:root {
  --color-surface: #f5f5f5;
  --color-surface-alt: #eeeded;
  --color-surface-deep: #e3e3e2;
  --color-ink: #605b53;
  --color-ink-soft: #747067;
  --color-ink-muted: #868179;
  --color-line: #dad9d8;
  --color-primary: #81735a;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e5e3df;
  --color-accent: #a85b57;
  --color-accent-ink: #ffffff;
  --color-highlight: #e7d9d9;
  --color-focus: #b44f4b;
  --color-contrast-surface: #201f1b;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #4c4b47;
  --color-contrast-accent: #b67572;
  --overlay-scrim: linear-gradient(180deg, rgba(32, 31, 27, 0.35) 0%, rgba(32, 31, 27, 0.72) 55%, rgba(32, 31, 27, 0.92) 100%);
  --font-heading: "Songti SC", STSong, "Source Han Serif SC", SimSun, serif;
  --font-body: "Songti SC", STSong, "Source Han Serif SC", SimSun, serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 13.0px;
  --text-sm: 14.9px;
  --text-base: 16px;
  --text-lg: 18.4px;
  --text-xl: 21.2px;
  --text-2xl: 24.3px;
  --text-3xl: 28.0px;
  --text-4xl: 32.2px;
  --text-display: clamp(36px, 7.5vw, 96px);
  --text-figure: clamp(30px, 5.4vw, 69px);
  --weight-heading: 429;
  --weight-body: 400;
  --leading-body: 1.95;
  --leading-heading: 1.26;
  --tracking-heading: 0.019em;
  --radius-sm: 0px;
  --radius-md: 1px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1020px;
  --measure: 64ch;
  --gutter: 16px;
  --section-y: 110px;
  --section-y-lg: 154px;
}

/* ==========================================================================
   1. 重置
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  letter-spacing: 0.02em;
}

body, h1, h2, h3, h4, h5, h6, p, li { overflow-wrap: break-word; }

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

p { margin: 0; }
figure, blockquote, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
table { border-collapse: collapse; }
button { font: inherit; color: inherit; background: none; border: 0; }
a { color: var(--color-primary); text-decoration: none; }
hr { border: 0; }

::selection { background-color: var(--color-primary-soft); color: var(--color-ink); }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ==========================================================================
   2. 排版基调（细字重、字距略松、数字用等宽）
   ========================================================================== */

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

.text-sm { font-size: var(--text-sm); }
.text-xs { font-size: var(--text-xs); }
.text-muted { color: var(--color-ink-muted); }
.text-soft { color: var(--color-ink-soft); }
.text-accent { color: var(--color-accent); }

.num,
.figure-num,
time,
[data-num] {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

.eyebrow {
  display: inline-block;
  font-size: var(--text-xs);
  letter-spacing: 0.3em;
  color: var(--color-primary);
}

.display-title {
  display: block;
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.08;
  letter-spacing: 0.02em;
  color: var(--color-ink);
}

.figure-num {
  display: block;
  font-size: var(--text-figure);
  font-weight: var(--weight-body);
  line-height: 1;
  color: var(--color-ink);
}

.link-underline,
.prose a {
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 40%, transparent);
  padding-bottom: 1px;
  transition: border-color 220ms ease-out, color 220ms ease-out;
}

.link-underline:hover,
.prose a:hover {
  border-bottom-color: var(--color-primary);
}

/* ==========================================================================
   3. 布局骨架
   ========================================================================== */

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding-left: var(--space-3);
  padding-right: var(--space-3);
}

.section {
  padding-top: var(--section-y);
  padding-bottom: var(--section-y);
}

.section--lg {
  padding-top: var(--section-y-lg);
  padding-bottom: var(--section-y-lg);
}

.section--tight {
  padding-top: var(--space-8);
  padding-bottom: var(--space-8);
}

.section--ruled { border-top: var(--border-thin) solid var(--color-line); }

.rule {
  height: 0;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  margin: var(--space-6) 0;
}

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.prose > * + * { margin-top: var(--space-3); }
.prose h2 { font-size: var(--text-2xl); margin-top: var(--space-6); }
.prose h3 { font-size: var(--text-lg); margin-top: var(--space-4); }

.prose ul { list-style: none; }
.prose ul > li { position: relative; padding-left: 1.6em; }
.prose ul > li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.95em;
  width: 14px;
  height: var(--border-thin);
  background-color: var(--color-primary);
}
.prose ol { list-style: decimal; padding-left: 1.5em; }
.prose ol > li { padding-left: 0.2em; }
.prose strong { font-weight: var(--weight-heading); color: var(--color-ink); }

/* 12 列栅格 */
.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}

.grid--2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-6); }
.grid--3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: var(--space-6); }
.grid--7-5 { display: grid; grid-template-columns: 7fr 5fr; gap: var(--gutter); }
.grid--5-7 { display: grid; grid-template-columns: 5fr 7fr; gap: var(--gutter); }

.col-2 { grid-column: span 2; }
.col-3 { grid-column: span 3; }
.col-4 { grid-column: span 4; }
.col-5 { grid-column: span 5; }
.col-6 { grid-column: span 6; }
.col-7 { grid-column: span 7; }
.col-8 { grid-column: span 8; }
.col-9 { grid-column: span 9; }
.col-10 { grid-column: span 10; }
.col-12 { grid-column: span 12; }

/* ==========================================================================
   4. 头部：左右分置 + 细线分界
   ========================================================================== */

.skip-link {
  position: fixed;
  top: -80px;
  left: var(--space-2);
  z-index: 200;
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  border-radius: var(--radius-md);
  transition: top 200ms ease-out;
}

.skip-link:focus { top: var(--space-2); }

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 120;
  height: 2px;
  background-color: var(--color-primary);
  transform: scaleX(0);
  transform-origin: 0 50%;
  opacity: 0;
  pointer-events: none;
  transition: opacity 220ms ease-out;
}

.scroll-progress[data-active="true"] { opacity: 1; }

.site-header {
  position: relative;
  z-index: 100;
  background-color: var(--color-surface);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.site-header__inner {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-6);
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-3);
}

.brand {
  display: inline-flex;
  align-items: baseline;
  gap: var(--space-2);
  flex: none;
  color: var(--color-ink);
}

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: 0.14em;
}

.brand__tagline {
  font-size: var(--text-xs);
  letter-spacing: 0.3em;
  color: var(--color-ink-muted);
}

.nav-toggle {
  display: none;
  align-items: center;
  padding: var(--space-1) var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-soft);
  background-color: transparent;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color 220ms ease-out, color 220ms ease-out,
    border-color 220ms ease-out;
}

.nav-toggle:hover {
  background-color: var(--color-primary-soft);
  color: var(--color-ink);
  border-color: var(--color-primary-soft);
}

.nav-toggle[aria-expanded="true"] {
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.site-nav { display: block; }

.site-nav__list {
  display: flex;
  align-items: baseline;
  gap: var(--space-4);
}

.site-nav__item { flex: none; }

.site-nav__link {
  position: relative;
  display: inline-block;
  padding: var(--space-1) 0;
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-ink-soft);
  transition: color 220ms ease-out;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -2px;
  height: var(--border-thin);
  background-color: var(--color-primary);
  opacity: 0;
  transition: opacity 220ms ease-out;
}

.site-nav__link:hover { color: var(--color-ink); }
.site-nav__link:hover::after { opacity: 0.45; }

.site-nav__link[aria-current="page"] { color: var(--color-primary); }
.site-nav__link[aria-current="page"]::after { opacity: 1; }

/* ==========================================================================
   5. 页脚：同色延续 + 细线分层
   ========================================================================== */

.site-footer {
  margin-top: var(--section-y-lg);
  background-color: var(--color-surface);
  border-top: var(--border-thin) solid var(--color-line);
}

.site-footer__inner {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-8) var(--space-3) var(--space-6);
}

.footer-head {
  display: flex;
  align-items: baseline;
  gap: var(--space-3);
  flex-wrap: wrap;
  padding-bottom: var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.footer-brand {
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  letter-spacing: 0.14em;
  color: var(--color-ink);
}

.footer-tagline {
  font-size: var(--text-xs);
  letter-spacing: 0.3em;
  color: var(--color-ink-muted);
}

.footer-nav {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: var(--space-4);
  padding: var(--space-8) 0;
}

.footer__col { min-width: 0; }

.footer__col-title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.22em;
  color: var(--color-ink-muted);
}

.footer__list {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.footer__list a {
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) solid transparent;
  transition: color 220ms ease-out, border-color 220ms ease-out;
}

.footer__list a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.footer__rule {
  height: 0;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  margin: 0 0 var(--space-4);
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
}

.footer-contact {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.9;
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.footer-legal__item { flex: none; }

.footer-legal__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.footer-legal__links a {
  color: var(--color-ink-muted);
  border-bottom: var(--border-thin) solid transparent;
  transition: color 220ms ease-out, border-color 220ms ease-out;
}

.footer-legal__links a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ==========================================================================
   6. 通用组件
   ========================================================================== */

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-4);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  line-height: 1.5;
  letter-spacing: 0.18em;
  color: var(--color-primary);
  background-color: transparent;
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color 220ms ease-out, color 220ms ease-out,
    border-color 220ms ease-out;
}

.btn:hover { background-color: var(--color-primary-soft); }

.btn--solid {
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
}

.btn--solid:hover {
  background-color: color-mix(in srgb, var(--color-primary) 82%, var(--color-ink));
  color: var(--color-primary-ink);
}

.btn--quiet {
  color: var(--color-ink-soft);
  border-color: var(--color-line);
}

.btn--quiet:hover {
  background-color: var(--color-surface-alt);
  color: var(--color-ink);
  border-color: var(--color-line);
}

/* 面包屑 */
.breadcrumb {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
}

.breadcrumb__list li {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
}

.breadcrumb__list li + li::before {
  content: "/";
  color: var(--color-line);
}

.breadcrumb__list a {
  color: var(--color-ink-muted);
  transition: color 220ms ease-out;
}

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

/* 图片容器（图片只贴在纸面上，不用圆角裁切、不加外发光） */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  overflow: hidden;
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
}

.media-frame > img,
.media-frame > picture > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 4 / 5; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--auto { aspect-ratio: auto; }
.media-frame--auto > img { height: auto; }

.media-frame__scrim {
  position: absolute;
  inset: 0;
  background-image: var(--overlay-scrim);
  pointer-events: none;
}

.media-frame__caption {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  font-size: var(--text-xs);
  line-height: 1.7;
  letter-spacing: 0.1em;
  color: var(--color-contrast-ink);
}

.figure { display: block; }

.figure__caption {
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  line-height: 1.8;
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

/* 反色小块：全站唯一强对比手段 */
.invert {
  padding: var(--space-6);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-lg);
}

.invert a { color: var(--color-contrast-ink); }
.invert .rule,
.invert hr { border-top-color: var(--color-contrast-line); }
.invert p { color: var(--color-contrast-ink); }

.invert__label {
  display: inline-block;
  margin-bottom: var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.28em;
  color: var(--color-contrast-accent);
}

.invert__figure {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-figure);
  line-height: 1;
  color: var(--color-contrast-ink);
}

.invert .status-dot { background-color: var(--color-contrast-accent); }

/* 标签与状态 */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 2px 10px;
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-soft);
  background-color: var(--color-surface-alt);
  border-radius: var(--radius-md);
}

.tag--accent {
  color: var(--color-accent);
  background-color: var(--color-highlight);
}

.status-dot {
  display: inline-block;
  flex: none;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--color-accent);
}

/* 结构化表格 */
.data-table {
  width: 100%;
  font-size: var(--text-sm);
  line-height: 1.7;
}

.data-table caption {
  padding-bottom: var(--space-2);
  text-align: left;
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.data-table th,
.data-table td {
  padding: var(--space-2);
  text-align: left;
  vertical-align: top;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.data-table thead th {
  background-color: var(--color-surface-deep);
  color: var(--color-ink-soft);
  font-weight: var(--weight-body);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
}

.data-table tbody tr {
  transition: background-color 220ms ease-out;
}

.data-table tbody tr:hover { background-color: var(--color-primary-soft); }

.data-table td[data-state="on"] { background-color: var(--color-highlight); }

/* 滚动刻度（章节索引） */
.section-index { font-size: var(--text-xs); }

.section-index__list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.section-index__item {
  position: relative;
  padding-left: var(--space-3);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  transition: color 220ms ease-out;
}

.section-index__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 10px;
  height: var(--border-thin);
  background-color: var(--color-line);
  transition: background-color 220ms ease-out;
}

.section-index__item:hover { color: var(--color-ink); }

.section-index__item[data-active="true"] { color: var(--color-accent); }

.section-index__item[data-active="true"]::before {
  background-color: var(--color-accent);
}

/* ==========================================================================
   7. 响应式
   ========================================================================== */

@media (max-width: 1000px) {
  .footer-nav { grid-template-columns: repeat(3, minmax(0, 1fr)); row-gap: var(--space-6); }
}

@media (max-width: 900px) {
  .section { padding-top: var(--space-8); padding-bottom: var(--space-8); }
  .section--lg { padding-top: var(--section-y); padding-bottom: var(--section-y); }
  .site-footer { margin-top: var(--section-y); }
}

@media (max-width: 820px) {
  .grid--2,
  .grid--3,
  .grid--7-5,
  .grid--5-7 { grid-template-columns: minmax(0, 1fr); }

  .col-2, .col-3, .col-4, .col-5, .col-6,
  .col-7, .col-8, .col-9, .col-10, .col-12 { grid-column: 1 / -1; }
}

@media (max-width: 780px) {
  .site-header__inner {
    align-items: center;
    padding-top: var(--space-2);
    padding-bottom: var(--space-2);
    gap: var(--space-3);
  }

  .brand__tagline { display: none; }

  .nav-toggle { display: inline-flex; }

  /* 底部状态栏式索引：不弹全屏菜单，横向可滑动 */
  .site-nav,
  .site-nav[data-open],
  .site-nav[data-open="true"] {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    top: auto;
    z-index: 90;
    background-color: var(--color-surface);
    border-top: var(--border-thin) solid var(--color-line);
    transform: translateY(100%);
    visibility: hidden;
    padding: var(--space-1) 0 calc(var(--space-1) + env(safe-area-inset-bottom, 0px));
    transition: transform 220ms ease-out, visibility 0s linear 220ms;
  }

  .site-nav[data-open="true"] {
    transform: translateY(0);
    visibility: visible;
    transition: transform 220ms ease-out, visibility 0s linear 0s;
  }

  .site-nav__list {
    display: flex;
    flex-direction: row;
    align-items: stretch;
    gap: 0;
    overflow-x: auto;
    overflow-y: hidden;
    padding: 0 var(--space-2);
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
  }

  .site-nav__list::-webkit-scrollbar { display: none; }

  .site-nav__link {
    display: block;
    padding: var(--space-2) var(--space-3);
    font-size: var(--text-xs);
    letter-spacing: 0.2em;
    white-space: nowrap;
  }

  .site-nav__link::after {
    left: var(--space-3);
    right: var(--space-3);
    bottom: 6px;
  }

  .footer-head { padding-bottom: var(--space-4); }
  .footer-nav { grid-template-columns: repeat(2, minmax(0, 1fr)); padding: var(--space-6) 0; }
  .footer-meta { flex-direction: column; align-items: flex-start; }
  .footer-contact { max-width: none; }
}

@media (max-width: 560px) {
  .site-header__inner { padding-left: var(--space-2); padding-right: var(--space-2); }
  .container { padding-left: var(--space-2); padding-right: var(--space-2); }
  .site-footer__inner { padding-left: var(--space-2); padding-right: var(--space-2); }
  .invert { padding: var(--space-4); }
}

/* ==========================================================================
   8. 动效与无障碍
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .site-nav,
  .site-nav[data-open],
  .site-nav[data-open="true"] {
    transition: none !important;
  }

  .scroll-progress { transition: none !important; }
}