:root {
  --ink: #172033;
  --muted: #5d6878;
  --blue: #0b3a67;
  --blue-2: #123f6d;
  --line: #d8dee8;
  --paper: #ffffff;
  --soft: #f6f8fb;
  --note: #eef4fa;
  --warn: #fff7e8;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", "Hiragino Sans", Meiryo, sans-serif;
  font-size: 17px;
  line-height: 1.9;
  letter-spacing: 0.015em;
}

.site-header {
  background: linear-gradient(135deg, var(--blue), var(--blue-2));
  color: #fff;
  border-bottom: 1px solid rgba(255, 255, 255, 0.18);
}

.header-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 22px 28px;
}

.brand {
  margin: 0;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.header-sub {
  margin: 4px 0 0;
  color: rgba(255, 255, 255, 0.82);
  font-size: 0.9rem;
}

main {
  width: 100%;
  min-height: 100vh;
  padding: 0 28px 72px;
  background: var(--paper);
}

article {
  max-width: 1040px;
  margin: 0 auto;
  padding-top: 44px;
}

.hero {
  padding-bottom: 28px;
  border-bottom: 4px solid var(--blue);
}

.kicker {
  margin: 0 0 12px;
  color: var(--blue);
  font-size: 0.92rem;
  font-weight: 700;
  letter-spacing: 0.12em;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.3;
  letter-spacing: 0.02em;
}

.lead {
  margin: 22px 0 0;
  font-size: 1.12rem;
  line-height: 2;
}

section {
  margin-top: 46px;
}

h2 {
  margin: 0 0 20px;
  padding: 8px 0 8px 16px;
  border-left: 6px solid var(--blue);
  border-bottom: 1px solid var(--line);
  font-size: 1.45rem;
  line-height: 1.45;
}

h3 {
  margin: 28px 0 10px;
  color: var(--blue);
  font-size: 1.12rem;
}

p {
  margin: 1em 0;
}

ul,
ol {
  margin: 1em 0;
  padding-left: 1.6em;
}

li {
  margin: 0.38em 0;
}

a {
  color: #064f91;
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.18em;
}

.note,
.warning,
.source-box {
  margin: 24px 0;
  padding: 18px 20px;
  border-left: 5px solid var(--blue);
  background: var(--note);
}

.warning {
  border-left-color: #b46a00;
  background: var(--warn);
}

.source-box {
  background: #f8fafc;
}

.source-box h3 {
  margin-top: 0;
}

.flow {
  margin: 26px 0;
  padding: 22px 24px;
  background: #f8fafc;
  border: 1px solid var(--line);
}

.flow ol {
  margin: 0;
}

.flow li + li {
  margin-top: 0.65em;
}

.diagram-figure {
  margin: 32px 0 36px;
  padding: 0;
  background: transparent;
  border: 0;
}

.diagram-figure figcaption {
  margin-top: 12px;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.7;
}

.diagram-scroll {
  overflow-x: visible;
  padding-bottom: 0;
}

.diagram-scroll img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
}

.diagram-scroll img.wide-diagram {
  min-width: 0;
  max-width: 100%;
}

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  margin-top: 18px;
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 720px;
}

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

th {
  background: #f1f5f9;
  color: var(--blue);
  font-weight: 700;
}

.primary-summary,
.toc {
  margin-top: 34px;
  padding: 22px 24px;
  border-left: 5px solid var(--blue);
  background: #f8fafc;
}

.primary-summary h2,
.toc h2 {
  margin-top: 0;
}

.toc-list {
  columns: 2;
  column-gap: 2.5rem;
}

.toc-list li {
  break-inside: avoid;
  margin: 0 0 0.45em;
}

.footer-links {
  margin-top: 42px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.95rem;
}

.site-footer {
  background: #10233d;
  color: #dbe6f2;
}

.footer-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 24px 28px;
  font-size: 0.9rem;
}

.footer-inner a {
  color: #ffffff;
}

@media (max-width: 720px) {
  main {
    padding: 0 18px 56px;
  }

  article {
    padding-top: 32px;
  }

  .header-inner {
    padding: 18px;
  }

  h2 {
    font-size: 1.26rem;
  }

  .diagram-figure {
    margin-left: 0;
    margin-right: 0;
  }

  .toc-list {
    columns: 1;
  }
}