/* ============================================================================
   book-parchment.css — Parchment Reader
   Re-skin mdBook with a book-page feel: serif typography (LXGW WenKai),
   wider measure, generous line-height, quiet borders, and a soft "paper" palette
   derived from the existing Catppuccin Latte/Mocha variables (no brand recolor).
   Zero code copied from external themes; only the structural *pattern* of a
   book reader is reused. All colors resolve through mdBook's --bg/--fg/--links
   so theme switching (latte / mocha) still works.
   ============================================================================ */

/* ---- self-hosted serif (subset for this book's character set) ----
   Subsets are produced from LXGW WenKai (OFL-1.1, 2021-2026 LXGW).
   See fonts/OFL.txt for the full license. We host the subset locally so the
   page does not depend on fonts.googleapis.com (unreliable in mainland CN). */
@font-face {
  font-family: "Parchment Serif";
  src: url("./fonts/wenkai-regular.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Parchment Serif";
  src: url("./fonts/wenkai-medium.woff2") format("woff2");
  font-weight: 500 700;
  font-style: normal;
  font-display: swap;
}

:root {
  /* Parchment-specific tokens. All colors are resolved from existing mdBook
     variables so theme switching stays consistent with the rest of the book. */
  --prch-serif: "Parchment Serif", "Source Han Serif SC", "Noto Serif SC",
                 "Songti SC", Georgia, "Times New Roman", serif;
  --prch-mono:  "JetBrains Mono", "SF Mono", ui-monospace, Consolas,
                 "Parchment Serif", monospace;

  --prch-measure: 46rem;        /* ideal reading width ~ 720-740px */
  --prch-measure-wide: 64rem;  /* wide content (figures, tables) on big screens */
  --prch-line: 1.85;            /* book-page rhythm */
  --prch-base:  17px;           /* body font-size */
  --prch-radius: 10px;
  --prch-shadow: 0 1px 2px rgba(0,0,0,.04), 0 8px 24px rgba(0,0,0,.06);

  /* Soften the chrome: top bar is paper, not a slab */
  --prch-bar-bg: color-mix(in srgb, var(--bg) 92%, transparent);
  --prch-line-quiet: color-mix(in srgb, var(--fg) 8%, transparent);
  --prch-line-soft:   color-mix(in srgb, var(--fg) 12%, transparent);

  /* Active nav uses the brand link color, not the loud default */
  --prch-nav-active: var(--links);
}

/* ---------- typography ---------- */
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
}

body {
  font-family: var(--prch-serif);
  font-size: var(--prch-base);
  line-height: var(--prch-line);
  letter-spacing: .005em;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "kern" 1, "liga" 1;
}

code, pre, kbd, .hljs, .mono {
  font-family: var(--prch-mono);
}

p { text-wrap: pretty; }
.content p { margin-block-end: 1em; }

/* ---------- top bar (mdBook's #menu-bar) ---------- */
#menu-bar,
#menu-bar-hover-placeholder {
  background: var(--prch-bar-bg);
  backdrop-filter: saturate(140%) blur(8px);
  -webkit-backdrop-filter: saturate(140%) blur(8px);
  border-block-end: 1px solid var(--prch-line-quiet);
}
#menu-bar {
  font-family: var(--prch-serif);
}
.menu-title {
  font-weight: 500 !important;
  font-size: 1.05rem !important;
  letter-spacing: .01em;
  color: var(--fg);
}
#menu-bar i, #menu-bar .icon-button {
  padding: 0 10px;
  line-height: var(--menu-bar-height);
  color: var(--icons);
  transition: color .16s ease;
}
#menu-bar i:hover, #menu-bar .icon-button:hover {
  color: var(--links);
}

/* ---------- sidebar ---------- */
.sidebar {
  font-family: var(--prch-serif);
  font-size: 14px;
  background-color: var(--sidebar-bg);
  border-inline-end: 1px solid var(--prch-line-quiet);
}
.sidebar .sidebar-scrollbox {
  padding: 14px 14px 24px;
}
.chapter { line-height: 1.9; }
.chapter li.chapter-item {
  line-height: 1.55;
  margin-block-start: .25em;
}
.chapter li a {
  color: var(--sidebar-fg);
  border-radius: 6px;
  padding: 2px 4px;
  transition: background-color .14s ease, color .14s ease;
}
.chapter li a:hover {
  background: color-mix(in srgb, var(--sidebar-fg) 6%, transparent);
  color: var(--prch-nav-active);
}
.chapter li a.active {
  color: var(--prch-nav-active);
  font-weight: 600;
  background: color-mix(in srgb, var(--links) 10%, transparent);
}
.chapter li.part-title {
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--prch-nav-active);
  margin-block: 18px 6px;
  padding-inline-start: 4px;
  opacity: .9;
}
.chapter li > a.toggle { opacity: .55; }
.chapter li > a.toggle:hover { opacity: 1; color: var(--prch-nav-active); }

.spacer {
  height: 1px;
  margin: 14px 0;
  background: var(--prch-line-quiet);
}

/* ---------- main content ----------
   .content fills the available width (viewport minus sidebar). The reading
   measure (~46rem) is applied to *text blocks* (p/li/h*/blockquote/ul/ol)
   so tables, code blocks, figures, and the blockquote-rule can stretch to
   use the leftover width on wide screens — only text lines stay book-width. */
.content {
  padding: 28px 0 60px;
  font-family: var(--prch-serif);
}

/* text blocks: cap the reading measure but center within the wide container */
.content > h1:first-child,
.content > p,
.content > ul,
.content > ol,
.content > blockquote,
.content > dl,
.content > h2,
.content > h3,
.content > h4,
.content > h5,
.content > h6 {
  max-width: var(--prch-measure);
  margin-inline-start: 0;
  margin-inline-end: auto;
}
/* headings centered to the measure block */
.content > h1:first-child,
.content > h2,
.content > h3,
.content > h4,
.content > h5,
.content > h6 {
  margin-inline-start: 0;
}

/* page title block — mdBook renders <h1> at top of .content */
.content > h1:first-child {
  font-size: 2.05rem;
  font-weight: 600;
  line-height: 1.25;
  margin: 6px 0 28px;
  letter-spacing: .005em;
  color: var(--fg);
}
.content h2 {
  font-size: 1.45rem;
  font-weight: 600;
  line-height: 1.35;
  margin: 2em 0 .6em;
  letter-spacing: .005em;
  color: var(--fg);
  border-bottom: 1px solid var(--prch-line-quiet);
  padding-bottom: .25em;
}
.content h3 {
  font-size: 1.18rem;
  font-weight: 600;
  margin: 1.6em 0 .5em;
  color: var(--fg);
}
.content h4, .content h5, .content h6 {
  font-size: 1.02rem;
  font-weight: 600;
  margin: 1.2em 0 .4em;
  color: var(--fg);
}
.content strong { color: var(--fg); }
.content em { font-style: italic; }

.content ul, .content ol { margin-block-end: 1em; padding-inline-start: 1.4em; }
.content li { margin-block-end: .35em; }
.content li::marker { color: var(--links); }

/* links — quiet underline appears on hover */
.content a:link,
.content a:visited,
#searchresults a {
  color: var(--links);
  text-decoration: underline;
  text-decoration-color: transparent;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: text-decoration-color .16s ease, color .16s ease;
}
.content a:hover {
  color: var(--links);
  text-decoration-color: var(--links);
}

/* ---------- blockquote ---------- */
.content blockquote {
  margin: 1.2em .4em 1.2em 1em;
  padding: .1em 0 .1em 1.1em;
  border-inline-start: 3px solid var(--prch-line-soft);
  color: color-mix(in srgb, var(--fg) 78%, transparent);
  font-style: italic;
  background: transparent;
}

.content hr {
  border: 0;
  border-top: 1px solid var(--prch-line-quiet);
  margin: 2em 0;
}

/* ---------- inline code ---------- */
:not(pre) > .hljs {
  font-family: var(--prch-mono);
  font-size: .85em;
  padding: .08em .35em;
  border-radius: 5px;
  background: color-mix(in srgb, var(--fg) 7%, transparent);
  color: var(--inline-code-color);
  border: 1px solid var(--prch-line-quiet);
}

/* ---------- code blocks ---------- */
pre {
  border: 1px solid var(--prch-line-quiet);
  border-radius: var(--prch-radius);
  background: var(--quote-bg);
  box-shadow: var(--prch-shadow);
  overflow: hidden;
}
pre > code {
  padding: 1rem 1.15rem;
  font-size: 13.5px;
  line-height: 1.65;
  font-family: var(--prch-mono);
  letter-spacing: 0;
}
.hljs { background: var(--quote-bg); }

/* tighten the copy button position to sit in the rounded corner */
pre > .buttons { top: 6px; right: 6px; }

/* ---------- tables ---------- */
.content table {
  width: 100%;
  max-width: var(--prch-measure-wide);
  border-collapse: collapse;
  font-size: 14.5px;
  line-height: 1.65;
  margin: 1.2em 0;
  border: 1px solid var(--prch-line-quiet);
  border-radius: var(--prch-radius);
  overflow: hidden;
}
.content th {
  text-align: left;
  font-weight: 600;
  color: var(--fg);
  padding: 10px 14px;
  background: color-mix(in srgb, var(--links) 6%, transparent);
  border-bottom: 1.5px solid var(--prch-line-soft);
}
.content td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--prch-line-quiet);
}
.content tbody tr:last-child td { border-bottom: 0; }
.content tbody tr { transition: background .12s ease; }
.content tbody tr:hover { background: color-mix(in srgb, var(--links) 4%, transparent); }

/* ---------- figures ---------- */
.content figure { margin: 1.6em 0; max-width: var(--prch-measure-wide); }
.content figure img {
  max-width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
  border-radius: var(--prch-radius);
  background: var(--bg);
  border: 1px solid var(--prch-line-quiet);
}

/* ---------- search ---------- */
#searchbar {
  border-radius: 999px;
  padding: 8px 16px;
  font-family: var(--prch-serif);
  border: 1px solid var(--prch-line-soft);
}
#searchbar:focus {
  border-color: var(--links);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--links) 18%, transparent);
}
ul#searchresults li { border-radius: 6px; padding: 4px 8px; }
ul#searchresults li.focus {
  background: color-mix(in srgb, var(--links) 10%, transparent);
}

/* ---------- theme picker ---------- */
.theme-popup {
  border-radius: 8px;
  box-shadow: var(--prch-shadow);
  font-family: var(--prch-serif);
}

/* ---------- nav chapter arrows (wide) ---------- */
.nav-chapters {
  color: color-mix(in srgb, var(--fg) 35%, transparent);
  font-family: var(--prch-serif);
  transition: color .16s ease, background-color .16s ease;
}
.nav-chapters:hover {
  color: var(--links);
  background-color: color-mix(in srgb, var(--links) 6%, transparent);
}

/* ---------- progress bar (injected by book-enhance.js) ---------- */
#prch-progress {
  position: fixed; inset: 0 0 auto 0; height: 2px; z-index: 60;
  background: transparent; pointer-events: none;
}
#prch-progress > span {
  display: block; height: 100%; width: 0;
  background: var(--links);
  transition: width .1s linear;
}

/* ---------- to-top button (injected by book-enhance.js) ---------- */
#prch-totop {
  position: fixed; right: 22px; bottom: 22px; z-index: 45;
  width: 40px; height: 40px;
  display: grid; place-items: center;
  border-radius: var(--prch-radius);
  background: var(--bg);
  color: var(--fg);
  border: 1px solid var(--prch-line-soft);
  box-shadow: var(--prch-shadow);
  font-family: var(--prch-serif);
  font-size: 18px; line-height: 1;
  cursor: pointer;
  opacity: 0; pointer-events: none;
  transform: translateY(6px);
  transition: opacity .2s ease, transform .2s ease, color .16s ease, border-color .16s ease;
}
#prch-totop.show {
  opacity: 1; pointer-events: auto; transform: none;
}
#prch-totop:hover {
  color: var(--links);
  border-color: var(--links);
}

/* ---------- focus visibility ---------- */
a:focus-visible, button:focus-visible, input:focus-visible {
  outline: 2px solid var(--links);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---------- print ---------- */
@media print {
  body { font-size: 11pt; line-height: 1.6; }
  .content { max-width: none; padding: 0; }
  pre, .content table { break-inside: avoid; }
  .content h1, .content h2, .content h3 { break-after: avoid; }
  #menu-bar, .sidebar, #prch-progress, #prch-totop { display: none !important; }
}

/* ---------- responsive ---------- */
@media only screen and (max-width: 720px) {
  body { font-size: 16.5px; line-height: 1.8; }
  .content { padding: 22px 0 48px; }
  .content > h1:first-child { font-size: 1.7rem; }
  .content h2 { font-size: 1.25rem; }
}