:root {
  --color-surface: #f9f9f9;
  --color-surface-alt: #efefef;
  --color-surface-deep: #e2e1e1;
  --color-ink: #372f35;
  --color-ink-soft: #685a64;
  --color-ink-muted: #857580;
  --color-line: #d6d5d6;
  --color-primary: #db1a9f;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #f5daec;
  --color-accent: #128738;
  --color-accent-ink: #ffffff;
  --color-highlight: #cfe4d6;
  --color-focus: #098130;
  --color-contrast-surface: #271321;
  --color-contrast-ink: #e7e4e6;
  --color-contrast-line: #51414c;
  --color-contrast-accent: #1de25d;
  --overlay-scrim: linear-gradient(180deg, rgba(39, 19, 33, 0.35) 0%, rgba(39, 19, 33, 0.72) 55%, rgba(39, 19, 33, 0.92) 100%);
  --font-heading: "Source Han Sans SC", "Noto Sans SC", SimHei, "Microsoft YaHei", sans-serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 8.7px;
  --text-sm: 13.1px;
  --text-base: 16px;
  --text-lg: 24.0px;
  --text-xl: 36.0px;
  --text-2xl: 54.0px;
  --text-3xl: 81.0px;
  --text-4xl: 121.5px;
  --text-display: clamp(51px, 10.4vw, 133px);
  --text-figure: clamp(42px, 7.5vw, 96px);
  --weight-heading: 883;
  --weight-body: 400;
  --leading-body: 1.73;
  --leading-heading: 1.26;
  --tracking-heading: -0.017em;
  --radius-sm: 2px;
  --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: 1120px;
  --measure: 71ch;
  --gutter: 24px;
  --section-y: 114px;
  --section-y-lg: 160px;
}

/* ============ 01. 基础重置 ============ */
*, *::before, *::after { box-sizing: border-box; }

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

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 { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }
img, svg, video { display: block; max-width: 100%; }
img { height: auto; }
table { width: 100%; border-collapse: collapse; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
input, select, textarea { font: inherit; color: inherit; }

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

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

/* ============ 02. 布局基元 ============ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.rule-dotted {
  border: 0;
  border-top: 1px dashed var(--color-line);
  margin: 0;
}

.grid-9 {
  display: grid;
  grid-template-columns: repeat(9, minmax(0, 1fr));
  gap: var(--gutter);
}
.grid-9 > * { min-width: 0; }

.u-span-3 { grid-column: span 3; }
.u-span-4 { grid-column: span 4; }
.u-span-5 { grid-column: span 5; }
.u-span-6 { grid-column: span 6; }
.u-span-9 { grid-column: span 9; }

.prose {
  max-width: var(--measure);
  color: var(--color-ink-soft);
}
.prose p + p { margin-top: var(--space-2); }
.prose strong { color: var(--color-ink); font-weight: var(--weight-heading); }

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0;
}

/* ============ 03. 章节题头 ============ */
.section-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: baseline;
  gap: var(--space-3) var(--space-4);
  margin-bottom: var(--space-6);
}

.section-index {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 0.84;
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

.section-title {
  font-size: var(--text-2xl);
  color: var(--color-ink);
}

.section-kicker {
  display: block;
  margin-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

/* ============ 04. 按钮 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}
.btn:hover { background: var(--color-surface-deep); border-color: var(--color-ink-muted); }

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

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

.btn--quiet {
  background: transparent;
  border-color: transparent;
  color: var(--color-ink-soft);
  padding-inline: 0;
  border-bottom: 1px dashed var(--color-line);
  border-radius: 0;
}
.btn--quiet:hover { background: transparent; color: var(--color-primary); border-bottom-color: var(--color-primary); }

/* ============ 05. 面包屑 ============ */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}
.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
}
.breadcrumb li {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
}
.breadcrumb li + li::before {
  content: "·";
  color: var(--color-primary);
  font-size: var(--text-sm);
}
.breadcrumb a { border-bottom: 1px dashed var(--color-line); }
.breadcrumb a:hover { color: var(--color-primary); border-bottom-color: var(--color-primary); }

/* ============ 06. 标签、数据块、深色面板 ============ */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 2px var(--space-1);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.5;
  color: var(--color-ink-soft);
}
.tag--batch {
  border-color: var(--color-primary);
  background: var(--color-primary-soft);
  color: var(--color-ink);
}
.tag--accent {
  border-color: var(--color-accent);
  background: var(--color-highlight);
  color: var(--color-ink);
}

.stat {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: var(--space-3);
  border: 1px dashed var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
}
.stat__value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 0.88;
  color: var(--color-ink);
}
.stat__label {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.panel-dark {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-sm);
  border: var(--border-thin) solid var(--color-contrast-line);
}
.panel-dark a { color: var(--color-contrast-accent); }
.panel-dark .rule-dotted { border-top-color: var(--color-contrast-line); }

/* ============ 07. 图片容器 ============ */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
}
.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
}
.media-frame--16x9 { aspect-ratio: 16 / 9; }
.media-frame--1x1 { aspect-ratio: 1 / 1; }
.media-frame--4x3 { aspect-ratio: 4 / 3; }

.media-frame[data-overlay]::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.media-frame__body {
  position: absolute;
  inset: 0;
  z-index: 1;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: var(--space-1);
  padding: var(--space-3);
  color: var(--color-primary-ink);
}
.media-caption {
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

/* ============ 08. 显现动效 ============ */
[data-reveal] { opacity: 1; }

html[data-reveal-ready] [data-reveal] {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.42s ease-out, transform 0.42s ease-out;
}
html[data-reveal-ready] [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ============ 09. 跳至主内容 ============ */
.skip-link {
  position: fixed;
  top: -80px;
  left: var(--space-2);
  z-index: 300;
  padding: var(--space-2) var(--space-3);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  border-radius: var(--radius-sm);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  transition: top 0.18s ease;
}
.skip-link:focus { top: var(--space-2); }

/* ============ 10. 头部 ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.header-rail { border-bottom: 1px dashed var(--color-contrast-line); }

.rail-inner {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: var(--space-4);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-3) var(--gutter);
  transition: padding 0.22s ease;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  min-width: 0;
  grid-column: 1;
}
.brand-mark {
  flex: none;
  width: 10px;
  height: 28px;
  background: var(--color-primary);
  clip-path: polygon(0 0, 100% 0, 100% 74%, 0 100%);
}
.brand-text {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
}
.brand-name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1;
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}
.brand-sub {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  line-height: 1.2;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}

.header-status {
  grid-column: 2;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: var(--space-1) var(--space-3);
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent);
}
.status-dot {
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: var(--radius-pill);
  background: var(--color-contrast-accent);
}
.status-item {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  white-space: nowrap;
}
.status-key {
  letter-spacing: 0.12em;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}
.status-val {
  font-variant-numeric: tabular-nums;
  color: var(--color-contrast-ink);
}

.nav-toggle {
  grid-column: 3;
  justify-self: end;
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-2);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
}
.nav-toggle:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}
.nav-toggle-bars {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  width: 16px;
}
.nav-toggle-bars i {
  display: block;
  height: 1px;
  background: currentColor;
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: 0 var(--gutter);
}
.nav-list {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
}
.nav-item { display: flex; }
.nav-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2);
  border-bottom: 2px solid transparent;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent);
  transition: color 0.2s ease, border-color 0.2s ease;
}
.nav-link:hover {
  color: var(--color-contrast-ink);
  border-bottom-color: var(--color-contrast-accent);
}
.nav-idx {
  padding: 1px 4px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}
.nav-link[aria-current="page"] {
  color: var(--color-contrast-ink);
  border-bottom-color: var(--color-primary);
}
.nav-link[aria-current="page"] .nav-idx {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.nav-entry {
  flex: none;
  padding: var(--space-1) var(--space-2);
  border: var(--border-thin) solid var(--color-contrast-accent);
  border-radius: var(--radius-sm);
  color: var(--color-contrast-accent);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  white-space: nowrap;
  transition: background-color 0.2s ease, color 0.2s ease;
}
.nav-entry:hover {
  background: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}

/* 滚动压缩态 */
.site-header[data-compact] .rail-inner { padding-block: var(--space-1); }
.site-header[data-compact] .brand-sub { display: none; }
.site-header[data-compact] .brand-name { font-size: var(--text-base); }
.site-header[data-compact] .nav-link { padding-block: var(--space-1); }

/* ============ 11. 页脚 ============ */
.site-footer {
  margin-top: var(--section-y-lg);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer-scale {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-4) var(--gutter) var(--space-2);
}
.scale-cap {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
  white-space: nowrap;
}
.scale-track {
  position: relative;
  flex: 1 1 auto;
  min-width: 40px;
  height: 14px;
  border-top: var(--border-thin) solid var(--color-contrast-line);
}
.scale-track::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    90deg,
    var(--color-contrast-line) 0 1px,
    transparent 1px 14px
  );
  background-repeat: repeat-x;
  background-size: 14px 7px;
  background-position: left top;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: var(--space-6) var(--space-4);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-4) var(--gutter) var(--space-6);
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding-right: var(--space-4);
  border-right: 1px dashed var(--color-contrast-line);
}
.footer-brand-name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1.1;
  letter-spacing: var(--tracking-heading);
}
.footer-brand-line {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.18em;
  color: var(--color-contrast-accent);
}
.footer-brand-note {
  max-width: 32ch;
  margin-top: var(--space-1);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
}

.footer-col-title {
  margin-bottom: var(--space-2);
  padding-bottom: var(--space-1);
  border-bottom: 1px dashed var(--color-contrast-line);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--weight-body);
  letter-spacing: 0.16em;
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
}
.footer-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}
.footer-links a {
  display: inline-block;
  padding-block: 2px;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent);
  border-bottom: 1px dashed transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}
.footer-col-note {
  margin-top: var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}

.footer-base {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-4) var(--gutter) var(--space-6);
  border-top: 1px dashed var(--color-contrast-line);
}
.footer-contact {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.8;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}
.footer-legal {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}

/* ============ 12. 响应式 ============ */
@media (max-width: 980px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-brand {
    grid-column: 1 / -1;
    padding-right: 0;
    border-right: 0;
    border-bottom: 1px dashed var(--color-contrast-line);
    padding-bottom: var(--space-3);
  }
  .grid-9 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .u-span-9 { grid-column: span 6; }
  .u-span-6 { grid-column: span 6; }
  .u-span-5 { grid-column: span 4; }
  .u-span-4 { grid-column: span 3; }
  .u-span-3 { grid-column: span 3; }
}

@media (max-width: 880px) {
  .rail-inner {
    grid-template-columns: minmax(0, 1fr) auto;
    gap: var(--space-2);
    padding-block: var(--space-2);
  }
  .brand { grid-column: 1; }
  .nav-toggle {
    grid-column: 2;
    display: inline-flex;
  }
  .header-status {
    grid-column: 1 / -1;
    grid-row: 2;
    justify-content: flex-start;
    padding-top: var(--space-1);
    border-top: 1px dashed var(--color-contrast-line);
    font-size: var(--text-xs);
    letter-spacing: 0.04em;
  }
  .header-status .status-item:nth-child(3) { display: none; }

  .site-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: var(--space-2) var(--gutter) var(--space-4);
    background: var(--color-contrast-surface);
    border-bottom: var(--border-thin) solid var(--color-contrast-line);
  }
  .site-nav[data-open] { display: flex; }
  .nav-list { flex-direction: column; }
  .nav-link {
    width: 100%;
    justify-content: flex-start;
    padding: var(--space-2) 0;
    border-bottom: 1px dashed var(--color-contrast-line);
  }
  .nav-entry { align-self: flex-start; margin-top: var(--space-2); }

  .section { padding-block: calc(var(--section-y) * 0.68); }
  .section--lg { padding-block: calc(var(--section-y-lg) * 0.66); }
  .section-head {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-2);
  }
  .section-index { font-size: calc(var(--text-figure) * 0.72); }
  .section-title { font-size: var(--text-xl); }

  .footer-scale { flex-wrap: wrap; gap: var(--space-2); }
  .scale-track { order: 3; flex-basis: 100%; }
}

@media (max-width: 640px) {
  .grid-9 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .u-span-3, .u-span-4, .u-span-5, .u-span-6, .u-span-9 { grid-column: span 2; }
  .footer-grid { grid-template-columns: 1fr; gap: var(--space-4); }
  .footer-brand { padding-bottom: var(--space-3); }
  .brand-name { font-size: var(--text-base); }
  .brand-sub { font-size: var(--text-xs); }
}

/* ============ 13. 动效与可访问性 ============ */
@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;
    scroll-behavior: auto !important;
  }
  html[data-reveal-ready] [data-reveal] {
    opacity: 1;
    transform: none;
  }
  .skip-link { transition: none; }
}