:root {
  --paper: #faf9f5;
  --ink: #252d25;
  --muted: #566052;
  --accent: #b94223;
  --line: #dce0d5;
  --panel: #edf0e7;
  --white: #fffefa;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 32px; }
body { margin: 0; background: var(--paper); color: var(--ink); font-family: Arial, sans-serif; font-size: 20px; line-height: 1.65; }
a { color: inherit; text-underline-offset: 5px; }
button, input { font: inherit; }
a, button, summary, input { touch-action: manipulation; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 5px; }
.wrap { width: min(1080px, calc(100% - 80px)); margin-inline: auto; }
.skip { position: absolute; top: -100px; padding: 12px; background: var(--ink); color: white; z-index: 10; }
.skip:focus { top: 0; }
.site-header { display: flex; justify-content: space-between; align-items: center; padding-block: 30px; border-bottom: 1px solid var(--line); }
.wordmark { display: inline-flex; align-items: center; gap: 10px; font-size: 38px; font-weight: 700; letter-spacing: -2px; text-decoration: none; line-height: 1; }
.wordmark span { color: var(--accent); margin-left: -10px; }
.site-header nav { display: flex; gap: 30px; font-size: 18px; }
.site-header nav a { text-decoration: none; }
.site-header nav a:hover, .secondary-link:hover { color: var(--accent); }
.hero { padding-block: 65px; }
.brand-name { color: var(--muted); margin: 0 0 25px; font-size: 23px; }
h1 { font-size: clamp(43px, 5.5vw, 72px); line-height: 1.12; letter-spacing: -2px; font-weight: 600; margin: 0 0 36px; }
h1 span { color: var(--accent); }
h2 { font-size: 36px; line-height: 1.25; letter-spacing: -.8px; font-weight: 600; margin: 0 0 24px; }
p { margin: 0 0 24px; }
.intro { max-width: 920px; color: var(--muted); }
.lead { max-width: 920px; margin-block: 28px; font-size: 23px; line-height: 1.55; }
.lead strong { font-weight: 500; }
.hero-actions { display: flex; gap: 30px; align-items: center; flex-wrap: wrap; margin-top: 35px; }
.button { display: inline-flex; align-items: center; justify-content: space-between; gap: 24px; padding: 14px 22px; border-radius: 6px; text-decoration: none; background: var(--ink); color: white; font-size: 18px; }
.button:hover { background: #414e3a; }
.secondary-link { font-size: 18px; }
.meaning, .capabilities, .explore, .promise { border-top: 1px solid var(--line); padding-block: 50px; }
.meaning-list { margin: 0 0 32px; }
.meaning-list>div { display: grid; grid-template-columns: 170px 1fr; gap: 30px; margin-bottom: 20px; }
dt { font-weight: 600; }
dd { margin: 0; color: var(--muted); }
.capability-list { margin: 30px 0; }
.capability-list>div { display: grid; grid-template-columns: 310px 1fr; gap: 30px; border-top: 1px solid var(--line); padding-block: 24px; }
.capability-list dt, .capability-list dd { font-size: 19px; }
.note { font-size: 16px; color: var(--muted); line-height: 1.65; }
.sandbox { margin: 30px 0 20px; border: 1px solid #cdd5c4; border-radius: 8px; background: var(--panel); overflow: hidden; }
.controls { padding: 26px 32px; border-bottom: 1px solid #cdd5c4; }
.control-top { display: flex; justify-content: space-between; align-items: center; gap: 20px; }
.controls label { font-size: 20px; font-weight: 600; }
.controls output { font-size: 32px; color: var(--accent); font-weight: 600; }
input[type=range] { width: 100%; accent-color: var(--accent); cursor: pointer; margin: 20px 0 0; min-height: 28px; }
.range-labels { display: flex; justify-content: space-between; font-size: 16px; color: var(--muted); }
.presets { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 20px; }
.presets button { font-size: 16px; min-height: 44px; padding: 8px 16px; border: 1px solid #a9b69d; border-radius: 5px; cursor: pointer; background: transparent; color: var(--ink); }
.presets button[aria-pressed=true] { color: white; background: var(--ink); border-color: var(--ink); }
.network { position: relative; height: 360px; }
.connections { position: absolute; top: 15px; left: 0; width: 100%; height: 330px; }
.connections path:not(defs path) { fill: none; stroke: #a5b09b; stroke-width: 2; marker-end: url(#arrow); }
.node { position: absolute; width: 170px; min-height: 130px; padding: 16px 9px; background: var(--white); border: 1px solid #cdd5c4; border-radius: 6px; text-align: center; display: flex; flex-direction: column; justify-content: center; }
.node .node-label { color: var(--ink); font-size: 16px; line-height: 1.3; }
.node strong { font-size: 31px; font-weight: 600; line-height: 1.4; margin-block: 4px; }
.node>span:last-child { color: var(--muted); font-size: 16px; line-height: 1.3; }
.oil { left: 2%; top: 115px; background: #f9e4d9; border-color: #e5b39b; }
.fuel { left: 27%; top: 115px; }
.fares { left: 52%; top: 26px; }
.demand { left: 52%; top: 202px; }
.profit { right: 2%; top: 115px; background: var(--ink); color: white; border-color: var(--ink); }
.profit .node-label, .profit>span:last-child { color: #e0e6d8; }
details { border-top: 1px solid var(--line); padding-top: 18px; }
summary { cursor: pointer; font-size: 18px; font-weight: 600; }
.assumptions { margin-top: 25px; font-size: 18px; color: var(--muted); }
.assumptions p:last-child { margin-bottom: 0; }
.promise { padding-bottom: 60px; }
.engine-statement { font-size: 25px; font-weight: 600; line-height: 1.5; margin-top: 34px; margin-bottom: 0; }
footer { border-top: 1px solid var(--line); display: flex; justify-content: space-between; gap: 20px; padding-block: 27px 35px; font-size: 16px; color: var(--muted); }
@media (max-width: 950px) {
  .node { width: 145px; }
  .node strong { font-size: 28px; }
  .node .node-label, .node>span:last-child { font-size: 16px; }
  .fuel { left: 25%; } .fares, .demand { left: 49%; }
  .capability-list>div { grid-template-columns: 250px 1fr; gap: 25px; }
}
@media (max-width: 760px) {
  .wrap { width: calc(100% - 40px); }
  body { font-size: 19px; }
  .site-header { padding-block: 23px; }
  .site-header nav { gap: 18px; font-size: 16px; }
  .wordmark { font-size: 33px; }
  .wordmark img { width: 32px; height: 32px; }
  .hero { padding-block: 43px; }
  .brand-name { font-size: 19px; }
  h1 { font-size: clamp(39px, 7vw, 54px); letter-spacing: -1.4px; }
  h2 { font-size: 29px; }
  .lead { font-size: 21px; }
  .meaning, .capabilities, .explore, .promise { padding-block: 38px; }
  .meaning-list>div { grid-template-columns: 130px 1fr; gap: 20px; }
  .capability-list>div { grid-template-columns: 1fr; gap: 9px; padding-block: 20px; }
  .network { display: grid; grid-template-columns: repeat(2, 1fr); height: auto; gap: 16px; padding: 24px; }
  .connections { display: none; }
  .node { position: static; width: auto; min-height: 135px; }
  .oil { grid-column: 1 / -1; }
  .controls { padding: 22px 24px; }
  footer { flex-direction: column; gap: 8px; }
}
@media (max-width: 430px) {
  .site-header nav { gap: 14px; font-size: 16px; }
  .wordmark { font-size: 30px; gap: 7px; }
  .wordmark img { width: 29px; height: 29px; }
  h1 { font-size: 38px; }
  .meaning-list>div { grid-template-columns: 1fr; gap: 4px; }
  .hero-actions { gap: 20px; }
  .network { padding: 16px; gap: 12px; }
  .node { min-height: 145px; padding-inline: 7px; }
  .node strong { font-size: 27px; }
  .controls { padding-inline: 16px; }
  .presets { gap: 8px; }
  .presets button { padding-inline: 11px; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }