.clause em { font-style: italic; color: var(--ink); }
.lede { font-size: 1.1rem; }

.clause ul, .clause ol { max-width: var(--measure); margin: 0 0 1.05rem; padding-left: 1.2rem; }
.clause li { margin-bottom: 0.5rem; }
.clause li::marker { color: var(--ink-faint); }

/* ---------- citations ---------- */

sup.cite { font-family: var(--f-mono); font-size: 0.62rem; line-height: 0; }
sup.cite a { text-decoration: none; padding: 0 0.1em; }

.refs { padding: 2.5rem 0 0; }
.refs h2 {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.13em;
  text-transform: uppercase; font-weight: 400; color: var(--ink-faint);
  margin: 0 0 1.1rem; padding-bottom: 0.6rem; border-bottom: 1px solid var(--rule);
}
.refs ol { margin: 0; padding-left: 1.6rem; font-size: 0.875rem; line-height: 1.6; color: var(--ink-muted); }
.refs li { margin-bottom: 0.65rem; max-width: 52rem; }
.refs li:target { color: var(--ink); }

/* ---------- data tables ---------- */

.visually-hidden {
  position: absolute; width: 1px; height: 1px; margin: -1px;
  padding: 0; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
.tscroll { overflow-x: auto; margin: 1.4rem 0; }
table {
  border-collapse: collapse; width: 100%; min-width: 30rem;
  font-family: var(--f-mono); font-size: 0.8rem;
  font-variant-numeric: tabular-nums;
}
th, td {
  text-align: left; padding: 0.62rem 1.1rem 0.62rem 0;
  border-bottom: 1px solid var(--rule); vertical-align: baseline;
}
thead th {
  font-size: 0.67rem; letter-spacing: 0.11em; text-transform: uppercase;
  color: var(--ink-faint); font-weight: 400; border-bottom-color: var(--rule-strong);
}
tbody th { font-weight: 400; color: var(--ink-muted); }
td { color: var(--ink); }
td.num { font-variant-numeric: tabular-nums; }

/* ---------- figures & schematics ---------- */

figure { margin: 2rem 0; }
figure svg { display: block; width: 100%; height: auto; overflow: visible; }
.figframe {
  border: 1px solid var(--rule); background: var(--ground-sunk);
  padding: 1.5rem 1.35rem 1.25rem;
}
figcaption {
  margin-top: 0.9rem; padding-top: 0.7rem; border-top: 1px solid var(--rule);
  font-family: var(--f-mono); font-size: 0.715rem; line-height: 1.65;
  color: var(--ink-muted); max-width: 60ch;
}
figcaption b {
  color: var(--ink); font-weight: 400; letter-spacing: 0.08em;
  text-transform: uppercase; font-size: 0.68rem;
}

/* schematic primitives — themed through tokens */
.d-zone      { fill: none; stroke: var(--rule-strong); stroke-width: 1; stroke-dasharray: 4 3; }
.d-zone-trust{ fill: none; stroke: var(--accent); stroke-width: 1.5; }
.d-box       { fill: var(--ground); stroke: var(--rule-strong); stroke-width: 1; }
.d-box-key   { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.25; }
.d-box-stop  { fill: none; stroke: var(--stop); stroke-width: 1.25; }
.d-line      { stroke: var(--rule-strong); stroke-width: 1; fill: none; }
.d-line-stop { stroke: var(--stop); stroke-width: 1.25; fill: none; }
.d-line-soft { stroke: var(--rule); stroke-width: 1; fill: none; stroke-dasharray: 3 3; }
.d-fill-soft { fill: var(--ground-sunk); stroke: none; }
.d-fill-hatch{ fill: var(--stop); opacity: 0.13; stroke: none; }
.d-fill-safe { fill: var(--accent); opacity: 0.12; stroke: none; }

.d-t   { font-family: var(--f-mono); font-size: 11px; fill: var(--ink); }
.d-t-s { font-family: var(--f-mono); font-size: 9.5px; fill: var(--ink-muted); }
.d-t-x { font-family: var(--f-mono); font-size: 9px; fill: var(--ink-faint); letter-spacing: 0.09em; }
.d-t-a { font-family: var(--f-mono); font-size: 9px; fill: var(--accent); letter-spacing: 0.09em; }
.d-t-r { font-family: var(--f-mono); font-size: 9px; fill: var(--stop); letter-spacing: 0.09em; }
.d-mid { text-anchor: middle; }
.d-end { text-anchor: end; }

/* ---------- status ledger ---------- */

.ledger {
  list-style: none; margin: 1.4rem 0; padding: 0;
  display: grid; gap: 1px; background: var(--rule);
  border-block: 1px solid var(--rule);
}
.ledger > li {
  background: var(--ground); padding: 0.95rem 0; margin: 0;
  display: grid; grid-template-columns: 8rem minmax(0, 1fr);
  gap: 1.2rem; align-items: baseline;
}
.tag {
  font-family: var(--f-mono); font-size: 0.655rem;
  letter-spacing: 0.11em; text-transform: uppercase;
}
.tag-proven  { color: var(--accent); }
.tag-built   { color: var(--ink-muted); }
.tag-assumed { color: var(--ink-faint); }
.tag-no      { color: var(--stop); }
.ledger p { margin: 0; font-size: 0.96rem; max-width: 48ch; }

/* ---------- callouts ---------- */

blockquote {
  margin: 1.6rem 0; padding: 0.9rem 0 0.9rem 1.35rem;
  border-left: 3px solid var(--accent); max-width: var(--measure);
}
blockquote p { font-size: 1.04rem; font-style: italic; }
blockquote cite {
  display: block; margin-top: 0.6rem; font-family: var(--f-mono);
  font-size: 0.68rem; font-style: normal; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--ink-faint);
}

.note {
  margin: 1.5rem 0; padding: 1.05rem 1.2rem;
  background: var(--ground-sunk); border-left: 3px solid var(--rule-strong);
  max-width: var(--measure);
}
.note p { margin: 0; font-size: 0.97rem; }
.note p + p { margin-top: 0.7rem; }
.note .note-label {
  display: block; font-family: var(--f-mono); font-size: 0.655rem;
  letter-spacing: 0.11em; text-transform: uppercase;
  color: var(--ink-faint); margin-bottom: 0.5rem;
}
.note.warn { border-left-color: var(--stop); }
.note.warn .note-label { color: var(--stop); }

/* ---------- two-column compare ---------- */

.split { display: grid; gap: 1.75rem; margin: 1.4rem 0; }
@media (min-width: 46rem) { .split { grid-template-columns: 1fr 1fr; gap: 2.5rem; } }
.split-col h3 {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.11em;
  text-transform: uppercase; font-weight: 400; margin: 0 0 0.7rem;
  padding-bottom: 0.5rem; border-bottom: 1px solid var(--rule);
}
.split-col.yes h3 { color: var(--accent); }
.split-col.no  h3 { color: var(--ink-faint); }
.split-col p { font-size: 0.98rem; margin: 0 0 0.8rem; max-width: none; }
.split-col p:last-child { margin-bottom: 0; }

/* ---------- next-page links ---------- */

.onward { padding: 3rem 0 0; display: grid; gap: 1px; background: var(--rule); border-top: 1px solid var(--rule); margin-top: 3rem; }
.onward-item {
  background: var(--ground); padding: 1.35rem 0; text-decoration: none;
  display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 1rem; align-items: baseline;
}
.onward-item:hover .onward-title { color: var(--accent); }
.onward-title {
  font-family: var(--f-display); font-weight: 700; font-size: 1.05rem;
  letter-spacing: -0.01em; color: var(--ink); display: block; margin-bottom: 0.3rem;
}
.onward-desc { font-size: 0.94rem; color: var(--ink-muted); display: block; max-width: 52ch; }
.onward-arrow { font-family: var(--f-mono); font-size: 0.8rem; color: var(--ink-faint); }

/* ---------- footer ---------- */

.foot { border-top: 2px solid var(--ink); margin-top: 4rem; padding: 2.25rem 0 4rem; }
.foot-grid { display: grid; gap: 2rem; }
@media (min-width: 46rem) { .foot-grid { grid-template-columns: 1.2fr 1fr 1fr; gap: 2.5rem; } }
.foot h2 {
  font-family: var(--f-mono); font-size: 0.66rem; letter-spacing: 0.12em;
  text-transform: uppercase; font-weight: 400; color: var(--ink-faint); margin: 0 0 0.8rem;
}
.foot ul { list-style: none; margin: 0; padding: 0; font-size: 0.92rem; line-height: 1.9; }
.foot p { margin: 0; font-size: 0.92rem; color: var(--ink-muted); max-width: 30ch; }
.colophon {
  margin-top: 2.5rem; padding-top: 1.1rem; border-top: 1px solid var(--rule);
  font-family: var(--f-mono); font-size: 0.685rem; line-height: 1.95;
  letter-spacing: 0.03em; color: var(--ink-faint);
}

/* ---------- narrow screens ---------- */

@media (max-width: 40rem) {
  :root { --rail: 0rem; --gutter: 0rem; }
  .clause { grid-template-columns: minmax(0, 1fr); padding: 2.5rem 0; }
  .clause::before, .clause::after { display: none; }
  .marker { padding-top: 0; margin-bottom: 0.85rem; }
  .ledger > li { grid-template-columns: 1fr; gap: 0.3rem; }
  .stamp { margin-left: 0; }
  body { font-size: 1.02rem; }
}

/* ---------- call to action ---------- */

.cta-block {
  margin: 3rem 0 0;
  padding: 2rem 1.9rem;
  border: 1px solid var(--accent);
  background: var(--accent-soft);
}
.cta-block .eyebrow { margin-bottom: 0.8rem; color: var(--accent); }
.cta-block h2 {
  font-family: var(--f-display); font-weight: 800;
  font-size: clamp(1.35rem, 3.2vw, 1.85rem); line-height: 1.15;
  letter-spacing: -0.02em; text-wrap: balance;
  margin: 0 0 0.9rem; max-width: 22ch; color: var(--ink);
}
.cta-block p { margin: 0 0 0.85rem; max-width: 46ch; font-size: 1.02rem; }
.cta-block p:last-of-type { margin-bottom: 1.5rem; }
.cta-actions { display: flex; flex-wrap: wrap; gap: 0.7rem 0.9rem; align-items: center; }
.btn {
  display: inline-block;
  font-family: var(--f-mono); font-size: 0.75rem;
  letter-spacing: 0.1em; text-transform: uppercase;
  padding: 0.62rem 1.05rem; text-decoration: none;
  border: 1px solid var(--ink); color: var(--ink); background: transparent;
}
.btn:hover { background: var(--ink); color: var(--ground); }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.btn-quiet { border-color: var(--rule-strong); color: var(--ink-muted); }
.btn-quiet:hover { background: transparent; border-color: var(--ink); color: var(--ink); }
/* scoped to beat .cta-block p and .cta-block p:last-of-type */
.cta-block p.cta-fine {
  margin: 1.6rem 0 0; font-family: var(--f-mono); font-size: 0.72rem;
  line-height: 1.75; letter-spacing: 0.01em; color: var(--ink-muted); max-width: 52ch;
}
@media (max-width: 40rem) {
  .cta-block { padding: 1.5rem 1.25rem; }
}

/* copy-to-clipboard control, matches .btn */
button.btn { font: inherit; cursor: pointer; background: transparent;
  font-family: var(--f-mono); font-size: 0.75rem; letter-spacing: 0.1em;
  text-transform: uppercase; }
button.btn.is-copied {
  background: var(--accent); border-color: var(--accent); color: var(--ground);
}
button.btn.is-failed { border-color: var(--stop); color: var(--stop); }
.visually-hidden-live { position:absolute; width:1px; height:1px; margin:-1px;
  padding:0; overflow:hidden; clip:rect(0 0 0 0); white-space:nowrap; border:0; }
.cta-block .cta-addr { margin: 1.1rem 0 0; font-family: var(--f-mono);
  font-size: 0.75rem; color: var(--ink-muted); }
.cta-block .cta-addr a { color: var(--ink); }

/* hero jump to the call to action */
.hero-actions { margin: 1.6rem 0 0; display: flex; flex-wrap: wrap; gap: 0.7rem 0.9rem; }

.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 10;
  background: var(--accent); color: var(--ground); padding: 0.5rem 1rem;
  font-family: var(--f-mono); font-size: 0.75rem; text-transform: uppercase;
  letter-spacing: 0.08em; text-decoration: none;
}
.skip-link:focus { left: 0; }