:root {
  --color-surface: #f2f2f1;
  --color-surface-alt: #eae9e8;
  --color-surface-deep: #dedddb;
  --color-ink: #49453b;
  --color-ink-soft: #706a5c;
  --color-ink-muted: #8a8475;
  --color-line: #d4d3d0;
  --color-primary: #897239;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e3e0d7;
  --color-accent: #b55c1c;
  --color-accent-ink: #ffffff;
  --color-highlight: #e7d7cb;
  --color-focus: #ad5110;
  --color-contrast-surface: #201e16;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #4c4a43;
  --color-contrast-accent: #dd7022;
  --overlay-scrim: linear-gradient(180deg, rgba(32, 30, 22, 0.35) 0%, rgba(32, 30, 22, 0.72) 55%, rgba(32, 30, 22, 0.92) 100%);
  --font-heading: "Songti SC", "Source Han Serif SC", "Noto Serif SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 12.9px;
  --text-sm: 15.5px;
  --text-base: 17px;
  --text-lg: 20.4px;
  --text-xl: 24.5px;
  --text-2xl: 29.4px;
  --text-3xl: 35.3px;
  --text-4xl: 42.3px;
  --text-display: clamp(34px, 5.6vw, 72px);
  --text-figure: clamp(28px, 4.1vw, 52px);
  --weight-heading: 689;
  --weight-body: 400;
  --leading-body: 1.7;
  --leading-heading: 1.2;
  --tracking-heading: 0.008em;
  --radius-sm: 3px;
  --radius-md: 4px;
  --radius-lg: 5px;
  --radius-pill: 5px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: 0 1px 0 rgba(73, 69, 59, 0.12);
  --shadow-2: 0 2px 0 rgba(73, 69, 59, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1100px;
  --measure: 69ch;
  --gutter: 32px;
  --section-y: 74px;
  --section-y-lg: 104px;
}

/* ============================================================
   纸张叠层 · 共享样式表 /assets/site.css
   ============================================================ */

/* ---------- 重置与纸面底纹 ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 132px;
}

body {
  margin: 0;
  background: 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: 0.012em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.55;
  background-image:
    linear-gradient(to right, color-mix(in srgb, var(--color-line) 42%, transparent) 1px, transparent 1px),
    linear-gradient(to bottom, color-mix(in srgb, var(--color-line) 42%, transparent) 1px, transparent 1px);
  background-size: 64px 64px, 64px 64px;
}

body[data-nav-open="true"] { overflow: hidden; }

img, svg, video { display: block; max-width: 100%; height: auto; }
button, input, select, textarea { font: inherit; color: inherit; }
[hidden] { display: none !important; }

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

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

main { display: block; scroll-margin-top: 132px; }

/* ---------- 排版 ---------- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  margin: 0 0 var(--space-2);
  text-wrap: balance;
}

h1 { font-size: var(--text-4xl); }
h2 {
  font-size: var(--text-2xl);
  position: relative;
  padding-left: 15px;
}
h2::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.16em;
  bottom: 0.16em;
  width: 3px;
  background: var(--color-primary);
  border-radius: 1px;
}
h3 { font-family: var(--font-body); font-size: var(--text-lg); font-weight: 600; letter-spacing: 0.004em; }
h4 { font-family: var(--font-body); font-size: var(--text-base); font-weight: 600; }

p { margin: 0 0 var(--space-2); }
ul, ol { margin: 0 0 var(--space-2); padding-left: 1.15em; }
li { margin-bottom: 6px; }

a {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--color-primary) 42%, transparent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}
a:hover { color: var(--color-focus); text-decoration-color: currentColor; }

strong { font-weight: 600; }

.display {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.05;
  letter-spacing: -0.012em;
  margin: 0 0 var(--space-3);
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.01em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  margin: 0 0 var(--space-2);
}
.eyebrow::before {
  content: "";
  width: 22px;
  height: 3px;
  background: var(--color-primary);
  flex: none;
}

.prose { max-width: var(--measure); }
.prose p { color: var(--color-ink-soft); }
.prose h2 { margin-top: var(--space-6); color: var(--color-ink); }
.prose h3 { margin-top: var(--space-4); }
.prose a { font-weight: 500; }

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

/* ---------- 容器与栅格 ---------- */
.wrap {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
  align-items: start;
}
.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-12 { grid-column: 1 / -1; }
.start-2 { grid-column-start: 2; }

@media (max-width: 900px) {
  .col-3, .col-4, .col-5, .col-6, .col-7, .col-8, .col-9 { grid-column: 1 / -1; }
  .start-2 { grid-column-start: auto; }
  .grid { gap: var(--space-3); }
}

/* ---------- 区块节奏 ---------- */
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-4); }
.section--alt { background: var(--color-surface-alt); }
.section--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--deep h2, .section--deep h3 { color: var(--color-contrast-ink); }
.section--deep a { color: var(--color-contrast-accent); }
.section--deep .eyebrow { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }

/* ---------- 页面起始块 ---------- */
.page-head {
  padding-block: var(--space-6) var(--space-4);
  border-bottom: 1px dashed var(--color-line);
}
.page-head__kicker {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
  margin-bottom: var(--space-2);
}
.page-head__title { margin-bottom: var(--space-2); }
.page-head__lede {
  max-width: var(--measure);
  font-size: var(--text-lg);
  color: var(--color-ink-soft);
  margin: 0;
}

/* ---------- 纸张组件 ---------- */
.paper-stack {
  position: relative;
  margin: 0 14px 14px 0;
}
.paper-stack::before,
.paper-stack::after {
  content: "";
  position: absolute;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  z-index: 0;
}
.paper-stack::before {
  inset: 7px -7px -7px 7px;
  background: var(--color-surface-alt);
}
.paper-stack::after {
  inset: 14px -14px -14px 14px;
  background: var(--color-surface-deep);
}
.paper-stack > * { position: relative; z-index: 1; }

.paper-panel {
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-2);
  padding: var(--space-3);
}
.paper-panel--pad-lg { padding: var(--space-4); }
.paper-panel--flat { box-shadow: var(--shadow-1); }

/* ---------- 贴纸标签 ---------- */
.sticker {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  line-height: 1.3;
  padding: 4px 9px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-soft);
  color: var(--color-ink);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 28%, transparent);
  box-shadow: var(--shadow-1);
  transition: transform 140ms cubic-bezier(0.2, 0.7, 0.3, 1), box-shadow 140ms linear;
}
.sticker:hover { transform: translateY(-2px); box-shadow: var(--shadow-2); }
.sticker--accent {
  background: var(--color-highlight);
  color: color-mix(in srgb, var(--color-accent) 78%, var(--color-ink));
  border-color: color-mix(in srgb, var(--color-accent) 34%, transparent);
}
.sticker--corner {
  position: absolute;
  top: -11px;
  left: 16px;
  transform: rotate(-2deg);
  z-index: 3;
}
.sticker--corner-r {
  position: absolute;
  bottom: -11px;
  right: 16px;
  transform: rotate(3deg);
  z-index: 3;
}
.sticker--corner:hover { transform: rotate(-2deg) translateY(-2px); }
.sticker--corner-r:hover { transform: rotate(3deg) translateY(-2px); }

/* ---------- 分隔与切角 ---------- */
.rule-dashed {
  position: relative;
  display: block;
  height: 0;
  border: 0;
  border-top: var(--border-thin) dashed var(--color-line);
  margin: var(--space-4) 0;
}
.rule-dashed::after {
  content: "";
  position: absolute;
  top: -2px;
  left: 0;
  width: 56px;
  height: 3px;
  background: var(--color-primary);
  border-radius: 1px;
}
.slash-cut {
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--slash, 96px)), 0 100%);
}

/* ---------- 数据组件 ---------- */
.data-figure {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--color-accent);
}
.data-figure--ink { color: var(--color-ink); }
.data-label {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  line-height: 1.5;
  color: var(--color-ink-muted);
  margin-top: 6px;
}
.section--deep .data-label { color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent); }

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  padding: var(--space-2) 0;
  border-top: var(--border-thin) dashed var(--color-line);
  border-bottom: var(--border-thin) dashed var(--color-line);
}
.meta-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}
.meta-item b {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-accent);
  letter-spacing: -0.01em;
}

.tag-row { display: flex; flex-wrap: wrap; gap: 8px; padding: 0; margin: 0; list-style: none; }
.tag-row li { margin: 0; }

/* ---------- 图片容器 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-deep);
  box-shadow: var(--shadow-2);
  transition: transform 320ms cubic-bezier(0.2, 0.7, 0.3, 1);
}
.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--offset { margin-top: calc(var(--space-4) * -1); }

.media-frame__caption {
  position: absolute;
  inset: auto 0 0 0;
  padding: 14px 16px 12px;
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  line-height: 1.5;
}
.media-frame__caption b { color: var(--color-contrast-accent); }

.media-frame[data-zoomable] { cursor: zoom-in; }
.media-frame[data-zoomed="true"] { cursor: zoom-out; }
@media (min-width: 901px) {
  .media-frame[data-zoomed="true"] {
    grid-column: 1 / -1;
    aspect-ratio: 16 / 9;
  }
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  line-height: 1.2;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  text-decoration: none;
  cursor: pointer;
  transition: transform 140ms cubic-bezier(0.2, 0.7, 0.3, 1), box-shadow 140ms linear, background-color 140ms linear;
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn--primary {
  background: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-2);
}
.btn--primary:hover { background: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface)); color: var(--color-primary-ink); }
.btn--accent {
  background: var(--color-accent);
  color: var(--color-accent-ink);
  box-shadow: var(--shadow-2);
}
.btn--accent:hover { background: color-mix(in srgb, var(--color-accent) 84%, var(--color-contrast-surface)); color: var(--color-accent-ink); }
.btn--outline {
  background: var(--color-surface);
  color: var(--color-ink);
  border-color: color-mix(in srgb, var(--color-line) 80%, var(--color-ink));
  box-shadow: var(--shadow-1);
}
.btn--outline:hover { background: var(--color-primary-soft); color: var(--color-ink); }
.btn-row { display: flex; flex-wrap: wrap; gap: var(--space-2); margin: var(--space-3) 0 0; }

/* ---------- 面包屑 ---------- */
.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: var(--space-2) 0 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.breadcrumbs li { margin: 0; }
.breadcrumbs li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--color-line);
}
.breadcrumbs a {
  color: var(--color-ink-soft);
  text-decoration: none;
  border-bottom: var(--border-thin) dashed var(--color-line);
}
.breadcrumbs a:hover { color: var(--color-focus); border-bottom-color: currentColor; }

/* ---------- 章节索引 ---------- */
.toc {
  position: sticky;
  top: 118px;
  font-size: var(--text-sm);
}
.toc__title {
  margin: 0 0 10px;
  padding-bottom: 8px;
  border-bottom: var(--border-thin) dashed var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}
.toc ol { list-style: none; margin: 0; padding: 0; counter-reset: toc; }
.toc li { margin: 0; }
.toc a {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 6px 8px 6px 10px;
  border-left: var(--border-thick) solid transparent;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  text-decoration: none;
}
.toc a::before {
  counter-increment: toc;
  content: counter(toc, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.toc a:hover { background: color-mix(in srgb, var(--color-surface-alt) 70%, transparent); color: var(--color-ink); }
.toc a[aria-current="true"] {
  color: var(--color-ink);
  font-weight: 600;
  border-left-color: var(--color-accent);
  background: linear-gradient(90deg, var(--color-highlight), transparent 82%);
}
@media (max-width: 1080px) {
  .toc { position: static; }
}

/* ---------- 折叠细则 ---------- */
.disclosure {
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
  margin-bottom: 10px;
}
.disclosure summary {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--space-2);
  padding: 14px 16px;
  cursor: pointer;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-ink);
  list-style: none;
}
.disclosure summary::-webkit-details-marker { display: none; }
.disclosure summary::after {
  content: "＋";
  font-family: var(--font-mono);
  color: var(--color-primary);
  flex: none;
}
.disclosure[open] summary::after { content: "－"; }
.disclosure[open] summary { border-bottom: var(--border-thin) dashed var(--color-line); }
.disclosure__body {
  padding: 12px 16px 16px;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
}
.disclosure__body > :last-child { margin-bottom: 0; }

/* ---------- 进入视口 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 320ms linear, transform 320ms cubic-bezier(0.2, 0.7, 0.3, 1);
}
[data-reveal][data-revealed="true"] { opacity: 1; transform: none; }
[data-reveal="2"] { transition-delay: 60ms; }
[data-reveal="3"] { transition-delay: 120ms; }

/* ---------- 滚动进度 ---------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  z-index: 100;
  pointer-events: none;
}

/* ---------- 返回顶部 ---------- */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 13px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-2);
  cursor: pointer;
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  transition: opacity 240ms linear, transform 240ms cubic-bezier(0.2, 0.7, 0.3, 1);
}
.back-to-top.is-visible { opacity: 1; transform: none; pointer-events: auto; }
.back-to-top__chapter {
  max-width: 12ch;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--color-accent);
}
.back-to-top__chapter:empty { display: none; }

/* ============================================================
   头部：双层信息导航
   ============================================================ */
.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 200;
  padding: 10px 16px;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  text-decoration: none;
  transform: translateY(-160%);
  transition: transform 180ms cubic-bezier(0.2, 0.7, 0.3, 1);
}
.skip-link:focus { transform: none; color: var(--color-contrast-ink); }

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: var(--color-surface);
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-line) 78%, var(--color-ink));
  transition: box-shadow 220ms linear;
}
.site-header[data-scrolled="true"] { box-shadow: var(--shadow-2); }

/* 上层：品牌说明条 */
.brand-bar {
  background: linear-gradient(180deg, var(--color-surface) 0%, var(--color-surface-alt) 100%);
  max-height: 130px;
  overflow: hidden;
  transition: max-height 320ms cubic-bezier(0.2, 0.7, 0.3, 1), opacity 220ms linear;
}
.site-header[data-scrolled="true"] .brand-bar { max-height: 0; opacity: 0; }

.brand-bar__inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: 96px;
  padding-block: 12px;
}

.brand-bar__tag {
  flex: none;
  writing-mode: vertical-rl;
  transform: rotate(-3deg);
  background: var(--color-primary-soft);
  color: var(--color-ink);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 26%, transparent);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  padding: 10px 5px;
}

.brand-bar__brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex: none;
  text-decoration: none;
  color: var(--color-ink);
}
.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  flex: none;
  background: var(--color-primary);
  color: var(--color-primary-ink);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.02em;
  box-shadow: var(--shadow-1);
}
.brand-mark--inverse {
  background: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}
.brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: 0.01em;
  line-height: 1.1;
}

.brand-bar__line {
  flex: 1 1 auto;
  margin: 0;
  padding-left: var(--space-3);
  border-left: var(--border-thin) dashed var(--color-line);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}
.brand-bar__mail {
  flex: none;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  padding: 5px 9px;
  border: var(--border-thin) dashed var(--color-line);
  border-radius: var(--radius-sm);
}

/* 下层：栏目导航 */
.main-nav {
  position: relative;
  background: var(--color-surface-alt);
  border-top: var(--border-thin) dashed var(--color-line);
}
.main-nav__inner {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding-block: 10px;
}
.nav-drawer { display: contents; }
.nav-drawer__head { display: none; }

.nav-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav-list li { margin: 0; }
.nav-list a {
  display: block;
  padding: 8px 14px;
  font-size: var(--text-sm);
  font-weight: 500;
  line-height: 1.2;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-line) 84%, var(--color-ink));
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-1);
  text-decoration: none;
  transition: transform 140ms cubic-bezier(0.2, 0.7, 0.3, 1), box-shadow 140ms linear, background-color 140ms linear;
}
.nav-list a:hover {
  background: var(--color-primary-soft);
  transform: translateY(-2px);
  box-shadow: var(--shadow-2);
  color: var(--color-ink);
}
.nav-list a[aria-current="page"] {
  background: var(--color-primary-soft);
  border-color: var(--color-primary);
  transform: translateY(2px);
  box-shadow: none;
  color: var(--color-ink);
  font-weight: 600;
}

.main-nav__now {
  margin-left: auto;
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
  white-space: nowrap;
  max-width: 40%;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 8px 12px;
  background: var(--color-surface);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-line) 84%, var(--color-ink));
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink);
  cursor: pointer;
}
.nav-toggle__bars { display: inline-flex; flex-direction: column; gap: 3px; width: 14px; }
.nav-toggle__bars i { display: block; height: 2px; background: var(--color-primary); border-radius: 1px; }
.nav-toggle__bars i:nth-child(1) { width: 14px; }
.nav-toggle__bars i:nth-child(2) { width: 10px; }
.nav-toggle__bars i:nth-child(3) { width: 12px; }

/* ============================================================
   页脚：反色纸
   ============================================================ */
.site-footer {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: 3px solid var(--color-primary);
  padding-block: var(--space-6) var(--space-4);
  margin-top: var(--section-y-lg);
}
.site-footer a {
  color: var(--color-contrast-ink);
  text-decoration: none;
  border-bottom: var(--border-thin) dashed var(--color-contrast-line);
}
.site-footer a:hover { color: var(--color-contrast-accent); border-bottom-color: currentColor; }

.footer-grid {
  display: grid;
  grid-template-columns: 5fr 3fr 4fr;
  gap: var(--space-4);
  padding-bottom: var(--space-4);
}
.footer-brand__name {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1.1;
}
.footer-brand__line {
  margin: 0 0 8px;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
}
.footer-brand__meta {
  margin: 0;
  font-size: var(--text-xs);
  line-height: 1.6;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}
.footer-col__title {
  margin: 0 0 10px;
  padding-bottom: 8px;
  border-bottom: var(--border-thin) dashed var(--color-contrast-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-contrast-accent);
}
.footer-col ul { list-style: none; margin: 0; padding: 0; }
.footer-col li { margin-bottom: 8px; font-size: var(--text-sm); }
.footer-contact li {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-bottom: 10px;
  line-height: 1.5;
}
.footer-contact__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}
.footer-contact .mono { font-size: var(--text-sm); }

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding-top: var(--space-3);
  border-top: var(--border-thin) dashed var(--color-contrast-line);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent);
}
.footer-bottom__note { margin: 0; }
.footer-legal { display: flex; gap: var(--space-2); list-style: none; margin: 0; padding: 0; }
.footer-legal li { margin: 0; }
.footer-sign {
  margin: var(--space-2) auto 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 48%, transparent);
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1080px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
}

@media (max-width: 960px) {
  .brand-bar__inner { min-height: 72px; gap: var(--space-2); }
  .brand-bar__line { display: none; }
  .brand-bar__tag {
    writing-mode: horizontal-tb;
    transform: rotate(-2deg);
    letter-spacing: 0.12em;
    padding: 5px 9px;
  }
  .brand-name { font-size: var(--text-lg); }
}

@media (max-width: 880px) {
  html { scroll-padding-top: 96px; }

  .nav-toggle { display: inline-flex; margin-left: auto; }
  .main-nav__now { display: none; }
  .main-nav__inner { position: relative; }

  .nav-drawer {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: min(86vw, 340px);
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
    padding: 26px 22px 36px;
    background: var(--color-surface);
    border-left: var(--border-thin) dashed var(--color-line);
    box-shadow: -6px 0 0 color-mix(in srgb, var(--color-ink) 8%, transparent);
    overflow-y: auto;
    z-index: 80;
    transform: translateX(102%);
    transition: transform 320ms cubic-bezier(0.2, 0.7, 0.3, 1);
  }
  [data-nav][data-open] .nav-drawer { transform: translateX(0); }

  [data-nav]::after {
    content: "";
    position: fixed;
    inset: 0;
    z-index: 70;
    background: color-mix(in srgb, var(--color-contrast-surface) 58%, transparent);
    opacity: 0;
    pointer-events: none;
    transition: opacity 240ms linear;
  }
  [data-nav][data-open]::after { opacity: 1; pointer-events: auto; }

  .nav-drawer__head {
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding-bottom: var(--space-2);
    border-bottom: var(--border-thin) dashed var(--color-line);
  }
  .nav-drawer__tag {
    align-self: flex-start;
    background: var(--color-primary-soft);
    border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 26%, transparent);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-1);
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    letter-spacing: 0.12em;
    padding: 5px 9px;
    transform: rotate(-2deg);
  }
  .nav-drawer__line { margin: 0; font-size: var(--text-sm); color: var(--color-ink-soft); }
  .nav-drawer__mail {
    font-size: var(--text-xs);
    color: var(--color-ink-muted);
    word-break: break-all;
  }

  .nav-list { flex-direction: column; align-items: stretch; gap: 8px; }
  .nav-list a { padding: 12px 14px; box-shadow: var(--shadow-1); }
  .nav-list a[aria-current="page"] { transform: translateY(2px) translateX(-2px); }

  .nav-toggle { position: relative; z-index: 90; }

  .grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: var(--space-3); }
  .back-to-top { right: 14px; bottom: 14px; }
}

@media (max-width: 720px) {
  .wrap { padding-inline: 18px; }
  .brand-bar__mail { display: none; }
  .page-head { padding-block: var(--space-4) var(--space-3); }
  .page-head__lede { font-size: var(--text-base); }
  h2 { font-size: var(--text-xl); }
  .paper-panel { padding: var(--space-2); }
  .paper-stack { margin-right: 10px; margin-bottom: 10px; }
  .paper-stack::before { inset: 6px -6px -6px 6px; }
  .paper-stack::after { inset: 10px -10px -10px 10px; }
  .back-to-top__chapter { display: none; }
}

/* ---------- 无障碍：减弱动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    transition-delay: 0ms !important;
  }
  [data-reveal] { opacity: 1; transform: none; }
  .btn:hover, .sticker:hover, .nav-list a:hover { transform: none; }
  .back-to-top { transform: none; }
}