:root {
  --color-surface: #f0f0f0;
  --color-surface-alt: #e9e8e8;
  --color-surface-deep: #dfdedd;
  --color-ink: #605752;
  --color-ink-soft: #756c66;
  --color-ink-muted: #877d78;
  --color-line: #d6d4d4;
  --color-primary: #837268;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e1dedd;
  --color-accent: #b6496c;
  --color-accent-ink: #ffffff;
  --color-highlight: #e6d2d8;
  --color-focus: #bb3a64;
  --color-contrast-surface: #1e1c1b;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4a4847;
  --color-contrast-accent: #c36a87;
  --overlay-scrim: linear-gradient(180deg, rgba(30, 28, 27, 0.35) 0%, rgba(30, 28, 27, 0.72) 55%, rgba(30, 28, 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: 12.2px;
  --text-sm: 14.6px;
  --text-base: 16px;
  --text-lg: 19.2px;
  --text-xl: 23.0px;
  --text-2xl: 27.6px;
  --text-3xl: 33.2px;
  --text-4xl: 39.8px;
  --text-display: clamp(39px, 8.0vw, 103px);
  --text-figure: clamp(33px, 5.8vw, 74px);
  --weight-heading: 466;
  --weight-body: 400;
  --leading-body: 1.94;
  --leading-heading: 1.28;
  --tracking-heading: 0.011em;
  --radius-sm: 1px;
  --radius-md: 1px;
  --radius-lg: 1px;
  --radius-pill: 1px;
  --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: 16px;
  --section-y: 151px;
  --section-y-lg: 211px;
}

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

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

body {
  --header-h: 72px;
  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;
  font-variant-numeric: tabular-nums;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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);
}

p, figure, blockquote, dl, dd { margin: 0; }
p + p { margin-top: var(--space-3); }

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

a { color: inherit; text-decoration: none; }

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

button, input, select, textarea {
  font: inherit;
  color: inherit;
  letter-spacing: inherit;
  background: none;
  border: 0;
  margin: 0;
}

button { cursor: pointer; }

table { border-collapse: collapse; width: 100%; }

strong { font-weight: var(--weight-heading); color: var(--color-ink); }

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

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

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

/* ===== 骨架 ===== */
.container {
  width: 100%;
  max-width: calc(var(--container) + var(--space-3) * 2);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.main-offset { padding-top: var(--header-h); }

#main-content { scroll-margin-top: calc(var(--header-h) + var(--space-2)); }

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-8); }
.section--alt { background-color: var(--color-surface-alt); }

.section--deep {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.section--deep .section-index { color: var(--color-contrast-accent); }
.section--deep .section-note { color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent); }
.section--deep .note-panel { color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent); }
.section--deep .note-panel__meta { color: var(--color-contrast-accent); }
.section--deep strong { color: var(--color-contrast-ink); }
.section--deep hr { border-top-color: var(--color-contrast-line); }

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

.grid--roomy { gap: var(--space-6); }

.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-12 { grid-column: span 12; }

.layout-asym {
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 3fr) minmax(0, 2fr);
  gap: var(--space-6);
  align-items: start;
}

.layout-asym__main { grid-column: 1; }
.layout-asym__side { grid-column: 2; }

/* ===== 章节标题组 ===== */
.section-head {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
  align-items: baseline;
  margin-bottom: var(--space-8);
}

.section-index {
  grid-column: 1 / span 1;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-primary);
}

.section-title {
  grid-column: 2 / span 6;
  font-size: var(--text-2xl);
  letter-spacing: var(--tracking-heading);
}

.section-note {
  grid-column: 9 / span 4;
  font-size: var(--text-sm);
  line-height: 1.8;
  color: var(--color-ink-soft);
}

.section--deep .section-title { color: var(--color-contrast-ink); }

/* ===== 展示字号 ===== */
.display-type {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.04;
  letter-spacing: var(--tracking-heading);
  margin: 0;
}

.figure-num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-body);
  line-height: 1;
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
  display: block;
}

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

/* ===== 框体 ===== */
.frame {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.frame + .frame,
.frame + .timeline { margin-top: calc(-1 * var(--border-thin)); }

.frame__head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--space-2) var(--space-4);
  padding: var(--space-2) var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
}

.frame__body { padding: var(--space-4); }
.frame__body--roomy { padding: var(--space-6); }

.section--deep .frame { border-color: var(--color-contrast-line); }
.section--deep .frame__head {
  border-bottom-color: var(--color-contrast-line);
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}

/* ===== 强调块 ===== */
.emphasis {
  position: relative;
  margin: 0;
  padding: var(--space-4) var(--space-6) var(--space-4) var(--space-8);
  background-color: var(--color-highlight);
  border-radius: var(--radius-sm);
  font-size: var(--text-lg);
  line-height: 1.7;
  color: var(--color-ink);
}

.emphasis::before {
  content: "\201C";
  position: absolute;
  left: var(--space-3);
  top: var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  line-height: 1;
  color: var(--color-accent);
}

.section--deep .emphasis {
  background-color: color-mix(in srgb, var(--color-contrast-surface) 55%, var(--color-highlight));
  color: var(--color-contrast-ink);
}

/* ===== 旁注栏 ===== */
.note-panel {
  font-size: var(--text-sm);
  line-height: 1.85;
  color: var(--color-ink-soft);
}

.note-panel__meta {
  display: block;
  margin-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}

/* ===== 数据表 ===== */
.data-table {
  font-size: var(--text-sm);
  font-variant-numeric: tabular-nums;
}

.data-table th {
  padding: var(--space-2) var(--space-3);
  text-align: left;
  font-weight: var(--weight-body);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
  border-bottom: var(--border-thin) solid var(--color-line);
  white-space: nowrap;
}

.data-table td {
  padding: var(--space-2) var(--space-3);
  border-bottom: var(--border-thin) solid var(--color-line);
  vertical-align: baseline;
}

.data-table tbody tr {
  transition: background-color 0.2s ease;
}

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

.data-table tbody td:first-child {
  border-left: 2px solid transparent;
  padding-left: var(--space-3);
}

.data-table tbody tr:hover td:first-child { border-left-color: var(--color-primary); }

.data-table .num {
  text-align: right;
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.data-table .num--accent { color: var(--color-accent); }

.section--deep .data-table th {
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
  border-bottom-color: var(--color-contrast-line);
}

.section--deep .data-table td { border-bottom-color: var(--color-contrast-line); }
.section--deep .data-table tbody tr:hover { background-color: color-mix(in srgb, var(--color-contrast-surface) 60%, var(--color-contrast-ink)); }
.section--deep .data-table tbody tr:hover td:first-child { border-left-color: var(--color-contrast-accent); }
.section--deep .data-table .num--accent { color: var(--color-contrast-accent); }

/* ===== 时间轴 ===== */
.timeline { position: relative; }

.timeline__track {
  display: flex;
  overflow-x: auto;
  border-top: var(--border-thin) solid var(--color-line);
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
}

.timeline__item {
  position: relative;
  flex: 0 0 172px;
  scroll-snap-align: start;
  padding: var(--space-6) var(--space-4) var(--space-6) 0;
}

.timeline__item::before {
  content: "";
  position: absolute;
  top: calc(-1 * var(--border-thin));
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-primary);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.35s ease-out;
}

.timeline__item:hover::before,
.timeline__item[data-current="true"]::before { transform: scaleX(1); }

.timeline__item[data-current="true"]::after {
  content: "";
  position: absolute;
  top: -5px;
  left: 0;
  width: 8px;
  height: 8px;
  border-radius: var(--radius-pill);
  background-color: var(--color-accent);
}

.timeline__round {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

.timeline__label {
  display: block;
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.section--deep .timeline__track { border-top-color: var(--color-contrast-line); }
.section--deep .timeline__round { color: var(--color-contrast-ink); }
.section--deep .timeline__label { color: color-mix(in srgb, var(--color-contrast-ink) 55%, transparent); }
.section--deep .timeline__item::before { background-color: var(--color-contrast-accent); }
.section--deep .timeline__item[data-current="true"]::after { background-color: var(--color-contrast-accent); }

/* ===== 媒体 ===== */
.media {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-md);
  background-color: var(--color-surface-deep);
  aspect-ratio: 16 / 9;
  margin: 0;
}

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

.media--wide { aspect-ratio: 21 / 9; }
.media--portrait { aspect-ratio: 3 / 4; }
.media--square { aspect-ratio: 1 / 1; }
.media--tilt { transform: rotate(-1.1deg); }

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

.media__text {
  position: absolute;
  left: var(--space-4);
  right: var(--space-4);
  bottom: var(--space-4);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.7;
  letter-spacing: 0.04em;
}

.media__caption {
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.section--deep .media { background-color: color-mix(in srgb, var(--color-contrast-surface) 70%, var(--color-contrast-ink)); }
.section--deep .media__caption { color: color-mix(in srgb, var(--color-contrast-ink) 55%, transparent); }

/* ===== 按钮与链接 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-4);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-primary);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  line-height: 1.4;
  transition: background-color 0.25s ease-out, color 0.25s ease-out, border-color 0.25s ease-out;
}

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

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

.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 78%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 78%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
}

.btn--ghost {
  border-color: color-mix(in srgb, var(--color-contrast-ink) 42%, transparent);
  color: var(--color-contrast-ink);
}

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

.link-more {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding-bottom: 2px;
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-primary);
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 42%, transparent);
  transition: color 0.25s ease-out, border-color 0.25s ease-out;
}

.link-more::after { content: "\2192"; }

.link-more:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.section--deep .link-more {
  color: var(--color-contrast-accent);
  border-bottom-color: color-mix(in srgb, var(--color-contrast-accent) 45%, transparent);
}

.section--deep .link-more:hover { color: var(--color-contrast-ink); border-bottom-color: var(--color-contrast-ink); }

/* ===== 筛选标片 ===== */
.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-2);
}

.chip {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  background-color: transparent;
  transition: border-color 0.25s ease-out, color 0.25s ease-out;
}

.chip:hover { border-color: var(--color-primary); color: var(--color-primary); }

.chip[aria-pressed="true"],
.chip.is-active {
  border-color: var(--color-focus);
  color: var(--color-focus);
}

.section--deep .chip { border-color: var(--color-contrast-line); color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent); }
.section--deep .chip:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }
.section--deep .chip[aria-pressed="true"] { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }

/* ===== 面包屑 ===== */
.breadcrumb {
  padding-block: var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
}

.breadcrumb__item + .breadcrumb__item::before {
  content: "/";
  margin-right: var(--space-1);
  color: var(--color-line);
}

.breadcrumb__link:hover { color: var(--color-primary); }
.breadcrumb__item[aria-current="page"] { color: var(--color-ink-soft); }

.section--deep .breadcrumb { color: color-mix(in srgb, var(--color-contrast-ink) 55%, transparent); }
.section--deep .breadcrumb__link:hover { color: var(--color-contrast-accent); }

/* ===== 正文容器 ===== */
.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
}

.prose > * + * { margin-top: var(--space-3); }

.prose h2 {
  font-size: var(--text-xl);
  margin-top: var(--space-8);
}

.prose h3 {
  font-size: var(--text-lg);
  margin-top: var(--space-6);
}

.prose ul { list-style: none; }

.prose li {
  position: relative;
  padding-left: var(--space-3);
}

.prose li + li { margin-top: var(--space-1); }

.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: var(--space-2);
  height: var(--border-thin);
  background-color: var(--color-primary);
}

.section--deep .prose li::before { background-color: var(--color-contrast-accent); }

/* ===== 页头（内页通用） ===== */
.page-head {
  padding-block: var(--space-8) var(--space-6);
}

.page-head__kicker {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.page-head__title {
  font-size: var(--text-3xl);
  font-weight: var(--weight-heading);
}

.page-head__lead {
  max-width: var(--measure);
  margin-top: var(--space-4);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
}

.section--deep .page-head__title { color: var(--color-contrast-ink); }
.section--deep .page-head__kicker { color: var(--color-contrast-accent); }
.section--deep .page-head__lead { color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent); }

/* ===== 跳至主要内容 ===== */
.skip-link {
  position: fixed;
  top: var(--space-2);
  left: var(--space-2);
  z-index: 90;
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  transform: translateY(-300%);
  transition: transform 0.2s ease-out;
}

.skip-link:focus { transform: translateY(0); }

/* ===== 头部 ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 60;
  background-color: var(--color-surface);
  color: var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-line);
  transition: background-color 0.3s ease-out, color 0.3s ease-out, border-color 0.3s ease-out;
}

.site-header.is-overlay:not(.is-scrolled):not(.is-open) {
  background-color: transparent;
  background-image: var(--overlay-scrim);
  border-bottom-color: transparent;
  color: var(--color-contrast-ink);
}

.header-bar {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: calc(var(--header-h) - var(--space-4));
  padding-block: var(--space-2);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 0 0 auto;
}

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.2;
  letter-spacing: 0.16em;
  color: inherit;
}

.brand__sub {
  font-size: var(--text-xs);
  line-height: 1.3;
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
}

.site-header.is-overlay:not(.is-scrolled):not(.is-open) .brand__sub {
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.header-nav { margin-left: auto; }

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-link {
  position: relative;
  display: inline-block;
  padding: var(--space-1) var(--space-2);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  line-height: 1.6;
  white-space: nowrap;
  color: inherit;
  transition: color 0.25s ease-out;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: var(--space-2);
  right: var(--space-2);
  bottom: 2px;
  height: var(--border-thin);
  background-color: currentColor;
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.28s ease-out;
}

.nav-link:hover::after { transform: scaleX(1); }

.nav-link[aria-current="page"] { color: var(--color-accent); }

.nav-link[aria-current="page"]::after { transform: scaleX(1); }

.site-header.is-overlay:not(.is-scrolled):not(.is-open) .nav-link[aria-current="page"] {
  color: var(--color-contrast-accent);
}

.site-header.is-overlay:not(.is-scrolled):not(.is-open) .nav-link:hover { color: var(--color-contrast-ink); }

.header-contact {
  margin-left: var(--space-6);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  line-height: 1.5;
  white-space: nowrap;
  color: var(--color-ink-muted);
}

.site-header.is-overlay:not(.is-scrolled):not(.is-open) .header-contact {
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}

.nav-toggle {
  display: none;
  position: relative;
  width: 44px;
  height: 40px;
  flex: 0 0 auto;
  margin-left: auto;
  border: var(--border-thin) solid color-mix(in srgb, currentColor 40%, transparent);
  border-radius: var(--radius-sm);
  color: inherit;
}

.nav-toggle__bar {
  position: absolute;
  left: 12px;
  right: 12px;
  height: var(--border-thin);
  background-color: currentColor;
  transition: transform 0.25s ease-out, opacity 0.2s ease-out;
}

.nav-toggle__bar:nth-child(1) { top: 13px; }
.nav-toggle__bar:nth-child(2) { top: 19px; }
.nav-toggle__bar:nth-child(3) { top: 25px; }

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ===== 页脚 ===== */
.site-footer {
  padding-block: var(--space-8) var(--space-6);
  background-color: var(--color-surface);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.footer-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3) var(--space-6);
}

.footer-brand {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  letter-spacing: 0.18em;
  color: var(--color-ink);
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1) var(--space-4);
  margin-left: auto;
}

.footer-link {
  padding-block: 2px;
  transition: color 0.25s ease-out;
}

.footer-link:hover { color: var(--color-primary); }

.footer-icp { white-space: nowrap; }

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-4);
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-line);
  line-height: 1.8;
}

.footer-meta__item + .footer-meta__item::before {
  content: "·";
  margin-right: var(--space-2);
  color: var(--color-line);
}

/* ===== 返回顶部 ===== */
.to-top {
  position: fixed;
  right: var(--space-4);
  bottom: var(--space-4);
  z-index: 40;
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  color: var(--color-primary);
  font-size: var(--text-sm);
  line-height: 1;
  transition: color 0.25s ease-out, border-color 0.25s ease-out;
}

.to-top:hover { color: var(--color-accent); border-color: var(--color-accent); }

.to-top[hidden] { display: none; }

/* ===== 滚动显现 ===== */
.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.4s ease-out, transform 0.4s ease-out;
  will-change: opacity, transform;
}

.reveal.is-visible {
  opacity: 1;
  transform: none;
  will-change: auto;
}

/* ===== 响应式：平板 ===== */
@media (max-width: 1080px) {
  .header-contact { display: none; }
  .section-title { grid-column: 2 / span 7; }
  .section-note { grid-column: 9 / span 4; }
}

@media (max-width: 960px) {
  :root {
    --section-y: 104px;
    --section-y-lg: 136px;
  }

  .layout-asym {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-6);
  }

  .layout-asym__main,
  .layout-asym__side { grid-column: 1; }

  .col-4, .col-5 { grid-column: span 12; }
  .col-7, .col-8, .col-9 { grid-column: span 12; }
}

/* ===== 响应式：手机 ===== */
@media (max-width: 860px) {
  body { --header-h: 64px; }

  .nav-toggle { display: block; }

  .header-nav {
    position: fixed;
    left: 0;
    right: 0;
    top: var(--header-h);
    margin-left: 0;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    background-color: var(--color-surface);
    border-bottom: var(--border-thin) solid var(--color-line);
    padding-block: var(--space-2) var(--space-4);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    pointer-events: none;
    transition: opacity 0.25s ease-out, transform 0.25s ease-out, visibility 0.25s ease-out;
  }

  .header-nav[data-open="true"] {
    opacity: 1;
    visibility: visible;
    transform: none;
    pointer-events: auto;
  }

  .nav-list {
    flex-direction: row;
    align-items: stretch;
    gap: var(--space-2);
    padding-inline: var(--space-3);
    overflow-x: auto;
    scroll-snap-type: x proximity;
    -webkit-overflow-scrolling: touch;
  }

  .nav-list::-webkit-scrollbar { height: 0; }

  .nav-link {
    scroll-snap-align: start;
    font-size: var(--text-base);
    padding: var(--space-2) var(--space-1);
  }

  .nav-link::after { left: var(--space-1); right: var(--space-1); bottom: 6px; }

  .site-header:not(.is-overlay) .header-nav,
  .site-header.is-scrolled .header-nav,
  .site-header.is-open .header-nav {
    color: var(--color-ink);
  }

  .footer-row {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-3);
  }

  .footer-nav { margin-left: 0; }

  .section-head {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-2);
  }

  .section-index,
  .section-title,
  .section-note { grid-column: 1; }

  .section-note { margin-top: var(--space-2); }

  .grid { gap: var(--space-3); }

  .col-2, .col-3, .col-6 { grid-column: span 12; }

  .frame__body { padding: var(--space-3); }
  .frame__body--roomy { padding: var(--space-4); }

  .emphasis {
    padding: var(--space-3) var(--space-4) var(--space-3) var(--space-6);
    font-size: var(--text-base);
  }

  .timeline__item { flex-basis: 148px; }
}

@media (max-width: 560px) {
  .brand__sub { display: none; }
  .data-table th,
  .data-table td { padding-inline: var(--space-2); }
  .to-top { right: var(--space-2); bottom: var(--space-2); }
}

/* ===== 动效克制 ===== */
@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;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }

  .skip-link { transition: none; }
  .timeline__item::before { transform: scaleX(1); }
}