:root {
  --bg: #FFFFFE;
  --ink: #101413;
  --sub: #697371;
  --line: #E8ECEA;
  --surface: #F6F8F7;
  --accent: #D8323C;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0E1211;
    --ink: #F2F5F4;
    --sub: #8A9694;
    --line: #232928;
    --surface: #171C1B;
    --accent: #E8555E;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px 90px;
}

/* ヘッダー */
header {
  padding: 54px 0 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: inherit;
}

.mark {
  width: 34px; height: 34px;
  border-radius: 8px;
  position: relative;
  overflow: hidden;
  flex: none;
  background: linear-gradient(115deg,
    #D8323C 0 48.3%, #1A1A1E 48.3% 51.7%, #FFFFFE 51.7% 100%);
  display: flex; align-items: center; justify-content: center;
}
.mark span {
  position: relative;
  font-size: 21px; font-weight: 700; line-height: 1;
  color: #FFFFFE;
  text-shadow: 0 0 2px #1A1A1E, 0 0 2px #1A1A1E, 0 0 1px #1A1A1E;
}

.brand b {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: .16em;
}

nav {
  margin-top: 30px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--line);
  display: flex;
  gap: 22px;
  font-size: 14px;
}
nav a { color: var(--sub); text-decoration: none; }
nav a:hover { color: var(--accent); }
nav a[aria-current] { color: var(--accent); font-weight: 600; }

/* 本文 */
h1 {
  font-size: 30px;
  line-height: 1.5;
  margin: 52px 0 10px;
  letter-spacing: .01em;
}

.lead {
  color: var(--sub);
  font-size: 15px;
  margin: 0 0 44px;
}

h2 {
  font-size: 18px;
  margin: 46px 0 12px;
  padding-top: 26px;
  border-top: 1px solid var(--line);
}

h2:first-of-type { border-top: none; padding-top: 0; }

p, li { font-size: 15px; }
p { margin: 0 0 16px; }
ul { padding-left: 22px; margin: 0 0 16px; }
li { margin-bottom: 7px; }

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

dl { margin: 0; }
dt {
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--sub);
  margin-top: 20px;
}
dd { margin: 3px 0 0; font-size: 15px; }

.card {
  background: var(--surface);
  border-radius: 4px;
  padding: 22px 24px;
  margin: 26px 0;
}
.card p:last-child { margin-bottom: 0; }

.note {
  font-size: 13px;
  color: var(--sub);
}

footer {
  margin-top: 76px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  font-size: 12.5px;
  color: var(--sub);
}
footer a { color: var(--sub); }