:root {
  color-scheme: light;
  --blue: #0755c8;
  --blue-dark: #043d92;
  --ink: #162033;
  --muted: #667085;
  --line: #dce4f0;
  --surface: #f6f9fe;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background: #fff;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
  line-height: 1.8;
}

a { color: var(--blue); }

.site-header {
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, .96);
}

.nav {
  width: min(1040px, calc(100% - 40px));
  min-height: 68px;
  margin: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  color: var(--ink);
  font-size: 1.2rem;
  font-weight: 800;
  text-decoration: none;
}

.nav-links { display: flex; gap: 18px; flex-wrap: wrap; }
.nav-links a { color: var(--muted); font-size: .9rem; text-decoration: none; }

.hero {
  background: linear-gradient(145deg, #f8fbff 0%, #eaf2ff 100%);
  padding: 84px 20px;
}

.hero-inner {
  width: min(880px, 100%);
  margin: auto;
  text-align: center;
}

.app-icon {
  width: 112px;
  height: 112px;
  border-radius: 26px;
  box-shadow: 0 14px 38px rgba(7, 85, 200, .2);
}

h1 { margin: 24px 0 10px; font-size: clamp(2.2rem, 7vw, 4.5rem); line-height: 1.15; }
.tagline { margin: 0 auto; max-width: 620px; color: var(--muted); font-size: 1.15rem; }

.main, .document {
  width: min(880px, calc(100% - 40px));
  margin: 0 auto;
  padding: 56px 0 80px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.card {
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: #fff;
}

.card h2 { margin-top: 0; font-size: 1.08rem; }
.card p { margin-bottom: 0; color: var(--muted); }

.document { max-width: 760px; }
.document h1 { margin-top: 0; font-size: clamp(2rem, 5vw, 3rem); }
.document h2 { margin-top: 38px; padding-top: 24px; border-top: 1px solid var(--line); font-size: 1.2rem; }
.updated { color: var(--muted); font-size: .9rem; }
.notice { padding: 20px; border-left: 4px solid var(--blue); border-radius: 8px; background: var(--surface); }

.button {
  display: inline-block;
  margin-top: 12px;
  padding: 11px 20px;
  border-radius: 999px;
  color: #fff;
  background: var(--blue);
  font-weight: 700;
  text-decoration: none;
}

.site-footer {
  padding: 28px 20px;
  color: var(--muted);
  background: var(--surface);
  text-align: center;
  font-size: .85rem;
}

.footer-links { margin-bottom: 8px; }
.footer-links a { margin: 0 8px; }

@media (max-width: 720px) {
  .nav { align-items: flex-start; flex-direction: column; padding: 16px 0; }
  .nav-links { gap: 12px; }
  .hero { padding: 60px 20px; }
  .cards { grid-template-columns: 1fr; }
}