:root {
  --color-surface: #ececeb;
  --color-surface-alt: #e5e4e3;
  --color-surface-deep: #dadad8;
  --color-ink: #5a564e;
  --color-ink-soft: #6f6a62;
  --color-ink-muted: #868179;
  --color-line: #d2d1cf;
  --color-primary: #82755f;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #dddbd7;
  --color-accent: #6a7b37;
  --color-accent-ink: #ffffff;
  --color-highlight: #d5d8cb;
  --color-focus: #5c6d27;
  --color-contrast-surface: #171614;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #454442;
  --color-contrast-accent: #98b04f;
  --overlay-scrim: linear-gradient(180deg, rgba(23, 22, 20, 0.35) 0%, rgba(23, 22, 20, 0.72) 55%, rgba(23, 22, 20, 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(42px, 8.7vw, 111px);
  --text-figure: clamp(35px, 6.2vw, 80px);
  --weight-heading: 419;
  --weight-body: 400;
  --leading-body: 1.96;
  --leading-heading: 1.25;
  --tracking-heading: 0.025em;
  --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: 1060px;
  --measure: 66ch;
  --gutter: 24px;
  --section-y: 126px;
  --section-y-lg: 176px;
}

/* ===== 02 reset ===== */
*,
*::before,
*::after { box-sizing: border-box; }

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

body {
  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: 0.02em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}
table { border-collapse: collapse; width: 100%; }
hr { border: 0; margin: 0; }

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

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
}

/* ===== 03 中文排版 ===== */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  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); }

.display {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.04;
  letter-spacing: 0.01em;
  color: var(--color-ink);
}

.figure-value {
  font-family: var(--font-body);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 1;
  letter-spacing: -0.01em;
  font-variant-numeric: tabular-nums;
  color: var(--color-accent);
}

.panel-dark .figure-value { color: var(--color-contrast-accent); }

.prose { max-width: var(--measure); }
.prose p + p { margin-top: var(--space-3); }
.prose h2, .prose h3 { margin-top: var(--space-6); }
.prose ul, .prose ol { margin-top: var(--space-3); padding-left: 1.4em; list-style: disc; }

.lead {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.8;
  color: var(--color-ink-soft);
}

.eyebrow {
  display: block;
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-ink-muted);
  margin-bottom: var(--space-2);
}

.section-marker {
  display: block;
  font-size: var(--text-xs);
  letter-spacing: 0.22em;
  color: var(--color-ink-muted);
  transition: color 0.45s ease;
}

[data-section].is-current .section-marker { color: var(--color-focus); }

/* ===== 04 布局 ===== */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.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; }

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

/* ===== 05 分隔语言：刻度取代线条 ===== */
.rule-ticks {
  height: 5px;
  background-image: repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 10px);
  background-repeat: repeat-x;
}

.rule-ticks--dark {
  background-image: repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 10px);
}

/* ===== 06 标签与徽标 ===== */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  background-color: var(--color-primary-soft);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  border-radius: var(--radius-sm);
}

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

.tag--dark {
  background-color: transparent;
  border: var(--border-thin) solid var(--color-contrast-line);
  color: var(--color-contrast-accent);
}

/* ===== 07 深色面板 ===== */
.panel-dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding: var(--space-8) var(--space-6);
  border-radius: var(--radius-md);
}

.panel-dark h2,
.panel-dark h3,
.panel-dark h4 { color: var(--color-contrast-ink); }

.panel-dark p {
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}

.panel-dark .figure-frame { background-color: var(--color-contrast-line); }

/* ===== 08 按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 44px;
  padding: 12px 24px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-ink);
  background-color: transparent;
  box-shadow: var(--shadow-1);
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

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

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

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

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

.btn--on-dark:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

/* ===== 09 图片容器基础 ===== */
.figure-frame {
  position: relative;
  width: 100%;
  margin: 0;
  overflow: hidden;
  background-color: var(--color-surface-deep);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-1);
}

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

.figure-frame--wide { aspect-ratio: 16 / 9; }
.figure-frame--photo { aspect-ratio: 3 / 2; }
.figure-frame--tall { aspect-ratio: 3 / 4; }
.figure-frame--square { aspect-ratio: 1 / 1; }

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

.figure-frame__body {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
  padding: var(--space-4);
  color: var(--color-contrast-ink);
}

.figure-frame__caption {
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

/* ===== 10 面包屑 ===== */
.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.breadcrumbs__item a {
  color: var(--color-ink-soft);
  transition: color 0.25s ease;
}

.breadcrumbs__item a:hover { color: var(--color-accent); }

.breadcrumbs__sep {
  color: color-mix(in srgb, var(--color-ink-muted) 55%, transparent);
}

.breadcrumbs [aria-current="page"] { color: var(--color-ink); }

/* ===== 11 跳转链接 ===== */
.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -72px;
  z-index: 120;
  padding: 10px 18px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  border-radius: var(--radius-sm);
  transition: top 0.2s ease;
}

.skip-link:focus { top: var(--space-2); }

/* ===== 12 头部 ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background-color: var(--color-surface);
}

.site-header__inner {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  padding-block: var(--space-3);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-right: auto;
  padding: 4px 0;
}

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

.brand__sig {
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.header-mark {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: color-mix(in srgb, var(--color-ink-muted) 70%, transparent);
  white-space: nowrap;
}

.header-utility {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.header-utility__link {
  padding: 6px 0;
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) solid transparent;
  transition: color 0.25s ease, border-color 0.25s ease;
}

.header-utility__link:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  padding: 6px 0;
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-ink-soft);
}

.nav-toggle:hover { color: var(--color-primary); }

.nav-toggle__bars {
  display: flex;
  flex-direction: column;
  gap: 4px;
  width: 18px;
}

.nav-toggle__bars span {
  display: block;
  height: 1px;
  background-color: currentColor;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(1) {
  transform: translateY(5px) 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(-5px) rotate(-45deg);
}

.site-nav {
  border-bottom: var(--border-thin) solid var(--color-line);
}

.site-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
}

.site-nav__list {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-6);
}

.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  min-height: 44px;
  padding: 14px 0 20px;
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-ink-soft);
  transition: color 0.3s ease;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 8px;
  height: 1px;
  background-color: var(--color-line);
  transition: background-color 0.35s ease;
}

.site-nav__link:hover { color: var(--color-ink); }
.site-nav__link:hover::after { background-color: var(--color-primary); }

.site-nav__link[aria-current="page"] { color: var(--color-primary); }
.site-nav__link[aria-current="page"]::after { background-color: var(--color-primary); }

.site-nav__num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  transition: color 0.3s ease;
}

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

.site-nav__cta { margin-block: 8px; }

/* ===== 13 页脚 ===== */
.site-footer {
  padding-block: var(--section-y) var(--space-8);
  background-color: var(--color-surface);
}

.footer-panels {
  display: grid;
  grid-template-columns: 1.2fr 0.95fr 0.75fr;
  gap: var(--space-3);
  align-items: start;
}

.footer-panel {
  background-color: var(--color-surface-deep);
  padding: var(--space-4) var(--space-3) var(--space-3);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
}

.footer-panel:nth-child(2) { margin-top: var(--space-6); }
.footer-panel:nth-child(3) { margin-top: var(--space-3); }

.footer-panel__title {
  position: relative;
  margin-bottom: var(--space-3);
  padding-bottom: 12px;
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.24em;
  color: var(--color-ink-muted);
}

.footer-panel__title::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 5px;
  background-image: repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 10px);
  background-repeat: repeat-x;
}

.footer-panel__list li {
  font-size: var(--text-sm);
  line-height: 1.9;
  color: var(--color-ink-soft);
  letter-spacing: 0.04em;
}

.footer-panel__list li + li { margin-top: var(--space-2); }

.footer-panel__list a {
  color: var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-line);
  transition: color 0.25s ease, border-color 0.25s ease;
}

.footer-panel__list a:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2) var(--space-6);
  margin-top: var(--space-8);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.footer-meta__brand { color: var(--color-ink-soft); }

/* ===== 14 脚本注入型组件 ===== */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 100;
  height: 1px;
  width: 0;
  background-color: var(--color-primary);
  transition: width 0.12s linear;
}

.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.js [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ===== 15 响应式 ===== */
@media (max-width: 1080px) {
  .header-mark { display: none; }
}

@media (max-width: 860px) {
  .grid { grid-template-columns: minmax(0, 1fr); }
  .col-3, .col-4, .col-5, .col-6, .col-7, .col-8, .col-9, .col-12 {
    grid-column: 1 / -1;
  }

  .section { padding-block: calc(var(--section-y) * 0.62); }
  .section--lg { padding-block: calc(var(--section-y-lg) * 0.62); }

  .brand__name { font-size: var(--text-lg); }
  .brand__sig { display: none; }
  .header-utility { gap: var(--space-2); }
  .header-utility__link { font-size: var(--text-xs); letter-spacing: 0.08em; }

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

  .site-nav {
    display: none;
    border-top: var(--border-thin) solid var(--color-line);
  }

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

  .site-nav__inner { display: block; padding-block: var(--space-2); }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav__item + .site-nav__item {
    border-top: var(--border-thin) solid var(--color-line);
  }

  .site-nav__link {
    justify-content: flex-start;
    padding: 16px 0 14px;
    font-size: var(--text-base);
  }

  .site-nav__link::after { display: none; }

  .site-nav__cta {
    display: flex;
    width: 100%;
    margin-block: var(--space-3);
  }

  .footer-panels { grid-template-columns: minmax(0, 1fr); }
  .footer-panel:nth-child(2),
  .footer-panel:nth-child(3) { margin-top: 0; }

  .panel-dark { padding: var(--space-6) var(--space-3); }
}

@media (max-width: 520px) {
  .site-header__inner { padding-block: var(--space-2); }
  .panel-dark { padding: var(--space-4) var(--space-2); }
  .figure-frame__body { padding: var(--space-3); }
}

/* ===== 16 无障碍与动态偏好 ===== */
@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] {
    opacity: 1;
    transform: none;
  }

  .reading-progress { transition: none; }
}