:root {
  --color-surface: #f5f5f4;
  --color-surface-alt: #edeceb;
  --color-surface-deep: #e1e0de;
  --color-ink: #4c443e;
  --color-ink-soft: #756a61;
  --color-ink-muted: #8a7f75;
  --color-line: #d7d5d3;
  --color-primary: #9d6a3e;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e9e2db;
  --color-accent: #297cb7;
  --color-accent-ink: #ffffff;
  --color-highlight: #d0dfe9;
  --color-focus: #1b72b1;
  --color-contrast-surface: #231d18;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4e4945;
  --color-contrast-accent: #2f8dd0;
  --overlay-scrim: linear-gradient(180deg, rgba(35, 29, 24, 0.35) 0%, rgba(35, 29, 24, 0.72) 55%, rgba(35, 29, 24, 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: 13.7px;
  --text-sm: 16.4px;
  --text-base: 18px;
  --text-lg: 21.6px;
  --text-xl: 25.9px;
  --text-2xl: 31.1px;
  --text-3xl: 37.3px;
  --text-4xl: 44.8px;
  --text-display: clamp(34px, 6.2vw, 80px);
  --text-figure: clamp(28px, 4.5vw, 58px);
  --weight-heading: 693;
  --weight-body: 400;
  --leading-body: 1.87;
  --leading-heading: 1.19;
  --tracking-heading: -0.001em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --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: 1100px;
  --measure: 65ch;
  --gutter: 24px;
  --section-y: 75px;
  --section-y-lg: 105px;
}

/* =========================================================
   1. RESET 与基础
   ========================================================= */
*,
*::before,
*::after { box-sizing: border-box; }

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

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);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img,
svg,
video {
  display: block;
  max-width: 100%;
  height: auto;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

p { margin: 0 0 var(--space-3); }

a {
  color: var(--color-accent);
  text-decoration: none;
  text-underline-offset: 0.2em;
}

a:hover { text-decoration: underline; text-decoration-thickness: 1px; }

button { font: inherit; color: inherit; }

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

/* =========================================================
   2. 排版
   ========================================================= */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-2);
  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: clamp(var(--text-2xl), 4.6vw, var(--text-4xl)); }
h2 { font-size: clamp(var(--text-xl), 3.4vw, var(--text-3xl)); }
h3 { font-size: var(--text-lg); }
h4 { font-size: var(--text-base); }

.display-title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  line-height: 1.06;
  letter-spacing: var(--tracking-heading);
  margin: 0 0 var(--space-3);
}

.prose { max-width: var(--measure); }
.prose > *:last-child { margin-bottom: 0; }

.lede {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.66;
  color: var(--color-ink);
}

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

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

.figure {
  display: block;
  margin-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-variant-numeric: tabular-nums;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--color-primary);
}

.section--deep .figure { color: var(--color-contrast-accent); }

/* =========================================================
   3. 布局
   ========================================================= */
.wrap {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--flush { padding-block: 0; }
.section--alt { background: var(--color-surface-alt); }

.section--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-block: var(--border-thin) solid var(--color-contrast-line);
}

.section--deep h1,
.section--deep h2,
.section--deep h3,
.section--deep h4 { color: var(--color-contrast-ink); }

.section--deep a { color: var(--color-contrast-accent); }

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

.rail__main { grid-column: 1 / span 8; }
.rail__aside { grid-column: 10 / span 3; }

.grid {
  display: grid;
  gap: var(--gutter);
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.span-full { grid-column: 1 / -1; }

/* =========================================================
   4. 印刷标签 / 跨栏标题 / 引文 / 旁注 / 分隔线
   ========================================================= */
.tag {
  display: inline-block;
  padding: 3px 9px;
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  line-height: 1.5;
  letter-spacing: 0.01em;
}

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

.tag--soft {
  background: var(--color-primary-soft);
  border-color: var(--color-primary-soft);
  color: var(--color-ink);
}

.tag--line {
  background: transparent;
  border-color: var(--color-line);
  color: var(--color-ink-soft);
}

.section--deep .tag {
  background: var(--color-contrast-accent);
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}

.cross-title {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
}

.section--deep .cross-title { border-top-color: var(--color-contrast-line); }

.cross-title h2 {
  margin: 0;
  font-size: clamp(var(--text-2xl), 3.6vw, var(--text-4xl));
}

.cross-title__no,
.cross-title-no {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  transition: background-color 200ms ease, color 200ms ease;
}

.cross-title[data-active] .cross-title__no,
.cross-title[data-active] .cross-title-no {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.pullquote {
  margin: var(--space-4) 0;
  padding: var(--space-3) var(--space-3) var(--space-3) var(--space-4);
  border-left: 2px solid var(--color-primary);
  background: var(--color-primary-soft);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink);
}

.pullquote > *:last-child { margin-bottom: 0; }

.section--deep .pullquote {
  background: color-mix(in srgb, var(--color-contrast-surface) 78%, var(--color-contrast-accent));
  border-left-color: var(--color-contrast-accent);
  color: var(--color-contrast-ink);
}

.aside-note {
  font-size: calc(var(--text-base) * 0.8);
  line-height: 1.75;
  color: var(--color-ink-soft);
}

.aside-note h3,
.aside-note h4 {
  margin-bottom: var(--space-1);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--color-ink-muted);
}

.aside-note > *:last-child { margin-bottom: 0; }

.section--deep .aside-note {
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
}

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

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

.section--deep .rule,
.section--deep .rule--double {
  border-color: var(--color-contrast-line);
}

/* =========================================================
   5. 按钮
   ========================================================= */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 11px 20px;
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-primary);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  line-height: 1.4;
  text-align: left;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 140ms ease, color 140ms ease, border-color 140ms ease;
}

.btn:hover {
  background: var(--color-primary);
  color: var(--color-primary-ink);
  text-decoration: none;
}

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

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

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

.btn--quiet:hover {
  border-color: var(--color-accent);
  background: var(--color-highlight);
  color: var(--color-accent);
}

.btn--onDark {
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}

.btn--onDark:hover {
  border-color: var(--color-contrast-accent);
  background: var(--color-contrast-accent);
  color: var(--color-accent-ink);
}

/* =========================================================
   6. 表格与数据
   ========================================================= */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

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

.data-table th,
.data-table td {
  padding: 11px 14px;
  text-align: left;
  vertical-align: top;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.data-table thead th {
  background: var(--color-surface-deep);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  font-weight: 600;
  white-space: nowrap;
}

.data-table tbody tr:nth-child(even) { background: var(--color-surface-alt); }
.data-table tbody tr[aria-selected="true"] { background: var(--color-highlight); }

.section--deep .data-table th,
.section--deep .data-table td { border-bottom-color: var(--color-contrast-line); }

.section--deep .data-table thead th {
  background: color-mix(in srgb, var(--color-contrast-surface) 70%, var(--color-contrast-line));
  color: var(--color-contrast-ink);
}

.section--deep .data-table tbody tr:nth-child(even) {
  background: color-mix(in srgb, var(--color-contrast-surface) 88%, var(--color-contrast-line));
}

/* =========================================================
   7. 图片容器
   ========================================================= */
.media {
  position: relative;
  overflow: hidden;
  background: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

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

.media--16x9 { aspect-ratio: 16 / 9; }
.media--4x3 { aspect-ratio: 4 / 3; }
.media--1x1 { aspect-ratio: 1 / 1; }
.media--21x9 { aspect-ratio: 21 / 9; }

.media--duo > img {
  filter: grayscale(1) contrast(1.08) brightness(0.96);
}

.media--duo::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(
    150deg,
    color-mix(in srgb, var(--color-accent) 42%, transparent),
    color-mix(in srgb, var(--color-primary) 58%, transparent)
  );
  mix-blend-mode: multiply;
}

.media__caption {
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

.media__overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: flex-end;
  padding: var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.6;
}

/* =========================================================
   8. 档案条目
   ========================================================= */
.entry {
  display: block;
  padding: var(--space-3) 0;
  border-top: var(--border-thin) solid var(--color-line);
  color: inherit;
  text-decoration: none;
}

.entry:hover { text-decoration: none; }

.entry__title {
  margin: var(--space-1) 0 4px;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.32;
  color: var(--color-ink);
  transition: color 140ms ease;
}

.entry:hover .entry__title { color: var(--color-accent); }

.entry__meta {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.entry__text {
  margin: var(--space-1) 0 0;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

.section--deep .entry { border-top-color: var(--color-contrast-line); }
.section--deep .entry__title { color: var(--color-contrast-ink); }
.section--deep .entry__text { color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent); }

/* =========================================================
   9. 折叠面板
   ========================================================= */
.fold { border-top: var(--border-thin) solid var(--color-line); }
.fold:last-of-type { border-bottom: var(--border-thin) solid var(--color-line); }

.fold__head {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  width: 100%;
  padding: 14px 0;
  border: 0;
  background: transparent;
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 600;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
  transition: color 140ms ease;
}

.fold__head:hover { color: var(--color-accent); }
.fold__head[aria-expanded="true"] { color: var(--color-accent); }

.fold__no {
  flex: none;
  padding: 2px 7px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-soft);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
}

.fold__sign {
  flex: none;
  margin-left: auto;
  font-family: var(--font-mono);
  color: var(--color-ink-muted);
}

.fold__sign::after { content: "+"; }
.fold__head[aria-expanded="true"] .fold__sign::after { content: "–"; }

.fold__body {
  padding: 0 0 var(--space-3);
  font-size: var(--text-sm);
  line-height: 1.8;
  color: var(--color-ink-soft);
}

.fold__body[hidden] { display: none; }

.section--deep .fold,
.section--deep .fold:last-of-type { border-color: var(--color-contrast-line); }
.section--deep .fold__head { color: var(--color-contrast-ink); }
.section--deep .fold__body { color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent); }

/* =========================================================
   10. 面包屑与章节导航
   ========================================================= */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding-block: var(--space-3);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.crumbs li { display: flex; align-items: center; gap: var(--space-1); }
.crumbs li + li::before { content: "/"; color: var(--color-line); }
.crumbs a { color: var(--color-ink-soft); }
.crumbs a:hover { color: var(--color-accent); }
.crumbs [aria-current="page"] { color: var(--color-ink); }

.spy {
  position: sticky;
  top: var(--space-3);
  font-size: var(--text-xs);
}

.spy__title {
  margin: 0 0 var(--space-2);
  padding-bottom: var(--space-1);
  border-bottom: var(--border-thin) solid var(--color-line);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-ink-muted);
}

.spy a {
  display: block;
  padding: 6px 0 6px 12px;
  border-left: 2px solid var(--color-line);
  color: var(--color-ink-soft);
  text-decoration: none;
  transition: color 140ms ease, border-color 140ms ease;
}

.spy a:hover { color: var(--color-accent); text-decoration: none; }

.spy a[aria-current="true"] {
  border-left-color: var(--color-accent);
  color: var(--color-accent);
}

/* =========================================================
   11. 头部
   ========================================================= */
.site-header {
  position: relative;
  z-index: 50;
}

.skip-link {
  position: fixed;
  left: var(--space-2);
  top: -100px;
  z-index: 90;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  text-decoration: none;
}

.skip-link:focus {
  top: var(--space-2);
  text-decoration: none;
}

.read-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  z-index: 70;
  pointer-events: none;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  transform: scaleX(0);
  transform-origin: 0 50%;
}

.topbar {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.topbar__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-block: 15px;
}

.topbar__brand {
  display: block;
  color: var(--color-contrast-ink);
  text-decoration: none;
}

.topbar__brand:hover { text-decoration: none; }

.topbar__mark {
  display: block;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1.14;
  letter-spacing: var(--tracking-heading);
}

.topbar__sub {
  display: block;
  margin-top: 5px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.5;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
  transition: color 140ms ease;
}

.topbar__brand:hover .topbar__sub { color: var(--color-contrast-accent); }

.topbar__note {
  max-width: 34ch;
  margin: 0;
  padding-left: 10px;
  border-left: 2px solid var(--color-primary);
  font-size: var(--text-xs);
  line-height: 1.6;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
}

.nav-bar {
  background: var(--color-surface);
  border-bottom: 4px double var(--color-line);
}

.nav-bar__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-3);
}

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

.nav__link {
  display: inline-block;
  padding: 15px 0 13px;
  border-bottom: 2px solid transparent;
  color: var(--color-ink);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: color 140ms ease, border-color 140ms ease;
}

.nav__link:hover {
  color: var(--color-accent);
  text-decoration: none;
}

.nav__link[aria-current="page"] {
  border-bottom-color: var(--color-accent);
  color: var(--color-accent);
}

.nav-bar__cta {
  flex: none;
  display: inline-flex;
  align-items: center;
  padding: 9px 16px;
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  color: var(--color-primary);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: background-color 140ms ease, color 140ms ease;
}

.nav-bar__cta:hover {
  background: var(--color-primary);
  color: var(--color-primary-ink);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 9px 12px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-ink);
  font-size: var(--text-sm);
  cursor: pointer;
}

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

.nav-toggle__bars {
  display: block;
  width: 16px;
  height: 7px;
  border-top: var(--border-thin) solid currentColor;
  border-bottom: var(--border-thin) solid currentColor;
}

.nav-toggle__text { font-size: var(--text-sm); }

/* =========================================================
   12. 页脚
   ========================================================= */
.site-footer {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: 4px double var(--color-contrast-line);
}

.footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-block: var(--space-4);
  font-size: var(--text-xs);
}

.footer__brand {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.footer__links a {
  padding-bottom: 2px;
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
  text-decoration: none;
  transition: color 140ms ease, border-color 140ms ease;
}

.footer__links a:hover {
  border-bottom-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
  text-decoration: none;
}

.footer__meta {
  margin: 0;
  font-family: var(--font-mono);
  line-height: 1.6;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

/* =========================================================
   13. 动效
   ========================================================= */
.js-reveal [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
}

.js-reveal [data-reveal][data-revealed] {
  opacity: 1;
  transform: none;
  transition: opacity 220ms ease, transform 220ms ease;
}

/* =========================================================
   14. 工具类
   ========================================================= */
.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.stack > * + * { margin-top: var(--space-3); }
.flow-sm > * + * { margin-top: var(--space-2); }

.deep-note {
  font-size: var(--text-sm);
  line-height: 1.75;
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
}

/* =========================================================
   15. 响应式
   ========================================================= */
@media (max-width: 1080px) {
  .rail__main { grid-column: 1 / -1; }
  .rail__aside { grid-column: 1 / -1; }
}

@media (max-width: 900px) {
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 820px) {
  .section { padding-block: calc(var(--section-y) * 0.78); }
  .section--lg { padding-block: calc(var(--section-y-lg) * 0.72); }

  .topbar__inner { align-items: flex-start; padding-block: 14px; }
  .topbar__mark { font-size: var(--text-lg); }
  .topbar__note { max-width: none; }

  .nav-bar__inner { padding-block: 10px; }

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

  .nav {
    order: 3;
    flex: 1 0 100%;
    display: none;
  }

  .nav[data-open] { display: block; }

  .nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    margin-top: 10px;
    border-top: var(--border-thin) solid var(--color-line);
  }

  .nav__link {
    display: block;
    padding: 14px 0 14px 12px;
    border-bottom: var(--border-thin) solid var(--color-line);
    border-left: 2px solid transparent;
  }

  .nav__link[aria-current="page"] {
    background: var(--color-surface-alt);
    border-left-color: var(--color-accent);
    border-bottom-color: var(--color-line);
  }

  .nav-bar__cta { padding: 8px 12px; }

  .spy { position: static; }
}

@media (max-width: 620px) {
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }

  .topbar__note { font-size: var(--text-xs); }

  .footer__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
  }

  .pullquote {
    padding: var(--space-2) var(--space-2) var(--space-2) var(--space-3);
    font-size: var(--text-base);
  }
}

@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-reveal [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }
}