:root {
  color-scheme: light;
  --page: #f7f8f6;
  --surface: #ffffff;
  --surface-muted: #eef2ef;
  --ink: #17211f;
  --ink-muted: #5d6865;
  --rule: #ccd6d1;
  --rule-strong: #98a9a1;
  --accent: #0b6f68;
  --accent-strong: #084f4b;
  --accent-warm: #8b3144;
  --accent-blue: #315f83;
  --code-bg: #111918;
  --code-ink: #ecf5f1;
  --code-rule: #2c403b;
  --shadow: 0 20px 55px rgba(23, 33, 31, 0.08);
  --font-serif: "Source Serif 4", "Hiragino Mincho ProN", "Yu Mincho", "Noto Serif CJK JP", Georgia, serif;
  --font-sans: "Inter", "Hiragino Sans", "Yu Gothic", "Noto Sans CJK JP", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Menlo, Consolas, monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--font-serif);
  font-size: 18px;
  line-height: 1.68;
}

body::selection {
  background: rgba(11, 111, 104, 0.18);
}

a {
  color: var(--accent-strong);
  text-decoration-color: rgba(11, 111, 104, 0.35);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.16em;
}

a:hover {
  color: var(--accent-warm);
  text-decoration-color: rgba(139, 49, 68, 0.5);
}

button,
input,
textarea,
select {
  font: inherit;
}

.skip-link {
  position: fixed;
  left: 16px;
  top: 12px;
  z-index: 100;
  transform: translateY(-140%);
  background: var(--ink);
  color: var(--surface);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 700;
  padding: 8px 12px;
  text-decoration: none;
}

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

.site-shell {
  width: min(1120px, calc(100% - 40px));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid rgba(204, 214, 209, 0.78);
  background: rgba(247, 248, 246, 0.92);
  backdrop-filter: blur(14px);
}

.header-inner {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

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

.brand-mark {
  font-size: 0.92rem;
  font-weight: 800;
  letter-spacing: 0;
}

.brand-text {
  color: var(--ink-muted);
  font-size: 0.82rem;
  font-weight: 600;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.site-nav a {
  border-bottom: 2px solid transparent;
  color: var(--ink-muted);
  font-family: var(--font-sans);
  font-size: 0.83rem;
  font-weight: 650;
  padding: 10px 9px 8px;
  text-decoration: none;
  white-space: nowrap;
}

.site-nav a:hover,
.site-nav a.is-active {
  border-bottom-color: var(--accent);
  color: var(--ink);
}

.section-band {
  border-bottom: 1px solid var(--rule);
  padding: clamp(62px, 8vw, 104px) 0;
}

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

.hero {
  padding-top: clamp(56px, 8vw, 104px);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(260px, 0.85fr);
  gap: clamp(36px, 7vw, 82px);
  align-items: end;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--accent-warm);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-serif);
  font-weight: 650;
  letter-spacing: 0;
  line-height: 1.08;
}

h1 {
  max-width: 880px;
  font-size: clamp(3rem, 6.4vw, 5.45rem);
}

h2 {
  font-size: clamp(2rem, 4.2vw, 3.6rem);
}

h3 {
  font-size: clamp(1.25rem, 2.2vw, 1.62rem);
}

p {
  margin: 0;
}

.lede {
  max-width: 760px;
  margin-top: 28px;
  color: var(--ink-muted);
  font-size: clamp(1.15rem, 2vw, 1.46rem);
  line-height: 1.56;
}

.hero-aside {
  border-top: 3px solid var(--ink);
  padding-top: 22px;
}

.hero-aside h2 {
  margin-bottom: 18px;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 800;
  text-transform: uppercase;
}

.scope-list {
  display: grid;
  gap: 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.scope-list li {
  border-top: 1px solid var(--rule);
  padding-top: 14px;
}

.scope-list strong {
  display: block;
  color: var(--accent-blue);
  font-family: var(--font-sans);
  font-size: 0.86rem;
  font-weight: 800;
}

.scope-list span {
  display: block;
  margin-top: 4px;
  color: var(--ink-muted);
  font-size: 1rem;
  line-height: 1.45;
}

.section-grid,
.notation-grid,
.profile-grid {
  display: grid;
  grid-template-columns: minmax(220px, 0.72fr) minmax(0, 1.28fr);
  gap: clamp(34px, 7vw, 86px);
  align-items: start;
}

.section-heading {
  position: sticky;
  top: 92px;
}

.section-heading p:not(.eyebrow) {
  margin-top: 22px;
  color: var(--ink-muted);
  max-width: 460px;
}

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

.research-item {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: 20px;
  border-bottom: 1px solid var(--rule);
  padding: 28px 0 30px;
}

.research-item .item-index {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
}

.research-item h3,
.research-item p:not(.item-index),
.research-item a {
  grid-column: 2;
}

.research-item p:not(.item-index) {
  margin-top: 10px;
  color: var(--ink-muted);
}

.research-item a {
  justify-self: start;
  margin-top: 16px;
  font-family: var(--font-sans);
  font-size: 0.92rem;
  font-weight: 750;
}

.document-table {
  border-top: 1px solid var(--rule-strong);
}

.document-table a {
  display: grid;
  grid-template-columns: minmax(160px, 0.45fr) minmax(0, 1fr);
  gap: 24px;
  border-bottom: 1px solid var(--rule);
  color: var(--ink);
  padding: 18px 0;
  text-decoration: none;
}

.document-table span {
  color: var(--accent-blue);
  font-family: var(--font-sans);
  font-size: 0.86rem;
  font-weight: 800;
}

.document-table strong {
  font-weight: 520;
}

.document-table a:hover strong {
  color: var(--accent-warm);
}

.sample-stack {
  display: grid;
  gap: 24px;
}

.math-panel,
.code-panel {
  position: relative;
  margin: 0;
  border: 1px solid var(--rule);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.math-panel figcaption,
.code-panel figcaption {
  border-bottom: 1px solid var(--rule);
  color: var(--ink-muted);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 800;
  padding: 12px 16px;
  text-transform: uppercase;
}

.math-block {
  overflow-x: auto;
  padding: 28px 20px;
  color: var(--ink);
  font-size: clamp(1.02rem, 2vw, 1.22rem);
}

.code-panel {
  background: var(--code-bg);
  border-color: var(--code-rule);
  color: var(--code-ink);
}

.code-panel figcaption {
  border-bottom-color: var(--code-rule);
  color: #a7bbb4;
}

.code-panel pre {
  margin: 0;
  overflow-x: auto;
  padding: 24px 20px 28px;
}

.code-panel code {
  color: var(--code-ink);
  font-family: var(--font-mono);
  font-size: clamp(0.82rem, 1.9vw, 0.98rem);
  font-variant-ligatures: none;
  line-height: 1.72;
  tab-size: 2;
}

.copy-code {
  position: absolute;
  top: 8px;
  right: 10px;
  border: 1px solid #526962;
  border-radius: 6px;
  background: #172522;
  color: #dceae5;
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 0.76rem;
  font-weight: 800;
  min-height: 32px;
  padding: 0 10px;
}

.copy-code:hover,
.copy-code:focus-visible {
  border-color: #8cb8ad;
  outline: none;
}

.link-list {
  display: grid;
  border-top: 1px solid var(--rule-strong);
}

.link-list a {
  border-bottom: 1px solid var(--rule);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: clamp(1.08rem, 2.2vw, 1.38rem);
  font-weight: 700;
  padding: 20px 0;
  text-decoration: none;
}

.link-list a:hover {
  color: var(--accent-warm);
}

.profile-band {
  background: var(--surface);
}

.profile-copy {
  max-width: 680px;
}

.profile-copy p {
  color: var(--ink-muted);
  font-size: clamp(1.05rem, 2vw, 1.25rem);
}

.profile-copy a {
  display: inline-block;
  margin-top: 20px;
  font-family: var(--font-sans);
  font-weight: 750;
}

.article-hero {
  padding: clamp(54px, 7vw, 92px) 0 clamp(40px, 6vw, 72px);
}

.article-hero .lede {
  max-width: 840px;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 18px;
  color: var(--ink-muted);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 700;
}

.breadcrumb a {
  color: var(--accent-strong);
  text-decoration: none;
}

.breadcrumb a::after {
  content: "/";
  margin-left: 8px;
  color: var(--rule-strong);
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(220px, 0.36fr) minmax(0, 1fr);
  gap: clamp(32px, 6vw, 70px);
  align-items: start;
}

.article-sidebar {
  position: sticky;
  top: 92px;
  display: grid;
  gap: 22px;
}

.toc-panel,
.source-panel,
.version-panel,
.boundary-note {
  border-top: 3px solid var(--ink);
  padding-top: 16px;
}

.toc-panel h2,
.source-panel h2,
.version-panel h2,
.boundary-note h2 {
  margin-bottom: 10px;
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 850;
  text-transform: uppercase;
}

.toc-panel ol,
.toc-panel ul,
.source-panel ul,
.boundary-note ul,
.chapter-list,
.term-list,
.status-list {
  display: grid;
  gap: 9px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.toc-panel a,
.source-panel a {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 700;
  line-height: 1.35;
  text-decoration: none;
}

.source-panel p,
.version-panel p,
.boundary-note p,
.boundary-note li {
  color: var(--ink-muted);
  font-size: 0.96rem;
  line-height: 1.52;
}

.version-panel dl {
  display: grid;
  gap: 8px;
  margin: 0;
}

.version-panel dt {
  color: var(--accent-blue);
  font-family: var(--font-sans);
  font-size: 0.74rem;
  font-weight: 850;
  text-transform: uppercase;
}

.version-panel dd {
  margin: 0;
  color: var(--ink-muted);
  font-size: 0.94rem;
  line-height: 1.42;
}

.article-main {
  display: grid;
  gap: 42px;
}

.article-section {
  border-top: 1px solid var(--rule-strong);
  padding-top: 28px;
}

.article-section h2 {
  font-size: clamp(1.65rem, 3vw, 2.45rem);
}

.article-section h3 {
  margin-top: 26px;
  font-size: clamp(1.16rem, 2vw, 1.42rem);
}

.article-section p,
.article-section li {
  color: var(--ink-muted);
}

.article-section p {
  margin-top: 16px;
}

.article-section ul,
.article-section ol {
  margin: 16px 0 0;
  padding-left: 1.2em;
}

.chapter-list,
.term-list,
.status-list {
  gap: 0;
  border-top: 1px solid var(--rule-strong);
  margin: 16px 0 0;
  padding: 0;
}

.chapter-list li,
.term-list li,
.status-list li {
  border-bottom: 1px solid var(--rule);
  padding: 18px 0;
}

.chapter-list a,
.term-list strong,
.status-list strong {
  display: block;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 800;
  text-decoration: none;
}

.chapter-list a:hover {
  color: var(--accent-warm);
}

.chapter-list span,
.term-list span,
.status-list span {
  display: block;
  margin-top: 4px;
  color: var(--ink-muted);
  font-size: 0.98rem;
  line-height: 1.48;
}

.claim-strip {
  border-left: 4px solid var(--accent-warm);
  background: var(--surface);
  padding: 18px 20px;
}

.claim-strip p {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 0.98rem;
  font-weight: 650;
  line-height: 1.52;
}

.article-table {
  margin-top: 18px;
  overflow-x: auto;
}

.article-table table {
  width: 100%;
  border-collapse: collapse;
  border-top: 1px solid var(--rule-strong);
  font-size: 0.98rem;
}

.article-table th,
.article-table td {
  border-bottom: 1px solid var(--rule);
  padding: 12px 14px;
  text-align: left;
  vertical-align: top;
}

.article-table th {
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 850;
  text-transform: uppercase;
}

.article-table td {
  color: var(--ink-muted);
}

.page-nav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  border-top: 1px solid var(--rule-strong);
  padding-top: 24px;
}

.page-nav a {
  border: 1px solid var(--rule);
  background: var(--surface);
  color: var(--ink);
  display: grid;
  gap: 4px;
  min-height: 104px;
  padding: 16px;
  text-decoration: none;
}

.page-nav a:last-child {
  text-align: right;
}

.page-nav span {
  color: var(--accent-blue);
  font-family: var(--font-sans);
  font-size: 0.74rem;
  font-weight: 850;
  text-transform: uppercase;
}

.page-nav strong {
  align-self: end;
  font-family: var(--font-serif);
  font-size: clamp(1.12rem, 2vw, 1.34rem);
  font-weight: 650;
  line-height: 1.16;
}

.page-nav a:hover strong {
  color: var(--accent-warm);
}

.site-footer {
  background: var(--ink);
  color: #d9e3df;
  font-family: var(--font-sans);
  font-size: 0.86rem;
  padding: 28px 0;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 20px;
}

.site-footer a {
  color: #f6faf8;
  text-decoration-color: rgba(246, 250, 248, 0.35);
}

@media (max-width: 880px) {
  body {
    font-size: 17px;
  }

  .site-shell {
    width: min(100% - 28px, 720px);
  }

  .header-inner {
    align-items: flex-start;
    flex-direction: column;
    gap: 0;
    padding: 12px 0;
  }

  .site-nav {
    max-width: 100%;
  }

  .site-nav a:first-child {
    padding-left: 0;
  }

  .hero-grid,
  .section-grid,
  .notation-grid,
  .profile-grid {
    grid-template-columns: 1fr;
  }

  .section-heading {
    position: static;
  }

  .article-layout {
    grid-template-columns: 1fr;
  }

  .article-sidebar {
    position: static;
  }

  h1 {
    font-size: clamp(2.62rem, 12vw, 4.2rem);
  }

  .hero-aside {
    align-self: stretch;
  }
}

@media (max-width: 560px) {
  .section-band {
    padding: 52px 0;
  }

  .hero {
    padding-top: 54px;
  }

  .brand {
    white-space: normal;
  }

  .brand-text {
    display: none;
  }

  .research-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .research-item h3,
  .research-item p:not(.item-index),
  .research-item a {
    grid-column: 1;
  }

  .document-table a {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .page-nav {
    grid-template-columns: 1fr;
  }

  .page-nav a:last-child {
    text-align: left;
  }

  .math-block {
    padding: 22px 14px;
  }

  .code-panel pre {
    padding: 20px 14px 24px;
  }

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

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