:root {
  --color-surface: #0f0f0f;
  --color-surface-alt: #202020;
  --color-surface-deep: #343635;
  --color-ink: #c8d0cc;
  --color-ink-soft: #88968f;
  --color-ink-muted: #79867f;
  --color-line: #303231;
  --color-primary: #35ca7d;
  --color-primary-ink: #111814;
  --color-primary-soft: #14291e;
  --color-accent: #25da7d;
  --color-accent-ink: #111814;
  --color-highlight: #133423;
  --color-focus: #18e77c;
  --color-contrast-surface: #f4f5f5;
  --color-contrast-ink: #303633;
  --color-contrast-line: #c9cbca;
  --color-contrast-accent: #157f48;
  --overlay-scrim: linear-gradient(180deg, rgba(244, 245, 245, 0.35) 0%, rgba(244, 245, 245, 0.72) 55%, rgba(244, 245, 245, 0.92) 100%);
  --font-heading: ui-monospace, SFMono-Regular, Menlo, Consolas, "PingFang SC", monospace;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, 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(46px, 9.5vw, 121px);
  --text-figure: clamp(38px, 6.8vw, 87px);
  --weight-heading: 646;
  --weight-body: 400;
  --leading-body: 1.7;
  --leading-heading: 1.15;
  --tracking-heading: 0.014em;
  --radius-sm: 3px;
  --radius-md: 4px;
  --radius-lg: 6px;
  --radius-pill: 6px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1320px;
  --measure: 72ch;
  --gutter: 28px;
  --section-y: 64px;
  --section-y-lg: 90px;
}

/* ----------------------------------------------------------
   1. Reset
   ---------------------------------------------------------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 108px;
}

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;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, pre {
  margin: 0;
}

ul, ol { margin: 0; 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;
}

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

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

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

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

/* ----------------------------------------------------------
   2. 中文排版与技术文档式层级
   ---------------------------------------------------------- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
}

h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

p { max-width: var(--measure); }

strong { color: var(--color-ink); font-weight: 600; }

.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
  letter-spacing: 0.012em;
}

.section-label {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.section-label::after {
  content: "";
  display: block;
  width: 34px;
  height: 1px;
  background: var(--color-line);
}

.rule {
  display: block;
  width: 100%;
  height: 0;
  border: 0;
  border-top: 1px dotted var(--color-line);
  margin: var(--space-6) 0;
}

[id] { scroll-margin-top: 108px; }

/* ----------------------------------------------------------
   3. 容器与栅格
   ---------------------------------------------------------- */
.shell {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}

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

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

.prose > * + * { margin-top: var(--space-3); }
.prose h2 { margin-top: var(--space-6); margin-bottom: var(--space-2); }
.prose h3 { margin-top: var(--space-4); margin-bottom: var(--space-1); }
.prose ul { list-style: none; }
.prose ul li {
  position: relative;
  padding-left: var(--space-3);
  margin-top: var(--space-1);
}
.prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 8px;
  height: 1px;
  background: var(--color-primary);
}

/* ----------------------------------------------------------
   4. 头部命令栏
   ---------------------------------------------------------- */
.skip-link {
  position: absolute;
  left: var(--space-4);
  top: -80px;
  z-index: 120;
  padding: 10px 18px;
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  transition: top 0.15s ease;
}

.skip-link:focus {
  top: 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: var(--color-surface);
  border-bottom: 1px dotted var(--color-line);
}

.command-bar {
  background: var(--color-surface);
}

.command-bar__inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: 62px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
  padding: var(--space-1) 0;
}

.brand:hover .brand__name { color: var(--color-primary); }

.brand__glyph {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 21px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.04em;
  line-height: 1;
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.08em;
  color: var(--color-ink);
  transition: color 0.15s ease;
}

.brand__sub {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  margin-left: auto;
  padding: 7px 11px;
  border: 1px dotted var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.nav-toggle:hover {
  color: var(--color-ink);
  border-color: var(--color-ink-soft);
}

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

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 13px;
  height: 1px;
  background: currentColor;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 13px;
  height: 1px;
  background: currentColor;
}

.nav-toggle__bars::before { top: -4px; }
.nav-toggle__bars::after { top: 4px; }

.primary-nav {
  display: block;
  margin-left: auto;
}

.primary-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  counter-reset: navitem;
}

.primary-nav__list a {
  display: inline-flex;
  align-items: center;
  padding: 20px 0;
  border-bottom: 2px solid transparent;
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.03em;
  white-space: nowrap;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.primary-nav__list a:hover {
  color: var(--color-ink);
}

.primary-nav__list a[aria-current="page"] {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

@media (min-width: 961px) {
  .primary-nav__list a::before {
    counter-increment: navitem;
    content: counter(navitem, decimal-leading-zero);
    margin-right: 7px;
    font-size: 10px;
    letter-spacing: 0.08em;
    color: var(--color-ink-muted);
  }
  .primary-nav__list a[aria-current="page"]::before {
    color: var(--color-primary);
  }
}

.command-bar__status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
  max-width: none;
  padding-left: var(--space-3);
  border-left: 1px dotted var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  white-space: nowrap;
}

.command-bar__status::before {
  content: "";
  display: block;
  width: 6px;
  height: 6px;
  border-radius: 1px;
  background: var(--color-primary);
}

.status-strip {
  background: var(--color-surface-alt);
  border-top: 1px dotted var(--color-line);
}

.status-strip__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-top: 4px;
  padding-bottom: 4px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}

.status-strip__index { color: var(--color-primary); }
.status-strip__range { color: var(--color-ink-muted); }

.progress-line {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  pointer-events: none;
}

.progress-line__bar {
  display: block;
  height: 100%;
  background: var(--color-primary);
  transform: scaleX(0);
  transform-origin: 0 50%;
}

@media (max-width: 1180px) {
  .command-bar__status { display: none; }
}

@media (max-width: 960px) {
  .command-bar__inner {
    flex-wrap: wrap;
    gap: var(--space-2) var(--space-3);
    padding-top: var(--space-1);
    padding-bottom: var(--space-1);
    min-height: 54px;
  }
  .nav-toggle { display: inline-flex; }
  .command-bar__status {
    display: inline-flex;
    flex: 1 0 100%;
    margin-left: 0;
    padding-left: 0;
    border-left: 0;
    order: 4;
  }
  .primary-nav {
    display: none;
    order: 5;
    flex: 1 0 100%;
    margin-left: 0;
    padding: var(--space-1) 0 var(--space-2);
    border-top: 1px dotted var(--color-line);
  }
  .primary-nav[data-open] { display: block; }
  .primary-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }
  .primary-nav__list a {
    display: block;
    padding: 11px var(--space-2);
    border-bottom: 1px dotted var(--color-line);
    border-left: 2px solid transparent;
    white-space: normal;
  }
  .primary-nav__list a:hover {
    background: var(--color-surface-alt);
  }
  .primary-nav__list a[aria-current="page"] {
    border-bottom-color: var(--color-line);
    border-left-color: var(--color-primary);
    background: var(--color-primary-soft);
    color: var(--color-primary);
  }
  .status-strip__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    padding-top: 6px;
    padding-bottom: 6px;
  }
}

/* ----------------------------------------------------------
   5. 页脚：边框式收口 + 赛季刻度轴
   ---------------------------------------------------------- */
.site-footer {
  margin-top: var(--section-y-lg);
  background: var(--color-surface-alt);
  border-top: 1px solid var(--color-line);
}

.site-footer__inner {
  padding-top: var(--space-6);
  padding-bottom: var(--space-4);
}

.footer-brand {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2);
  padding-bottom: var(--space-4);
  border-bottom: 1px dotted var(--color-line);
}

.footer-brand__mark {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: 0.06em;
  color: var(--color-ink);
}

.footer-brand__sub {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.season-axis {
  padding: var(--space-4) 0 var(--space-3);
}

.season-axis__caption {
  max-width: none;
  margin-bottom: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.season-axis__list {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
}

.season-axis__item {
  position: relative;
  padding-top: 9px;
  border-top: 1px solid var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-soft);
}

.season-axis__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 1px;
  height: 7px;
  background: var(--color-line);
}

.season-axis__item--current {
  color: var(--color-primary);
}

.season-axis__item--current::before {
  background: var(--color-primary);
  height: 10px;
}

.footer-index {
  padding: var(--space-4) 0;
  border-top: 1px dotted var(--color-line);
  border-bottom: 1px dotted var(--color-line);
}

.footer-index__label {
  max-width: none;
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.footer-index__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
}

.footer-index__list a {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-soft);
  transition: color 0.15s ease;
}

.footer-index__list a::before {
  content: "";
  display: block;
  width: 5px;
  height: 5px;
  border-radius: 1px;
  background: var(--color-surface-deep);
  transition: background 0.15s ease;
}

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

.footer-index__list a:hover::before {
  background: var(--color-primary);
}

.footer-meta {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr);
  gap: var(--space-4);
  padding: var(--space-4) 0;
  border-bottom: 1px dotted var(--color-line);
}

.footer-meta__contact p {
  max-width: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
}

.footer-meta__contact p + p { margin-top: var(--space-1); }

.footer-meta__key {
  display: inline-block;
  min-width: 60px;
  color: var(--color-ink-muted);
}

.footer-meta__note {
  max-width: 46ch;
  font-size: var(--text-xs);
  line-height: 1.75;
  color: var(--color-ink-muted);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

@media (max-width: 820px) {
  .footer-meta { grid-template-columns: minmax(0, 1fr); gap: var(--space-3); }
  .season-axis__list { grid-template-columns: repeat(3, minmax(0, 1fr)); row-gap: var(--space-3); }
  .season-axis__item:nth-child(n + 4) { border-top-style: dotted; }
}

/* ----------------------------------------------------------
   6. 通用组件
   ---------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.05em;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

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

.btn--primary {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-weight: 600;
}

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

.btn--ghost {
  background: transparent;
}

.panel {
  position: relative;
  padding: var(--space-3);
  border: 1px dotted var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
}

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

.panel--contrast {
  background: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
  border-style: solid;
  color: var(--color-contrast-ink);
}

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

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

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

.panel--contrast .tag--live {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.panel--contrast .quote {
  border-left-color: var(--color-contrast-accent);
  color: var(--color-contrast-ink);
}

.panel--contrast .section-label,
.panel--contrast .section-label::after {
  color: var(--color-contrast-ink);
  background: var(--color-contrast-line);
}

.panel--contrast .section-label { background: transparent; }

.panel__title {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
  padding-bottom: var(--space-2);
  margin-bottom: var(--space-3);
  border-bottom: 1px dotted var(--color-line);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
}

.panel--contrast .panel__title { border-bottom-color: var(--color-contrast-line); }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 2px 8px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  white-space: nowrap;
}

.tag--live {
  background: var(--color-primary-soft);
  border-color: color-mix(in srgb, var(--color-primary) 48%, transparent);
  color: var(--color-primary);
}

.tag--muted {
  color: var(--color-ink-muted);
  background: transparent;
}

.quote {
  max-width: var(--measure);
  padding: var(--space-2) 0 var(--space-2) var(--space-4);
  border-left: 2px solid var(--color-primary);
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  line-height: 1.8;
}

.breadcrumbs {
  padding: var(--space-3) 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 7px;
}

.breadcrumbs li::after {
  content: "/";
  margin-left: 7px;
  color: var(--color-ink-muted);
}

.breadcrumbs li:last-child::after { content: ""; }

.breadcrumbs a:hover { color: var(--color-primary); }

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

/* 图像容器：衬底 + 细边框，图片像贴在档案纸面上 */
.media-frame {
  position: relative;
  display: block;
  padding: var(--space-2);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
}

.media-frame__slot {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
}

.media-frame__slot img,
.media-frame__slot svg {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.72) contrast(1.06);
}

.media-frame__scrim {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: flex-end;
  padding: var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}

.media-frame__caption {
  max-width: none;
  margin-top: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-muted);
}

/* 内页左侧索引侧栏 */
.index-rail {
  position: sticky;
  top: 116px;
  padding: var(--space-2) 0;
  border: 1px dotted var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
}

.index-rail__title {
  max-width: none;
  margin-bottom: var(--space-2);
  padding: 0 var(--space-3) var(--space-2);
  border-bottom: 1px dotted var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.index-rail a {
  position: relative;
  display: block;
  padding: 8px var(--space-3) 8px calc(var(--space-3) + 10px);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.03em;
  color: var(--color-ink-soft);
  transition: background 0.15s ease, color 0.15s ease;
}

.index-rail a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: var(--color-line);
  transition: background 0.15s ease, transform 0.15s ease;
  transform: scaleY(0.4);
  transform-origin: 50% 0;
}

.index-rail a:hover {
  background: var(--color-surface-deep);
  color: var(--color-ink);
}

.index-rail a.is-active,
.index-rail a[aria-current="true"] {
  background: var(--color-primary-soft);
  color: var(--color-primary);
}

.index-rail a.is-active::before,
.index-rail a[aria-current="true"]::before {
  background: var(--color-primary);
  transform: scaleY(1);
}

/* 可展开内容组 */
.accordion {
  border-top: 1px dotted var(--color-line);
}

.accordion__item {
  border-bottom: 1px dotted var(--color-line);
}

.accordion__trigger {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-3);
  width: 100%;
  padding: var(--space-3) 0;
  text-align: left;
  cursor: pointer;
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  transition: color 0.15s ease;
}

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

.accordion__trigger[aria-expanded="true"] { color: var(--color-primary); }

.accordion__index {
  margin-right: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.accordion__mark {
  position: relative;
  flex: 0 0 auto;
  width: 12px;
  height: 12px;
  margin-top: 4px;
}

.accordion__mark::before,
.accordion__mark::after {
  content: "";
  position: absolute;
  background: var(--color-primary);
  transition: transform 0.15s ease, opacity 0.15s ease;
}

.accordion__mark::before { left: 0; top: 5.5px; width: 12px; height: 1px; }
.accordion__mark::after { top: 0; left: 5.5px; width: 1px; height: 12px; }

.accordion__trigger[aria-expanded="true"] .accordion__mark::after {
  transform: scaleY(0);
  opacity: 0;
}

.accordion__panel {
  display: none;
  padding: var(--space-3) var(--space-4);
  border-left: 2px solid var(--color-primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--color-primary-soft);
}

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

.accordion__panel > * + * { margin-top: var(--space-2); }

@media (max-width: 960px) {
  .index-rail { position: static; top: auto; }
  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
}

@media (max-width: 600px) {
  .grid-12 { grid-template-columns: minmax(0, 1fr); gap: var(--space-3); }
  .accordion__trigger { font-size: var(--text-base); }
  .accordion__panel { padding: var(--space-2) var(--space-3); }
}

/* ----------------------------------------------------------
   7. 动效降级
   ---------------------------------------------------------- */
@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;
  }
  .index-rail a::before { transform: scaleY(1); }
}