:root {
  color-scheme: light;
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --accent: #2563eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
}

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

.container {
  max-width: 760px;
  margin: 0 auto;
  padding: 32px 20px 64px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px 32px;
  box-shadow: 0 1px 2px rgba(15, 23, 42, 0.04);
}

header {
  margin-bottom: 24px;
}

header h1 {
  margin: 0 0 8px;
  font-size: 1.75rem;
  line-height: 1.3;
}

.meta {
  color: var(--muted);
  font-size: 0.95rem;
}

nav.back {
  margin-bottom: 16px;
  font-size: 0.95rem;
}

h2 {
  margin: 32px 0 12px;
  font-size: 1.2rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 8px;
}

h2:first-of-type {
  margin-top: 0;
}

ul {
  padding-left: 1.25rem;
}

li + li {
  margin-top: 6px;
}

footer {
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.9rem;
}

.extension-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.extension-list li {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
  background: var(--surface);
}

.extension-list li + li {
  margin-top: 12px;
}

.extension-list h2 {
  margin: 0 0 6px;
  border: none;
  padding: 0;
  font-size: 1.1rem;
}

.extension-list p {
  margin: 0 0 10px;
  color: var(--muted);
  font-size: 0.95rem;
}