:root { color-scheme: light dark; }
* { box-sizing: border-box; }
body {
  margin: 0; padding: 0;
  font-family: system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.8; color: #23202b; background: #f3efe6;
}
header { padding: 20px 20px 0; }
.brand { font-weight: 900; font-size: 20px; letter-spacing: .04em; color: #23202b; text-decoration: none; }
main { max-width: 720px; margin: 0 auto; padding: 20px; }
h1 { font-size: 26px; margin: 24px 0 8px; }
h2 { font-size: 17px; margin: 28px 0 6px; }
p { margin: 8px 0; font-size: 15px; }
.lead { font-size: 16px; }
.card { background: #fffdf8; border: 1px solid #e0d9c8; border-radius: 12px; padding: 16px 18px; margin: 20px 0; }
.card p { font-size: 14px; margin: 4px 0; }
.logo { display: block; width: min(260px, 70%); margin: 8px auto 0; }
a { color: #3f6f4f; }
footer { max-width: 720px; margin: 40px auto 32px; padding: 0 20px; font-size: 13px; color: #6b6577; }
footer a { color: #6b6577; }
@media (prefers-color-scheme: dark) {
  body { color: #ece9f2; background: #131a26; }
  .brand { color: #ece9f2; }
  .card { background: #1b2333; border-color: #2b3446; }
  a { color: #8fd0a6; }
  footer, footer a { color: #9aa3b5; }
}