:root {
  --bg: #f3efe5;
  --panel: rgba(255, 250, 240, 0.88);
  --panel-strong: #fffaf0;
  --line: #d8cdb7;
  --text: #2a2218;
  --muted: #6f6453;
  --accent: #8b4513;
  --accent-soft: #efe0ca;
  --code-bg: #2a2218;
  --code-text: #f8f4ec;
  --shadow: 0 24px 60px rgba(76, 50, 18, 0.12);
  --font-serif: "Source Han Serif SC", "Noto Serif SC", "Songti SC", serif;
  --font-sans: "LXGW WenKai", "PingFang SC", "Hiragino Sans GB", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(255, 245, 222, 0.85), transparent 35%),
    linear-gradient(180deg, #f7f3e9 0%, #efe4d1 100%);
  font-family: var(--font-sans);
  line-height: 1.75;
}

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

a:hover {
  text-decoration: underline;
}

.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  padding: 24px 18px;
  border-right: 1px solid var(--line);
  background: rgba(255, 248, 235, 0.84);
  backdrop-filter: blur(12px);
}

.book-home {
  display: inline-block;
  margin-bottom: 18px;
  padding: 10px 14px;
  border-radius: 999px;
  background: var(--accent);
  color: #fffaf0;
  font-weight: 700;
}

.sidebar ul,
.page-toc ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.sidebar li {
  margin: 0 0 8px;
  border-radius: 12px;
}

.sidebar li.active,
.sidebar li:hover {
  background: var(--accent-soft);
}

.sidebar li a {
  display: block;
  padding: 10px 12px;
  color: var(--text);
}

.content {
  display: grid;
  grid-template-columns: minmax(0, 920px) 240px;
  gap: 24px;
  padding: 32px 28px 56px;
  align-items: start;
}

.content-index {
  grid-template-columns: minmax(0, 920px);
}

.article,
.page-toc {
  background: var(--panel);
  border: 1px solid rgba(216, 205, 183, 0.72);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.article {
  padding: 40px clamp(20px, 4vw, 56px);
}

.page-toc {
  position: sticky;
  top: 24px;
  padding: 20px;
}

.page-toc h2 {
  margin-top: 0;
  font-size: 1rem;
}

.page-toc li {
  margin-bottom: 10px;
}

.page-toc .toc-level-3 {
  padding-left: 14px;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-serif);
  line-height: 1.25;
  color: #24190d;
}

h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  margin: 0 0 1rem;
}

h2 {
  margin-top: 2.4rem;
  font-size: clamp(1.45rem, 2.3vw, 2rem);
}

h3 {
  margin-top: 1.8rem;
  font-size: 1.25rem;
}

p,
li,
blockquote,
td,
th {
  font-size: 1rem;
}

pre,
code {
  font-family: "SFMono-Regular", "JetBrains Mono", monospace;
}

pre {
  overflow: auto;
  padding: 18px;
  border-radius: 16px;
  background: var(--code-bg);
  color: var(--code-text);
}

code {
  padding: 0.15em 0.35em;
  border-radius: 6px;
  background: rgba(139, 69, 19, 0.08);
}

pre code {
  padding: 0;
  background: transparent;
}

blockquote {
  margin: 1.4rem 0;
  padding: 10px 18px;
  border-left: 4px solid var(--accent);
  background: rgba(139, 69, 19, 0.06);
  color: var(--muted);
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  overflow: hidden;
  border-radius: 16px;
}

th,
td {
  padding: 12px 14px;
  border: 1px solid var(--line);
  vertical-align: top;
}

th {
  background: rgba(139, 69, 19, 0.08);
}

hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 2rem 0;
}

.mermaid-block {
  margin: 1.6rem 0;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--panel-strong);
  overflow: auto;
}

.mermaid {
  min-width: 320px;
}

.pager {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.pager a,
.pager span {
  flex: 1;
}

.pager a:last-child,
.pager span:last-child {
  text-align: right;
}

@media (max-width: 1100px) {
  .content {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-toc {
    position: static;
  }
}

@media (max-width: 860px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    height: auto;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .content {
    padding: 20px 14px 40px;
  }

  .article {
    padding: 28px 18px;
    border-radius: 18px;
  }
}