/* VR GROUP — бумага, чернила, сургуч. Никаких градиентов и стекла. */

:root {
  --paper: #f1ece2;
  --paper-2: #e7e0d1;
  --paper-3: #dcd3c1;
  --ink: #17150f;
  --ink-2: #4a453b;
  --ink-3: #7a7365;
  --rule: rgba(23, 21, 15, 0.16);
  --rule-strong: rgba(23, 21, 15, 0.42);
  --seal: #a3341d;
  --seal-ink: #7d2614;
  --bottle: #0f2a20;
  --bottle-2: #173a2d;
  --bottle-rule: rgba(241, 236, 226, 0.16);
  --brass: #b8955a;

  --serif: "Spectral", "Georgia", serif;
  --sans: "Golos Text", "Helvetica Neue", Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;

  --gutter: clamp(16px, 4vw, 56px);
  --max: 1440px;
  --ease: cubic-bezier(0.2, 0.7, 0.1, 1);
}

*,
*::before,
*::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 17px/1.6 var(--sans);
  font-feature-settings: "kern", "liga";
  overflow-x: clip;
}

/* лёгкое зерно бумаги */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 100;
  opacity: 0.35;
  mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0.1  0 0 0 0 0.09  0 0 0 0 0.06  0 0 0 .09 0'/></filter><rect width='100%' height='100%' filter='url(%23n)'/></svg>");
}

img, video, svg { display: block; max-width: 100%; }
img, video { height: auto; }
a { color: inherit; }
::selection { background: var(--seal); color: var(--paper); }

.wrap { width: 100%; max-width: var(--max); margin: 0 auto; padding: 0 var(--gutter); }

.label {
  font: 500 11.5px/1.4 var(--mono);
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.serif { font-family: var(--serif); }
em, .it { font-family: var(--serif); font-style: italic; font-weight: 400; }

/* ───────── шапка ───────── */
.top {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--paper) 94%, transparent);
  border-bottom: 1px solid var(--rule);
  backdrop-filter: saturate(1.2);
}
.top__in {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 32px;
  height: 64px;
}
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.brand__mark { width: 40px; height: 32px; color: var(--ink); }
.brand__word { font: 500 19px/1 var(--serif); letter-spacing: 0.16em; white-space: nowrap; }
.brand__word span { color: var(--seal); }

.nav { display: flex; justify-content: center; gap: 28px; }
.nav a {
  font: 500 12px/1 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--ink-2);
  padding: 6px 0;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s, color 0.2s;
}
.nav a:hover { color: var(--ink); border-color: var(--ink); }

.collab { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.collab__txt { font: 400 12px/1.25 var(--serif); font-style: italic; color: var(--ink-2); text-align: right; }
.collab img { height: 26px; width: auto; }

.menu-btn { display: none; }

/* ───────── hero ───────── */
.hero { padding: clamp(40px, 7vw, 96px) 0 0; }
.hero__grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: 24px;
  align-items: end;
}
.hero__meta {
  grid-column: 1 / -1;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  border-top: 1px solid var(--ink);
  padding-top: 10px;
  margin-bottom: clamp(28px, 4vw, 52px);
}
.hero h1 {
  grid-column: 1 / 10;
  margin: 0;
  font: 300 clamp(50px, 8.6vw, 142px)/0.93 var(--serif);
  letter-spacing: -0.025em;
}
.hero h1 em { color: var(--seal); font-weight: 300; }
.hero__note {
  grid-column: 10 / -1;
  align-self: end;
  font-size: 15px;
  line-height: 1.55;
  color: var(--ink-2);
  border-left: 1px solid var(--rule-strong);
  padding-left: 16px;
  margin-bottom: 10px;
}
.hero__note b { color: var(--ink); font-weight: 500; }

.hero__plate {
  grid-column: 1 / -1;
  margin-top: clamp(32px, 5vw, 64px);
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 24px;
  align-items: end;
}
.plate { position: relative; margin: 0; }
.plate__frame {
  position: relative;
  background: var(--ink);
  padding: 10px;
  box-shadow: 0 1px 0 var(--rule-strong);
}
.plate__frame video, .plate__frame img { width: 100%; aspect-ratio: 16 / 9; object-fit: cover; }
.caption {
  display: flex;
  gap: 14px;
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.45;
  color: var(--ink-2);
}
.caption b { font: 500 11.5px/1.45 var(--mono); letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink); white-space: nowrap; }

.ledger { border-top: 1px solid var(--ink); }
.ledger__row {
  display: grid;
  grid-template-columns: 92px 1fr;
  gap: 12px;
  align-items: baseline;
  padding: 14px 0;
  border-bottom: 1px solid var(--rule);
}
.ledger__num { font: 300 46px/1 var(--serif); letter-spacing: -0.02em; }
.ledger__num small { font-size: 0.5em; }
.ledger__txt { font-size: 13px; line-height: 1.4; color: var(--ink-2); }

/* ───────── общие секции ───────── */
.section { padding: clamp(80px, 11vw, 160px) 0 0; }
.sec-head {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: 24px;
  border-top: 1px solid var(--ink);
  padding-top: 14px;
  margin-bottom: clamp(36px, 5vw, 72px);
}
.sec-head__no { grid-column: 1 / 3; }
.sec-head h2 {
  grid-column: 3 / 10;
  margin: 0;
  font: 300 clamp(38px, 5.4vw, 84px)/0.98 var(--serif);
  letter-spacing: -0.02em;
}
.sec-head h2 em { color: var(--seal); font-weight: 300; }
.sec-head__aside { grid-column: 10 / -1; font-size: 15px; color: var(--ink-2); align-self: end; }

/* ───────── оглавление направлений ───────── */
.toc { display: grid; grid-template-columns: 1fr 1fr; column-gap: 56px; }
.toc__item {
  display: grid;
  grid-template-columns: 48px 1fr auto;
  gap: 4px 12px;
  padding: 18px 0 20px;
  border-bottom: 1px solid var(--rule);
  text-decoration: none;
  transition: background 0.25s var(--ease);
}
a.toc__item:hover .toc__title { color: var(--seal); }
.toc__roman { font: italic 400 20px/1.3 var(--serif); color: var(--ink-3); }
.toc__title { font: 400 24px/1.25 var(--serif); transition: color 0.2s; }
.toc__ref { font: 500 11px/2.2 var(--mono); letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-3); white-space: nowrap; }
.toc__desc { grid-column: 2 / -1; font-size: 15px; color: var(--ink-2); line-height: 1.5; }

/* ───────── кейсы ───────── */
.case {
  padding: clamp(56px, 7vw, 104px) 0;
  border-top: 1px solid var(--rule-strong);
}
.case:first-of-type { border-top: 0; padding-top: 0; }
.case__head {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: 24px;
  margin-bottom: clamp(28px, 3.5vw, 48px);
}
.case__no {
  grid-column: 1 / 3;
  font: italic 300 clamp(56px, 6vw, 96px)/0.85 var(--serif);
  color: var(--seal);
}
.case__title { grid-column: 3 / 9; }
.case__title h3 {
  margin: 8px 0 10px;
  font: 400 clamp(32px, 3.6vw, 56px)/1.02 var(--serif);
  letter-spacing: -0.015em;
}
.case__lead { margin: 0; font-size: 18px; line-height: 1.55; color: var(--ink-2); max-width: 40em; }
.case__status { grid-column: 9 / -1; justify-self: end; text-align: right; }

.stamp {
  display: inline-block;
  font: 600 11px/1 var(--mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 7px 10px 6px;
  border: 1.5px solid currentColor;
  color: var(--seal);
  transform: rotate(-2.2deg);
}
.stamp--ink { color: var(--ink-2); transform: rotate(1.4deg); }
.stamp--green { color: var(--bottle-2); }

.case__body {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: 24px;
  row-gap: 24px;
}
.fig { margin: 0; }
.fig img, .fig video { width: 100%; background: var(--paper-3); }
.fig--frame { background: var(--ink); padding: 8px; }
.fig--frame + .caption, .fig .caption { margin-top: 10px; }

.specs { border-top: 1px solid var(--ink); align-self: start; }
.specs dl { margin: 0; }
.specs__row {
  display: grid;
  grid-template-columns: 112px 1fr;
  gap: 12px;
  padding: 11px 0;
  border-bottom: 1px solid var(--rule);
  font-size: 14.5px;
  line-height: 1.45;
}
.specs dt { font: 500 11px/1.6 var(--mono); letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-3); }
.specs dd { margin: 0; }
.specs p { font-size: 15.5px; color: var(--ink-2); margin: 16px 0 0; }

.span-7 { grid-column: span 7; }
.span-5 { grid-column: span 5; }
.span-8 { grid-column: span 8; }
.span-4 { grid-column: span 4; }
.span-6 { grid-column: span 6; }
.span-3 { grid-column: span 3; }
.span-12 { grid-column: 1 / -1; }

.strip { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.strip .fig img { aspect-ratio: 4 / 3; object-fit: cover; }
.strip .caption { font-size: 12.5px; margin-top: 6px; }

/* аннотация «от руки» поверх карты */
.annot { position: relative; }
.annot svg.annot__ink {
  position: absolute;
  inset: 8px;
  width: calc(100% - 16px);
  height: calc(100% - 16px);
  pointer-events: none;
  overflow: visible;
}
.annot__ink path { fill: none; stroke: var(--seal); stroke-width: 2.2; stroke-linecap: round; stroke-linejoin: round; vector-effect: non-scaling-stroke; }
.annot__ink text { font: italic 500 22px var(--serif); fill: var(--paper); paint-order: stroke; stroke: var(--seal); stroke-width: 8px; stroke-linejoin: round; }

/* игры — таблица 12 */
.games { display: grid; grid-template-columns: repeat(6, 1fr); gap: 1px; background: var(--rule); border: 1px solid var(--rule); }
.game { background: var(--paper); margin: 0; padding: 10px 10px 14px; }
.game img { aspect-ratio: 4 / 3; object-fit: cover; width: 100%; }
.game figcaption { display: flex; gap: 8px; margin-top: 9px; font: 400 15px/1.25 var(--serif); }
.game figcaption span { font: 500 10.5px/1.7 var(--mono); color: var(--ink-3); }
.game figcaption small { display: block; font: 400 12px/1.35 var(--sans); color: var(--ink-3); margin-top: 3px; }

.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; counter-reset: s; }
.step { border-top: 1px solid var(--ink); padding-top: 12px; }
.step b { display: block; font: 400 22px/1.25 var(--serif); margin: 6px 0 6px; }
.step p { margin: 0; font-size: 15px; color: var(--ink-2); }

.concepts { display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid var(--ink); }
.concept { padding: 18px 18px 22px 0; border-bottom: 1px solid var(--rule); }
.concept:not(:nth-child(3n+1)) { padding-left: 18px; border-left: 1px solid var(--rule); }
.concept h4 { margin: 6px 0 6px; font: 400 24px/1.15 var(--serif); }
.concept p { margin: 0; font-size: 14.5px; color: var(--ink-2); }

/* схема станции */
.schema { background: var(--paper-2); border: 1px solid var(--rule-strong); padding: 18px; }
.schema svg { width: 100%; height: auto; }
.schema .s-line { fill: none; stroke: var(--ink); stroke-width: 1.4; }
.schema .s-thin { fill: none; stroke: var(--ink-2); stroke-width: 0.8; stroke-dasharray: 3 3; }
.schema .s-seal { fill: none; stroke: var(--seal); stroke-width: 2; }
.schema text { font: 500 10px var(--mono); fill: var(--ink-2); letter-spacing: 0.04em; }
.schema .s-big { font: italic 400 15px var(--serif); fill: var(--ink); letter-spacing: 0; }

/* софт */
.soft { display: grid; grid-template-columns: 5fr 7fr; gap: 24px 56px; align-items: start; }
.soft__list { border-top: 1px solid var(--ink); }
.soft__item { display: grid; grid-template-columns: 1fr auto; gap: 2px 16px; padding: 16px 0; border-bottom: 1px solid var(--rule); }
.soft__item h4 { margin: 0; font: 400 23px/1.2 var(--serif); }
.soft__item p { grid-column: 1 / -1; margin: 0; font-size: 14.5px; color: var(--ink-2); }

/* ───────── готовые решения ───────── */
.chapter {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: 24px;
  margin-top: clamp(48px, 6vw, 88px);
}
.chapter:first-of-type { margin-top: 0; }
.chapter__aside { grid-column: 1 / 4; position: sticky; top: 92px; align-self: start; }
.chapter__aside h3 { margin: 6px 0 10px; font: 300 clamp(30px, 3vw, 44px)/1.02 var(--serif); letter-spacing: -0.01em; }
.chapter__aside p { margin: 0; font-size: 14.5px; color: var(--ink-2); max-width: 22em; }
.chapter__list { grid-column: 4 / -1; border-top: 1px solid var(--ink); }

.sol { border-bottom: 1px solid var(--rule); }
.sol summary {
  list-style: none;
  cursor: pointer;
  display: grid;
  grid-template-columns: 64px 1fr auto;
  gap: 24px;
  align-items: baseline;
  padding: 20px 0;
}
.sol summary::-webkit-details-marker { display: none; }
.sol__no { font: 500 11.5px/1 var(--mono); color: var(--ink-3); letter-spacing: 0.06em; }
.sol__name { font: 400 clamp(22px, 2.2vw, 30px)/1.15 var(--serif); transition: color 0.2s; }
.sol__name small { display: block; margin-top: 6px; font: 400 15px/1.45 var(--sans); color: var(--ink-2); }
.sol summary:hover .sol__name { color: var(--seal); }
.sol__toggle {
  width: 30px; height: 30px; border: 1px solid var(--rule-strong); border-radius: 50%;
  position: relative; flex: none; align-self: center;
  transition: transform 0.35s var(--ease), background 0.2s;
}
.sol__toggle::before, .sol__toggle::after {
  content: ""; position: absolute; left: 50%; top: 50%; width: 11px; height: 1.5px; background: var(--ink);
  transform: translate(-50%, -50%);
}
.sol__toggle::after { transform: translate(-50%, -50%) rotate(90deg); transition: opacity 0.2s; }
.sol[open] .sol__toggle { transform: rotate(180deg); background: var(--ink); }
.sol[open] .sol__toggle::before { background: var(--paper); }
.sol[open] .sol__toggle::after { opacity: 0; }

.sol__body {
  display: grid;
  grid-template-columns: 64px 1fr 1fr 1fr;
  gap: 16px 24px;
  padding: 0 0 28px;
}
.sol__body > div { font-size: 14.5px; line-height: 1.55; color: var(--ink-2); }
.sol__body > div:first-child { grid-column: 2; }
.sol__body h5 { margin: 0 0 6px; font: 500 11px/1.4 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink); }
.sol__body p { margin: 0; }
.sol__body .base { color: var(--bottle-2); }
.sol__body .base a { text-decoration-color: var(--rule-strong); text-underline-offset: 3px; }

/* ───────── как делаем ───────── */
.method { display: grid; grid-template-columns: repeat(5, 1fr); border-top: 1px solid var(--ink); }
.method__step { padding: 16px 20px 24px 0; }
.method__step + .method__step { padding-left: 20px; border-left: 1px solid var(--rule); }
.method__step b { display: block; font: 400 26px/1.15 var(--serif); margin: 18px 0 8px; }
.method__step p { margin: 0; font-size: 14.5px; color: var(--ink-2); }
.method__step .label { color: var(--seal); }

.ai { margin-top: clamp(56px, 7vw, 96px); display: grid; grid-template-columns: repeat(12, 1fr); column-gap: 24px; }
.ai__quote { grid-column: 1 / 6; margin: 0; font: 300 clamp(30px, 3.2vw, 46px)/1.12 var(--serif); letter-spacing: -0.01em; }
.ai__quote em { color: var(--seal); }
.ai__cols { grid-column: 7 / -1; display: grid; grid-template-columns: 1fr 1fr; gap: 0 32px; }
.ai__cols h4 { margin: 0 0 6px; padding-bottom: 8px; border-bottom: 1px solid var(--ink); font: 500 11.5px/1.4 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; }
.ai__cols ul { list-style: none; margin: 0; padding: 0; }
.ai__cols li { padding: 9px 0; border-bottom: 1px solid var(--rule); font-size: 14.5px; color: var(--ink-2); }

/* ───────── партнёрство (тёмный) ───────── */
.dark { background: var(--bottle); color: var(--paper); margin-top: clamp(80px, 11vw, 160px); padding: clamp(72px, 9vw, 128px) 0; }
.dark .label { color: rgba(241, 236, 226, 0.6); }
.dark .sec-head { border-color: var(--paper); }
.dark .sec-head h2 em { color: var(--brass); }
.dark .sec-head__aside { color: rgba(241, 236, 226, 0.72); }
.duo { display: grid; grid-template-columns: 1fr 1fr; border-top: 1px solid var(--bottle-rule); }
.duo__col { padding: 28px 40px 8px 0; }
.duo__col + .duo__col { padding-left: 40px; border-left: 1px solid var(--bottle-rule); padding-right: 0; }
.duo__logo { height: 44px; display: flex; align-items: center; gap: 14px; margin-bottom: 24px; }
.duo__logo img { height: 40px; width: auto; }
.duo__logo .brand__mark { width: 52px; height: 42px; color: var(--paper); }
.duo__logo .brand__word { font-size: 26px; }
.duo__logo .brand__word span { color: var(--brass); }
.duo ul { list-style: none; margin: 0; padding: 0; }
.duo li { padding: 12px 0; border-bottom: 1px solid var(--bottle-rule); font-size: 15.5px; color: rgba(241, 236, 226, 0.82); display: grid; grid-template-columns: 28px 1fr; }
.duo li span { font: 500 11px/1.9 var(--mono); color: var(--brass); }
.duo__join {
  margin-top: 48px;
  font: 300 clamp(26px, 2.6vw, 38px)/1.2 var(--serif);
  max-width: 30em;
}
.duo__join em { color: var(--brass); }

/* ───────── контакт ───────── */
.contact { padding: clamp(80px, 11vw, 150px) 0 clamp(64px, 8vw, 110px); }
.contact__grid { display: grid; grid-template-columns: repeat(12, 1fr); column-gap: 24px; row-gap: 40px; }
.contact h2 {
  grid-column: 1 / 7;
  margin: 0;
  font: 300 clamp(44px, 6vw, 96px)/0.95 var(--serif);
  letter-spacing: -0.025em;
}
.contact h2 em { color: var(--seal); }
.contact__intro { grid-column: 1 / 6; font-size: 16px; color: var(--ink-2); margin: 20px 0 0; }
.form { grid-column: 7 / -1; grid-row: 1 / span 2; border-top: 1px solid var(--ink); }
.field { display: grid; grid-template-columns: 130px 1fr; gap: 12px; align-items: baseline; border-bottom: 1px solid var(--rule); padding: 6px 0; }
.field > label { font: 500 11px/1 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-3); padding-top: 14px; }
.field input, .field textarea {
  font: 400 19px/1.4 var(--serif);
  color: var(--ink);
  background: transparent;
  border: 0;
  padding: 10px 0;
  width: 100%;
  resize: vertical;
}
.field input:focus, .field textarea:focus { outline: none; }
.field:focus-within { border-color: var(--ink); }
.field:focus-within > label { color: var(--seal); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; padding: 12px 0; }
.chip { position: relative; }
.chip input { position: absolute; inset: 0; opacity: 0; pointer-events: none; }
.chip span {
  display: inline-block;
  font: 400 14px/1 var(--sans);
  padding: 9px 13px;
  border: 1px solid var(--rule-strong);
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
}
.chip input:checked + span { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.chip input:focus-visible + span { outline: 2px solid var(--seal); outline-offset: 2px; }
.form__foot { display: flex; justify-content: space-between; align-items: center; gap: 16px; padding-top: 20px; }
.form__foot small { font-size: 12.5px; color: var(--ink-3); max-width: 26em; line-height: 1.45; }
.btn {
  font: 500 13px/1 var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--paper);
  background: var(--seal);
  border: 0;
  padding: 18px 26px 17px;
  cursor: pointer;
  transition: background 0.2s, transform 0.15s;
  white-space: nowrap;
}
.btn:hover { background: var(--seal-ink); }
.btn:active { transform: translateY(1px); }
.form__ok { display: none; padding: 20px 0 0; font: italic 400 20px/1.4 var(--serif); color: var(--bottle-2); }
.form.is-sent .form__ok { display: block; }

/* ───────── подвал ───────── */
.foot { border-top: 1px solid var(--ink); padding: 24px 0 40px; }
.foot__in { display: grid; grid-template-columns: repeat(12, 1fr); column-gap: 24px; row-gap: 20px; align-items: start; }
.foot__brand { grid-column: 1 / 5; }
.foot__colophon { grid-column: 5 / 10; font-size: 13px; color: var(--ink-3); line-height: 1.55; }
.foot__links { grid-column: 10 / -1; justify-self: end; text-align: right; display: grid; gap: 6px; }
.foot__links a { font: 500 11.5px/1.4 var(--mono); letter-spacing: 0.08em; text-transform: uppercase; text-decoration: none; color: var(--ink-2); }
.foot__links a:hover { color: var(--seal); }

/* ───────── появление ───────── */
.rv { opacity: 0; transform: translateY(14px); transition: opacity 0.9s var(--ease), transform 0.9s var(--ease); }
.rv.is-in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .rv { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

:focus-visible { outline: 2px solid var(--seal); outline-offset: 3px; }

/* ───────── адаптив ───────── */
@media (max-width: 1180px) {
  .nav { gap: 18px; }
  .collab__txt { display: none; }
  .hero h1 { grid-column: 1 / -1; }
  .hero__note { grid-column: 1 / 8; margin-top: 28px; }
  .hero__plate { grid-template-columns: 1fr; }
  .ledger { display: grid; grid-template-columns: repeat(4, 1fr); column-gap: 24px; }
  .ledger__row { grid-template-columns: 1fr; }
  .games { grid-template-columns: repeat(4, 1fr); }
  .method { grid-template-columns: repeat(3, 1fr); }
  .method__step:nth-child(4) { padding-left: 0; border-left: 0; }
  .method__step:nth-child(n+4) { border-top: 1px solid var(--rule); }
}

@media (max-width: 900px) {
  .top__in { grid-template-columns: auto 1fr auto; gap: 12px; }
  .nav {
    position: absolute; top: 64px; left: 0; right: 0;
    flex-direction: column; gap: 0;
    background: var(--paper);
    border-bottom: 1px solid var(--ink);
    padding: 0 var(--gutter);
    max-height: 0; overflow: hidden;
    transition: max-height 0.35s var(--ease);
  }
  .nav a { padding: 16px 0; border-bottom: 1px solid var(--rule); font-size: 13px; }
  .top.is-open .nav { max-height: 360px; }
  .collab { justify-self: end; }
  .menu-btn {
    display: inline-flex; align-items: center; gap: 8px;
    font: 500 11.5px/1 var(--mono); letter-spacing: 0.08em; text-transform: uppercase;
    background: transparent; border: 1px solid var(--rule-strong); color: var(--ink);
    padding: 9px 11px; cursor: pointer;
  }
  .sec-head__no, .sec-head h2, .sec-head__aside { grid-column: 1 / -1; }
  .sec-head h2 { margin: 14px 0 0; }
  .sec-head__aside { margin-top: 16px; }
  .toc { grid-template-columns: 1fr; }
  .case__no { grid-column: 1 / -1; }
  .case__title { grid-column: 1 / -1; }
  .case__status { grid-column: 1 / -1; justify-self: start; text-align: left; margin-top: 16px; }
  .span-7, .span-5, .span-8, .span-4, .span-6 { grid-column: 1 / -1; }
  .span-3 { grid-column: span 6; }
  .strip { grid-template-columns: repeat(2, 1fr); }
  .games { grid-template-columns: repeat(3, 1fr); }
  .steps { grid-template-columns: 1fr; gap: 0; }
  .step { padding: 12px 0 18px; }
  .concepts { grid-template-columns: 1fr 1fr; }
  .concept, .concept:not(:nth-child(3n+1)) { padding: 16px 12px 18px 0; border-left: 0; }
  .concept:nth-child(2n) { padding-left: 14px; border-left: 1px solid var(--rule); }
  .soft { grid-template-columns: 1fr; }
  .chapter__aside { grid-column: 1 / -1; position: static; margin-bottom: 20px; }
  .chapter__list { grid-column: 1 / -1; }
  .sol__body { grid-template-columns: 1fr; padding-left: 0; }
  .sol__body > div:first-child { grid-column: auto; }
  .method { grid-template-columns: 1fr 1fr; }
  .method__step, .method__step + .method__step { padding: 16px 16px 22px 0; border-left: 0; border-top: 1px solid var(--rule); }
  .method__step:nth-child(2n) { padding-left: 16px; border-left: 1px solid var(--rule); }
  .ai__quote, .ai__cols { grid-column: 1 / -1; }
  .ai__cols { margin-top: 32px; }
  .duo { grid-template-columns: 1fr; }
  .duo__col, .duo__col + .duo__col { padding: 28px 0 8px; border-left: 0; }
  .duo__col + .duo__col { border-top: 1px solid var(--bottle-rule); margin-top: 24px; }
  .contact h2, .contact__intro, .form { grid-column: 1 / -1; grid-row: auto; }
  .foot__brand, .foot__colophon, .foot__links { grid-column: 1 / -1; justify-self: start; text-align: left; }
}

@media (max-width: 560px) {
  body { font-size: 16px; }
  .brand__word { font-size: 16px; letter-spacing: 0.12em; }
  .brand__mark { width: 34px; height: 28px; }
  .collab img { height: 20px; }
  .hero__meta .label:last-child { display: none; }
  .hero__note { grid-column: 1 / -1; }
  .ledger { grid-template-columns: 1fr 1fr; }
  .ledger__num { font-size: 38px; }
  .caption { flex-direction: column; gap: 2px; }
  .games { grid-template-columns: 1fr 1fr; }
  .concepts { grid-template-columns: 1fr; }
  .concept:nth-child(2n) { padding-left: 0; border-left: 0; }
  .span-3 { grid-column: 1 / -1; }
  .toc__item { grid-template-columns: 36px 1fr; }
  .toc__ref { grid-column: 2; line-height: 1.4; }
  .sol summary { grid-template-columns: 1fr auto; }
  .sol__no { grid-column: 1 / -1; }
  .method { grid-template-columns: 1fr; }
  .method__step:nth-child(2n) { padding-left: 0; border-left: 0; }
  .ai__cols { grid-template-columns: 1fr; gap: 28px; }
  .field { grid-template-columns: 1fr; gap: 0; }
  .field label { padding-top: 12px; }
  .form__foot { flex-direction: column; align-items: stretch; }
  .specs__row { grid-template-columns: 96px 1fr; }
}

.specs-4 { display: grid; grid-template-columns: repeat(4, 1fr); column-gap: 24px; }
.specs-4 .specs__row { grid-template-columns: 1fr; gap: 4px; }
@media (max-width: 900px) { .specs-4 { grid-template-columns: 1fr 1fr; } }
@media (max-width: 560px) { .specs-4 { grid-template-columns: 1fr; } .specs-4 .specs__row { grid-template-columns: 96px 1fr; } }
@media (max-width: 560px) { .soft__item { grid-template-columns: 1fr; } .soft__item .label { order: -1; } }