:root {
  --color-surface: #eceaea;
  --color-surface-alt: #e4e1e1;
  --color-surface-deep: #d8d5d5;
  --color-ink: #493f3c;
  --color-ink-soft: #6f615d;
  --color-ink-muted: #8a7a75;
  --color-line: #cfcbcb;
  --color-primary: #b05e45;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4d6d3;
  --color-accent: #0e7db9;
  --color-accent-ink: #ffffff;
  --color-highlight: #c4d6e1;
  --color-focus: #036da5;
  --color-contrast-surface: #251c19;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #504846;
  --color-contrast-accent: #12a1ed;
  --overlay-scrim: linear-gradient(180deg, rgba(37, 28, 25, 0.35) 0%, rgba(37, 28, 25, 0.72) 55%, rgba(37, 28, 25, 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: 16.1px;
  --text-base: 18px;
  --text-lg: 22.5px;
  --text-xl: 28.1px;
  --text-2xl: 35.2px;
  --text-3xl: 43.9px;
  --text-4xl: 54.9px;
  --text-display: clamp(36px, 7.3vw, 94px);
  --text-figure: clamp(30px, 5.3vw, 68px);
  --weight-heading: 649;
  --weight-body: 400;
  --leading-body: 1.87;
  --leading-heading: 1.25;
  --tracking-heading: 0.003em;
  --radius-sm: 0px;
  --radius-md: 1px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 2px;
  --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: 1060px;
  --measure: 62ch;
  --gutter: 24px;
  --section-y: 85px;
  --section-y-lg: 119px;
}

/* ============ 1. 重置与基础 ============ */
*, *::before, *::after { box-sizing: border-box; }
html {
  background-color: var(--color-surface);
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}
body, h1, h2, h3, h4, h5, h6, p, ul, ol, li, figure, blockquote, dl, dt, dd { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
button { font: inherit; color: inherit; }
table { border-collapse: collapse; }
[hidden] { display: none !important; }

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  color: var(--color-ink);
  background-color: var(--color-surface);
  background-image:
    radial-gradient(120% 70% at 8% -12%, color-mix(in srgb, var(--color-primary-soft) 46%, transparent) 0%, transparent 58%),
    repeating-linear-gradient(0deg, color-mix(in srgb, var(--color-ink) 2.4%, transparent) 0 1px, transparent 1px 4px);
  background-attachment: fixed, fixed;
  min-height: 100%;
  overflow-x: hidden;
}
body.nav-open { overflow: hidden; }

a { color: var(--color-accent); text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--color-primary); }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

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

/* ============ 2. 屏幕阅读器与跳过链接 ============ */
.skip-link {
  position: fixed;
  top: var(--space-1);
  left: var(--space-1);
  z-index: 120;
  transform: translateY(-160%);
  display: inline-block;
  padding: 10px var(--space-2);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-primary-ink);
  background: var(--color-primary);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  text-decoration: none;
}
.skip-link:focus { transform: none; color: var(--color-primary-ink); }

/* ============ 3. 布局容器与栅格 ============ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}
.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}
.layout-split {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
  align-items: start;
}
.layout-split > .main-col { grid-column: 1 / span 8; min-width: 0; }
.layout-split > .tick-gutter {
  grid-column: 9 / span 1;
  align-self: stretch;
  min-height: 100%;
  border-left: var(--border-thin) solid var(--color-line);
  background-image: repeating-linear-gradient(
    180deg,
    var(--color-line) 0 var(--border-thin),
    transparent var(--border-thin) 16px
  );
}
.layout-split > .aside-col { grid-column: 10 / span 3; min-width: 0; }

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.stack > * + * { margin-top: var(--space-3); }

.section-head {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
  align-items: end;
  padding-bottom: var(--space-2);
  margin-bottom: var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.section-head > .section-title { grid-column: 1 / span 8; }
.section-head > .section-note {
  grid-column: 10 / span 3;
  font-size: var(--text-xs);
  line-height: 1.7;
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}
.section-title {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: clamp(var(--text-2xl), 4.1vw, var(--text-3xl));
  line-height: 1.2;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-head {
  padding-block: var(--space-6) var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.eyebrow {
  display: inline-block;
  margin-bottom: var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
}
.lede {
  max-width: var(--measure);
  margin-top: var(--space-2);
  font-size: var(--text-lg);
  line-height: 1.7;
  color: var(--color-ink-soft);
}

.frame-window {
  position: relative;
  padding: var(--space-4);
  border: var(--border-thin) solid var(--color-line);
  background: color-mix(in srgb, var(--color-surface) 88%, var(--color-surface-alt));
}
.frame-window::before {
  content: "";
  position: absolute;
  inset: 6px;
  border: var(--border-thin) solid var(--color-line);
  pointer-events: none;
}
.frame-window > * { position: relative; }

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding-block: var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.breadcrumb a { color: var(--color-ink-soft); text-decoration: none; }
.breadcrumb a:hover { color: var(--color-primary); text-decoration: underline; }
.breadcrumb [aria-current="page"] { color: var(--color-primary); }
.crumb-sep { color: var(--color-ink-muted); }

/* ============ 4. 正文排版 ============ */
.prose { max-width: var(--measure); }
.prose p + p { margin-top: var(--space-3); }
.prose h3 { margin-top: var(--space-4); margin-bottom: var(--space-2); }
.prose ul, .prose ol { margin-top: var(--space-2); }
.prose li { margin-top: 6px; padding-left: var(--space-2); position: relative; }
.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 8px;
  height: 1px;
  background: var(--color-primary);
}

.label-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--color-primary);
  background: var(--color-primary-soft);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
}
.label-tag--ghost {
  color: var(--color-ink-soft);
  background: transparent;
  border-color: var(--color-line);
}
.label-tag--accent {
  color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 12%, var(--color-surface));
  border-color: var(--color-accent);
}

.rule-double {
  height: 5px;
  margin-block: var(--space-4);
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.pull-quote {
  margin-block: var(--space-4);
  padding-left: var(--space-2);
  border-left: 3px solid var(--color-primary);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink);
}
.pull-quote cite {
  display: block;
  margin-top: var(--space-1);
  font-family: var(--font-body);
  font-style: normal;
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.aside-note {
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-sm);
  line-height: 1.75;
  color: var(--color-ink-soft);
}
.aside-note + .aside-note { margin-top: var(--space-3); }
.aside-head {
  display: block;
  margin-bottom: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.mark {
  text-decoration: underline;
  text-decoration-color: var(--color-primary);
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
  color: inherit;
}
.mark--accent { text-decoration-color: var(--color-accent); }
.hl {
  padding: 0 3px;
  background: var(--color-highlight);
  color: var(--color-ink);
}

/* ============ 5. 按钮与控件 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 10px var(--space-3);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--color-primary-ink);
  background: var(--color-primary);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  text-decoration: none;
  cursor: pointer;
}
.btn:hover { color: var(--color-primary-ink); background: color-mix(in srgb, var(--color-primary) 82%, var(--color-ink)); }
.btn--ghost { color: var(--color-primary); background: transparent; }
.btn--ghost:hover { color: var(--color-primary); background: var(--color-primary-soft); }
.btn--accent { color: var(--color-accent-ink); background: var(--color-accent); border-color: var(--color-accent); }
.btn--accent:hover { color: var(--color-accent-ink); background: color-mix(in srgb, var(--color-accent) 82%, var(--color-ink)); }
.btn--line { color: var(--color-ink); background: var(--color-surface); border-color: var(--color-line); }
.btn--line:hover { color: var(--color-primary); background: var(--color-primary-soft); border-color: var(--color-primary); }

/* ============ 6. 数据模块 ============ */
.data-band {
  padding: var(--space-4);
  color: var(--color-contrast-ink);
  background: var(--color-contrast-surface);
  border: var(--border-thin) solid var(--color-contrast-line);
}
.data-band h2, .data-band h3, .data-band h4 { color: var(--color-contrast-ink); }
.data-band a { color: var(--color-contrast-accent); }
.data-band .label-tag {
  color: var(--color-contrast-accent);
  background: transparent;
  border-color: var(--color-contrast-line);
}
.data-band .section-note, .data-band .aside-head, .data-band .stat-label { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }
.data-band .stat { background: transparent; }
.data-band .stat-value { color: var(--color-contrast-ink); }
.data-band .strip-unit, .data-band .stat-unit { color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent); }

.stat-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  background: var(--color-line);
  border: var(--border-thin) solid var(--color-line);
}
.stat { padding: var(--space-3); background: var(--color-surface-alt); }
.stat-value {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(var(--text-xl), 3.4vw, var(--text-3xl));
  line-height: 1.05;
  letter-spacing: -0.01em;
  color: var(--color-ink);
}
.stat-unit {
  margin-left: 4px;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}
.stat-label {
  display: block;
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.table-wrap {
  overflow-x: auto;
  border: var(--border-thin) solid var(--color-line);
  background: var(--color-surface);
}
.data-table {
  width: 100%;
  min-width: 520px;
  font-size: var(--text-sm);
}
.data-table th, .data-table td {
  padding: 10px var(--space-2);
  text-align: left;
  border-bottom: var(--border-thin) solid var(--color-line);
  font-variant-numeric: tabular-nums;
}
.data-table thead th {
  position: sticky;
  top: 0;
  z-index: 1;
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--color-ink);
  background: var(--color-primary-soft);
  border-bottom: var(--border-thick) solid var(--color-primary);
}
.data-table tbody tr:nth-child(even) { background: var(--color-surface-alt); }
.data-table tr.is-current { background: var(--color-highlight); }
.data-table td.num { font-family: var(--font-mono); }
.data-table .flag {
  display: inline-block;
  width: 8px;
  height: 8px;
  background: var(--color-primary);
  transform: rotate(45deg);
}
.data-table .flag--pending {
  background: transparent;
  border: var(--border-thin) solid var(--color-ink-muted);
}

/* ============ 7. 图像容器 ============ */
.media-plate {
  display: block;
  padding: var(--space-1);
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
}
.media-frame {
  position: relative;
  overflow: hidden;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--color-surface-deep);
}
.media-frame--tall { aspect-ratio: 4 / 5; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame img, .media-frame .media-fill {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.media-frame--scrim::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.media-text {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 1;
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.35;
}
.media-caption {
  margin-top: var(--space-1);
  padding-left: var(--space-1);
  border-left: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

/* ============ 8. 目录与引导线 ============ */
.toc {
  padding-block: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.toc-title {
  display: block;
  margin-bottom: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}
.toc-list { display: flex; flex-direction: column; gap: 2px; }
.toc-link {
  display: block;
  padding: 5px 0 5px 10px;
  border-left: var(--border-thick) solid transparent;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  text-decoration: none;
}
.toc-link:hover { color: var(--color-primary); }
.toc-link.is-active,
.toc-link[aria-current="true"] {
  color: var(--color-accent);
  border-left-color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 9%, transparent);
}

.guide-line {
  position: relative;
  height: 56px;
  margin-block: calc(-1 * var(--space-2));
  overflow: hidden;
  pointer-events: none;
}
.guide-line::before {
  content: "";
  position: absolute;
  left: 0;
  bottom: 14px;
  width: 100%;
  height: var(--border-thin);
  background: var(--color-line);
  transform: rotate(-6deg);
  transform-origin: left bottom;
}
.guide-line::after {
  content: "";
  position: absolute;
  right: 4px;
  top: 8px;
  width: 8px;
  height: 8px;
  border: var(--border-thin) solid var(--color-primary);
  transform: rotate(45deg);
}

/* ============ 9. 显现动效 ============ */
[data-reveal] { transition: opacity 0.45s ease, transform 0.45s ease; }
.js [data-reveal]:not(.is-in) { opacity: 0; transform: translateY(12px); }

/* ============ 10. 头部 ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: color-mix(in srgb, var(--color-surface) 93%, var(--color-surface-alt));
}
.read-progress {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: var(--border-thick);
  background: var(--color-primary);
  transform: scaleX(0);
  transform-origin: left center;
}
.header-frame {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-2) var(--space-3) 0;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-bottom: var(--space-2);
}
.header-rule {
  height: 5px;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.brand-block { display: flex; align-items: center; flex: 0 0 auto; }
.brand {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  color: var(--color-ink);
  text-decoration: none;
}
.brand:hover { color: var(--color-ink); }
.brand-mark {
  padding: 4px 8px;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--color-primary-ink);
  background: var(--color-primary);
  border-radius: var(--radius-sm);
}
.brand-words { display: flex; flex-direction: column; }
.brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.2;
  letter-spacing: 0.02em;
  color: var(--color-ink);
}
.brand-line {
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}
.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 8px 10px;
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  cursor: pointer;
}
.nav-toggle:hover { color: var(--color-primary); border-color: var(--color-primary); }
.nav-toggle-bars { display: inline-flex; flex-direction: column; gap: 3px; width: 16px; }
.nav-toggle-bars span { display: block; height: var(--border-thin); background: currentColor; transition: transform 0.2s ease; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(1) { transform: translateY(4px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(3) { transform: translateY(-4px) rotate(-45deg); }

.site-nav {
  display: flex;
  flex: 1 1 auto;
  align-items: center;
  justify-content: flex-end;
  gap: var(--space-3);
  min-width: 0;
}
.nav-list { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-1); }
.nav-link {
  display: inline-block;
  padding: 6px 10px;
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--color-ink-soft);
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  text-decoration: none;
  white-space: nowrap;
}
.nav-link:hover { color: var(--color-primary); background: var(--color-primary-soft); border-color: var(--color-primary); }
.nav-link[aria-current="page"] {
  color: var(--color-primary-ink);
  background: var(--color-primary);
  border-color: var(--color-primary);
}
.nav-tools {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding-left: var(--space-3);
  border-left: var(--border-thin) solid var(--color-line);
}
.tool-group { display: flex; align-items: center; gap: 6px; }
.tool-label { font-size: var(--text-xs); letter-spacing: 0.16em; color: var(--color-ink-muted); white-space: nowrap; }
.chip-row {
  display: flex;
  gap: 1px;
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
}
.chip {
  padding: 4px 8px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  background: transparent;
  border: 0;
  border-radius: 0;
  cursor: pointer;
  white-space: nowrap;
}
.chip:hover { color: var(--color-accent); background: color-mix(in srgb, var(--color-accent) 10%, transparent); }
.chip[aria-pressed="true"] { color: var(--color-accent-ink); background: var(--color-accent); }
.stepper {
  display: flex;
  align-items: center;
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
}
.step {
  width: 26px;
  height: 26px;
  line-height: 1;
  color: var(--color-ink-soft);
  background: transparent;
  border: 0;
  cursor: pointer;
}
.step:hover { color: var(--color-primary); background: var(--color-primary-soft); }
.step-value {
  padding: 0 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
  white-space: nowrap;
}
.nav-scrim {
  position: fixed;
  inset: 0;
  z-index: 70;
  padding: 0;
  background: color-mix(in srgb, var(--color-contrast-surface) 62%, transparent);
  border: 0;
  cursor: pointer;
}

/* ============ 11. 页脚 ============ */
.site-footer {
  margin-top: var(--section-y-lg);
  background: color-mix(in srgb, var(--color-surface-alt) 78%, var(--color-surface));
  border-top: var(--border-thin) solid var(--color-line);
}
.footer-frame {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}
.footer-strip {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-top: calc(-1 * var(--border-thin));
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-inline: var(--border-thin) solid var(--color-contrast-line);
}
.strip-cell {
  padding: var(--space-2) var(--space-3);
  border-left: var(--border-thin) solid var(--color-contrast-line);
}
.strip-cell:first-child { border-left: 0; }
.strip-label {
  display: block;
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}
.strip-value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-xl);
  line-height: 1.3;
  color: var(--color-contrast-ink);
}
.strip-unit {
  margin-left: 4px;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}
.footer-body {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
  padding-block: var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.footer-brand { grid-column: 1 / span 3; }
.footer-name {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1.25;
  color: var(--color-ink);
}
.footer-line { margin-top: 4px; font-size: var(--text-xs); letter-spacing: 0.1em; color: var(--color-ink-muted); }
.footer-cols {
  grid-column: 5 / span 8;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-3);
}
.footer-head {
  display: inline-block;
  margin-bottom: var(--space-2);
  padding-bottom: 4px;
  border-bottom: var(--border-thin) solid var(--color-primary);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--color-primary);
}
.footer-list li + li { margin-top: 6px; }
.footer-list a {
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  text-decoration: none;
}
.footer-list a:hover { color: var(--color-primary); text-decoration: underline; text-underline-offset: 3px; }
.footer-plain { font-size: var(--text-sm); color: var(--color-ink-muted); }
.footer-scale {
  height: 16px;
  border-bottom: var(--border-thin) solid var(--color-line);
  background-image:
    repeating-linear-gradient(to right, var(--color-line) 0 var(--border-thin), transparent var(--border-thin) 14px),
    repeating-linear-gradient(to right, var(--color-ink-muted) 0 var(--border-thin), transparent var(--border-thin) 80px);
  background-size: 100% 5px, 100% 10px;
  background-repeat: no-repeat, no-repeat;
  background-position: left top, left top;
}
.footer-foot {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-1) var(--space-3);
  padding-block: var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
}
.footer-contact { font-family: var(--font-mono); color: var(--color-ink-soft); }
.footer-note { color: var(--color-ink-muted); }
.footer-legal { font-family: var(--font-mono); color: var(--color-ink-muted); }

.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 50;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 12px;
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}
.to-top::before { content: "↑"; font-family: var(--font-mono); }
.to-top[data-visible] { opacity: 1; visibility: visible; }
.to-top:hover { color: var(--color-primary); background: var(--color-primary-soft); border-color: var(--color-primary); }

/* ============ 12. 响应式 ============ */
@media (max-width: 1100px) and (min-width: 961px) {
  .nav-list { gap: 2px; }
  .nav-link { padding: 6px 8px; letter-spacing: 0.1em; }
  .nav-tools { gap: var(--space-1); padding-left: var(--space-2); }
  .tool-label { display: none; }
}

@media (max-width: 960px) {
  .nav-toggle { display: inline-flex; }
  .site-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 80;
    width: min(86vw, 340px);
    display: flex;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: var(--space-3);
    padding: var(--space-6) var(--space-3) var(--space-4);
    overflow-y: auto;
    color: var(--color-contrast-ink);
    background-color: var(--color-contrast-surface);
    background-image: repeating-linear-gradient(
      to right,
      var(--color-contrast-line) 0 var(--border-thin),
      transparent var(--border-thin) 44px
    );
    border-left: var(--border-thick) solid var(--color-contrast-line);
    transform: translateX(102%);
    transition: transform 0.28s ease;
  }
  .site-nav[data-open] { transform: none; }
  .nav-list { flex-direction: column; align-items: stretch; gap: 2px; }
  .nav-link {
    display: block;
    padding: 10px var(--space-2);
    font-size: var(--text-sm);
    color: var(--color-contrast-ink);
    background: transparent;
    border-color: var(--color-contrast-line);
  }
  .nav-link:hover {
    color: var(--color-contrast-ink);
    background: color-mix(in srgb, var(--color-contrast-accent) 20%, transparent);
    border-color: var(--color-contrast-accent);
  }
  .nav-link[aria-current="page"] {
    color: var(--color-contrast-surface);
    background: var(--color-contrast-accent);
    border-color: var(--color-contrast-accent);
  }
  .nav-tools {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
    padding: var(--space-3) 0 0;
    border-left: 0;
    border-top: var(--border-thin) solid var(--color-contrast-line);
  }
  .tool-label { color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent); }
  .chip-row { background: transparent; border-color: var(--color-contrast-line); }
  .chip { color: var(--color-contrast-ink); }
  .chip:hover { color: var(--color-contrast-accent); background: color-mix(in srgb, var(--color-contrast-accent) 18%, transparent); }
  .chip[aria-pressed="true"] { color: var(--color-contrast-surface); background: var(--color-contrast-accent); }
  .stepper { background: transparent; border-color: var(--color-contrast-line); }
  .step { color: var(--color-contrast-ink); }
  .step:hover { background: color-mix(in srgb, var(--color-contrast-accent) 20%, transparent); color: var(--color-contrast-ink); }
  .step-value { color: var(--color-contrast-ink); }

  .layout-split > .main-col,
  .layout-split > .aside-col { grid-column: 1 / -1; }
  .layout-split > .tick-gutter { display: none; }
  .section-head { grid-template-columns: 1fr; align-items: start; }
  .section-head > .section-title,
  .section-head > .section-note { grid-column: 1 / -1; }

  .footer-body { display: block; }
  .footer-brand { margin-bottom: var(--space-4); }
  .footer-cols { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-4) var(--gutter); }
  .footer-strip { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .strip-cell:nth-child(3) { border-left: 0; }
  .strip-cell:nth-child(n + 3) { border-top: var(--border-thin) solid var(--color-contrast-line); }
}

@media (max-width: 560px) {
  .brand-line { display: none; }
  .header-frame { padding-inline: var(--space-2); }
  .container, .footer-frame { padding-inline: var(--space-2); }
  .footer-cols { grid-template-columns: 1fr; }
  .footer-foot { flex-direction: column; align-items: flex-start; }
  .to-top { right: var(--space-2); bottom: var(--space-2); }
  .frame-window { padding: var(--space-3); }
}

/* ============ 13. 动效降级 ============ */
@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;
  }
  .js [data-reveal]:not(.is-in) { opacity: 1; transform: none; }
  .read-progress { transition: none; }
}