:root {
  color-scheme: light;
  --navy: #1a3a6b;
  --navy-dark: #0f2548;
  --amber: #f5b942;
  --ink: #172033;
  --muted: #657086;
  --line: #e8ebf0;
  --paper: #fff;
  --wash: #f7f6f1;
  --content: 42rem;
  --shadow: 0 24px 80px rgba(18, 39, 73, .08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 92px; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 14% 0%, rgba(245, 185, 66, .13), transparent 26rem),
    radial-gradient(circle at 90% 8%, rgba(26, 58, 107, .08), transparent 28rem),
    var(--wash);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic UI",
    "Noto Sans JP", sans-serif;
  font-size: 16px;
  line-height: 1.9;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}
a {
  color: var(--navy);
  text-decoration-thickness: .08em;
  text-underline-offset: .2em;
}
a:focus-visible {
  outline: 3px solid rgba(245, 185, 66, .55);
  outline-offset: 4px;
  border-radius: 5px;
}
img { max-width: 100%; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid rgba(255, 255, 255, .72);
  background: rgba(255, 255, 255, .78);
  box-shadow: 0 1px 0 rgba(26, 58, 107, .07);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
}
.header-inner {
  max-width: 1040px;
  height: 64px;
  margin: auto;
  padding: 0 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--navy);
  font-weight: 750;
  text-decoration: none;
  letter-spacing: .02em;
}
.brand img { width: 34px; height: 34px; border-radius: 9px; }
.header-nav { display: flex; align-items: center; gap: 20px; font-size: 14px; }
.header-nav a { text-decoration: none; font-weight: 600; }
.header-cta {
  min-height: 42px;
  padding: 9px 16px;
  border-radius: 12px;
  color: #fff !important;
  background: var(--navy);
  box-shadow: 0 7px 18px rgba(26, 58, 107, .18);
  transition: transform 140ms ease, background-color 140ms ease;
}
.header-cta:hover { background: var(--navy-dark); }
.header-cta:active { transform: scale(.97); }
.breadcrumbs {
  max-width: 780px;
  margin: 32px auto 0;
  padding: 0 22px;
  color: var(--muted);
  font-size: 13px;
}
.breadcrumbs a { color: var(--muted); }
.article-shell {
  max-width: 780px;
  margin: 16px auto 88px;
  padding: 0 22px;
}
.article {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--paper);
  box-shadow: var(--shadow);
}
.article-header {
  position: relative;
  padding: 62px 58px 46px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(150deg, #fff 40%, #f7faff 100%);
}
.article-header::after {
  position: absolute;
  right: 54px;
  bottom: -1px;
  width: 72px;
  height: 4px;
  border-radius: 4px 4px 0 0;
  background: var(--amber);
  content: "";
}
.category {
  display: inline-block;
  margin-bottom: 16px;
  padding: 4px 11px;
  border-radius: 999px;
  color: #825b06;
  background: #fff4d6;
  font-size: 12px;
  font-weight: 700;
}
h1 {
  margin: 0 0 20px;
  font-size: clamp(30px, 5vw, 44px);
  line-height: 1.3;
  letter-spacing: -.035em;
  text-wrap: balance;
}
.lead {
  max-width: 38rem;
  margin: 0;
  color: #4d596e;
  font-size: 17px;
  line-height: 1.9;
}
.meta { margin-top: 22px; color: #8a93a3; font-size: 13px; }
.article-body {
  max-width: calc(var(--content) + 116px);
  padding: 46px 58px 62px;
  margin-inline: auto;
}
.takeaways {
  margin: 0 0 36px;
  padding: 25px 28px;
  border: 1px solid #f2dfaa;
  border-radius: 18px;
  background: linear-gradient(135deg, #fffaf0, #fffdf8);
  box-shadow: 0 8px 28px rgba(126, 89, 11, .06);
}
.takeaways strong {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
  color: #5f450a;
  font-size: 15px;
}
.takeaways strong::before {
  display: inline-grid;
  width: 24px;
  height: 24px;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: var(--amber);
  content: "✓";
  font-size: 13px;
}
.takeaways ul { margin: 0; padding-left: 1.25em; }
.toc {
  margin: 34px 0 42px;
  padding: 26px 28px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: #f8fafc;
}
.toc strong {
  display: block;
  margin-bottom: 13px;
  color: var(--navy-dark);
  font-size: 15px;
}
.toc ol {
  margin: 0;
  padding: 0;
  list-style-position: inside;
  counter-reset: toc;
}
.toc li {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 4px;
  align-items: baseline;
  counter-increment: toc;
}
.toc li::before {
  color: #9a7a2e;
  content: counter(toc, decimal-leading-zero);
  font-size: 11px;
  font-weight: 800;
}
.toc a {
  padding-block: 4px;
  color: #42516b;
  text-decoration: none;
}
.toc a:hover { color: var(--navy); text-decoration: underline; }
h2 {
  margin: 54px 0 20px;
  padding: 0 0 12px 16px;
  border-bottom: 1px solid #dce3ec;
  border-left: 4px solid var(--navy);
  color: var(--navy-dark);
  font-size: clamp(22px, 4vw, 26px);
  line-height: 1.5;
  letter-spacing: -.018em;
  text-wrap: balance;
}
h3 { margin: 32px 0 12px; color: #253653; font-size: 19px; line-height: 1.5; }
p { margin: 0 0 22px; }
.article-body section > p,
.article-body section > ul,
.article-body section > ol { max-width: var(--content); }
ul, ol { margin: 0 0 24px; padding-left: 1.4em; }
li + li { margin-top: 8px; }
.example {
  margin: 26px 0;
  padding: 23px 25px;
  border: 1px solid #dbe7f3;
  border-radius: 16px;
  background: linear-gradient(135deg, #f3f7fc, #f8fbff);
  box-shadow: inset 4px 0 0 #9ab7da;
}
.example strong { color: var(--navy); }
.checklist {
  margin: 26px 0;
  padding: 22px 24px;
  border: 1px solid #d9e5f3;
  border-radius: 16px;
}
.checklist li::marker { color: var(--navy); }
.source-note {
  margin-top: 38px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}
.source-note p { margin-bottom: 8px; }
.author-box {
  display: flex;
  gap: 16px;
  margin-top: 30px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #fafbfc;
}
.author-mark {
  width: 46px;
  height: 46px;
  flex: 0 0 46px;
  border-radius: 13px;
}
.author-box strong { display: block; margin-bottom: 4px; color: var(--navy-dark); }
.author-box p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.75; }
.article-cta {
  margin: 48px 0 10px;
  padding: 30px;
  border-radius: 20px;
  color: #fff;
  background:
    radial-gradient(circle at 90% 10%, rgba(245, 185, 66, .28), transparent 10rem),
    linear-gradient(145deg, var(--navy), var(--navy-dark));
  text-align: center;
}
.article-cta h2 {
  margin: 0 0 10px;
  padding: 0;
  border: 0;
  color: #fff;
  font-size: 23px;
}
.article-cta p { margin-bottom: 20px; color: #dce8f8; }
.article-cta a {
  display: inline-block;
  min-height: 48px;
  padding: 12px 22px;
  border-radius: 12px;
  color: var(--navy-dark);
  background: #fff;
  font-weight: 800;
  text-decoration: none;
  box-shadow: 0 8px 24px rgba(0, 0, 0, .16);
  transition: transform 140ms ease, box-shadow 140ms ease;
}
.article-cta a:hover { box-shadow: 0 11px 30px rgba(0, 0, 0, .22); }
.article-cta a:active { transform: scale(.97); }
.related { margin-top: 42px; }
.related h2 { margin-top: 0; }
.related-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
.related-card {
  display: block;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 14px;
  color: var(--ink);
  text-decoration: none;
  transition: transform 160ms ease, border-color 160ms ease, background-color 160ms ease;
}
.related-card:hover { transform: translateY(-2px); border-color: #b9cbe2; background: #f8fbff; }
.related-card small { display: block; margin-bottom: 5px; color: var(--muted); }
.site-footer { padding: 34px 22px; color: #798398; font-size: 13px; text-align: center; }
.site-footer a { color: #657086; }
.blog-hero {
  max-width: 1040px;
  margin: 0 auto;
  padding: 76px 22px 44px;
  text-align: center;
}
.blog-hero h1 { color: var(--navy-dark); }
.blog-hero p { max-width: 620px; margin: auto; color: var(--muted); font-size: 17px; }
.blog-grid {
  max-width: 1040px;
  margin: 0 auto 80px;
  padding: 0 22px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}
.blog-card {
  display: flex;
  min-height: 245px;
  padding: 28px;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: 20px;
  color: var(--ink);
  background: #fff;
  text-decoration: none;
  box-shadow: 0 10px 30px rgba(25, 43, 76, .04);
  transition: transform 160ms ease, border-color 160ms ease, box-shadow 160ms ease;
}
.blog-card:hover {
  transform: translateY(-3px);
  border-color: #bdcde0;
  box-shadow: 0 16px 38px rgba(25, 43, 76, .08);
}
.blog-card .number { color: #c58a10; font-size: 12px; font-weight: 800; }
.blog-card h2 { margin: 12px 0 10px; padding: 0; border: 0; font-size: 22px; }
.blog-card p { color: var(--muted); font-size: 14px; }
.blog-card .read { margin-top: auto; color: var(--navy); font-size: 13px; font-weight: 700; }

@media (max-width: 680px) {
  body { font-size: 15.5px; line-height: 1.88; }
  .header-nav > a:first-child { display: none; }
  .header-inner { height: 60px; padding-inline: 18px; }
  .breadcrumbs { margin-top: 22px; padding-inline: 18px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
  .article-shell { padding-inline: 12px; margin-bottom: 52px; }
  .article-header { padding: 38px 24px 32px; }
  .article-header::after { right: 24px; }
  .article-body { padding: 30px 24px 42px; }
  .article { border-radius: 20px; }
  .author-box { align-items: flex-start; }
  h1 { font-size: clamp(28px, 8.6vw, 34px); line-height: 1.34; }
  .lead { font-size: 16px; }
  h2 { margin-top: 44px; font-size: 22px; }
  .takeaways, .toc { padding: 21px 20px; }
  .example { margin-inline: -4px; padding: 20px; }
  .article-cta { margin-inline: -4px; padding: 28px 20px; }
  .related-grid, .blog-grid { grid-template-columns: 1fr; }
  .blog-hero { padding-top: 54px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header {
    background: #fff;
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}