:root {
  color-scheme: light dark;
  --bg: #f8fafc;
  --surface: #ffffff;
  --surface-muted: #f1f5f9;
  --text: #0f172a;
  --text-muted: #475569;
  --line: #d8e0ea;
  --line-strong: #b9c5d4;
  --accent: #0f766e;
  --accent-strong: #115e59;
  --accent-soft: #e6fffb;
  --code-bg: #0f172a;
  --code-text: #e2e8f0;
  --focus: #2563eb;
  --shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
  --radius: 16px;
  --shell: 1120px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0f14;
    --surface: #111820;
    --surface-muted: #0f151c;
    --text: #e7edf4;
    --text-muted: #a8b5c4;
    --line: #293440;
    --line-strong: #3b4857;
    --accent: #5eead4;
    --accent-strong: #99f6e4;
    --accent-soft: #0d2a27;
    --code-bg: #05080c;
    --code-text: #e7edf4;
    --focus: #93c5fd;
    --shadow: 0 18px 45px rgba(0, 0, 0, 0.28);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--accent-strong);
  text-underline-offset: 0.18em;
}

a:hover {
  text-decoration-thickness: 2px;
}

a:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 4px;
  border-radius: 4px;
}

code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.92em;
}

.shell {
  width: min(calc(100% - 40px), var(--shell));
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 100;
  padding: 10px 14px;
  background: var(--text);
  color: var(--bg);
  border-radius: 8px;
  transform: translateY(-180%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid color-mix(in srgb, var(--line) 86%, transparent);
  background: color-mix(in srgb, var(--bg) 90%, transparent);
  backdrop-filter: blur(14px);
}

.header-inner {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 750;
  text-decoration: none;
  letter-spacing: -0.02em;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border: 1px solid var(--line-strong);
  border-radius: 9px;
  background: var(--surface);
  color: var(--accent-strong);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.primary-nav {
  display: flex;
  align-items: center;
  gap: 22px;
  font-size: 14px;
  font-weight: 650;
}

.primary-nav a {
  color: var(--text-muted);
  text-decoration: none;
}

.primary-nav a:hover {
  color: var(--text);
}

.hero {
  padding: 92px 0 78px;
  border-bottom: 1px solid var(--line);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.65fr) minmax(280px, 0.75fr);
  gap: 72px;
  align-items: start;
}

.eyebrow,
.section-kicker,
.snapshot-label,
.source-label {
  margin: 0 0 14px;
  color: var(--accent-strong);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  max-width: 790px;
  margin-bottom: 24px;
  font-size: clamp(2.6rem, 6vw, 4.65rem);
  line-height: 1.02;
  letter-spacing: -0.055em;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(2rem, 4vw, 3.1rem);
  line-height: 1.08;
  letter-spacing: -0.042em;
}

h3 {
  margin-bottom: 6px;
  font-size: 1.04rem;
  line-height: 1.35;
  letter-spacing: -0.01em;
}

.hero-lede {
  max-width: 760px;
  margin-bottom: 32px;
  color: var(--text-muted);
  font-size: clamp(1.06rem, 2vw, 1.22rem);
  line-height: 1.7;
}

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

.button {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border: 1px solid var(--line-strong);
  border-radius: 9px;
  font-weight: 750;
  text-decoration: none;
}

.button-primary {
  border-color: var(--accent-strong);
  background: var(--accent-strong);
  color: var(--surface);
}

@media (prefers-color-scheme: dark) {
  .button-primary {
    color: #07110f;
  }
}

.button-secondary {
  background: var(--surface);
  color: var(--text);
}

.snapshot {
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.snapshot dl {
  margin: 0;
}

.snapshot dl > div {
  display: grid;
  grid-template-columns: 96px 1fr;
  gap: 14px;
  padding: 12px 0;
  border-top: 1px solid var(--line);
}

.snapshot dl > div:first-child {
  border-top: 0;
  padding-top: 2px;
}

.snapshot dt {
  color: var(--text-muted);
  font-size: 13px;
  font-weight: 700;
}

.snapshot dd {
  margin: 0;
  font-weight: 650;
}

.section {
  padding: 88px 0;
  border-bottom: 1px solid var(--line);
}

.section-muted {
  background: var(--surface-muted);
}

.two-column {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: 76px;
  align-items: start;
}

.prose p,
.section-heading > p,
.preservation-inner > p {
  color: var(--text-muted);
  font-size: 1.04rem;
}

.prose p:last-child {
  margin-bottom: 0;
}

.notice {
  display: grid;
  gap: 6px;
  margin-top: 28px;
  padding: 18px 20px;
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  color: var(--text-muted);
}

.notice strong {
  color: var(--text);
}

.section-heading {
  max-width: 790px;
  margin-bottom: 44px;
}

.section-heading.compact {
  max-width: 860px;
}

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

.principle {
  min-width: 0;
  padding: 28px 28px 28px 0;
}

.principle + .principle {
  padding-left: 28px;
  border-left: 1px solid var(--line-strong);
}

.principle p {
  margin-bottom: 0;
  color: var(--text-muted);
}

.doc-list {
  border-top: 1px solid var(--line-strong);
}

.doc-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 28px;
  align-items: center;
  padding: 22px 0;
  border-bottom: 1px solid var(--line);
}

.doc-row > div:first-child {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  column-gap: 14px;
  align-items: baseline;
}

.doc-number {
  grid-row: 1 / span 2;
  color: var(--text-muted);
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 12px;
  font-weight: 700;
}

.doc-row h3,
.doc-row p {
  margin-bottom: 0;
}

.doc-row p {
  color: var(--text-muted);
}

.doc-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 10px 16px;
  font-size: 14px;
  font-weight: 700;
}

.use-stack {
  border-top: 1px solid var(--line-strong);
}

.use-item {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 16px;
  padding: 24px 0;
  border-bottom: 1px solid var(--line-strong);
}

.use-item p {
  margin-bottom: 0;
  color: var(--text-muted);
}

.use-step {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: var(--surface);
  font-size: 13px;
  font-weight: 800;
}

.command {
  max-width: 100%;
  margin-top: 14px;
  overflow-x: auto;
  padding: 13px 15px;
  border-radius: 9px;
  background: var(--code-bg);
  color: var(--code-text);
  -webkit-overflow-scrolling: touch;
}

.command code {
  white-space: nowrap;
}

.source-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
  margin-bottom: 28px;
}

.source-block {
  min-width: 0;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
}

.source-block p {
  color: var(--text-muted);
}

.source-block a {
  font-weight: 750;
}

.details-block {
  border-top: 1px solid var(--line-strong);
}

.details-block:last-of-type {
  border-bottom: 1px solid var(--line-strong);
}

.details-block summary {
  cursor: pointer;
  padding: 20px 4px;
  font-weight: 800;
  list-style-position: outside;
}

.details-content {
  max-width: 850px;
  padding: 0 4px 20px 24px;
  color: var(--text-muted);
}

.details-content p:last-child {
  margin-bottom: 0;
}

.preservation {
  background: var(--surface);
}

.preservation-inner {
  display: grid;
  grid-template-columns: minmax(0, 0.75fr) minmax(0, 1.25fr);
  gap: 72px;
  align-items: end;
}

.preservation-inner h2 {
  margin-bottom: 0;
}

.preservation-inner > p {
  margin-bottom: 4px;
}

.site-footer {
  padding: 40px 0 48px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 40px;
}

.footer-inner p {
  max-width: 560px;
  margin: 6px 0 0;
  color: var(--text-muted);
}

.footer-inner nav {
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  justify-content: flex-end;
  gap: 12px 18px;
  font-size: 14px;
  font-weight: 700;
}

@media (max-width: 900px) {
  .hero-grid,
  .two-column,
  .preservation-inner {
    grid-template-columns: 1fr;
    gap: 42px;
  }

  .hero {
    padding-top: 72px;
  }

  .snapshot {
    max-width: 560px;
  }

  .source-grid,
  .principles {
    grid-template-columns: 1fr;
  }

  .principle {
    padding: 22px 0;
  }

  .principle + .principle {
    padding-left: 0;
    border-left: 0;
    border-top: 1px solid var(--line-strong);
  }

  .doc-row {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .doc-links {
    justify-content: flex-start;
    padding-left: 58px;
  }
}

@media (max-width: 700px) {
  .shell {
    width: min(calc(100% - 28px), var(--shell));
  }

  .site-header {
    position: static;
  }

  .header-inner {
    min-height: 62px;
  }

  .primary-nav a:not(:last-child) {
    display: none;
  }

  .hero {
    padding: 58px 0 56px;
  }

  h1 {
    font-size: clamp(2.35rem, 12vw, 3.25rem);
  }

  .section {
    padding: 64px 0;
  }

  .doc-row > div:first-child {
    grid-template-columns: 34px minmax(0, 1fr);
    column-gap: 10px;
  }

  .doc-links {
    padding-left: 44px;
  }

  .snapshot dl > div {
    grid-template-columns: 82px 1fr;
  }

  .footer-inner {
    flex-direction: column;
  }

  .footer-inner nav {
    justify-content: flex-start;
  }
}

@media (max-width: 420px) {
  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .doc-links {
    flex-direction: column;
    gap: 6px;
  }

  .snapshot {
    padding: 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}