:root {
  color-scheme: light;
  --fg: #1c2128;
  --muted: #57606a;
  --accent: #0969da;
  --border: #d0d7de;
  --bg: #ffffff;
  --card: #f6f8fa;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
    "Noto Sans JP", sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.8;
}

header {
  border-bottom: 1px solid var(--border);
  padding: 20px 16px;
}

header .brand {
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
}

header .brand .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  display: inline-block;
}

nav {
  max-width: 720px;
  margin: 10px auto 0;
  display: flex;
  flex-wrap: wrap;
  row-gap: 6px;
  column-gap: 18px;
  font-size: 14px;
}

nav a { color: var(--muted); text-decoration: none; white-space: nowrap; }
nav a:hover { color: var(--accent); text-decoration: underline; }

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 16px 64px;
}

h1 {
  font-size: 26px;
  margin-bottom: 4px;
}

.updated {
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 28px;
}

h2 {
  font-size: 17px;
  margin-top: 32px;
  margin-bottom: 8px;
  border-left: 3px solid var(--accent);
  padding-left: 10px;
}

p { margin: 0 0 14px; font-size: 15px; color: #24292f; }

.notice {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 16px;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 24px;
}

.cards {
  display: grid;
  gap: 12px;
  margin-top: 20px;
}

.card {
  display: block;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
  text-decoration: none;
  color: var(--fg);
}

.card:hover { border-color: var(--accent); }

.card .t { font-weight: 700; font-size: 15px; margin-bottom: 4px; }
.card .d { color: var(--muted); font-size: 13px; }

footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px 48px;
  color: var(--muted);
  font-size: 12.5px;
  border-top: 1px solid var(--border);
}

footer a { color: var(--muted); }