:root {
  color-scheme: light;
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --border: #e2e8f0;
  --accent: #2563eb;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
}
main {
  width: min(920px, calc(100% - 32px));
  margin: 32px auto 64px;
}
header, section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 24px;
  margin-bottom: 16px;
}
h1 { margin: 0 0 8px; font-size: clamp(28px, 5vw, 42px); }
h2 { margin-top: 0; font-size: 22px; }
h3 { margin-bottom: 6px; font-size: 17px; }
p, li { color: var(--muted); }
a { color: var(--accent); }
.notice {
  border-left: 4px solid #d97706;
  background: #fffbeb;
  padding: 14px 16px;
  border-radius: 10px;
  color: #92400e;
}
nav a { margin-right: 14px; white-space: nowrap; }
code { background: #eef2ff; padding: 2px 6px; border-radius: 6px; }
footer { color: #64748b; text-align: center; font-size: 13px; }