:root {
  --bg: #f6f5f1;
  --surface: #ffffff;
  --text: #1c232c;
  --muted: #5b6673;
  --line: #dcdcd5;
  --steel: #22384f;
  --steel-soft: #e6ecf2;
  --gold: #b88a2e;
  --code-bg: #121a24;
  --code-text: #d8dee6;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #10161e;
    --surface: #18212c;
    --text: #e4e8ed;
    --muted: #9aa6b3;
    --line: #2a3542;
    --steel: #9cc0e4;
    --steel-soft: #1d2a38;
    --gold: #d9ac52;
    --code-bg: #0a0f15;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.6 var(--sans);
}

a { color: var(--steel); text-underline-offset: 3px; }

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* Header */
.top {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 0; font-size: 15px;
}
.top .brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); font-weight: 600; }
.top .brand img { width: 28px; height: 28px; }
.top nav { display: flex; gap: 20px; }
.top nav a { color: var(--muted); text-decoration: none; }
.top nav a:hover { color: var(--text); }

/* Hero */
.hero {
  display: grid; grid-template-columns: 1fr auto; gap: 48px; align-items: center;
  padding: 56px 0 64px;
}
.hero h1 {
  font: 600 clamp(44px, 7vw, 72px)/1.05 var(--serif);
  margin: 0 0 18px; letter-spacing: -0.01em;
}
.hero .lead { font: 400 clamp(20px, 2.4vw, 24px)/1.45 var(--serif); margin: 0 0 16px; max-width: 34em; }
.hero p.sub { color: var(--muted); margin: 0; max-width: 36em; }
.hero img { width: 220px; height: 220px; filter: drop-shadow(0 18px 30px rgba(10, 20, 35, 0.25)); }

/* Experimental badge */
.badge {
  display: inline-block; vertical-align: middle; margin: 0 0 18px;
  font: 600 12px/1 var(--sans); letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--gold); border: 1px solid var(--gold); border-radius: 999px; padding: 6px 12px;
}
.hero .note { color: var(--muted); font-size: 14.5px; margin: 14px 0 0; max-width: 36em; }

/* Sections */
section { padding: 56px 0; border-top: 1px solid var(--line); }
h2 { font: 600 clamp(28px, 3.6vw, 36px)/1.2 var(--serif); margin: 0 0 12px; }
h3 { font: 600 22px/1.3 var(--serif); margin: 0 0 10px; }
.kicker { text-transform: uppercase; letter-spacing: 0.12em; font-size: 12px; color: var(--gold); font-weight: 600; margin: 0 0 8px; }
.intro { color: var(--muted); max-width: 40em; margin: 0 0 36px; }

/* The ingot hook */
.hook { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 28px; }
.figure-number { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 22px; }
.figure-number .n { font: 600 40px/1.1 var(--serif); color: var(--steel); }
.figure-number .l { color: var(--muted); font-size: 15px; margin-top: 6px; }

/* Questions */
.q { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 6fr); gap: 36px; align-items: center; padding: 28px 0; }
.q + .q { border-top: 1px dashed var(--line); }
.q.wide { grid-template-columns: 1fr; }
.q p { margin: 0 0 10px; }
.q .num { font: 600 15px var(--sans); color: var(--gold); }
figure { margin: 0; }
figure img {
  width: 100%; height: auto; display: block;
  background: #fff; border-radius: 10px; border: 1px solid var(--line); padding: 8px;
}
figcaption { color: var(--muted); font-size: 13.5px; margin-top: 8px; }

/* Terminal capture */
.terminal {
  background: var(--code-bg); color: var(--code-text); border-radius: 10px;
  font: 12.5px/1.55 var(--mono); padding: 0; overflow-x: auto; margin-top: 18px;
}
.terminal .bar { display: flex; gap: 6px; padding: 10px 14px; border-bottom: 1px solid #22303e; }
.terminal .bar i { width: 10px; height: 10px; border-radius: 50%; background: #3a4757; display: block; }
.terminal pre { margin: 0; padding: 14px 16px; white-space: pre; }
.terminal .prompt { color: #8fb3d9; }
.terminal .hl { color: #e7c27a; }

/* Chain */
.chain { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin: 8px 0 40px; }
.step { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 18px; position: relative; }
.step .tag { font: 600 12px var(--mono); color: var(--gold); }
.step h3 { font-size: 19px; margin: 6px 0 6px; }
.step p { color: var(--muted); font-size: 14.5px; margin: 0; }
.step:not(:last-child)::after {
  content: "→"; position: absolute; right: -13px; top: 50%; transform: translateY(-50%);
  color: var(--muted); font-size: 18px; background: var(--bg); line-height: 1;
}

.principles { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.principles p { color: var(--muted); margin: 0; font-size: 15.5px; }

/* Footer */
footer { border-top: 1px solid var(--line); padding: 36px 0 56px; color: var(--muted); font-size: 14.5px; }
footer p { margin: 0 0 8px; max-width: 46em; }

@media (max-width: 860px) {
  .hero { grid-template-columns: 1fr; padding-top: 28px; gap: 24px; }
  .hero img { width: 120px; height: 120px; order: -1; }
  .q { grid-template-columns: 1fr; gap: 18px; }
  .hook, .principles { grid-template-columns: 1fr; }
  .chain { grid-template-columns: 1fr 1fr; }
  .step:nth-child(2)::after { display: none; }
}

@media (max-width: 520px) {
  .wrap { padding: 0 16px; }
  body { font-size: 16px; }
  .top nav { gap: 14px; }
  .top nav a.optional { display: none; }
  .chain { grid-template-columns: 1fr; }
  .step::after { display: none; }
}