:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --fg-soft: #555;
  --accent: #2563eb;
  --card: #f5f6f8;
  --border: #e3e5e8;
  --max: 760px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101114;
    --fg: #ececec;
    --fg-soft: #a5a8ad;
    --accent: #6c9cff;
    --card: #1a1c20;
    --border: #2b2e33;
  }
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic UI", sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}
main { max-width: var(--max); margin: 0 auto; padding: 0 24px 80px; }
header.site {
  max-width: var(--max); margin: 0 auto; padding: 28px 24px;
  display: flex; align-items: center; justify-content: space-between;
}
header.site .brand { font-weight: 700; font-size: 1.1rem; text-decoration: none; color: var(--fg); }
header.site nav a { margin-left: 20px; text-decoration: none; color: var(--fg-soft); font-size: .95rem; }
header.site nav a:hover { color: var(--accent); }
.hero { text-align: center; padding: 64px 0 48px; }
.hero h1 { font-size: 2.4rem; line-height: 1.4; letter-spacing: .01em; }
.hero p.lead { margin-top: 16px; font-size: 1.15rem; color: var(--fg-soft); }
.hero .cta { margin-top: 32px; display: inline-block; background: var(--accent); color: #fff; padding: 12px 28px; border-radius: 10px; text-decoration: none; font-weight: 600; }
.hero .cta.disabled { background: var(--card); color: var(--fg-soft); border: 1px solid var(--border); cursor: default; }
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; margin-top: 48px; }
.features .card { background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 22px; }
.features .card h3 { font-size: 1.02rem; margin-bottom: 8px; }
.features .card p { font-size: .92rem; color: var(--fg-soft); line-height: 1.7; }
article h1 { font-size: 1.7rem; margin: 48px 0 8px; line-height: 1.5; }
article p.meta { color: var(--fg-soft); font-size: .9rem; margin-bottom: 32px; }
article h2 { font-size: 1.2rem; margin: 40px 0 12px; padding-top: 8px; }
article p, article li { color: var(--fg); font-size: .98rem; }
article ul { padding-left: 1.4em; margin: 12px 0; }
article li { margin: 6px 0; }
article a { color: var(--accent); }
footer.site {
  max-width: var(--max); margin: 0 auto; padding: 32px 24px 48px;
  border-top: 1px solid var(--border);
  color: var(--fg-soft); font-size: .88rem;
  display: flex; flex-wrap: wrap; gap: 8px 24px; justify-content: space-between;
}
footer.site a { color: var(--fg-soft); text-decoration: none; margin-right: 16px; }
footer.site a:hover { color: var(--accent); }
.faq dt { font-weight: 600; margin-top: 28px; }
.faq dd { margin: 8px 0 0; color: var(--fg-soft); }
.notice { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 16px 20px; font-size: .92rem; color: var(--fg-soft); margin: 24px 0; }