:root {
  --paper: #f2f1ed;
  --ink: #121212;
  --card: #ffffff;
  --muted: #5a5954;
  --body-2: #3a3936;
  --footer-text: #cfcdc6;
  --footer-dim: #8a8983;
  --dark-2: #222222;
  --rule-dark: #2c2c2c;
  --hover-dark: #333333;
  --rule: #e2e0d9;
  --ttt: #9cc9e4;
  --c4: #ec9a85;
  --nim: #93d6b8;
  --quarto: #b9bde9;
  --disc-x: #df5340;
  --disc-o: #ecd37a;
  --sans: 'Schibsted Grotesk', system-ui, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, monospace;
}
@supports (color: oklch(0 0 0)) {
  :root {
    --c4: oklch(0.78 0.11 30);
    --nim: oklch(0.82 0.09 165);
    --quarto: oklch(0.8 0.08 280);
    --disc-x: oklch(0.62 0.19 30);
    --disc-o: oklch(0.88 0.14 92);
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 17px/1.5 var(--sans);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--ink); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
h1, h2, h3, p { margin: 0; }
code, pre { font-variant-ligatures: none; }
code { font: 500 0.85em var(--mono); background: var(--card); padding: 2px 6px; border-radius: 6px; }
button, select, input { font: inherit; color: inherit; }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap;
}

.wrap { max-width: 1240px; margin: 0 auto; padding: 0 28px; }
.kicker, .label, .footer-head, .fineprint {
  font: 500 12px/1 var(--mono);
}
.kicker { color: var(--muted); }
.kicker a { color: inherit; text-decoration: none; }
.kicker a:hover { text-decoration: underline; }

/* Per-game color */
.tile--tic-tac-toe { background: var(--ttt); }
.tile--connect-four { background: var(--c4); }
.tile--nim { background: var(--nim); }
.tile--quarto { background: var(--quarto); }
.tile-ink--tic-tac-toe { color: var(--ttt); }
.tile-ink--connect-four { color: var(--c4); }
.tile-ink--nim { color: var(--nim); }
.tile-ink--quarto { color: var(--quarto); }

/* Buttons */
.button, .controls button {
  display: inline-block;
  background: var(--ink);
  color: var(--paper);
  border: 0;
  padding: 16px 22px;
  border-radius: 999px;
  font: 600 15px/1 var(--sans);
  text-decoration: none;
  cursor: pointer;
  transition: background 120ms;
}
.button:hover, .controls button:hover { background: var(--hover-dark); color: var(--paper); }
.button.secondary, .controls button.secondary {
  background: transparent;
  color: var(--ink);
  border: 1.5px solid var(--ink);
  padding: 14.5px 20.5px;
}
.button.secondary:hover, .controls button.secondary:hover { background: var(--ink); color: var(--paper); }
.buttons { display: flex; gap: 10px; flex-wrap: wrap; }
.buttons.small { gap: 8px; }
.buttons.small .button { font-size: 14px; padding: 12px 16px; }
.buttons.small .button.secondary { padding: 10.5px 14.5px; }

/* Header */
.masthead { background: var(--ink); color: var(--paper); }
.masthead .wrap {
  height: 64px; display: flex; align-items: center; justify-content: space-between; gap: 20px;
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--paper); }
.brand:hover { color: var(--paper); }
.mark4 { display: grid; grid-template-columns: repeat(2, 9px); gap: 2px; flex: none; }
.mark4 span { width: 9px; height: 9px; }
.mark4 span:nth-child(1) { background: var(--ttt); }
.mark4 span:nth-child(2) { background: var(--c4); }
.mark4 span:nth-child(3) { background: var(--nim); }
.mark4 span:nth-child(4) { background: var(--quarto); }
.wordmark { font: 800 20px/1 var(--sans); letter-spacing: -0.03em; color: var(--paper); white-space: nowrap; }
.wordmark span { font-weight: 400; color: var(--footer-dim); }
.masthead nav { display: flex; gap: 6px; font: 500 12px/1 var(--mono); }
.masthead nav a { color: var(--paper); text-decoration: none; padding: 9px 12px; border-radius: 999px; }
.masthead nav a:hover { background: #2a2a2a; }

/* Footer */
.site-footer { margin-top: 96px; background: var(--ink); color: var(--footer-text); }
.footer-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 36px;
  padding-top: 56px; padding-bottom: 28px;
}
.footer-about { grid-column: span 2; max-width: 400px; }
.footer-about .wordmark { font-size: 22px; margin-bottom: 14px; }
.footer-about p:last-child { font-size: 16px; line-height: 1.55; }
.footer-col { display: flex; flex-direction: column; gap: 8px; font: 500 15px/1.3 var(--sans); }
.footer-col a { color: var(--paper); text-decoration: none; }
.footer-col a:hover { text-decoration: underline; }
.footer-head { color: var(--footer-dim); margin-bottom: 8px; }
.fineprint {
  border-top: 1px solid var(--rule-dark);
  padding-top: 20px; padding-bottom: 28px;
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap;
  line-height: 1.5; font-weight: 400; color: var(--footer-dim);
}

/* Home */
.hero { padding: 80px 0 56px; }
.hero .kicker { margin-bottom: 28px; }
.hero h1 {
  font: 800 clamp(56px, 9.5vw, 132px)/0.9 var(--sans); letter-spacing: -0.055em;
  margin-bottom: 40px; max-width: 1100px; text-wrap: balance;
}
.hero-row { display: flex; gap: 40px; align-items: flex-end; justify-content: space-between; flex-wrap: wrap; }
.hero-row > p:first-child { font-size: 20px; max-width: 560px; color: var(--body-2); text-wrap: pretty; }

.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 520px), 1fr)); gap: 12px; }
.tile {
  border-radius: 20px; padding: 28px; min-height: 320px;
  display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 20px;
}
.tile-text { display: flex; flex-direction: column; justify-content: space-between; gap: 24px; }
.tile .label { margin-bottom: 14px; }
.result { font: 800 clamp(48px, 6vw, 76px)/0.9 var(--sans); letter-spacing: -0.05em; }
.tile > [aria-hidden] { align-self: center; width: max-content; }

/* Mini boards */
.mini-ttt { display: grid; grid-template-columns: repeat(3, 40px); grid-template-rows: repeat(3, 40px); gap: 4px; }
.mini-ttt span {
  border: 1.5px solid var(--ink); border-radius: 8px;
  display: grid; place-items: center; font: 800 22px/1 var(--sans);
}
.mini-ttt .x { background: var(--ink); color: var(--ttt); }
.mini-ttt.lg { grid-template-columns: repeat(3, 60px); grid-template-rows: repeat(3, 60px); gap: 6px; }
.mini-ttt.lg span { border-width: 2px; border-radius: 12px; font-size: 32px; }

.mini-c4 {
  display: grid; grid-template-columns: repeat(7, 14px); gap: 4px;
  background: var(--ink); padding: 8px; border-radius: 10px;
}
.mini-c4 span { width: 14px; height: 14px; border-radius: 50%; background: var(--paper); }
.mini-c4 .d-X { background: var(--disc-x); }
.mini-c4 .d-O { background: var(--disc-o); }
.mini-c4.lg { grid-template-columns: repeat(7, 24px); gap: 5px; padding: 10px; border-radius: 14px; }
.mini-c4.lg span { width: 24px; height: 24px; }

.mini-nim { display: flex; flex-direction: column; gap: 7px; }
.mini-nim > span { display: flex; gap: 6px; }
.mini-nim i { width: 16px; height: 16px; border-radius: 50%; background: var(--ink); }
.mini-nim.lg { gap: 14px; }
.mini-nim.lg > span { gap: 10px; }
.mini-nim.lg i { width: 26px; height: 26px; }

.mini-quarto { display: grid; grid-template-columns: repeat(4, 22px); gap: 6px; }
.mini-quarto span { width: 22px; height: 22px; border: 2px solid var(--ink); border-radius: 5px; }
.mini-quarto .round { border-radius: 50%; }
.mini-quarto .dark { background: var(--ink); }
.mini-quarto .light { background: var(--paper); }

/* Index intro (strategy, play, 404) */
.intro {
  padding: 72px 0 48px;
  display: flex; justify-content: space-between; align-items: flex-end; gap: 32px; flex-wrap: wrap;
}
.intro h1 { font: 800 clamp(56px, 9vw, 120px)/0.9 var(--sans); letter-spacing: -0.055em; }
.intro p { font-size: 19px; max-width: 440px; color: var(--body-2); text-wrap: pretty; }

/* Strategy index */
.rows { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 12px; }
.row {
  display: grid; grid-template-columns: minmax(160px, 260px) minmax(0, 1fr);
  background: var(--card); border-radius: 20px; overflow: hidden;
  text-decoration: none; transition: box-shadow 120ms;
}
.row:hover { box-shadow: 0 0 0 2px var(--ink); }
.row-color { padding: 24px; display: flex; flex-direction: column; justify-content: space-between; gap: 24px; }
.row-color .result { font-size: 40px; line-height: 0.95; letter-spacing: -0.04em; }
.row-text { padding: 28px 32px; }
.row-text h2 { font: 700 clamp(24px, 2.8vw, 34px)/1.1 var(--sans); letter-spacing: -0.03em; margin-bottom: 10px; }
.row-text .teaser { font-size: 17px; color: var(--muted); max-width: 620px; }

/* Article */
.band .wrap { padding-top: 56px; padding-bottom: 64px; }
.band .kicker { color: var(--ink); margin-bottom: 32px; }
.band h1, .page-head h1 {
  font: 800 clamp(44px, 7vw, 96px)/0.92 var(--sans); letter-spacing: -0.05em;
  margin-bottom: 28px; max-width: 1000px; text-wrap: balance;
}
.standfirst { font: 500 clamp(19px, 2vw, 23px)/1.4 var(--sans); max-width: 680px; text-wrap: pretty; }
.article-grid {
  padding-top: 56px;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 240px), 1fr));
  gap: 56px; align-items: start;
}
.toc { position: sticky; top: 24px; }
.toc .label { color: var(--muted); margin-bottom: 14px; }
.toc ol {
  list-style: none; margin: 0; padding: 0;
  display: flex; flex-direction: column; gap: 2px; font: 500 15px/1.3 var(--sans);
}
.toc li { padding: 9px 12px; border-radius: 10px; color: var(--muted); }
.toc li:first-child { background: var(--card); color: var(--ink); }
.play-card {
  margin-top: 20px; display: flex; justify-content: space-between; align-items: center;
  border-radius: 14px; padding: 16px; font: 700 16px/1.2 var(--sans); text-decoration: none;
  transition: box-shadow 120ms;
}
.play-card:hover { box-shadow: 0 0 0 2px var(--ink); }
.article-grid .prose { grid-column: span 2; min-width: 0; }

.prose { max-width: 700px; font-size: 19px; line-height: 1.7; }
.prose p, .prose ul, .prose ol, .prose table, .prose blockquote, .prose pre { margin: 0 0 22px; }
.prose p, .prose li { text-wrap: pretty; }
.prose h2 { font: 800 30px/1.1 var(--sans); letter-spacing: -0.03em; margin: 44px 0 12px; }
.prose > h2:first-child { margin-top: 0; }
.prose h3 { font: 700 22px/1.25 var(--sans); letter-spacing: -0.02em; margin: 32px 0 10px; }
.prose li { margin-bottom: 6px; }
.prose table {
  display: block; overflow-x: auto; border-collapse: collapse; width: max-content; max-width: 100%;
  background: var(--card); border-radius: 14px; font-size: 16px; line-height: 1.4;
}
.prose th, .prose td { padding: 10px 14px; border: 1px solid var(--rule); text-align: left; }
.prose th { background: var(--paper); font-weight: 600; }
.prose blockquote { background: var(--card); border-radius: 14px; padding: 16px 20px; }
.prose blockquote p:last-child { margin-bottom: 0; }
.prose pre {
  background: var(--ink); color: var(--paper); border-radius: 14px; padding: 16px 18px;
  overflow-x: auto; font-size: 14px; line-height: 1.55;
}
.prose pre code { background: none; padding: 0; color: inherit; font-size: inherit; }

.fade > p:last-child { position: relative; margin-bottom: 0; }
.fade > p:last-child::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: 0; height: 100px;
  background: linear-gradient(rgba(242, 241, 237, 0), var(--paper));
}
.door, .challenge {
  margin-top: 36px; background: var(--ink); color: var(--paper); border-radius: 20px; padding: 28px;
}
.door-top {
  display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap;
  margin-bottom: 18px; font: 500 12px/1 var(--mono); color: var(--footer-dim);
}
.door h2, .challenge h2 {
  font: 800 30px/1.05 var(--sans); letter-spacing: -0.03em; margin: 0 0 12px; color: var(--paper);
}
.door > p:not(.door-top), .challenge > p:not(.door-top) {
  font-size: 17px; line-height: 1.55; margin: 0 0 22px; color: var(--footer-text);
}
.door-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 10px; }
.door-cards > div { background: var(--dark-2); border-radius: 14px; padding: 16px 18px; }
.door-head { font: 700 14px/1 var(--sans); margin-bottom: 8px !important; color: var(--paper); }
.door-cards p { font-size: 15px; line-height: 1.5; margin: 0; color: var(--footer-text); }
.door code, .challenge code { font: 400 13px var(--mono); color: var(--paper); background: none; padding: 0; }
.door a { color: var(--paper); }

/* Play index */
.play-cards {
  list-style: none; margin: 0; padding: 0;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 12px;
}
.play-tile {
  height: 100%; border-radius: 20px; padding: 28px;
  display: flex; flex-direction: column; gap: 28px; text-decoration: none; transition: box-shadow 120ms;
}
.play-tile:hover { box-shadow: 0 0 0 2px var(--ink); }
.play-board { height: 220px; display: grid; place-items: center; }
.play-tile h2 { font: 800 34px/1 var(--sans); letter-spacing: -0.04em; margin-bottom: 8px; }
.play-tile .note { font-size: 16px; line-height: 1.45; }
.api-line { font: 400 13px/1.6 var(--mono); color: var(--muted); margin-top: 28px; }
.api-line code { font: inherit; background: none; padding: 0; }

/* Game pages */
.game {
  padding-top: 40px;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 380px), 1fr)); gap: 12px;
}
.board-panel { border-radius: 20px; display: grid; place-items: center; }
.side-panel {
  background: var(--card); border-radius: 20px; padding: 36px;
  display: flex; flex-direction: column; gap: 28px;
}
.side-panel h1 { font: 800 clamp(48px, 6vw, 80px)/0.9 var(--sans); letter-spacing: -0.05em; }
.status { font: 600 22px/1.3 var(--sans); padding: 16px 18px; background: var(--paper); border-radius: 14px; }
.side-panel .note { font-size: 16px; line-height: 1.55; color: var(--muted); margin-top: auto; }
.controls { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.controls .label { color: var(--muted); margin-right: 4px; }

.ttt {
  padding: 48px 24px;
  display: grid; grid-template-columns: repeat(3, min(22vw, 108px)); grid-template-rows: repeat(3, min(22vw, 108px));
  gap: 10px;
}
.ttt button, .ttt .mark {
  border: 2px solid var(--ink); border-radius: 18px; background: transparent;
  display: grid; place-items: center; font: 800 min(14vw, 64px)/1 var(--sans);
}
.ttt button { cursor: pointer; padding: 0; transition: background 120ms; }
.ttt button:hover { background: rgba(18, 18, 18, 0.08); }
.ttt .mark-X { background: var(--ink); color: var(--ttt); }

.board-panel:has(.c4) { padding: 36px 16px; }
.c4 { width: 100%; display: flex; flex-direction: column; align-items: center; }
.c4-drops, .c4-board {
  width: min(100%, 464px); display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); gap: 8px;
}
.c4-drops { padding: 0 14px; margin-bottom: 8px; }
.c4-drops button {
  height: 34px; border: 0; border-radius: 999px; background: transparent; cursor: pointer;
  font: 500 12px/34px var(--mono); padding: 0; transition: background 120ms;
}
.c4-drops button:hover { background: var(--ink); color: var(--paper); }
.c4-drops button:disabled { visibility: hidden; }
.c4-board { background: var(--ink); padding: 14px; border-radius: 22px; }
.slot { width: 100%; aspect-ratio: 1; border-radius: 50%; background: var(--paper); }
.disc-X { background: var(--disc-x); }
.disc-O { background: var(--disc-o); }
.slot.last { outline: 2px solid var(--paper); outline-offset: 3px; }
.status .legend {
  display: flex; gap: 18px; flex-wrap: wrap; margin-top: 10px;
  font: 500 12px/1 var(--mono); color: var(--muted);
}
.legend span { display: flex; align-items: center; gap: 8px; }
.legend i { width: 12px; height: 12px; border-radius: 50%; }
.dot-x { background: var(--disc-x); }
.dot-o { background: var(--disc-o); box-shadow: inset 0 0 0 1px var(--ink); }

.board-panel:has(.nim) { padding: 32px; place-items: stretch; }
.nim { display: flex; flex-direction: column; justify-content: center; gap: 12px; }
.heap {
  display: flex; align-items: center; gap: 20px; padding: 16px 18px;
  background: rgba(255, 255, 255, 0.45); border-radius: 16px;
}
.heap-label { width: 44px; flex: none; font: 800 30px/1 var(--sans); }
.heap-label small { display: block; font: 500 11px/1.6 var(--mono); }
.counters { display: flex; gap: 10px; flex-wrap: wrap; }
.counters button {
  width: 42px; height: 42px; border-radius: 50%; border: 0; padding: 0;
  background: var(--ink); cursor: pointer; transition: background 120ms, transform 120ms;
}
.counters button:hover, .counters button:hover ~ button { background: var(--disc-x); transform: scale(1.08); }
.counters button:disabled { background: rgba(18, 18, 18, 0.25); cursor: default; transform: none; }
.hint { font: 500 12px/1.5 var(--mono); margin-top: 8px; }
.controls select {
  font: 600 15px var(--sans); padding: 13px 16px; border: 1.5px solid var(--ink);
  border-radius: 999px; background: var(--card); color: var(--ink);
}
.toggle {
  border: 1.5px solid var(--ink); border-radius: 999px; margin: 0; padding: 3px;
  display: inline-flex; align-items: center; gap: 2px;
}
.toggle legend { float: left; padding: 0 8px 0 10px; color: var(--muted); }
.toggle input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.toggle label {
  font: 600 15px/1 var(--sans); padding: 10px 14px; border-radius: 999px; cursor: pointer;
}
.toggle input:checked + label { background: var(--ink); color: var(--paper); }
.toggle input:focus-visible + label { outline: 2px solid var(--ink); outline-offset: 2px; }

/* About and agents */
.page-head { padding: 72px 0 48px; }
.page-head .kicker { margin-bottom: 28px; }
.page-head .standfirst { max-width: 700px; color: var(--body-2); }
.results {
  list-style: none; margin: 0 0 56px; padding: 0;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 240px), 1fr)); gap: 12px;
}
.results li { border-radius: 16px; padding: 20px; }
.results .label { display: block; margin-bottom: 12px; }
.results li > span:last-child { font: 700 20px/1.25 var(--sans); }

.challenge { margin: 0 0 56px; }
.facts {
  margin: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); gap: 10px;
}
.facts div { background: var(--dark-2); border-radius: 14px; padding: 16px 18px; min-width: 0; }
.facts dt { font: 500 12px/1 var(--mono); color: var(--footer-dim); margin-bottom: 10px; }
.facts dd { margin: 0; font: 600 17px/1.4 var(--sans); overflow-wrap: anywhere; }
.challenge details { margin-top: 18px; color: var(--footer-text); }
.challenge summary { cursor: pointer; font: 500 13px/1.4 var(--mono); }
.challenge pre {
  margin: 12px 0 0; background: var(--dark-2); border-radius: 14px; padding: 16px 18px;
  overflow-x: auto; font: 400 13px/1.55 var(--mono);
}
.agent-steps ol { padding-left: 1.2em; }

@media (max-width: 560px) {
  .wrap { padding-left: 16px; padding-right: 16px; }
  .masthead nav { gap: 0; }
  .masthead nav a { padding: 9px 8px; }
  .masthead nav .wide { display: none; }
  .masthead .wrap { gap: 8px; }
  .row { grid-template-columns: 1fr; }
  .tile { grid-template-columns: 1fr; }
  .footer-about { grid-column: auto; }
  .side-panel { padding: 28px 22px; }
}
@media (max-width: 420px) {
  .wordmark span { display: none; }
}