:root {
  --bg: #f7f9fc;
  --card: #fff;
  --muted: #666;
  --accent: #0366d6;
  --maxw: 1200px;
  color-scheme: light;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Noto Sans JP",
    "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", sans-serif;
  background: var(--bg);
  color: #111;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  padding: 1.5rem;
}

.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
}

header {
  display: flex;
  gap: 1rem;
  align-items: center;
  border-bottom: 1px solid #e3e7ec;
  padding-bottom: 1rem;
  margin-bottom: 1.25rem;
}

.cover {
  width: 200px;
  flex: 0 0 200px;
}

.cover img {
  width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: 6px;
  display: block;
  box-shadow: 0 6px 18px rgba(20, 30, 40, 0.06);
}

h1 {
  font-size: 2rem;
  margin: 0;
}

.meta {
  font-size: 0.9rem;
  color: var(--muted);
  margin-top: 0.5rem;
}

nav {
  margin-top: 0.75rem;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* .grid removed (unused) */

main {
  min-width: 0;
}

h2 {
  margin-top: 0;
  font-size: 0.98rem;
}

ul,
ol {
  margin-top: 0.35rem;
  padding-left: 1.1rem;
}

aside .card {
  position: sticky;
  top: 1.25rem;
}

nav {
  margin-top: 1rem;
  border-radius: 10px;
  box-shadow: 0 1px 6px rgba(20, 30, 40, 0.05);
}

nav .toc li {
  margin-bottom: 0.45rem;
}
nav .meta-row {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  color: var(--muted);
  font-size: 0.9rem;
}
nav footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
  margin-top: 1.25rem;
}

@media (max-width: 700px) {
  header {
    flex-direction: column;
    align-items: flex-start;
  }
  .cover {
    width: 160px;
    flex: 0 0 160px;
  }
}

@media (max-width: 880px) {
  .cover {
    display: none;
  }
}