:root {
  --ink: #18202a;
  --muted: #5c6774;
  --line: #d9e0e8;
  --paper: #fbfcfd;
  --panel: #ffffff;
  --teal: #0f8b8d;
  --blue: #3157a4;
  --coral: #dd6b4d;
  --amber: #d89d22;
  --mint: #8ac6a8;
  --shadow: 0 18px 45px rgba(24, 32, 42, 0.10);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

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

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  padding: 0 32px;
  background: rgba(251, 252, 253, 0.88);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(217, 224, 232, 0.8);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 780;
  text-decoration: none;
}

.brand-mark {
  width: 22px;
  height: 22px;
  display: inline-block;
  background:
    linear-gradient(90deg, var(--teal) 0 50%, var(--amber) 50%),
    linear-gradient(90deg, var(--blue) 0 50%, var(--coral) 50%);
  background-size: 100% 50%, 100% 50%;
  background-position: top, bottom;
  background-repeat: no-repeat;
  border: 1px solid rgba(24, 32, 42, 0.18);
}

nav {
  display: flex;
  gap: 22px;
  color: var(--muted);
  font-size: 14px;
}

nav a {
  text-decoration: none;
}

.hero {
  min-height: calc(100vh - 68px);
  display: grid;
  grid-template-columns: minmax(0, 1.02fr) minmax(320px, 0.98fr);
  gap: 42px;
  align-items: center;
  max-width: 1180px;
  margin: 0 auto;
  padding: 56px 28px 48px;
}

.hero-copy {
  max-width: 650px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--teal);
  font-size: 13px;
  font-weight: 760;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  margin: 0;
  max-width: 760px;
  font-size: clamp(44px, 6.4vw, 84px);
  line-height: 0.98;
  letter-spacing: 0;
}

h2 {
  margin: 0;
  max-width: 850px;
  font-size: clamp(30px, 4vw, 54px);
  line-height: 1.05;
  letter-spacing: 0;
}

h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.lead {
  margin: 24px 0 0;
  max-width: 660px;
  color: var(--muted);
  font-size: 19px;
}

.authors {
  margin-top: 20px;
  color: var(--muted);
  font-size: 14px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.button {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  font-weight: 720;
  text-decoration: none;
}

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

.button.secondary {
  background: #fff;
}

.hero-art,
.wide-figure,
.panel-figure {
  display: block;
  width: 100%;
  height: auto;
}

.hero-art {
  filter: drop-shadow(0 28px 44px rgba(24, 32, 42, 0.18));
}

.band {
  padding: 82px 28px;
}

.section-heading {
  max-width: 1180px;
  margin: 0 auto 32px;
}

.summary {
  background: #eef6f3;
}

.summary-grid,
.principle-grid,
.code-grid {
  max-width: 1180px;
  margin: 0 auto;
  display: grid;
  gap: 16px;
}

.summary-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.summary-grid article,
.principle-grid div,
.code-grid div {
  min-height: 100%;
  padding: 24px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 6px 18px rgba(24, 32, 42, 0.04);
}

.summary-grid p,
.principle-grid p,
.code-grid p,
.split-copy p {
  margin: 0;
  color: var(--muted);
}

.visual {
  background: #fff;
}

.wide-figure {
  max-width: 1180px;
  margin: 0 auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.split {
  max-width: 1180px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 0.88fr) minmax(300px, 1.12fr);
  gap: 40px;
  align-items: center;
}

.split.reverse {
  grid-template-columns: minmax(300px, 1.12fr) minmax(0, 0.88fr);
}

.split-copy {
  max-width: 560px;
}

.split-copy p {
  margin-top: 18px;
  font-size: 17px;
}

.panel-figure {
  border-radius: 8px;
  border: 1px solid var(--line);
  background: #fff;
  box-shadow: var(--shadow);
}

.principles {
  background: #f6f2e8;
}

.principle-grid {
  grid-template-columns: repeat(5, minmax(0, 1fr));
}

.principle-grid span {
  display: block;
  color: var(--coral);
  font-size: 13px;
  font-weight: 820;
  margin-bottom: 12px;
}

.code {
  background: #eef2fa;
}

.code .button {
  margin: 28px auto 0;
  max-width: max-content;
}

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

footer {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  padding: 28px;
  color: var(--muted);
  border-top: 1px solid var(--line);
}

footer span:first-child {
  color: var(--ink);
  font-weight: 760;
}

@media (max-width: 880px) {
  .site-header {
    padding: 0 18px;
  }

  nav {
    gap: 12px;
    font-size: 13px;
  }

  .hero,
  .split,
  .split.reverse,
  .summary-grid,
  .principle-grid,
  .code-grid {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
    padding-top: 42px;
  }

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

  footer {
    flex-direction: column;
  }
}

@media (max-width: 520px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
    padding: 14px 18px;
  }

  .hero,
  .band {
    padding-left: 18px;
    padding-right: 18px;
  }

  h1 {
    font-size: 42px;
  }

  .principle-grid {
    grid-template-columns: 1fr;
  }
}