:root {
  --primary: #174267;
  --primary-strong: #123651;
  --accent: #1f75be;
  --paper: #ffffff;
  --canvas: #f4f7fb;
  --ink: #1f2a37;
  --muted: #5d6b7a;
  --border: #d8e0ea;
}

body {
  font-family: "Inter", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--canvas);
}

.book .book-summary {
  background: #ffffff;
  border-right: 1px solid var(--border);
}

.book .book-summary ul.summary li a,
.book .book-summary ul.summary li span {
  color: #314457;
  font-weight: 500;
}

.book .book-summary ul.summary li.active > a {
  color: var(--primary-strong);
  border-left: 3px solid var(--accent);
  background: #eef5fc;
}

.book .book-header {
  background: #ffffff;
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 6px rgba(16, 38, 59, 0.06);
}

.book .book-header h1 {
  opacity: 1;
  text-align: left;
  color: var(--primary-strong);
  font-weight: 700;
}

.book .book-body .page-wrapper .page-inner {
  max-width: 980px;
}

.book .book-body .page-wrapper .page-inner section.normal {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 2rem 2.2rem;
  margin-top: 1rem;
  margin-bottom: 1.4rem;
  box-shadow: 0 6px 16px rgba(28, 43, 58, 0.05);
}

#header .title {
  margin-bottom: 0.2em;
  color: var(--primary-strong);
}

#header h4.author {
  margin: 0;
  color: var(--muted);
}

#header h4.author em {
  font-style: normal;
}

p,
li {
  line-height: 1.75;
}

h1,
h2,
h3,
h4 {
  color: var(--primary-strong);
  font-weight: 700;
  line-height: 1.3;
}

h1 {
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.45rem;
}

a {
  color: var(--accent);
  text-underline-offset: 2px;
}

a:hover {
  color: var(--primary);
}

p.caption {
  color: var(--muted);
  margin-top: 10px;
}

p code,
li code {
  background: #f1f5fa;
  border: 1px solid #d8e3ef;
  border-radius: 5px;
  padding: 0.08rem 0.32rem;
}

pre code {
  white-space: inherit;
}

pre {
  word-break: normal;
  word-wrap: normal;
  background: #f7faff !important;
  border: 1px solid #d3deea !important;
  border-radius: 8px;
}

table {
  width: 100%;
  border-collapse: collapse;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}

table thead {
  background: #f0f5fb;
}

table th,
table td {
  padding: 0.55rem 0.65rem;
  border-bottom: 1px solid #e4ebf3;
}

blockquote {
  border-left: 4px solid #9ec0df;
  background: #f6f9fd;
  padding: 0.7rem 1rem;
  color: #2d3e50;
}

@media (max-width: 900px) {
  .book .book-body .page-wrapper .page-inner section.normal {
    border-radius: 0;
    border-left: 0;
    border-right: 0;
    padding: 1.3rem;
  }
}