/* rvco.co.uk — The Engineer's Notebook — design system v1a */

/* ---------- tokens ---------- */
:root {
  --paper: #EFEAE1;
  --paper-deep: #E3DCCD;
  --ink: #26241F;
  --ink-soft: #5A554A;
  --copper: #8A4B2C;
  --copper-dark: #6E3B22;
  --verdigris: #4F6B5E;
  --verdigris-deep: #435E50; /* for verdigris text on paper-deep grounds (AA) */
  --gold-hairline: #B08A45;
  --line: #C9C0AE;
  --serif: 'Iowan Old Style', 'Palatino Linotype', Palatino, 'Book Antiqua', Georgia, serif;
  --sans: 'Segoe UI', system-ui, 'Helvetica Neue', Arial, sans-serif;
  --mono: 'Cascadia Mono', Consolas, 'SF Mono', 'DejaVu Sans Mono', monospace;
  --measure: 66ch;
  --rail: 224px;
  --rail-gap: 48px;
}

/* ---------- reset-ish ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.7;
}
img { max-width: 100%; height: auto; display: block; border-radius: 2px; }
h1, h2, h3 { line-height: 1.15; font-weight: 600; margin: 0 0 0.6em; }
p { margin: 0 0 1.1em; }
a { color: var(--copper); text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--copper-dark); text-decoration-thickness: 2px; }
:focus-visible { outline: 2px solid var(--copper); outline-offset: 3px; border-radius: 1px; }
::selection { background: var(--copper-dark); color: var(--paper); }

/* ---------- skip link ---------- */
.skip-link {
  position: absolute; left: -9999px; top: 0;
  background: var(--ink); color: var(--paper);
  padding: 0.6rem 1rem; font-family: var(--sans); font-size: 0.9rem; z-index: 40;
}
.skip-link:focus { left: 0.5rem; top: 0.5rem; }

/* ---------- shell ---------- */
.shell { max-width: 1140px; margin: 0 auto; padding: 0 clamp(1.1rem, 4.5vw, 3rem); }

/* ---------- header ---------- */
.site-head { border-bottom: 3px double var(--ink); }
.site-head .shell {
  display: flex; align-items: center; gap: 1rem;
  padding-top: 1rem; padding-bottom: 1rem; flex-wrap: wrap;
}
.brand { display: flex; align-items: center; gap: 0.7rem; text-decoration: none; color: var(--ink); margin-right: auto; }
.brand img { width: 40px; height: 40px; border-radius: 0; }
.brand .brand-name { font-family: var(--serif); font-size: 1.12rem; font-weight: 600; letter-spacing: 0.01em; }
.nav-toggle {
  display: none; background: none; border: 1px solid var(--ink); color: var(--ink);
  font-family: var(--sans); font-size: 0.85rem; padding: 0.55rem 0.9rem; cursor: pointer; border-radius: 2px;
  min-height: 44px; min-width: 44px;
}
.site-nav ul { list-style: none; display: flex; gap: 1.15rem; margin: 0; padding: 0; flex-wrap: wrap; }
.site-nav a {
  font-family: var(--sans); font-size: 0.86rem; letter-spacing: 0.04em; text-transform: uppercase;
  color: var(--ink); text-decoration: none; padding: 0.72rem 0.1rem; display: inline-block;
}
.site-nav a:hover { color: var(--copper); }
.site-nav a[aria-current="page"] { color: var(--copper); border-bottom: 2px solid var(--copper); }

@media (max-width: 760px) {
  .nav-toggle { display: inline-block; }
  .site-nav { display: none; width: 100%; }
  .site-nav.open { display: block; }
  .site-nav ul { flex-direction: column; gap: 0; border-top: 1px solid var(--line); margin-top: 0.6rem; }
  .site-nav li { border-bottom: 1px solid var(--line); }
  .site-nav a { display: block; padding: 0.85rem 0.2rem; font-size: 0.95rem; }
}
/* no-JS fallback lives in nojs.css, linked inside <noscript> */

/* ---------- folio line ---------- */
.folio {
  font-family: var(--mono); font-size: 0.8125rem; letter-spacing: 0.08em;
  color: var(--ink-soft); text-transform: uppercase;
  margin: 2.4rem 0 0.9rem;
}
.folio::after { content: ""; display: block; width: 3.2rem; border-top: 2px solid var(--gold-hairline); margin-top: 0.55rem; }

/* ---------- article / margin apparatus ---------- */
.apparatus { padding-bottom: 4rem; }
.apparatus > * { max-width: var(--measure); }
.apparatus > .wide { max-width: none; }
h1.display { font-size: clamp(2.1rem, 5.2vw, 3.4rem); letter-spacing: -0.012em; margin-bottom: 0.35em; }
.standfirst { font-size: clamp(1.15rem, 2.4vw, 1.42rem); font-style: italic; color: var(--ink-soft); line-height: 1.45; margin-bottom: 1.6rem; }
h2.section { font-size: 1.35rem; margin-top: 2.6rem; padding-top: 1.1rem; border-top: 3px double var(--ink); }
h3 { font-size: 1.1rem; margin-top: 1.8rem; }

@media (min-width: 1100px) {
  .apparatus { padding-right: calc(var(--rail) + var(--rail-gap)); position: relative; }
  aside.margin {
    float: right; clear: right;
    width: var(--rail);
    margin-right: calc(-1 * (var(--rail) + var(--rail-gap)));
    margin-top: 0.3rem; margin-bottom: 1rem; margin-left: 0;
  }
}
aside.margin {
  font-family: var(--mono); font-size: 0.8rem; line-height: 1.55;
  color: var(--verdigris);
  border-left: 2px solid var(--verdigris);
  padding: 0.15rem 0 0.15rem 0.8rem;
  margin: 1.4rem 0;
}
aside.margin strong { letter-spacing: 0.06em; text-transform: uppercase; font-weight: 600; }

/* ---------- dossier meta card ---------- */
.meta-card {
  background: var(--paper-deep);
  border-top: 3px double var(--ink);
  padding: 1rem 1.2rem 1.1rem;
  margin: 1.6rem 0 2rem;
}
.meta-card dl { display: grid; grid-template-columns: auto 1fr; gap: 0.35rem 1.2rem; margin: 0; }
.meta-card dt { font-family: var(--mono); font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--ink-soft); padding-top: 0.14rem; }
.meta-card dd { margin: 0; font-size: 0.98rem; }
@media (max-width: 560px) { .meta-card dl { grid-template-columns: 1fr; gap: 0.1rem; } .meta-card dt { margin-top: 0.55rem; } }

/* ---------- index rows (contents / dossier lists) ---------- */
.index-list { list-style: none; margin: 1.2rem 0 0; padding: 0; }
.index-list li { border-top: 1px solid var(--line); }
.index-list li:last-child { border-bottom: 1px solid var(--line); }
.index-row {
  display: grid; grid-template-columns: 4.4rem minmax(0, 1fr); gap: 0.4rem 1.1rem;
  padding: 1.05rem 0.35rem; text-decoration: none; color: var(--ink);
}
a.index-row:hover { background: var(--paper-deep); }
a.index-row:hover .index-title { color: var(--copper); text-decoration: underline; text-underline-offset: 3px; }
a.index-row:hover .index-tag { color: var(--verdigris-deep); }
.index-no { font-family: var(--mono); font-size: 0.85rem; color: var(--ink-soft); font-variant-numeric: tabular-nums; padding-top: 0.3rem; }
a.index-row:hover .index-no { color: var(--copper); }
.index-title { font-size: 1.18rem; font-weight: 600; line-height: 1.3; }
.index-sub { grid-column: 2; color: var(--ink-soft); font-size: 0.95rem; line-height: 1.5; }
.index-tag { font-family: var(--mono); font-size: 0.76rem; letter-spacing: 0.05em; color: var(--verdigris); }
@media (max-width: 560px) {
  .index-row { grid-template-columns: 3.1rem minmax(0, 1fr); }
}

/* ---------- figures & plates ---------- */
figure { margin: 1.9rem 0; }
figcaption { font-family: var(--mono); font-size: 0.78rem; color: var(--ink-soft); margin-top: 0.55rem; line-height: 1.5; }
figcaption .fig-no { color: var(--verdigris); letter-spacing: 0.06em; text-transform: uppercase; }
.figure-pair { display: grid; gap: 1.2rem; grid-template-columns: 1fr 1fr; }
@media (max-width: 700px) { .figure-pair { grid-template-columns: 1fr; } }

.plate {
  background: var(--paper-deep);
  border: 1px solid var(--gold-hairline);
  padding: clamp(0.7rem, 2vw, 1.1rem);
  margin: 2.2rem 0;
}
.plate-label {
  font-family: var(--mono); font-size: 0.8rem; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--verdigris-deep); margin-bottom: 0.7rem;
}
.plate figcaption .fig-no { color: var(--verdigris-deep); }

/* ---------- matter-model module ---------- */
.mm-frame { position: relative; aspect-ratio: 1.85 / 1; overflow: hidden; border-radius: 2px; background: var(--ink); }
.mm-frame img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; margin: 0; }
.mm-frame .mm-model { opacity: 0; transition: opacity 180ms linear; }
.mm-static .mm-frame { position: static; aspect-ratio: auto; background: none; overflow: visible; }
.mm-static .mm-frame img { position: static; height: auto; }
.mm-static .mm-frame .mm-model { opacity: 1; margin-top: 1.2rem; }
.mm-controls { display: flex; align-items: center; gap: 0.8rem; margin-top: 0.9rem; flex-wrap: wrap; }
.mm-btn {
  font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.05em;
  background: none; border: 1px solid var(--ink-soft); color: var(--ink);
  padding: 0.6rem 0.85rem; cursor: pointer; border-radius: 2px; min-height: 44px;
}
.mm-btn:hover { border-color: var(--copper); color: var(--copper); }
.mm-btn[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.mm-range { flex: 1 1 160px; min-height: 44px; cursor: pointer; -webkit-appearance: none; appearance: none; background: transparent; }
.mm-range::-webkit-slider-runnable-track { height: 2px; background: var(--ink-soft); }
.mm-range::-webkit-slider-thumb { -webkit-appearance: none; appearance: none; width: 18px; height: 18px; background: var(--copper); border: 2px solid var(--paper-deep); border-radius: 2px; margin-top: -8px; }
.mm-range::-moz-range-track { height: 2px; background: var(--ink-soft); }
.mm-range::-moz-range-thumb { width: 18px; height: 18px; background: var(--copper); border: 2px solid var(--paper-deep); border-radius: 2px; }
.mm-captions { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-top: 0.6rem; }
.mm-captions .cap { font-family: var(--mono); font-size: 0.76rem; line-height: 1.5; }
.cap-matter { color: var(--copper); }
.cap-model { color: var(--verdigris-deep); text-align: right; }
@media (max-width: 560px) { .mm-captions { grid-template-columns: 1fr; } .cap-model { text-align: left; } }

/* ---------- timeline ---------- */
.timeline { list-style: none; margin: 1.4rem 0 0; padding: 0; }
.timeline li {
  display: grid; grid-template-columns: 11.5rem minmax(0, 1fr); gap: 0.2rem 1.3rem;
  padding: 0.7rem 0.2rem; border-top: 1px solid var(--line);
}
.timeline li:last-child { border-bottom: 1px solid var(--line); }
.tl-when { font-family: var(--mono); font-size: 0.8rem; color: var(--ink-soft); font-variant-numeric: tabular-nums; padding-top: 0.22rem; }
.tl-what { font-size: 0.99rem; }
@media (max-width: 640px) { .timeline li { grid-template-columns: 1fr; padding: 0.8rem 0.2rem; } }

/* ---------- honours list ---------- */
.honours { list-style: none; margin: 1.4rem 0 0; padding: 0; max-width: var(--measure); }
.honours li { border-top: 1px solid var(--line); padding: 1rem 0.2rem; display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 0.2rem 1.5rem; }
.honours li:last-child { border-bottom: 1px solid var(--line); }
.honour-name { font-size: 1.05rem; font-weight: 600; }
.honour-medal { font-family: var(--mono); font-size: 0.8rem; color: var(--copper); }
.honour-year { font-family: var(--mono); font-size: 0.85rem; color: var(--ink-soft); font-variant-numeric: tabular-nums; text-align: right; }
@media (max-width: 480px) { .honours li { grid-template-columns: 1fr; } .honour-year { text-align: left; } }

/* ---------- book plate ---------- */
.book-plate { display: grid; grid-template-columns: minmax(150px, 220px) minmax(0, 1fr); gap: 2rem; align-items: start; margin-top: 1.8rem; }
.book-plate img { border: 1px solid var(--line); }
.epigraph {
  font-style: italic; font-size: 1.12rem; line-height: 1.6; color: var(--ink-soft);
  border-left: 2px solid var(--gold-hairline); padding-left: 1.1rem; margin: 1rem 0 0.8rem;
}
.book-author { font-family: var(--mono); font-size: 0.85rem; letter-spacing: 0.07em; text-transform: uppercase; color: var(--ink-soft); }
@media (max-width: 620px) { .book-plate { grid-template-columns: 1fr; } .book-plate img { max-width: 220px; } }

/* ---------- contact block ---------- */
.contact-list { list-style: none; padding: 0; margin: 1.6rem 0; }
.contact-list li { display: grid; grid-template-columns: 7.5rem minmax(0,1fr); gap: 1rem; padding: 0.75rem 0.2rem; border-top: 1px solid var(--line); }
.contact-list li:last-child { border-bottom: 1px solid var(--line); }
.contact-list .k { font-family: var(--mono); font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--ink-soft); padding-top: 0.2rem; }
@media (max-width: 480px) { .contact-list li { grid-template-columns: 1fr; gap: 0.1rem; } }

/* ---------- prev / next dossier nav ---------- */
.dossier-nav { display: flex; justify-content: space-between; gap: 1rem; margin-top: 3rem; border-top: 3px double var(--ink); padding-top: 1.2rem; flex-wrap: wrap; }
.dossier-nav a { font-family: var(--sans); font-size: 0.88rem; text-decoration: none; }
.dossier-nav a:hover { text-decoration: underline; }
.dossier-nav .dn-label { display: block; font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-soft); margin-bottom: 0.2rem; }

/* ---------- home specifics ---------- */
.opening { margin-top: 0.4rem; }
.recognition-strip { border-top: 3px double var(--ink); margin-top: 3rem; padding-top: 1.2rem; }
.recognition-strip ul { list-style: none; margin: 0.8rem 0 0.4rem; padding: 0; max-width: var(--measure); }
.recognition-strip li { padding: 0.32rem 0; font-size: 0.98rem; display: grid; grid-template-columns: 8.5rem minmax(0, 1fr); gap: 0.9rem; align-items: baseline; }
.recognition-strip .medal { font-family: var(--mono); font-size: 0.78rem; color: var(--copper); }
@media (max-width: 480px) { .recognition-strip li { grid-template-columns: 1fr; gap: 0.05rem; } }
.home-book { border-top: 3px double var(--ink); margin-top: 2.6rem; padding-top: 1.2rem; }

/* ---------- footer ---------- */
.site-foot { border-top: 3px double var(--ink); margin-top: 4.5rem; background: var(--paper-deep); }
.site-foot .shell { padding-top: 1.6rem; padding-bottom: 2.2rem; }
.site-foot p { margin: 0.25rem 0; font-size: 0.9rem; color: var(--ink-soft); max-width: none; }
.site-foot .foot-brand { display: flex; align-items: center; gap: 0.6rem; margin-bottom: 0.7rem; }
.site-foot .foot-brand img { width: 28px; height: 28px; }
.site-foot .foot-note { font-family: var(--mono); font-size: 0.75rem; letter-spacing: 0.04em; }
.site-foot a { color: var(--copper); }

/* ---------- 404 ---------- */
.notfound { text-align: left; padding: 4rem 0 2rem; }
.notfound img { width: 56px; height: 56px; margin-bottom: 1.4rem; }

/* ---------- sppe schematic ---------- */
.schematic { margin: 2rem 0; }
.schematic svg { width: 100%; height: auto; display: block; }

/* ---------- utilities ---------- */
.visually-hidden {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap; border: 0;
}

/* ---------- linked section titles (ventures) ---------- */
h2 .title-link { color: inherit; text-decoration: none; }
h2 .title-link:hover, h2 .title-link:focus-visible { color: var(--copper); text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 4px; }
.ext-mark { color: var(--copper); font-size: 0.72em; }
h2 .title-link:hover .ext-mark { color: var(--copper-dark); }

/* ---------- desktop engineering journey (index only; decorative, ≥1200px) ---------- */
.journey { display: none; }
@media (min-width: 1200px) {
  main { position: relative; }
  .journey {
    position: absolute; top: 0; bottom: 0;
    left: calc(50% + 150px);
    width: min(560px, calc(50% - 174px));
    display: flex; flex-direction: column;
    z-index: -1; pointer-events: none;
  }
  .journey svg { width: 100%; display: block; }
  .journey .jstage { flex: 0 1 auto; min-height: 0; height: auto; }
  .journey .jlink { flex: 1 1 0; min-height: 36px; }
  /* margin notes keep their paper ground where the pencil line passes beneath */
  aside.margin { background: var(--paper); box-shadow: 0 0 0 8px var(--paper); }
}
.js-anim .jseg { opacity: 0; transform: translateY(12px); transition: opacity 0.8s ease, transform 0.8s ease; }
.js-anim .jseg.jf-in { opacity: 1; transform: none; }

/* ---------- motion policy: documents render instantly; motion = hover + plate only ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
  .js-anim .jseg { opacity: 1; transform: none; }
}

/* ---------- print ---------- */
@media print {
  .site-head, .site-foot, .dossier-nav, .skip-link, .mm-controls, .journey { display: none; }
  body { background: #fff; color: #000; }
  .apparatus { padding-right: 0; }
  a { color: #000; text-decoration: none; }
}