*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --pink: #A9C6BE;
  --pink-deep: #315F59;
  --pink-light: #E7EFEB;
  --black: #18140F;
  --off-white: #FAF7F3;
  --warm-gray: #626A63;
  --border: #D5D9D2;
  --serif: 'Playfair Display', Georgia, serif;
  --sans: 'DM Sans', system-ui, sans-serif;
}

html { scroll-behavior: smooth; }

body {
  background: var(--off-white);
  color: var(--black);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
}

.site-nav {
  max-width: 1180px;
  margin: 0 auto;
  padding: 26px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .12em;
  line-height: 1.2;
  text-transform: uppercase;
}

.site-nav a { color: var(--black); text-decoration: none; }
.site-nav-links { display: flex; gap: 26px; align-items: center; }
.site-nav .cta { border-bottom: 1px solid var(--black); padding-bottom: 3px; }

.article-hero {
  padding: 0 24px;
  background: var(--pink);
  border-top: 1px solid rgba(24, 20, 15, .08);
}

.article-hero-inner { max-width: 1180px; margin: 0 auto; padding: 78px 0 84px; }

.page { max-width: 728px; margin: 0 auto; padding: 82px 24px 96px; }

.eyebrow {
  margin-bottom: 24px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .14em;
  line-height: 1.5;
  text-transform: uppercase;
  color: rgba(24, 20, 15, .68);
}

.eyebrow span { color: var(--black); }

h1 {
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(48px, 7.2vw, 82px);
  line-height: .98;
  letter-spacing: -.025em;
  margin-bottom: 0;
  max-width: 920px;
}

.label {
  margin-top: 54px;
  margin-bottom: 14px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .13em;
  line-height: 1.4;
  text-transform: uppercase;
  color: var(--pink-deep);
}

.page > .label:first-child { margin-top: 0; }

.step-label {
  margin-top: 34px;
  margin-bottom: 10px;
  font-family: var(--serif);
  font-size: 23px;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -.01em;
}

p { margin-bottom: 20px; max-width: 62ch; }
p:last-child { margin-bottom: 0; }
em { font-style: italic; }

.mental-model {
  font-family: var(--serif);
  font-style: italic;
  font-size: 24px;
  line-height: 1.5;
  letter-spacing: -.005em;
  max-width: 58ch;
}

.chain {
  margin-top: 30px;
  margin-bottom: 34px;
  padding: 28px 30px;
  background: var(--pink-light);
  border-left: 3px solid var(--pink-deep);
}

.chain-spine {
  font-family: var(--serif);
  font-style: italic;
  font-size: 20px;
  line-height: 1.5;
}

.chain-spine .arrow,
.chain-case .arrow { color: var(--pink-deep); margin: 0 6px; font-style: normal; }

.chain-cases { margin-top: 18px; display: flex; flex-direction: column; gap: 12px; }
.chain-case { font-size: 16px; line-height: 1.65; }
.chain-case .fact { font-style: italic; }

.model-list {
  margin-top: 28px;
  padding: 28px 30px;
  background: var(--pink-light);
  border-left: 3px solid var(--pink-deep);
  list-style: none;
}

.model-list li {
  margin-bottom: 14px;
  font-size: 16px;
  line-height: 1.65;
  max-width: 58ch;
}

.model-list li:last-child { margin-bottom: 0; }
.model-list strong { font-weight: 600; }

.rule {
  border: 0;
  border-top: 1px solid var(--border);
  margin-top: 58px;
  margin-bottom: 58px;
}

.line-block { padding-left: 26px; border-left: 3px solid var(--pink-deep); }
.line-block p {
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(25px, 3vw, 31px);
  line-height: 1.35;
  letter-spacing: -.01em;
  max-width: 50ch;
}

.try-this {
  max-width: 760px;
  padding: 38px 40px;
  background: var(--black);
  color: var(--off-white);
}

.try-this .label { color: var(--pink); margin-top: 0; }
.try-this p { color: var(--off-white); max-width: 58ch; margin-bottom: 0; }

.lab-link {
  margin-top: 42px;
  font-size: 15px;
  color: var(--warm-gray);
  font-style: italic;
}

.lab-link a {
  color: var(--pink-deep);
  text-decoration: none;
  border-bottom: 1px solid var(--pink-deep);
}

.lab-link a:hover { color: var(--black); border-color: var(--black); }

.back-link {
  display: block;
  margin-top: 56px;
  padding-top: 28px;
  border-top: 1px solid var(--border);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--warm-gray);
  text-decoration: none;
}

.back-link:hover { color: var(--pink-deep); }
.back-link .arrow-left { margin-right: 8px; }

@media (max-width: 720px) {
  .site-nav { padding: 20px; }
  .site-nav-links { gap: 14px; font-size: 10px; }
  .article-hero { padding: 0 20px; }
  .article-hero-inner { padding: 58px 0 62px; }
  .page { padding: 58px 20px 72px; }
  .eyebrow { margin-bottom: 20px; }
  h1 { font-size: 46px; }
  .mental-model { font-size: 21px; }
  .try-this { padding: 32px 26px; }
}

@media (max-width: 520px) {
  .site-nav { align-items: flex-start; gap: 18px; }
  .site-nav-links { flex-wrap: wrap; justify-content: flex-end; row-gap: 8px; }
  .eyebrow { font-size: 10px; }
  .step-label { font-size: 21px; }
  .chain { padding: 24px 22px; }
  .model-list { padding: 24px 22px; }
}

/* Keep mobile ecosystem navigation legible and easier to select. */
.site-nav-links a{display:inline-flex;align-items:center;min-height:32px}
@media(max-width:820px){.site-nav-links{flex-wrap:wrap}.site-nav-links a{font-size:13px;padding-top:8px;padding-bottom:8px;min-height:32px}}