:root {
  --color-surface: #f9f9f9;
  --color-surface-alt: #f0f0f0;
  --color-surface-deep: #e3e4e3;
  --color-ink: #444a40;
  --color-ink-soft: #697165;
  --color-ink-muted: #7e8679;
  --color-line: #d8dad8;
  --color-primary: #6b7863;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e5e7e4;
  --color-accent: #3b8410;
  --color-accent-ink: #ffffff;
  --color-highlight: #d7e4cf;
  --color-focus: #337d08;
  --color-contrast-surface: #151714;
  --color-contrast-ink: #e5e7e4;
  --color-contrast-line: #434542;
  --color-contrast-accent: #66e31c;
  --overlay-scrim: linear-gradient(180deg, rgba(21, 23, 20, 0.35) 0%, rgba(21, 23, 20, 0.72) 55%, rgba(21, 23, 20, 0.92) 100%);
  --font-heading: STZhongsong, "Source Han Serif SC", "Songti SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 9.3px;
  --text-sm: 13.9px;
  --text-base: 17px;
  --text-lg: 25.5px;
  --text-xl: 38.2px;
  --text-2xl: 57.4px;
  --text-3xl: 86.1px;
  --text-4xl: 129.1px;
  --text-display: clamp(40px, 8.3vw, 106px);
  --text-figure: clamp(33px, 5.9vw, 76px);
  --weight-heading: 590;
  --weight-body: 400;
  --leading-body: 1.92;
  --leading-heading: 1.27;
  --tracking-heading: -0.007em;
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 0px;
  --radius-pill: 0px;
  --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: 1040px;
  --measure: 65ch;
  --gutter: 24px;
  --section-y: 96px;
  --section-y-lg: 134px;
}

/* ==========================================================================
   0. 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);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, ol, ul { margin: 0; }
ol, ul { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; padding: 0; cursor: pointer; }
a { color: var(--color-accent); text-decoration: none; }
a:hover, a:focus-visible { color: var(--color-focus); }
[hidden] { display: none !important; }

/* ==========================================================================
   1. 中文排版与字族
   ========================================================================== */
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);
  text-wrap: balance;
}

p { text-wrap: pretty; }
strong, b { font-weight: 600; }
mark { background: var(--color-highlight); color: inherit; padding: 0 0.12em; }

.mono,
.num,
[data-num] {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
}

/* ==========================================================================
   2. 焦点、跳转与可访问性
   ========================================================================== */
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  top: var(--space-2);
  left: var(--space-2);
  z-index: 60;
  padding: var(--space-1) var(--space-3);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  transform: translateY(calc(-100% - var(--space-4)));
}

.skip-link:focus,
.skip-link:focus-visible {
  transform: translateY(0);
  color: var(--color-contrast-ink);
}

#main-content:focus { outline: none; }

/* ==========================================================================
   3. 布局容器与分区
   ========================================================================== */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.container--narrow { max-width: calc(var(--measure) + var(--gutter) * 2); }

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

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

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

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

.section--contrast a { color: var(--color-contrast-accent); }
.section--contrast a:hover,
.section--contrast a:focus-visible { color: var(--color-contrast-accent); }

.section--contrast .eyebrow,
.section--contrast .stat-label,
.section--contrast .figure__caption { color: var(--color-contrast-ink); opacity: 0.72; }

.section--contrast .stat-value { color: var(--color-contrast-ink); }

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

@media (min-width: 900px) {
  .section { padding-block: var(--section-y-lg); }
}

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

/* ==========================================================================
   4. 排版组件
   ========================================================================== */
.display {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.02;
  letter-spacing: -0.03em;
  color: var(--color-ink);
  margin: 0;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.lead {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.62;
  color: var(--color-ink-soft);
}

.prose { max-width: var(--measure); }

.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-4);
}

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

.prose li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
}

.prose a {
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.28em;
}

/* ==========================================================================
   5. 数据与强调
   ========================================================================== */
.stat-value {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

.stat-label {
  display: block;
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.tag {
  display: inline-block;
  padding: 2px var(--space-1);
  background-color: var(--color-primary-soft);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

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

.mark {
  background-color: var(--color-highlight);
  color: inherit;
  padding: 0 0.12em;
}

.kw {
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 0.26em;
}

/* ==========================================================================
   6. 按钮
   ========================================================================== */
.btn {
  display: inline-block;
  padding-block: var(--space-1);
  border-bottom: var(--border-thin) solid currentColor;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  transition: color 0.24s ease;
}

.btn:hover,
.btn:focus-visible { color: var(--color-focus); }

.btn--ghost {
  border-bottom-color: transparent;
  color: var(--color-ink-soft);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  color: var(--color-focus);
  border-bottom-color: currentColor;
}

/* ==========================================================================
   7. 面包屑
   ========================================================================== */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1);
}

.breadcrumb li { display: inline-flex; align-items: baseline; gap: var(--space-1); }

.breadcrumb li + li::before {
  content: "/";
  color: var(--color-line);
}

.breadcrumb a { color: var(--color-ink-soft); }
.breadcrumb a:hover,
.breadcrumb a:focus-visible { color: var(--color-focus); }

/* ==========================================================================
   8. 图片容器（页面阶段放置图片使用）
   ========================================================================== */
.figure { margin: 0; }

.figure__frame {
  position: relative;
  overflow: hidden;
  background-color: var(--color-surface-deep);
}

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

.figure__frame--band { aspect-ratio: 21 / 6; }
.figure__frame--wide { aspect-ratio: 16 / 6; }
.figure__frame--tall { aspect-ratio: 3 / 4; }
.figure__frame--square { aspect-ratio: 1 / 1; }

.figure__overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: var(--space-1);
  padding: var(--space-4);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
}

.figure__overlay h3,
.figure__overlay p { color: var(--color-contrast-ink); }
.figure__overlay a { color: var(--color-contrast-accent); }

.figure__caption {
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.figure--offset { margin-top: var(--space-8); }

@media (min-width: 900px) {
  .figure--offset { margin-top: var(--space-8); }
}

/* ==========================================================================
   9. 轮次轨道
   ========================================================================== */
.track {
  display: flex;
  gap: var(--space-6);
  overflow-x: auto;
  padding-block: var(--space-4);
  scroll-snap-type: x mandatory;
  scrollbar-color: var(--color-primary) var(--color-surface-deep);
}

.track > * { flex: 0 0 auto; scroll-snap-align: start; }

.track__item {
  min-width: 152px;
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
}

.section--contrast .track__item { border-top-color: var(--color-contrast-line); }

.track__round {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

.track__meta {
  display: block;
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.section--contrast .track__meta { color: var(--color-contrast-ink); opacity: 0.68; }

/* ==========================================================================
   10. 折叠归档面板
   ========================================================================== */
.archive-disclosure { border-top: var(--border-thin) solid var(--color-line); }

.archive-disclosure summary {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-3);
  cursor: pointer;
  list-style: none;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.archive-disclosure summary::-webkit-details-marker { display: none; }

.archive-disclosure summary::after {
  content: "＋";
  font-family: var(--font-mono);
  font-size: var(--text-base);
  color: var(--color-accent);
}

.archive-disclosure[open] summary::after { content: "－"; }

.archive-disclosure__body {
  padding-bottom: var(--space-4);
  max-width: var(--measure);
  color: var(--color-ink-soft);
}

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

/* ==========================================================================
   11. 站点头部
   ========================================================================== */
.site-header {
  position: relative;
  z-index: 30;
  background-color: var(--color-surface);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.header-top__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-1) var(--space-4);
  padding-block: var(--space-3) var(--space-2);
}

.brand {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-3);
  color: var(--color-ink);
}

.brand:hover,
.brand:focus-visible { color: var(--color-ink); }

.brand__mark {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: -0.035em;
  line-height: 1.1;
}

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

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

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

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding-block: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-soft);
}

.nav-toggle:hover,
.nav-toggle:focus-visible { color: var(--color-focus); }

.nav-toggle__bars {
  position: relative;
  display: inline-block;
  width: 22px;
  height: 9px;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: var(--border-thin);
  background-color: currentColor;
  transition: transform 0.3s ease, top 0.3s ease, bottom 0.3s ease;
}

.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { bottom: 0; }

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before {
  top: 4px;
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after {
  bottom: 4px;
  transform: rotate(-45deg);
}

.site-nav {
  flex-basis: 100%;
  max-height: 0;
  overflow: hidden;
  visibility: hidden;
  transition: max-height 0.34s ease, visibility 0.34s ease;
}

.site-nav[data-open] {
  max-height: 70vh;
  overflow-y: auto;
  visibility: visible;
}

.site-nav__list {
  display: flex;
  flex-direction: column;
}

.site-nav__list > li { border-top: var(--border-thin) solid var(--color-line); }
.site-nav__list > li:first-child { border-top: 0; }

.site-nav a {
  position: relative;
  display: block;
  padding-block: var(--space-2);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
}

.site-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: var(--border-thin);
  background-color: currentColor;
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.34s ease;
}

.site-nav a:hover,
.site-nav a:focus-visible { color: var(--color-focus); }

.site-nav a:hover::after,
.site-nav a:focus-visible::after,
.site-nav a[aria-current="page"]::after { transform: scaleX(1); }

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

@media (min-width: 900px) {
  .nav-toggle { display: none; }

  .site-nav {
    flex-basis: auto;
    max-height: none;
    overflow: visible;
    visibility: visible;
    margin-left: auto;
  }

  .site-nav__list {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: baseline;
    gap: var(--space-4);
  }

  .site-nav__list > li { border-top: 0; }

  .site-nav a { padding-block: var(--space-1); }
}

/* ==========================================================================
   12. 站点页脚
   ========================================================================== */
.site-footer {
  background-color: var(--color-surface-alt);
  border-top: var(--border-thin) solid var(--color-primary);
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
}

.footer-top {
  display: grid;
  gap: var(--space-6);
  padding-block: var(--space-8) var(--space-6);
}

@media (min-width: 860px) {
  .footer-top {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.5fr);
    gap: var(--space-8);
  }
}

.footer-brand__mark {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: -0.035em;
  color: var(--color-ink);
}

.footer-brand__line {
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.footer-brand__desc {
  margin-top: var(--space-2);
  max-width: 34ch;
  color: var(--color-ink-soft);
}

.footer-index ul {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: var(--space-2) var(--space-4);
}

.footer-index a {
  display: inline-block;
  padding-block: 2px;
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  transition: color 0.24s ease;
}

.footer-index a:hover,
.footer-index a:focus-visible { color: var(--color-focus); }

.footer-band {
  display: grid;
  gap: var(--space-2);
  padding-block: var(--space-6);
  border-top: var(--border-thin) solid var(--color-line);
}

@media (min-width: 860px) {
  .footer-band {
    grid-template-columns: 120px minmax(0, 1fr) auto;
    align-items: baseline;
    gap: var(--space-4);
  }
}

.footer-band__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
}

.footer-band__text {
  max-width: 62ch;
  color: var(--color-ink-soft);
}

.footer-band__stamp {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.footer-legal {
  display: grid;
  gap: var(--space-3);
  padding-block: var(--space-6) var(--space-8);
  border-top: var(--border-thin) solid var(--color-line);
  color: var(--color-ink-muted);
}

@media (min-width: 860px) {
  .footer-legal {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: var(--space-4) var(--space-8);
    align-items: start;
  }
}

.footer-legal__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-3);
}

.footer-legal__links a { color: var(--color-ink-soft); }
.footer-legal__links a:hover,
.footer-legal__links a:focus-visible { color: var(--color-focus); }

.footer-contact { display: grid; gap: var(--space-1); }

.footer-contact__row { color: var(--color-ink-muted); }

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

.copy-mail {
  margin-left: var(--space-1);
  padding: 1px var(--space-1);
  border-bottom: var(--border-thin) solid currentColor;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-accent);
  transition: color 0.24s ease;
}

.copy-mail:hover,
.copy-mail:focus-visible { color: var(--color-focus); }

.copy-mail[data-copied] { color: var(--color-focus); }

.footer-copyright {
  grid-column: 1 / -1;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 40;
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  transition: color 0.24s ease;
}

.to-top:hover,
.to-top:focus-visible { color: var(--color-contrast-accent); }

/* ==========================================================================
   13. 滚动显现（渐进增强）
   ========================================================================== */
@supports (animation-timeline: view()) {
  @media (prefers-reduced-motion: no-preference) {
    [data-reveal] {
      animation: reveal-in linear both;
      animation-timeline: view();
      animation-range: entry 4% cover 30%;
    }
  }
}

@keyframes reveal-in {
  from { opacity: 0; transform: translateY(18px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ==========================================================================
   14. Reduced motion
   ========================================================================== */
@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;
  }

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