/* @font-face {
  font-family: "LXGW WenKai GB";
  src: url("./fonts/LXGWWenKaiGB-Regular.ttf") format("truetype");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
} */

:root {
  --bg: #f6f8fb;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --line: #e5e7eb;
  --accent: #2563eb;
  --accent-bg: #eff6ff;
  --title1-color: #273849; /*深藏青 */
  --title2-color: #003399; /*深海蓝*/
  --title3-color: #008833; /*草木绿*/
  --title4-color: #E66100; /*暖橙色*/
  --title5-color: #772299; /*葡萄紫*/
  --title6-color: #008899; /*湖青色*/
  --shadow: 0 10px 28px rgba(15, 23, 42, 0.08);

  /* 桌面端整体宽度：左侧大纲 300 + 间距 28 + 正文卡片约 960 + 两侧 padding 48 ≈ 1336 */
  --page-width: 1340px;
  --side-width: 300px;
  --gap-width: 28px;
  --topbar-height: 58px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  width: 100%;
  max-width: 100%;
  overflow-x: hidden;
  scroll-behavior: smooth;
}

body {
  width: 100%;
  max-width: 100%;
  margin: 0;
  overflow-x: hidden;
  overscroll-behavior-x: none;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI",
               "Microsoft YaHei", "Noto Sans CJK SC", Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.8;
  /* 【新增这一行】为 fixed 导航栏预留空间，高度与导航栏一致 */
  padding-top: var(--topbar-height);
}

body.drawer-open {
  overflow: hidden;
}

/* =========================
   防止移动端横向滑动/轻微拉宽回弹
   ========================= */

.topbar,
.desktop-topbar,
.mobile-topbar,
.content,
article,
.toc-panel,
.drawer,
.drawer-toc,
.chapter-nav,
.chapter-nav-bottom {
  max-width: 100%;
}

.content,
article {
  overflow-wrap: break-word;
  word-break: normal;
}

/* =========================
   顶部导航通用
   ========================= */

.topbar {
  position: fixed; /* 【修改】从 sticky 改为 fixed */
  top: 0;
  left: 0;         /* 【新增】 */
  right: 0;        /* 【新增】 */
  margin: 0 auto;  /* 【新增】配合 left/right 0 保证桌面端限制宽度时居中 */
  width: 100%;     /* 【新增】确保背景色铺满 */
  z-index: 50;
  height: var(--topbar-height);
  background: rgba(246, 248, 251, 0.96);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
  transition: transform 0.2s ease-out; /* 建议将 0.12s 改为 0.2s，动画更自然 */
  will-change: transform;
}

.topbar.hide {
  transform: translateY(-100%);
}

.topbar:not(.hide) {
  transform: translateY(0) !important;
}

/* =========================
   桌面端顶部导航
   首页 | 上一章 | 本章标题 | 下一章
   ========================= */

.desktop-topbar {
  max-width: var(--page-width);
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 86px var(--side-width) minmax(280px, 1fr) auto;
  column-gap: 18px;
  align-items: center;
}

.topbar-home {
  grid-column: 1;
  text-align: left;
}

.topbar-prev {
  grid-column: 2;
  text-align: left;
}

.topbar-title {
  grid-column: 3;
  text-align: center;
  font-size: 20px;
  font-weight: 800;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topbar-next {
  grid-column: 4;
  text-align: right;
}

.topbar-btn {
  display: inline-block;
  max-width: 100%;
  padding: 8px 15px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  background: var(--card);
  text-decoration: none;
  font-size: 15px;
  line-height: 1.45;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.04);
}

.topbar-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-bg);
}

.topbar-btn.home {
  color: white;
  background: var(--accent);
  border-color: var(--accent);
  font-weight: 800;
  min-width: 64px;
  text-align: center;
}

.topbar-btn.disabled {
  color: #9ca3af;
  background: #f3f4f6;
  box-shadow: none;
}

/* =========================
   手机端顶部导航
   ☰ | 本章标题
   ========================= */

.mobile-topbar {
  display: none;
}

.menu-btn {
  width: 38px;
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--card);
  cursor: pointer;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.04);
}

.menu-btn span {
  width: 17px;
  height: 2px;
  border-radius: 999px;
  background: var(--text);
}

.menu-btn:hover {
  border-color: var(--accent);
  background: var(--accent-bg);
}

.mobile-title {
  min-width: 0;
  text-align: center;
  font-size: 17px;
  font-weight: 800;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* =========================
   抽屉
   ========================= */

.drawer-mask {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: none;
  background: rgba(15, 23, 42, 0.35);
}

.drawer-mask.open {
  display: block;
}

.drawer {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 90;
  width: min(390px, 88vw);
  max-width: 88vw;
  height: 100vh;
  background: var(--card);
  box-shadow: 18px 0 42px rgba(15, 23, 42, 0.18);
  transform: translateX(-105%);
  transition: transform 0.22s ease;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

.drawer.open {
  transform: translateX(0);
}

.drawer-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 42px;
  gap: 12px;
  align-items: center;
  padding: 18px 18px 14px;
  border-bottom: 1px solid var(--line);
}

.drawer-title {
  font-size: 18px;
  font-weight: 800;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.drawer-close {
  width: 38px;
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  color: var(--text);
  font-size: 24px;
  line-height: 1;
  cursor: pointer;
}

.drawer-close:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-bg);
}

.drawer-nav {
  display: grid;
  gap: 10px;
  padding: 16px 18px;
  border-bottom: 1px solid var(--line);
}

.drawer-link {
  display: block;
  padding: 10px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  background: var(--card);
  text-align: center;
  text-decoration: none;
  font-size: 15px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.drawer-link:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-bg);
}

.drawer-link.home {
  color: white;
  background: var(--accent);
  border-color: var(--accent);
  font-weight: 800;
}

.drawer-link.disabled {
  color: #9ca3af;
  background: #f3f4f6;
}

.drawer-toc {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 14px 14px 18px;
}

/* =========================
   主体布局
   ========================= */

.layout {
  max-width: var(--page-width);
  margin: 0 auto;
  padding: 8px 24px 70px;
  display: grid;
  grid-template-columns: var(--side-width) minmax(0, 1fr);
  gap: var(--gap-width);
  align-items: start;
}

/* =========================
   本章大纲
   电脑端固定悬停；不随正文滚动
   ========================= */

.toc-panel {
  position: fixed;
  left: max(24px, calc((100vw - var(--page-width)) / 2 + 24px));
  top: var(--topbar-height);

  width: var(--side-width);
  height: calc(100vh - var(--topbar-height));

  overflow-y: auto;
  overflow-x: hidden;

  padding: 12px 20px 20px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--card);
  box-shadow: var(--shadow);

  z-index: 30;
}

.toc-toggle {
  width: 100%;
  display: block;
  margin: 0 0 8px;
  padding: 0;
  border: none;
  background: transparent;
  color: var(--text);
  text-align: left;
  font-size: 18px;
  font-weight: 800;
  cursor: pointer;
}

.toc-toggle::after {
  content: "  ▾";
  color: var(--muted);
  font-size: 14px;
}

.toc-collapsed .toc-toggle::after {
  content: "  ▸";
}

.toc-collapsed .toc-content {
  display: none;
}

/* Pandoc TOC 容器 */
.toc-content,
.drawer-toc {
  margin: 0;
  padding: 0;
}

.toc-content nav,
.drawer-toc nav,
.toc-content #TOC,
.drawer-toc #TOC {
  margin: 0;
  padding: 0;
}

/*
  彻底去掉 Pandoc TOC 的所有 ul/ol/li 项目符号。
*/
.toc-content ul,
.drawer-toc ul,
.toc-content ol,
.drawer-toc ol,
.toc-content nav ul,
.drawer-toc nav ul,
.toc-content nav ol,
.drawer-toc nav ol,
.toc-content #TOC ul,
.drawer-toc #TOC ul,
.toc-content #TOC ol,
.drawer-toc #TOC ol {
  list-style: none !important;
  list-style-type: none !important;
  list-style-image: none !important;
  margin: 0 !important;
  padding-left: 0 !important;
}

.toc-content li,
.drawer-toc li,
.toc-content nav li,
.drawer-toc nav li,
.toc-content #TOC li,
.drawer-toc #TOC li {
  list-style: none !important;
  list-style-type: none !important;
  list-style-image: none !important;
  display: block !important;
  margin: 2px 0 !important;
  padding-left: 0 !important;
}

.toc-content li::marker,
.drawer-toc li::marker,
.toc-content nav li::marker,
.drawer-toc nav li::marker,
.toc-content #TOC li::marker,
.drawer-toc #TOC li::marker {
  content: "" !important;
  font-size: 0 !important;
  color: transparent !important;
}

.toc-content li::before,
.drawer-toc li::before,
.toc-content nav li::before,
.drawer-toc nav li::before,
.toc-content #TOC li::before,
.drawer-toc #TOC li::before {
  content: none !important;
  display: none !important;
}

/* 层级缩进：每一级约两个空格视觉距离 */
.toc-content ul ul,
.drawer-toc ul ul,
.toc-content ol ol,
.drawer-toc ol ol,
.toc-content ul ol,
.drawer-toc ul ol,
.toc-content ol ul,
.drawer-toc ol ul {
  padding-left: 1em !important;
}

/* 链接样式 */
.toc-content a,
.drawer-toc a {
  display: block;
  padding: 3px 4px;
  border: none;
  border-radius: 7px;
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  line-height: 1.5;
  word-break: break-word;
}

.toc-content a:hover,
.drawer-toc a:hover {
  color: var(--accent);
  background: var(--accent-bg);
}

.toc-empty {
  color: var(--muted);
  font-size: 13px;
}

/* =========================
   大纲滚动条：窄一点、浅一点
   ========================= */

.toc-panel::-webkit-scrollbar,
.drawer-toc::-webkit-scrollbar {
  width: 4px;
}

.toc-panel::-webkit-scrollbar-track,
.drawer-toc::-webkit-scrollbar-track {
  background: transparent;
}

.toc-panel::-webkit-scrollbar-thumb,
.drawer-toc::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.22);
  border-radius: 999px;
}

.toc-panel::-webkit-scrollbar-thumb:hover,
.drawer-toc::-webkit-scrollbar-thumb:hover {
  background: rgba(100, 116, 139, 0.45);
}

.toc-panel,
.drawer-toc {
  scrollbar-width: thin;
  scrollbar-color: rgba(148, 163, 184, 0.45) transparent;
}

/* =========================
   正文卡片
   ========================= */

.content {
  grid-column: 2;
  min-width: 0;
  padding: 34px 40px 44px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--card);
  box-shadow: var(--shadow);
  overflow-x: hidden;
}

article {
  /* 正文实际阅读宽度，接近 ChatGPT 的舒适阅读宽度，不让一行文字过长 */
  max-width: 880px;
  margin: 0 auto;
}

/* 正文排版 */
h1, h2, h3, h4, h5 {
  line-height: 1.35;
  scroll-margin-top: 88px;
}

h1 {
  margin-top: 0;
  font-size: 34px;
  color: var(--title1-color);
}

h2 {
  margin-top: 2.2em;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
  font-size: 26px;
  color: var(--title2-color);
}

h3 {
  margin-top: 1.8em;
  font-size: 22px;
  color: var(--title3-color);
}

h4 {
  margin-top: 1.5em;
  font-size: 18px;
  color: var(--title4-color);
}

h5 {
  margin-top: 1.5em;
  font-size: 17px;
  color: var(--title5-color);
}

h6 {
  margin-top: 1.5em;
  font-size: 16px;
  color: var(--title6-color);
}

p {
  margin: 0.8em 0;
  font-size: 14px;
}

li {
  font-size: 14px;
}

a {
  color: var(--accent);
}

/* 图片控制 */
img {
  display: block;
  max-width: 82%;
  max-height: 680px;
  width: auto;
  height: auto;
  margin: 22px auto;
  border-radius: 8px;
  box-shadow: 0 4px 18px rgba(15, 23, 42, 0.13);
}

figure {
  margin: 24px auto;
  text-align: center;
}

figcaption {
  margin-top: 8px;
  color: var(--muted);
  font-size: 14px;
}

/* 表格 */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 22px 0;
  font-size: 14px;
}

th, td {
  border: 1px solid #d1d5db;
  padding: 8px 10px;
  vertical-align: top;
}

th {
  background: #f3f4f6;
  font-weight: 700;
}

/* 代码块 */
pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 14px;
  border-radius: 10px;
  background: #f6f8fa;
}

code {
  font-family: Consolas, Monaco, "Courier New", monospace;
}

blockquote {
  margin: 18px 0;
  padding: 10px 16px;
  border-left: 4px solid var(--accent);
  background: #f8fafc;
  color: #374151;
}

/* =========================
   底部导航
   ========================= */

.chapter-nav {
  display: grid;
  align-items: center;
}

.chapter-nav-bottom {
  grid-template-columns: 1fr auto 1fr;
  column-gap: 12px;
  margin-top: 44px;
  padding: 24px 0 0;
  border-top: 1px solid var(--line);
}

.nav-left {
  text-align: left;
}

.nav-center {
  text-align: center;
}

.nav-right {
  text-align: right;
}

.nav-btn {
  display: inline-block;
  max-width: 100%;
  padding: 9px 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  background: var(--card);
  text-decoration: none;
  font-size: 15px;
  line-height: 1.45;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.04);
}

.nav-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-bg);
}

.nav-btn.home {
  color: white;
  background: var(--accent);
  border-color: var(--accent);
  font-weight: 700;
  min-width: 70px;
  text-align: center;
}

.nav-btn.disabled {
  color: #9ca3af;
  background: #f3f4f6;
  box-shadow: none;
}

/* 回到顶部 */
.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 60;
  display: none;
  width: 42px;
  height: 42px;
  border: none;
  border-radius: 50%;
  color: white;
  background: var(--accent);
  font-size: 20px;
  cursor: pointer;
  box-shadow: var(--shadow);
}

.back-to-top.show {
  display: block;
}

/* =========================
   响应式
   ========================= */

@media (max-width: 1100px) {
  :root {
    --side-width: 260px;
    --gap-width: 22px;
  }

  .desktop-topbar {
    grid-template-columns: 74px var(--side-width) minmax(220px, 1fr) auto;
    column-gap: 12px;
  }

  .topbar-title {
    font-size: 18px;
  }

  .content {
    padding: 28px 30px 38px;
  }

  p {
    font-size: 14px;
  }

  li {
    font-size: 14px;
  }
}

/* 平板和手机 */
@media (max-width: 980px) {
  .desktop-topbar {
    display: none;
  }

  .mobile-topbar {
    display: grid;
    grid-template-columns: 44px minmax(0, 1fr) 44px;
    column-gap: 8px;
    align-items: center;
    padding: 0 10px;
  }

  .menu-btn {
    display: inline-flex;
  }

  .layout {
    display: block;
    width: 100%;
    max-width: 100vw;
    margin: 0;
    padding: 14px 10px 48px;
  }

  .toc-panel {
    display: none;
  }

  .content {
    grid-column: auto;
    width: 100%;
    max-width: 100%;
    min-width: 0;
    padding: 28px 24px 36px;
    overflow-x: hidden;
  }

  article {
    width: 100%;
    max-width: 100%;
  }

  img {
    max-width: 100%;
  }

  pre {
    max-width: 100%;
    overflow-x: auto;
  }

  .content table {
    display: block;
    width: 100%;
    max-width: 100%;
    overflow-x: auto;
    white-space: nowrap;
  }
}

/* 桌面端隐藏手机导航 */
@media (min-width: 981px) {
  .mobile-topbar {
    display: none;
  }

  .desktop-topbar {
    display: grid;
  }
}

/* 小屏幕 */
@media (max-width: 640px) {
  :root {
    --topbar-height: 50px;
  }

  .mobile-topbar {
    width: 100%;
    max-width: 100vw;
    height: var(--topbar-height);
    overflow: hidden;
  }

  .mobile-title {
    font-size: 16px;
  }

  .menu-btn {
    width: 36px;
    height: 36px;
    border-radius: 12px;
  }

  .drawer {
    width: min(88vw, 360px);
    max-width: 88vw;
  }

  .drawer-header {
    padding: 14px 14px 12px;
  }

  .drawer-title {
    font-size: 16px;
  }

  .drawer-nav {
    padding: 14px;
  }

  .drawer-toc {
    padding: 14px;
  }

  .layout {
    width: 100%;
    max-width: 100vw;
    padding: 14px 10px 48px;
  }

  .content {
    width: 100%;
    max-width: 100%;
    padding: 22px 16px 30px;
    border-radius: 16px;
    overflow-x: hidden;
  }

  article {
    width: 100%;
    max-width: 100%;
    overflow-wrap: break-word;
  }

  h1 {
    font-size: 26px;
  }

  h2 {
    font-size: 22px;
  }

  h3 {
    font-size: 19px;
  }

  p,
  li {
    font-size: 16px;
  }

  img {
    max-width: 100%;
    height: auto;
  }

  pre {
    max-width: 100%;
    overflow-x: auto;
  }

  .content table {
    display: block;
    width: 100%;
    max-width: 100%;
    overflow-x: auto;
    white-space: nowrap;
  }

  .chapter-nav-bottom {
    grid-template-columns: 1fr;
    row-gap: 12px;
  }

  .nav-left,
  .nav-center,
  .nav-right {
    text-align: center;
  }

  .nav-btn {
    width: 100%;
  }

  .back-to-top {
    right: 16px;
    bottom: 16px;
  }
}