:root {
  --ink: #18302d;
  --muted: #5e706d;
  --paper: #f7f5ee;
  --surface: #fffef9;
  --green: #173b36;
  --green-2: #2e665c;
  --yellow: #f4b942;
  --coral: #df6548;
  --blue: #4a7185;
  --line: #d8ddd5;
  --focus: #005fcc;
  --shadow: 0 12px 32px rgb(23 59 54 / 10%);
  --radius: 8px;
  --max: 1160px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: 0;
}
a { color: inherit; text-decoration-thickness: 1px; text-underline-offset: 4px; }
a:hover { color: var(--coral); }
img, svg { display: block; max-width: 100%; }
button, select { font: inherit; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }
.skip-link { position: fixed; left: 12px; top: -80px; z-index: 100; padding: 10px 14px; background: #fff; }
.skip-link:focus { top: 12px; }
.site-header { position: sticky; top: 0; z-index: 20; border-bottom: 1px solid rgb(216 221 213 / 88%); background: rgb(247 245 238 / 94%); backdrop-filter: blur(12px); }
.header-inner { width: min(calc(100% - 32px), var(--max)); min-height: 72px; margin: 0 auto; display: flex; align-items: center; gap: 28px; }
.brand { display: inline-flex; align-items: center; gap: 10px; flex: 0 0 auto; font-weight: 800; font-size: 19px; text-decoration: none; }
.brand img { width: 40px; height: 40px; }
.nav { display: flex; align-items: center; gap: 22px; margin-left: auto; }
.nav a { text-decoration: none; font-weight: 650; font-size: 14px; }
.lang-switcher { min-height: 44px; padding: 0 34px 0 12px; border: 1px solid var(--line); border-radius: 6px; color: var(--ink); background: var(--surface); cursor: pointer; }
.menu-button { display: none; width: 44px; height: 44px; border: 1px solid var(--line); border-radius: 6px; background: var(--surface); color: var(--ink); cursor: pointer; }
.container { width: min(calc(100% - 32px), var(--max)); margin-inline: auto; }
.hero { border-bottom: 1px solid var(--line); overflow: hidden; }
.hero-inner { min-height: 610px; display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(390px, .95fr); align-items: center; gap: 64px; padding-block: 72px 64px; }
.eyebrow { margin: 0 0 14px; color: var(--coral); font-weight: 800; font-size: 13px; text-transform: uppercase; }
h1, h2, h3 { margin-top: 0; line-height: 1.25; letter-spacing: 0; text-wrap: balance; }
h1 { max-width: 820px; margin-bottom: 22px; font-size: clamp(38px, 5.2vw, 68px); }
h2 { margin-bottom: 18px; font-size: clamp(27px, 3vw, 38px); }
h3 { margin-bottom: 9px; font-size: 21px; }
.lead { max-width: 720px; margin: 0; color: var(--muted); font-size: 19px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 30px; }
.button { min-height: 46px; display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 8px 17px; border: 1px solid var(--green); border-radius: 6px; background: var(--green); color: #fff; font-weight: 750; text-decoration: none; transition: transform 160ms ease, background 160ms ease; }
.button:hover { transform: translateY(-2px); background: var(--green-2); color: #fff; }
.button.secondary { background: transparent; color: var(--green); }
.button.secondary:hover { background: #e8eee8; color: var(--green); }
.ladder-figure { position: relative; min-height: 430px; padding: 30px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); }
.figure-label { display: flex; justify-content: space-between; margin-bottom: 18px; color: var(--muted); font-size: 13px; font-weight: 700; }
.ladder-svg { width: 100%; height: auto; }
.path { stroke-dasharray: 520; stroke-dashoffset: 520; animation: trace 2.2s 350ms ease forwards; }
@keyframes trace { to { stroke-dashoffset: 0; } }
.section { padding-block: 70px; border-bottom: 1px solid var(--line); }
.section.alt { background: var(--surface); }
.section-heading { max-width: 760px; margin-bottom: 34px; }
.section-heading p { color: var(--muted); }
.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.card { min-height: 100%; padding: 24px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.card .kicker { margin: 0 0 8px; color: var(--coral); font-size: 12px; font-weight: 800; text-transform: uppercase; }
.card p { color: var(--muted); }
.card-link { font-weight: 750; }
.compare { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.compare > div { padding: 25px; background: var(--surface); }
.compare > div + div { border-left: 1px solid var(--line); }
.swatch { width: 42px; height: 6px; margin-bottom: 18px; border-radius: 99px; background: var(--yellow); }
.swatch.coral { background: var(--coral); }
.swatch.blue { background: var(--blue); }
.page-hero { padding-block: 72px 52px; border-bottom: 1px solid var(--line); }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 22px; color: var(--muted); font-size: 14px; }
.page-hero h1 { max-width: 920px; font-size: clamp(34px, 4.6vw, 58px); }
.article-layout { display: grid; grid-template-columns: minmax(0, 760px) 260px; gap: 72px; align-items: start; padding-block: 60px 80px; }
.article-body { min-width: 0; }
.article-body > section { margin-bottom: 50px; scroll-margin-top: 100px; }
.article-body p { margin: 0 0 18px; }
.article-body ul, .article-body ol { padding-left: 24px; }
.article-body li + li { margin-top: 8px; }
.article-body .note { padding: 18px 20px; border-left: 4px solid var(--yellow); background: #fff9e8; }
.toc { position: sticky; top: 98px; padding-left: 20px; border-left: 1px solid var(--line); }
.toc strong { display: block; margin-bottom: 12px; }
.toc a { display: block; padding: 5px 0; color: var(--muted); font-size: 14px; text-decoration: none; }
.diagram { margin: 28px 0; padding: 24px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.diagram figcaption { margin-top: 14px; color: var(--muted); font-size: 14px; }
.board { display: grid; grid-template-columns: repeat(6, 1fr); gap: 4px; }
.board span { aspect-ratio: 1; display: grid; place-items: center; border-radius: 4px; background: #e9eee8; font-weight: 800; }
.board span:nth-child(4n) { background: #ffe7a8; }
.board span:nth-child(7n) { background: #e9b8aa; }
.facts { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; margin: 28px 0; border: 1px solid var(--line); background: var(--line); }
.facts div { padding: 20px; background: var(--surface); }
.facts strong { display: block; font-size: 24px; }
.related { padding: 32px; border-radius: var(--radius); background: var(--green); color: #fff; }
.related a { color: #fff; }
.site-footer { padding-block: 48px 28px; background: var(--green); color: #eaf2ef; }
.footer-grid { display: grid; grid-template-columns: 1.2fr 1fr 1fr; gap: 40px; }
.footer-title { color: #fff; font-weight: 800; }
.footer-links { display: grid; gap: 8px; }
.footer-links a { color: #dbe8e3; text-decoration: none; }
.footer-note { margin-top: 36px; padding-top: 22px; border-top: 1px solid rgb(255 255 255 / 18%); color: #bcd0ca; font-size: 13px; }

@media (max-width: 900px) {
  .menu-button { display: grid; place-items: center; margin-left: auto; }
  .nav { position: absolute; inset: 72px 0 auto; display: none; padding: 18px 24px; border-bottom: 1px solid var(--line); background: var(--paper); }
  .nav.open { display: grid; }
  .lang-switcher { margin-left: 0; }
  .hero-inner { min-height: auto; grid-template-columns: 1fr; gap: 38px; padding-top: 52px; }
  .ladder-figure { min-height: auto; }
  .article-layout { grid-template-columns: 1fr; gap: 20px; }
  .toc { position: static; order: -1; padding: 18px; border: 1px solid var(--line); border-radius: var(--radius); }
}

@media (max-width: 680px) {
  .header-inner { width: min(calc(100% - 24px), var(--max)); }
  .container { width: min(calc(100% - 24px), var(--max)); }
  .hero-inner { padding-block: 42px 44px; }
  h1 { font-size: 37px; }
  .lead { font-size: 17px; }
  .section { padding-block: 52px; }
  .card-grid, .compare, .footer-grid, .facts { grid-template-columns: 1fr; }
  .compare > div + div { border-left: 0; border-top: 1px solid var(--line); }
  .page-hero { padding-block: 48px 38px; }
  .article-layout { padding-block: 38px 60px; }
  .ladder-figure { padding: 18px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
  .path { stroke-dashoffset: 0; }
}