:root {
  --bg: #f5f7fa;
  --surface: #ffffff;
  --surface-soft: #eef2f6;
  --ink: #101418;
  --muted: #4a5565;
  --line: #cbd5e1;
  --brand: #1c5d99;
  --brand-soft: #dcebfa;
  --warn: #86460d;
  --radius: 14px;
  --shadow: 0 10px 28px rgba(16, 20, 24, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  background: var(--bg);
  color: var(--ink);
  font-family:
    "Hiragino Sans", "Yu Gothic", "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont,
    sans-serif;
}

body {
  margin: 0;
}

a {
  color: var(--brand);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.shell {
  margin: 0 auto;
  max-width: 1060px;
  padding: 28px 18px 64px;
}

.topbar {
  align-items: center;
  display: flex;
  gap: 16px;
  justify-content: space-between;
  margin-bottom: 34px;
}

.brand {
  color: var(--ink);
  font-size: 20px;
  font-weight: 800;
  letter-spacing: 0;
  margin: 0;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: flex-end;
}

.nav a {
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
  padding: 8px 12px;
  text-decoration: none;
}

.nav a[aria-current="page"] {
  background: var(--brand-soft);
  border-color: var(--brand);
  color: var(--brand);
}

.hero {
  display: grid;
  gap: 18px;
  margin-bottom: 30px;
}

.kicker {
  color: var(--brand);
  font-size: 13px;
  font-weight: 800;
  margin: 0;
}

h1 {
  color: var(--ink);
  font-size: 36px;
  letter-spacing: 0;
  line-height: 1.15;
  margin: 0;
  max-width: 760px;
}

.lead {
  color: var(--muted);
  font-size: 17px;
  line-height: 1.75;
  margin: 0;
  max-width: 760px;
}

.meta {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
  margin: 0;
}

.grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.card,
.section {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.card {
  display: grid;
  gap: 10px;
  padding: 18px;
}

.card h2,
.section h2 {
  color: var(--ink);
  font-size: 20px;
  line-height: 1.35;
  margin: 0;
}

.card p,
.section p,
.section li {
  color: var(--muted);
  font-size: 15px;
  line-height: 1.75;
}

.card p,
.section p {
  margin: 0;
}

.section {
  display: grid;
  gap: 16px;
  margin-top: 16px;
  padding: 22px;
}

.section h3 {
  color: var(--ink);
  font-size: 17px;
  line-height: 1.4;
  margin: 4px 0 0;
}

.section ul {
  margin: 0;
  padding-left: 20px;
}

.notice {
  background: var(--surface-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--muted);
  line-height: 1.75;
  margin-top: 16px;
  padding: 16px;
}

.notice strong {
  color: var(--warn);
}

.footer {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.7;
  margin-top: 34px;
}

@media (max-width: 720px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

  .nav {
    justify-content: flex-start;
  }

  h1 {
    font-size: 30px;
  }

  .section {
    padding: 18px;
  }
}