:root {
  --color-navy-950: #0b1f33;
  --color-navy-900: #102a43;
  --color-navy-700: #274c6b;
  --color-blue-600: #2f6f9f;
  --color-blue-500: #3d83b8;
  --color-blue-100: #dcecf5;
  --color-blue-050: #eff7fb;
  --color-gray-900: #24313d;
  --color-gray-700: #4a5b68;
  --color-gray-500: #72808b;
  --color-gray-300: #cfd8df;
  --color-gray-200: #e4e9ed;
  --color-gray-100: #f4f6f8;
  --color-white: #ffffff;
  --color-focus: #f0a202;
  --font-sans: "Noto Sans JP", "Yu Gothic", "Hiragino Kaku Gothic ProN", system-ui, sans-serif;
  --font-serif: "Noto Serif JP", "Yu Mincho", "Hiragino Mincho ProN", serif;
  --content-width: 1120px;
  --reading-width: 760px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --shadow-soft: 0 12px 32px rgba(16, 42, 67, 0.08);
  --space-1: 0.5rem;
  --space-2: 0.75rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2rem;
  --space-6: 3rem;
  --space-7: 4.5rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--color-gray-900);
  background: var(--color-white);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.85;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-blue-600);
  text-underline-offset: 0.2em;
}

a:hover {
  color: var(--color-navy-900);
}

a:focus-visible,
button:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 3px;
}

img {
  max-width: 100%;
  height: auto;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.5rem;
  left: 0.5rem;
  padding: 0.6rem 1rem;
  color: var(--color-white);
  background: var(--color-navy-950);
  transform: translateY(-150%);
}

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

.site-header {
  position: sticky;
  z-index: 20;
  top: 0;
  border-bottom: 1px solid rgba(207, 216, 223, 0.8);
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(12px);
}

.header-inner {
  display: flex;
  width: min(calc(100% - 2rem), var(--content-width));
  min-height: 78px;
  margin: 0 auto;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.brand {
  display: inline-flex;
  color: var(--color-navy-900);
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 44px;
  height: 44px;
  border-radius: 10px;
  color: var(--color-white);
  background: var(--color-navy-900);
  font-family: Georgia, serif;
  font-weight: 700;
  letter-spacing: 0.06em;
  place-items: center;
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  letter-spacing: 0.05em;
}

.brand small {
  color: var(--color-gray-500);
  font-size: 0.72rem;
  line-height: 1.4;
}

.global-nav {
  display: flex;
  gap: 1.6rem;
}

.global-nav a {
  color: var(--color-navy-900);
  font-size: 0.92rem;
  font-weight: 700;
  text-decoration: none;
}

.menu-button {
  display: none;
  padding: 0.55rem 0.8rem;
  border: 1px solid var(--color-gray-300);
  border-radius: 8px;
  color: var(--color-navy-900);
  background: var(--color-white);
  font: inherit;
  font-weight: 700;
}

main {
  min-height: 62vh;
}

.breadcrumbs {
  width: min(calc(100% - 2rem), var(--content-width));
  margin: 1.1rem auto 0;
  color: var(--color-gray-500);
  font-size: 0.82rem;
}

.breadcrumbs ol {
  display: flex;
  overflow-x: auto;
  margin: 0;
  padding: 0;
  align-items: center;
  list-style: none;
  white-space: nowrap;
}

.breadcrumbs li:not(:last-child)::after {
  margin: 0 0.6rem;
  color: var(--color-gray-300);
  content: "/";
}

.hero {
  overflow: hidden;
  position: relative;
  padding: clamp(4rem, 9vw, 7rem) 1rem;
  color: var(--color-white);
  background:
    radial-gradient(circle at 80% 18%, rgba(61, 131, 184, 0.35), transparent 27rem),
    linear-gradient(135deg, var(--color-navy-950), var(--color-navy-900) 62%, #183f5d);
}

.hero::after {
  position: absolute;
  right: -5rem;
  bottom: -8rem;
  width: 25rem;
  height: 25rem;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 50%;
  content: "";
}

.hero-inner {
  position: relative;
  z-index: 1;
  width: min(100%, var(--content-width));
  margin: 0 auto;
}

.eyebrow {
  margin: 0 0 0.9rem;
  color: #a9d4ed;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.17em;
  text-transform: uppercase;
}

.hero h1 {
  max-width: 12em;
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(2.15rem, 6vw, 4.25rem);
  font-weight: 700;
  line-height: 1.33;
  letter-spacing: 0.04em;
}

.hero-copy {
  max-width: 680px;
  margin: 1.5rem 0 0;
  color: #d9e7f0;
  font-size: clamp(1rem, 2.2vw, 1.2rem);
}

.hero-actions,
.button-row {
  display: flex;
  margin-top: 2rem;
  flex-wrap: wrap;
  gap: 0.8rem;
}

.button {
  display: inline-flex;
  min-height: 46px;
  padding: 0.65rem 1.15rem;
  border: 1px solid transparent;
  border-radius: 8px;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  text-decoration: none;
}

.button-primary {
  color: var(--color-navy-950);
  background: var(--color-white);
}

.button-secondary {
  border-color: rgba(255, 255, 255, 0.35);
  color: var(--color-white);
  background: rgba(255, 255, 255, 0.06);
}

.button-dark {
  color: var(--color-white);
  background: var(--color-navy-900);
}

.section {
  width: min(calc(100% - 2rem), var(--content-width));
  margin: 0 auto;
  padding: var(--space-7) 0;
}

.section + .section {
  border-top: 1px solid var(--color-gray-200);
}

.section-tinted {
  width: 100%;
  max-width: none;
  padding-right: max(1rem, calc((100% - var(--content-width)) / 2));
  padding-left: max(1rem, calc((100% - var(--content-width)) / 2));
  background: var(--color-gray-100);
}

.section-heading {
  display: flex;
  margin-bottom: 1.6rem;
  align-items: end;
  justify-content: space-between;
  gap: 1rem;
}

.section-heading h2,
.page-header h1 {
  margin: 0;
  color: var(--color-navy-900);
  font-family: var(--font-serif);
  line-height: 1.45;
}

.section-heading h2 {
  font-size: clamp(1.65rem, 3vw, 2.25rem);
}

.section-heading p {
  max-width: 620px;
  margin: 0.4rem 0 0;
  color: var(--color-gray-700);
}

.text-link {
  white-space: nowrap;
  font-weight: 700;
}

.principle-grid,
.statement-grid,
.card-grid,
.related-site-grid,
.category-grid {
  display: grid;
  gap: 1rem;
}

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

.principle-card,
.statement-card {
  padding: 1.5rem;
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-md);
  background: var(--color-white);
}

.principle-number {
  display: block;
  margin-bottom: 0.8rem;
  color: var(--color-blue-600);
  font-family: Georgia, serif;
  font-size: 1.8rem;
  font-weight: 700;
}

.principle-card h3,
.statement-card h3 {
  margin: 0 0 0.5rem;
  color: var(--color-navy-900);
}

.principle-card p,
.statement-card p {
  margin: 0;
  color: var(--color-gray-700);
}

.statement-card {
  position: relative;
  overflow: hidden;
  border-top: 4px solid var(--color-blue-600);
  box-shadow: var(--shadow-soft);
}

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

.article-card,
.category-card,
.related-site-card {
  display: flex;
  min-width: 0;
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-md);
  color: inherit;
  background: var(--color-white);
  box-shadow: 0 2px 0 rgba(16, 42, 67, 0.02);
  flex-direction: column;
  text-decoration: none;
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
}

.article-card:hover,
.category-card:hover,
.related-site-card:hover {
  border-color: var(--color-blue-500);
  color: inherit;
  box-shadow: var(--shadow-soft);
  transform: translateY(-3px);
}

.article-card {
  padding: 1.35rem;
}

.card-category,
.category-count,
.article-category-label {
  color: var(--color-blue-600);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.04em;
}

.article-card h3,
.category-card h2,
.category-card h3,
.related-site-card h3 {
  margin: 0.45rem 0;
  color: var(--color-navy-900);
  line-height: 1.55;
}

.article-card p,
.category-card p,
.related-site-card p {
  margin: 0;
  color: var(--color-gray-700);
  font-size: 0.93rem;
}

.card-meta {
  margin-top: auto;
  padding-top: 1rem;
  color: var(--color-gray-500);
  font-size: 0.76rem;
}

.category-card {
  padding: 1.5rem;
}

.category-card h2 {
  font-size: 1.25rem;
}

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

.related-site-card {
  padding: 1.5rem;
}

.page-header {
  padding: 3.8rem 1rem;
  border-bottom: 1px solid var(--color-gray-200);
  background: linear-gradient(180deg, var(--color-blue-050), var(--color-white));
}

.page-header-inner {
  width: min(100%, var(--content-width));
  margin: 0 auto;
}

.page-header h1 {
  font-size: clamp(2rem, 5vw, 3rem);
}

.page-header p {
  max-width: 740px;
  margin: 1rem 0 0;
  color: var(--color-gray-700);
}

.empty-state {
  padding: 2rem;
  border: 1px dashed var(--color-gray-300);
  border-radius: var(--radius-md);
  color: var(--color-gray-700);
  background: var(--color-gray-100);
}

.article-header {
  width: min(calc(100% - 2rem), 900px);
  margin: 0 auto;
  padding: 3.5rem 0 2.5rem;
  border-bottom: 1px solid var(--color-gray-200);
}

.article-header h1 {
  margin: 0.5rem 0 1rem;
  color: var(--color-navy-900);
  font-family: var(--font-serif);
  font-size: clamp(2rem, 5vw, 3.25rem);
  line-height: 1.45;
  letter-spacing: 0.025em;
}

.article-lead {
  margin: 0;
  color: var(--color-gray-700);
  font-size: 1.06rem;
}

.article-dates {
  display: flex;
  margin-top: 1rem;
  color: var(--color-gray-500);
  flex-wrap: wrap;
  gap: 1rem;
  font-size: 0.82rem;
}

.article-shell {
  display: grid;
  width: min(calc(100% - 2rem), var(--content-width));
  margin: 0 auto;
  padding: 3rem 0 var(--space-7);
  grid-template-columns: minmax(0, var(--reading-width)) 260px;
  justify-content: space-between;
  gap: 3.5rem;
}

.article-body {
  min-width: 0;
  font-size: 1.02rem;
}

.article-body > :first-child {
  margin-top: 0;
}

.article-body h2,
.article-body h3,
.article-body h4 {
  color: var(--color-navy-900);
  font-family: var(--font-serif);
  line-height: 1.55;
  scroll-margin-top: 100px;
}

.article-body h2 {
  margin: 3.2rem 0 1.2rem;
  padding-bottom: 0.55rem;
  border-bottom: 2px solid var(--color-blue-100);
  font-size: clamp(1.5rem, 3vw, 2rem);
}

.article-body h3 {
  margin: 2.4rem 0 0.8rem;
  padding-left: 0.8rem;
  border-left: 4px solid var(--color-blue-600);
  font-size: 1.3rem;
}

.article-body h4 {
  margin: 2rem 0 0.6rem;
  font-size: 1.1rem;
}

.article-body p,
.article-body ul,
.article-body ol {
  margin-top: 0;
  margin-bottom: 1.4rem;
}

.article-body li + li {
  margin-top: 0.4rem;
}

.article-body blockquote {
  margin: 1.5rem 0;
  padding: 1rem 1.2rem;
  border-left: 4px solid var(--color-blue-500);
  color: var(--color-gray-700);
  background: var(--color-blue-050);
}

.table-scroll {
  overflow-x: auto;
  margin: 1.7rem 0;
  border: 1px solid var(--color-gray-300);
  border-radius: var(--radius-sm);
  -webkit-overflow-scrolling: touch;
}

table {
  width: 100%;
  min-width: 620px;
  border-collapse: collapse;
  font-size: 0.92rem;
}

th,
td {
  padding: 0.85rem 1rem;
  border-right: 1px solid var(--color-gray-200);
  border-bottom: 1px solid var(--color-gray-200);
  text-align: left;
  vertical-align: top;
}

th {
  color: var(--color-navy-900);
  background: var(--color-blue-050);
  white-space: nowrap;
}

tr:last-child td {
  border-bottom: 0;
}

th:last-child,
td:last-child {
  border-right: 0;
}

.formula-block,
.code-block {
  overflow-x: auto;
  margin: 1.5rem 0;
  padding: 1.1rem 1.25rem;
  border: 1px solid var(--color-blue-100);
  border-radius: var(--radius-sm);
  color: var(--color-navy-950);
  background: var(--color-blue-050);
  font-family: "Cascadia Mono", "BIZ UDゴシック", monospace;
  font-size: 0.92rem;
  line-height: 1.8;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.article-aside {
  min-width: 0;
}

.aside-sticky {
  position: sticky;
  top: 105px;
}

.toc,
.aside-panel {
  padding: 1.2rem;
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-sm);
  background: var(--color-gray-100);
}

.toc + .aside-panel,
.aside-panel + .aside-panel {
  margin-top: 1rem;
}

.toc strong,
.aside-panel strong {
  display: block;
  margin-bottom: 0.55rem;
  color: var(--color-navy-900);
}

.toc ol,
.aside-panel ul {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 0.82rem;
  line-height: 1.65;
}

.toc li + li,
.aside-panel li + li {
  margin-top: 0.45rem;
}

.toc .toc-level-3 {
  margin-left: 0.65rem;
}

.content-note,
.disclaimer-box {
  margin-top: 3rem;
  padding: 1.3rem 1.4rem;
  border-radius: var(--radius-sm);
  color: var(--color-gray-700);
  background: var(--color-gray-100);
  font-size: 0.88rem;
}

.disclaimer-box {
  border-left: 4px solid var(--color-navy-700);
}

.disclaimer-box h2 {
  margin: 0 0 0.55rem;
  padding: 0;
  border: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
}

.disclaimer-box p {
  margin: 0;
}

.related-card-section {
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-gray-200);
}

.related-card-section h2 {
  margin: 0 0 var(--space-3);
  color: var(--color-navy-900);
  font-family: var(--font-serif);
  font-size: 1.35rem;
}

.related-card-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.related-card {
  display: grid;
  gap: 0.5rem;
  padding: var(--space-4);
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-sm);
  color: inherit;
  background: var(--color-white);
  text-decoration: none;
}

.related-card:hover {
  border-color: var(--color-blue-600);
}

.related-card.is-cross-site {
  background: var(--color-blue-050);
}

.related-card-meta {
  color: var(--color-blue-600);
  font-size: 0.78rem;
  font-weight: 700;
}

.related-card h3 {
  margin: 0;
  color: var(--color-navy-900);
  font-size: 1.02rem;
  line-height: 1.55;
}

.related-card p {
  margin: 0;
  color: var(--color-gray-700);
  font-size: 0.9rem;
  line-height: 1.7;
}

.related-card-cta {
  color: var(--color-navy-700);
  font-size: 0.82rem;
  font-weight: 700;
}

.article-footer-block {
  width: min(calc(100% - 2rem), var(--content-width));
  margin: 0 auto;
  padding: 0 0 var(--space-7);
}

.article-footer-block h2 {
  color: var(--color-navy-900);
  font-family: var(--font-serif);
}

.metrics-list,
.external-links {
  display: flex;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
  gap: 0.55rem;
  list-style: none;
}

.metrics-list li {
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--color-blue-100);
  border-radius: 999px;
  color: var(--color-navy-700);
  background: var(--color-blue-050);
  font-size: 0.85rem;
  font-weight: 700;
}

.back-home {
  margin-top: 2rem;
}

.prose-page {
  width: min(calc(100% - 2rem), var(--reading-width));
  margin: 0 auto;
  padding: 3rem 0 var(--space-7);
}

.prose-page h2,
.prose-page h3 {
  margin-top: 2.6rem;
  color: var(--color-navy-900);
  font-family: var(--font-serif);
}

.prose-page h2 {
  padding-bottom: 0.45rem;
  border-bottom: 2px solid var(--color-blue-100);
}

.glossary-list {
  display: grid;
  margin: 0;
  padding: 0;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.8rem;
  list-style: none;
}

.glossary-list a {
  display: block;
  height: 100%;
  padding: 1.1rem 1.2rem;
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-sm);
  color: inherit;
  background: var(--color-white);
  text-decoration: none;
}

.glossary-list a:hover {
  border-color: var(--color-blue-500);
}

.glossary-list strong,
.glossary-list span,
.glossary-list small {
  display: block;
}

.glossary-list strong {
  color: var(--color-navy-900);
}

.glossary-list span {
  margin-top: 0.3rem;
  color: var(--color-gray-700);
  font-size: 0.9rem;
}

.glossary-list small {
  margin-top: 0.55rem;
  color: var(--color-blue-600);
}

.site-footer {
  padding: 3.5rem max(1rem, calc((100% - var(--content-width)) / 2));
  color: #d8e2e9;
  background: var(--color-navy-950);
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(220px, 0.5fr);
  gap: 3rem;
}

.footer-grid strong {
  color: var(--color-white);
  font-family: var(--font-serif);
  font-size: 1.25rem;
}

.footer-grid p {
  max-width: 620px;
  margin: 0.65rem 0 0;
}

.footer-grid nav {
  display: grid;
  align-content: start;
  gap: 0.4rem;
}

.site-footer a {
  color: #cce6f4;
}

.footer-note {
  margin: 2.5rem 0 0;
  padding-top: 1.25rem;
  border-top: 1px solid rgba(255, 255, 255, 0.13);
  font-size: 0.82rem;
}

.copyright {
  margin: 0.5rem 0 0;
  color: #9aabb8;
  font-size: 0.75rem;
}

@media (max-width: 900px) {
  .card-grid,
  .category-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .article-shell {
    grid-template-columns: minmax(0, 1fr);
  }

  .article-aside {
    grid-row: 1;
  }

  .aside-sticky {
    position: static;
  }
}

@media (max-width: 700px) {
  :root {
    --space-7: 3.25rem;
  }

  body {
    font-size: 15px;
  }

  .header-inner {
    min-height: 68px;
  }

  .brand small {
    display: none;
  }

  .brand-mark {
    width: 38px;
    height: 38px;
  }

  .menu-button {
    display: inline-flex;
  }

  .global-nav {
    display: none;
    position: absolute;
    top: 67px;
    right: 0;
    left: 0;
    padding: 1rem;
    border-bottom: 1px solid var(--color-gray-300);
    background: var(--color-white);
    box-shadow: var(--shadow-soft);
    flex-direction: column;
    gap: 0.8rem;
  }

  .global-nav.is-open {
    display: flex;
  }

  .hero {
    padding-top: 3.7rem;
    padding-bottom: 4rem;
  }

  .hero h1 {
    max-width: none;
  }

  .principle-grid,
  .statement-grid,
  .card-grid,
  .related-card-grid,
  .category-grid,
  .related-site-grid,
  .glossary-list,
  .footer-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .section-heading {
    align-items: start;
    flex-direction: column;
  }

  .article-header {
    padding-top: 2.5rem;
  }

  .article-shell {
    padding-top: 2rem;
    gap: 2rem;
  }

  .article-body {
    font-size: 1rem;
  }

  .footer-grid {
    gap: 2rem;
  }
}

@media print {
  .site-header,
  .site-footer,
  .article-aside,
  .breadcrumbs,
  .button-row,
  .back-home {
    display: none;
  }

  body {
    color: #000;
    font-size: 11pt;
  }

  .article-shell,
  .article-header {
    width: 100%;
    max-width: none;
  }

  a {
    color: inherit;
  }
}