:root {
  --bg: #fbfaf7;
  --fg: #1d1d1f;
  --muted: #6b6b70;
  --accent: #c8102e;
  --card: #ffffff;
  --line: #e6e3dc;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131315;
    --fg: #f2f2f3;
    --muted: #9a9aa0;
    --accent: #ff4d63;
    --card: #1c1c1f;
    --line: #2d2d31;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 17px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Hiragino Sans", "Noto Sans JP", sans-serif;
}
a { color: var(--accent); }
.wrap { max-width: 680px; margin: 0 auto; padding: 0 20px; }
header.site { border-bottom: 1px solid var(--line); }
header.site .wrap {
  display: flex; align-items: center; justify-content: space-between;
  height: 60px;
}
.brand { font-weight: 700; color: var(--fg); text-decoration: none; font-size: 1.05rem; }
nav a { margin-left: 18px; color: var(--muted); text-decoration: none; font-size: .95rem; }
nav a:hover { color: var(--fg); }
main { padding: 48px 0 64px; }
h1 { font-size: 2.1rem; line-height: 1.2; margin: 0 0 12px; }
h2 { font-size: 1.25rem; margin: 40px 0 8px; }
p, li { color: var(--fg); }
.lede { font-size: 1.2rem; color: var(--muted); margin-bottom: 28px; }
.btn {
  display: inline-block; background: var(--accent); color: #fff;
  padding: 13px 22px; border-radius: 12px; text-decoration: none; font-weight: 600;
}
.btn.disabled { background: var(--line); color: var(--muted); cursor: default; }
.card {
  background: var(--card); border: 1px solid var(--line);
  border-radius: 14px; padding: 18px 20px; margin: 20px 0;
}
.muted { color: var(--muted); font-size: .92rem; }
ul { padding-left: 22px; }
footer { border-top: 1px solid var(--line); padding: 24px 0 40px; color: var(--muted); font-size: .9rem; }
footer a { color: var(--muted); margin-right: 16px; }