:root {
  --bg: #f7f8fb;
  --paper: #ffffff;
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --brand: #4169e1;
  --brand-soft: #eef2ff;
  --radius: 18px;
  --shadow: 0 1px 2px rgba(0, 0, 0, .04), 0 8px 24px rgba(0, 0, 0, .06);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: 'Noto Sans', 'Noto Sans JP', ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, 'Helvetica Neue', Arial, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top right, rgba(65, 105, 225, .09), transparent 26%),
    linear-gradient(180deg, #fafbff 0%, var(--bg) 32%, var(--bg) 100%);
}

a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; }

.container { width: min(100% - 32px, 1040px); margin: 0 auto; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
  background: rgba(255, 255, 255, .88);
  border-bottom: 1px solid rgba(226, 232, 240, .9);
}

.site-header .inner {
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
}

.brand-mark {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, #4169e1 0%, #7493ff 100%);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .35);
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 14px;
}

.nav-links a {
  color: var(--muted);
  text-decoration: none;
}

.hero {
  padding: 56px 0 28px;
}

.hero-card,
.content-card {
  background: rgba(255, 255, 255, .92);
  border: 1px solid rgba(226, 232, 240, .95);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.hero-card {
  padding: 32px;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--brand-soft);
  color: var(--brand);
  font-size: 12px;
  font-weight: 700;
}

.hero h1 {
  margin: 16px 0 10px;
  font-size: clamp(30px, 5vw, 44px);
  line-height: 1.15;
}

.hero p {
  margin: 0;
  max-width: 760px;
  color: var(--muted);
  line-height: 1.85;
}

.meta {
  margin-top: 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.meta-item {
  padding: 10px 14px;
  border-radius: 14px;
  background: #fff;
  border: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}

.layout {
  padding: 0 0 56px;
  display: grid;
  gap: 20px;
}

.toc,
.content-card {
  padding: 24px;
}

.toc {
  background: rgba(255, 255, 255, .76);
  border: 1px solid rgba(226, 232, 240, .9);
  border-radius: 22px;
  box-shadow: var(--shadow);
}

.toc h2 {
  margin: 0 0 14px;
  font-size: 18px;
}

.toc ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.toc a {
  display: block;
  color: var(--muted);
  padding: 10px 12px;
  border-radius: 12px;
}

.toc a:hover {
  background: var(--brand-soft);
  color: var(--brand);
  text-decoration: none;
}

.content-card section + section {
  border-top: 1px solid var(--line);
  margin-top: 28px;
  padding-top: 28px;
}

.content-card h2 {
  margin: 0 0 14px;
  font-size: 24px;
}

.content-card h3 {
  margin: 20px 0 10px;
  font-size: 18px;
}

.content-card p,
.content-card li {
  color: #334155;
  line-height: 1.9;
}

.content-card p {
  margin: 0 0 12px;
}

.content-card ul,
.content-card ol {
  margin: 10px 0 0 20px;
  padding: 0;
}

.content-card li + li {
  margin-top: 8px;
}

.content-card table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 14px;
  font-size: 14px;
}

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

.content-card th {
  background: #f8fafc;
  color: #0f172a;
}

.table-wrap {
  overflow-x: auto;
}

.note,
.warning {
  padding: 14px 16px;
  border-radius: 16px;
  margin-top: 16px;
  font-size: 14px;
}

.note {
  background: #f8fafc;
  border: 1px solid var(--line);
  color: var(--muted);
}

.warning {
  background: #fff7ed;
  border: 1px solid #fed7aa;
  color: #9a3412;
}

.site-footer {
  border-top: 1px solid var(--line);
  background: rgba(255, 255, 255, .9);
}

.site-footer .inner {
  padding: 24px 0 36px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  font-size: 13px;
}

.site-footer .links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

@media (min-width: 960px) {
  .layout {
    grid-template-columns: 260px minmax(0, 1fr);
    align-items: start;
  }

  .toc {
    position: sticky;
    top: 86px;
  }
}

@media (max-width: 640px) {
  .hero-card,
  .toc,
  .content-card {
    padding: 20px;
    border-radius: 20px;
  }

  .site-header .inner {
    padding: 10px 0;
    align-items: flex-start;
    flex-direction: column;
  }

  .nav-links {
    font-size: 13px;
  }

  .content-card table,
  .content-card thead,
  .content-card tbody,
  .content-card th,
  .content-card td,
  .content-card tr {
    display: block;
  }

  .content-card thead {
    display: none;
  }

  .content-card td {
    padding: 10px 12px;
  }

  .content-card td + td {
    border-top: none;
  }
}