:root {
  --ink: #172033;
  --muted: #5d6878;
  --line: #d7e0ea;
  --paper: #ffffff;
  --page: #f5f7fa;
  --physical: #1f6fb7;
  --physical-soft: #e6f1fb;
  --semantic: #d36f18;
  --semantic-soft: #fff2de;
  --social: #bd3f57;
  --social-soft: #fbe7ec;
  --green: #2f855a;
  --green-soft: #e4f2e8;
  --shadow: 0 16px 38px rgba(23, 32, 51, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.55;
}

a {
  color: inherit;
}

img {
  max-width: 100%;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
  padding: 12px clamp(18px, 4vw, 56px);
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 800;
  text-decoration: none;
  white-space: nowrap;
}

.brand img {
  width: 38px;
  height: 38px;
}

nav {
  display: flex;
  gap: 17px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

nav a {
  text-decoration: none;
}

nav a:hover {
  color: var(--ink);
}

main {
  overflow: hidden;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 0.86fr) minmax(430px, 1.14fr);
  gap: clamp(30px, 5vw, 72px);
  align-items: center;
  min-height: calc(100vh - 63px);
  padding: clamp(36px, 6vw, 76px) clamp(18px, 5vw, 72px) 42px;
  background: #fff;
}

.hero-copy {
  max-width: 780px;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--physical);
  font-size: 13px;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  max-width: 820px;
  font-size: clamp(44px, 6.4vw, 76px);
  line-height: 0.98;
  letter-spacing: 0;
  overflow-wrap: normal;
  text-wrap: balance;
}

h2,
h3,
p {
  overflow-wrap: anywhere;
}

.subtitle {
  margin: 16px 0 0;
  color: var(--semantic);
  font-size: clamp(20px, 2.2vw, 27px);
  font-weight: 800;
  line-height: 1.2;
}

.authors {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 16px;
}

.lead {
  max-width: 740px;
  margin: 24px 0 0;
  color: #354255;
  font-size: clamp(19px, 2.1vw, 25px);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 10px 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  font-weight: 800;
  text-decoration: none;
}

.button.primary {
  color: #fff;
  background: var(--ink);
  border-color: var(--ink);
}

.button.secondary {
  color: var(--ink);
  background: #fff;
}

.hero-figure {
  margin: 0;
  background: #fff;
}

.hero-figure img {
  display: block;
  width: auto;
  max-width: min(580px, 100%);
  max-height: min(680px, calc(100vh - 220px));
  margin-left: auto;
  object-fit: contain;
  filter: drop-shadow(0 20px 36px rgba(23, 32, 51, 0.12));
}

.stat-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.stat-strip div {
  min-height: 116px;
  padding: 22px clamp(18px, 4vw, 42px);
  background: #fff;
}

.stat-strip strong {
  display: block;
  color: var(--physical);
  font-size: 36px;
  line-height: 1;
}

.stat-strip span {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font-weight: 700;
}

.section {
  padding: clamp(48px, 7vw, 88px) clamp(18px, 5vw, 72px);
}

.content-section {
  background: #fff;
}

.tinted-section {
  background: #edf3f8;
}

.section-heading {
  max-width: 980px;
  margin-bottom: 30px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(34px, 4.8vw, 56px);
  line-height: 1.04;
  letter-spacing: 0;
}

.section-heading p:last-child {
  max-width: 900px;
  margin: 15px 0 0;
  color: var(--muted);
  font-size: 19px;
}

.framework-grid,
.taxonomy-axis-grid,
.section-grid,
.evaluation-grid,
.application-grid,
.process-figure-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.loop-panel,
.taxonomy-axis-card,
.section-card,
.evaluation-card,
.application-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: var(--shadow);
}

.loop-panel {
  min-height: 184px;
  padding: 24px;
  border-top: 6px solid var(--physical);
}

.taxonomy-axis-card {
  padding: 23px;
  border-top: 6px solid var(--semantic);
}

.taxonomy-axis-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.taxonomy-axis-card h3 {
  margin: 0;
  font-size: 23px;
}

.taxonomy-axis-card p {
  margin: 12px 0 0;
  color: #354255;
}

.loop-panel.semantic {
  border-top-color: var(--semantic);
}

.loop-panel.social {
  border-top-color: var(--social);
}

.loop-panel h3,
.section-card h3,
.evaluation-card h3,
.application-card h3 {
  margin: 0;
  font-size: 24px;
  line-height: 1.12;
}

.loop-panel p,
.section-card p,
.evaluation-card p,
.application-card p {
  margin: 12px 0 0;
  color: #354255;
}

.taxonomy-formulation {
  display: grid;
  gap: 10px;
  margin: 20px 0 0;
  padding: 22px;
  border: 1px solid #cbd9e7;
  border-radius: 8px;
  background: #fff;
  box-shadow: var(--shadow);
}

.taxonomy-formulation code {
  display: block;
  overflow-x: auto;
  padding: 10px 12px;
  border: 1px solid #e3eaf2;
  border-radius: 8px;
  color: var(--ink);
  background: #f8fafc;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 15px;
}

.taxonomy-formulation p,
.taxonomy-lede {
  max-width: 980px;
  margin: 10px 0 0;
  color: #354255;
}

.taxonomy-lede {
  margin-top: 24px;
  font-size: 18px;
  font-weight: 800;
}

.wide-figure {
  margin: 28px 0 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: var(--shadow);
}

.wide-figure img {
  display: block;
  width: 100%;
  object-fit: contain;
  background: #fff;
}

figcaption {
  padding: 14px 18px 18px;
  color: var(--muted);
  font-size: 14px;
}

.section-card {
  display: flex;
  flex-direction: column;
  min-height: 360px;
  padding: 21px;
  border-top: 7px solid var(--physical);
}

.section-card.semantic {
  border-top-color: var(--semantic);
}

.section-card.social {
  border-top-color: var(--social);
}

.stage {
  margin: 0 0 10px;
  color: var(--physical);
  font-size: 13px;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.section-card.semantic .stage {
  color: var(--semantic);
}

.section-card.social .stage {
  color: var(--social);
}

.section-card ul {
  display: grid;
  gap: 8px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
}

.section-card li {
  padding: 9px 0 0;
  color: #39475a;
  border-top: 1px solid #e8edf3;
  font-weight: 700;
}

.evaluation-card {
  padding: 23px;
}

.evaluation-card.physical {
  background: var(--physical-soft);
}

.evaluation-card.semantic {
  background: var(--semantic-soft);
}

.evaluation-card.social {
  background: var(--social-soft);
}

.evaluation-card .question {
  color: var(--ink);
  font-weight: 800;
}

.callout {
  margin-top: 22px;
  padding: 24px;
  border: 1px solid #cbd9e7;
  border-radius: 8px;
  background: #fff;
}

.callout h3 {
  margin: 0;
  color: var(--physical);
  font-size: 23px;
}

.callout p {
  max-width: 980px;
  margin: 10px 0 0;
  color: #354255;
}

.application-card {
  padding: 23px;
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
}

.tag-row span {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--muted);
  background: #fff;
  font-size: 13px;
  font-weight: 800;
}

.challenge-list {
  margin-top: 28px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.challenge-list h3 {
  margin: 0;
  padding: 20px 22px;
  font-size: 26px;
  border-bottom: 1px solid var(--line);
}

.challenge-item {
  display: grid;
  grid-template-columns: 190px minmax(0, 1fr);
  border-bottom: 1px solid var(--line);
}

.challenge-item:last-child {
  border-bottom: 0;
}

.challenge-item strong {
  padding: 18px 20px;
  color: var(--physical);
  background: var(--physical-soft);
  border-right: 1px solid var(--line);
}

.challenge-item span {
  padding: 18px 20px;
  color: #354255;
}

.process-figure-grid {
  margin-top: 28px;
  grid-template-columns: 1fr;
  gap: 22px;
}

.process-figure-grid figure {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: var(--shadow);
}

.process-figure-grid img {
  display: block;
  width: 100%;
  object-fit: contain;
  background: #fff;
  height: auto;
}

footer {
  padding: 28px clamp(18px, 5vw, 72px);
  color: var(--muted);
  background: #fff;
  border-top: 1px solid var(--line);
}

footer p {
  margin: 0;
}

@media (max-width: 1080px) {
  .hero,
  .framework-grid,
  .taxonomy-axis-grid,
  .section-grid,
  .evaluation-grid,
  .application-grid,
  .process-figure-grid {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
  }

  .hero-figure img {
    width: min(560px, 100%);
    margin-right: auto;
  }
}

@media (max-width: 760px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

  nav {
    flex-wrap: wrap;
  }

  .stat-strip {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .challenge-item {
    grid-template-columns: 1fr;
  }

  .challenge-item strong {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }
}

@media (max-width: 520px) {
  body {
    font-size: 15px;
  }

  .brand {
    white-space: normal;
  }

  .stat-strip {
    grid-template-columns: 1fr;
  }
}