:root {
  --ink: #1a2028;
  --ink-soft: #4a5560;
  --ink-faint: #7c8792;
  --paper: #f5f6f3;
  --paper-raised: #ffffff;
  --indigo: #26456e;
  --indigo-soft: #e7ecf3;
  --indigo-line: #c3cfdf;
  --moss: #5c6b4a;
  --rule: #dfe1db;

  --display: 'Spectral', Georgia, serif;
  --body: 'IBM Plex Sans', system-ui, sans-serif;
  --data: 'IBM Plex Mono', ui-monospace, monospace;

  --measure: 34rem;
  --gutter: 1.5rem;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body);
  font-size: 1.0625rem;
  line-height: 1.7;
  font-weight: 400;
}

a { color: var(--indigo); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }

:focus-visible {
  outline: 2px solid var(--indigo);
  outline-offset: 3px;
}

.skip {
  position: absolute;
  left: -9999px;
}
.skip:focus {
  left: 1rem; top: 1rem;
  z-index: 10;
  background: var(--paper-raised);
  padding: 0.5rem 0.9rem;
  border: 1px solid var(--indigo);
}

/* ---------- annotation device (furigana) ---------- */

.ann {
  display: block;
  font-family: var(--data);
  font-size: 0.6875rem;
  font-weight: 400;
  letter-spacing: 0.11em;
  text-transform: uppercase;
  color: var(--indigo);
  margin: 0 0 0.35rem;
}

.prose .ann { margin-top: 2.9rem; }
.prose .ann + h2 { margin-top: 0; }
.prose > .ann:first-child { margin-top: 0; }

.ann--moss { color: var(--moss); }
.ann--quiet { color: var(--ink-faint); }

/* ---------- shell ---------- */

.wrap {
  width: 100%;
  max-width: 60rem;
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.masthead {
  border-bottom: 1px solid var(--rule);
  background: var(--paper);
}

.masthead__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.75rem 1.75rem;
  padding-top: 1.4rem;
  padding-bottom: 1.4rem;
}

.wordmark {
  font-family: var(--display);
  font-size: 1.4rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--ink);
  text-decoration: none;
  margin-right: auto;
}
.wordmark span { color: var(--indigo); }

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1.1rem;
  font-family: var(--data);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.nav a { color: var(--ink-soft); text-decoration: none; padding-bottom: 2px; border-bottom: 1px solid transparent; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--indigo); border-bottom-color: var(--indigo); }

/* ---------- hero ---------- */

.hero { padding: 3.5rem 0 2.75rem; border-bottom: 1px solid var(--rule); }

.hero__thesis {
  font-family: var(--display);
  font-size: clamp(1.75rem, 4.4vw, 2.6rem);
  line-height: 1.24;
  font-weight: 500;
  letter-spacing: -0.015em;
  margin: 0 0 1.1rem;
  max-width: 22ch;
}
.hero__thesis em { font-style: italic; color: var(--indigo); }

.hero__sub {
  max-width: var(--measure);
  color: var(--ink-soft);
  margin: 0;
}

/* ---------- index list ---------- */

.section { padding: 2.75rem 0; }
.section + .section { border-top: 1px solid var(--rule); }

.section__head {
  font-family: var(--display);
  font-size: 1.35rem;
  font-weight: 500;
  margin: 0 0 1.5rem;
}

.entry {
  display: block;
  padding: 1.4rem 0;
  border-top: 1px solid var(--rule);
  text-decoration: none;
  color: inherit;
}
.entry:first-of-type { border-top: none; }
.entry:hover .entry__title { color: var(--indigo); }

.entry__title {
  font-family: var(--display);
  font-size: 1.3rem;
  font-weight: 500;
  line-height: 1.35;
  margin: 0 0 0.4rem;
  transition: color 0.15s ease;
}

.entry__blurb {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.9375rem;
  max-width: var(--measure);
}

/* ---------- article ---------- */

.article { padding: 3rem 0 1rem; }

.article__title {
  font-family: var(--display);
  font-size: clamp(1.7rem, 4vw, 2.4rem);
  line-height: 1.22;
  font-weight: 500;
  letter-spacing: -0.015em;
  margin: 0 0 1rem;
  max-width: 24ch;
}

.article__standfirst {
  font-size: 1.125rem;
  color: var(--ink-soft);
  max-width: var(--measure);
  margin: 0 0 1.75rem;
}

.byline {
  font-family: var(--data);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  color: var(--ink-faint);
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 0.7rem 0;
  margin-bottom: 2.25rem;
}

.prose { max-width: var(--measure); }

.prose h2 {
  font-family: var(--display);
  font-size: 1.5rem;
  font-weight: 500;
  line-height: 1.3;
  margin: 2.75rem 0 0.9rem;
}
.prose h3 {
  font-family: var(--body);
  font-size: 1.0625rem;
  font-weight: 600;
  margin: 2rem 0 0.6rem;
}
.prose p { margin: 0 0 1.15rem; }
.prose ul, .prose ol { margin: 0 0 1.3rem; padding-left: 1.15rem; }
.prose li { margin-bottom: 0.5rem; }
.prose strong { font-weight: 600; }

.disclosure {
  background: var(--indigo-soft);
  border-left: 3px solid var(--indigo);
  padding: 0.9rem 1.1rem;
  font-size: 0.875rem;
  color: var(--ink-soft);
  margin-bottom: 2rem;
}
.disclosure p { margin: 0; }

.pullbox {
  border: 1px solid var(--indigo-line);
  background: var(--paper-raised);
  padding: 1.2rem 1.3rem;
  margin: 2rem 0;
}
.pullbox p:last-child { margin-bottom: 0; }

.cta {
  display: inline-block;
  font-family: var(--body);
  font-weight: 500;
  font-size: 0.9375rem;
  background: var(--indigo);
  color: #fff;
  padding: 0.7rem 1.25rem;
  text-decoration: none;
  margin: 0.35rem 0 0.5rem;
}
.cta:hover { background: #1b3555; color: #fff; }

.cta-note {
  font-family: var(--data);
  font-size: 0.75rem;
  color: var(--ink-faint);
  margin: 0 0 2rem;
}

/* ---------- breadcrumbs ---------- */

.crumbs {
  font-family: var(--data);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  color: var(--ink-faint);
  margin-bottom: 1.5rem;
}
.crumbs a { color: var(--ink-soft); text-decoration: none; border-bottom: 1px solid var(--indigo-line); }
.crumbs a:hover { color: var(--indigo); border-bottom-color: var(--indigo); }
.crumbs span[aria-hidden] { margin: 0 0.5rem; color: var(--indigo-line); }

/* ---------- table of contents ---------- */

.toc {
  border-top: 1px solid var(--indigo-line);
  border-bottom: 1px solid var(--indigo-line);
  padding: 1.1rem 0 1.2rem;
  margin: 0 0 2.5rem;
}
.toc .ann { margin-top: 0; }
.toc ol {
  list-style: none;
  margin: 0;
  padding: 0;
  columns: 2;
  column-gap: 2rem;
  font-size: 0.875rem;
}
.toc li { margin: 0 0 0.4rem; break-inside: avoid; }
.toc a { color: var(--ink-soft); text-decoration: none; border-bottom: 1px solid transparent; }
.toc a:hover { color: var(--indigo); border-bottom-color: var(--indigo); }

@media (max-width: 34rem) {
  .toc ol { columns: 1; }
}

/* 見出しへのジャンプ時にヘッダー分の余白を確保 */
.prose h2 { scroll-margin-top: 1.5rem; }

/* ---------- tables ---------- */

.table-scroll { overflow-x: auto; margin: 1.75rem 0 2rem; }

table {
  border-collapse: collapse;
  width: 100%;
  min-width: 34rem;
  font-size: 0.875rem;
}
caption {
  text-align: left;
  font-family: var(--data);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
  padding-bottom: 0.6rem;
}
th, td {
  text-align: left;
  padding: 0.65rem 0.8rem 0.65rem 0;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}
thead th {
  font-family: var(--data);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 500;
  color: var(--indigo);
  border-bottom: 1px solid var(--indigo-line);
}
tbody th { font-weight: 600; }
td.num { font-family: var(--data); white-space: nowrap; }

/* ---------- footer ---------- */

.foot {
  border-top: 1px solid var(--rule);
  margin-top: 3.5rem;
  padding: 2.25rem 0 3rem;
  font-size: 0.875rem;
  color: var(--ink-soft);
}
.foot__links {
  display: flex;
  flex-wrap: wrap;
  gap: 1.1rem;
  font-family: var(--data);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}
.foot p { max-width: var(--measure); margin: 0 0 0.6rem; }

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}