:root {
  color-scheme: light;
  --paper: #f7f3eb;
  --paper-deep: #eee7dc;
  --ink: #27231f;
  --muted: #716a61;
  --line: #d9d0c4;
  --accent: #9a5d3b;
  --focus: #245f78;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--paper);
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  margin: 0;
  color: var(--ink);
  background: var(--paper);
}

a {
  color: inherit;
}

a:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.75rem;
  left: 0.75rem;
  padding: 0.7rem 0.9rem;
  color: #fff;
  background: var(--focus);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.library-header {
  width: min(1100px, calc(100% - 2rem));
  min-height: 4.5rem;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border-bottom: 1px solid var(--line);
}

.library-brand {
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
}

.library-nav {
  display: flex;
  align-items: center;
  gap: clamp(1rem, 3vw, 2rem);
  color: var(--muted);
  font-size: 0.85rem;
}

.library-nav a {
  padding: 0.45rem 0;
  text-decoration: none;
}

.library-nav a:hover,
.library-nav a:focus-visible {
  color: var(--accent);
}

.document-shell {
  width: min(1100px, calc(100% - 2rem));
  margin: 0 auto;
}

.document-hero {
  max-width: 760px;
  padding: clamp(3.5rem, 8vw, 6.5rem) 0 clamp(2.5rem, 5vw, 4rem);
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  margin: 0 0 0.85rem;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.document-hero h1 {
  margin: 0;
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: clamp(2.25rem, 5vw, 4rem);
  font-weight: 500;
  line-height: 1.16;
  letter-spacing: -0.025em;
}

.document-description {
  max-width: 42rem;
  margin: 1.25rem 0 0;
  color: var(--muted);
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: 1.02rem;
  line-height: 1.8;
}

.document-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem 1.1rem;
  margin-top: 1.4rem;
  color: var(--muted);
  font-size: 0.76rem;
}

.document-actions a {
  color: var(--accent);
  text-underline-offset: 0.18em;
}

.document-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem 0.8rem;
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
  color: var(--muted);
  font-size: 0.74rem;
}

.document-tags a {
  text-decoration: none;
}

.document-tags a:hover,
.document-tags a:focus-visible {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 0.2rem;
}

.document-layout {
  display: grid;
  grid-template-columns: minmax(0, 760px) minmax(11rem, 14rem);
  gap: clamp(2.5rem, 7vw, 6rem);
  justify-content: space-between;
  align-items: start;
  padding: clamp(2.5rem, 6vw, 5rem) 0 6rem;
}

.document-toc-shell {
  position: sticky;
  top: 1.5rem;
  min-width: 0;
}

.document-toc {
  max-height: calc(100vh - 3rem);
  overflow: auto;
  padding-left: 1rem;
  border-left: 1px solid var(--line);
}

.document-toc summary {
  cursor: pointer;
  color: var(--accent);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.toc-list {
  display: grid;
  gap: 0.62rem;
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
  font-size: 0.78rem;
  line-height: 1.5;
}

.toc-list a {
  color: var(--muted);
  text-decoration: none;
}

.toc-list a:hover,
.toc-list a:focus-visible {
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 0.2rem;
}

.toc-level-3 {
  padding-left: 0.85rem;
}

.toc-empty {
  margin: 1rem 0 0;
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.6;
}

.markdown-body {
  min-width: 0;
  font-family: Georgia, "Songti SC", "STSong", serif;
  font-size: 1.02rem;
  line-height: 1.9;
}

.markdown-body > :first-child {
  margin-top: 0;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4 {
  scroll-margin-top: 1.5rem;
  line-height: 1.4;
}

.markdown-body h1 {
  font-size: 2rem;
}

.markdown-body h2 {
  margin-top: 3.4rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  font-size: 1.65rem;
}

.markdown-body h3 {
  margin-top: 2.4rem;
  font-size: 1.28rem;
}

.markdown-body h4 {
  margin-top: 2rem;
  font-size: 1.05rem;
}

.markdown-body p,
.markdown-body ul,
.markdown-body ol,
.markdown-body blockquote {
  margin: 1.1rem 0;
}

.markdown-body a {
  color: #7e4d33;
  text-decoration-thickness: 0.06em;
  text-underline-offset: 0.18em;
}

.markdown-body img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 2rem auto;
  border: 1px solid var(--line);
}

.markdown-body blockquote {
  padding: 0.15rem 0 0.15rem 1.15rem;
  border-left: 0.2rem solid #c79573;
  color: var(--muted);
}

.markdown-body pre {
  max-width: 100%;
  overflow: auto;
  padding: 1.1rem 1.25rem;
  border: 1px solid #3c3935;
  border-radius: 0.2rem;
  color: #f1eee8;
  background: #292724;
  font: 0.86rem/1.7 "Cascadia Code", "SFMono-Regular", Consolas, monospace;
}

.markdown-body code {
  padding: 0.1rem 0.25rem;
  border-radius: 0.15rem;
  color: #744128;
  background: #eadfd3;
  font: 0.88em "Cascadia Code", "SFMono-Regular", Consolas, monospace;
}

.markdown-body pre code {
  padding: 0;
  color: inherit;
  background: transparent;
}

.markdown-body table {
  display: block;
  width: 100%;
  max-width: 100%;
  margin: 1.5rem 0;
  overflow-x: auto;
  border-collapse: collapse;
  font-size: 0.86rem;
}

.markdown-body th,
.markdown-body td {
  padding: 0.65rem 0.72rem;
  border: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.markdown-body th {
  background: var(--paper-deep);
}

.markdown-body .align-left {
  text-align: left;
}

.markdown-body .align-center {
  text-align: center;
}

.markdown-body .align-right {
  text-align: right;
}

.markdown-body hr {
  margin: 3rem 0;
  border: 0;
  border-top: 1px solid var(--line);
}

.library-footer {
  width: min(1100px, calc(100% - 2rem));
  min-height: 5.5rem;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
  font-size: 0.75rem;
}

.library-footer a {
  color: var(--accent);
  text-underline-offset: 0.18em;
}

@media (max-width: 800px) {
  .document-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 2rem;
  }

  .document-toc-shell {
    position: static;
    grid-row: 1;
  }

  .document-toc {
    max-height: none;
    padding: 0.9rem 1rem;
    border: 1px solid var(--line);
  }

  .markdown-body {
    grid-row: 2;
  }
}

@media (max-width: 520px) {
  .library-header,
  .document-shell,
  .library-footer {
    width: min(100% - 1.25rem, 1100px);
  }

  .library-nav {
    gap: 0.85rem;
    font-size: 0.78rem;
  }

  .document-hero {
    padding-top: 3rem;
  }

  .document-actions {
    display: grid;
    gap: 0.45rem;
  }

  .library-footer {
    align-items: flex-start;
    flex-direction: column;
    justify-content: center;
  }
}

@media print {
  .library-header,
  .document-toc-shell,
  .library-footer,
  .document-actions {
    display: none;
  }

  body {
    background: #fff;
  }

  .document-shell {
    width: 100%;
  }

  .document-layout {
    display: block;
    padding-top: 2rem;
  }
}