/* ==========================================================================
   易游品牌 · yyupdate.com.cn
   共享样式表 /assets/site.css
   设计语言：工业档案 · 精密经纬网格 · 数字终端
   ========================================================================== */

/* 1. 变量 ------------------------------------------------------------------ */
:root {
  /* 色彩 */
  --navy-900: #061726;
  --navy-800: #0A2540;
  --navy-700: #123B5C;
  --orange-500: #FF6B35;
  --orange-400: #FF8C5A;
  --cyan-400: #00E5FF;
  --cyan-500: #00A3B8;
  --paper: #F5F7FA;
  --white: #FFFFFF;
  --ink: #1C2B36;
  --ink-muted: #64748B;
  --line: #D6DEE6;
  --line-on-dark: rgba(214, 222, 230, 0.20);
  --line-on-dark-strong: rgba(0, 229, 255, 0.45);
  --hover-tint: rgba(0, 229, 255, 0.07);

  /* 字体 */
  --font-mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Noto Sans Mono CJK SC", monospace;
  --font-sans: "Inter", "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;

  /* 字号（相邻层级约 1.5 倍差） */
  --fs-display: clamp(3rem, 7vw, 4.5rem);
  --fs-display-2: clamp(2.5rem, 5.4vw, 4rem);
  --fs-display-3: clamp(2rem, 4vw, 3rem);
  --fs-section: clamp(1.75rem, 3vw, 2.25rem);
  --fs-h3: 1.5rem;
  --fs-body: 1.0625rem;
  --fs-sm: 0.8125rem;

  /* 空间 */
  --sp-1: 0.25rem;
  --sp-2: 0.5rem;
  --sp-3: 0.75rem;
  --sp-4: 1rem;
  --sp-5: 1.5rem;
  --sp-6: 2rem;
  --sp-7: 3rem;
  --sp-8: 4rem;
  --sp-9: 6rem;

  --wrap: 1280px;
  --gutter: clamp(1.25rem, 4vw, 3.5rem);
  --radius: 2px;
  --hdr-h: 72px;

  --dur: 0.2s;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --scroll-progress: 0;
}

/* 2. Reset ---------------------------------------------------------------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: calc(var(--hdr-h) + 16px);
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

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

ul, ol { padding: 0; }

img, svg, video, canvas { max-width: 100%; height: auto; }

button, input, select, textarea { font: inherit; color: inherit; }

button {
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

table { border-collapse: collapse; border-spacing: 0; }

[hidden] { display: none !important; }

/* 3. 中文排版基底 ---------------------------------------------------------- */
body {
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: 1.75;
  letter-spacing: 0.01em;
  color: var(--ink);
  background-color: var(--paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  font-family: var(--font-mono);
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.02em;
  text-align: left;
  color: var(--navy-800);
}

h1 { font-size: var(--fs-display-2); }
h2 { font-size: var(--fs-section); }
h3 { font-size: var(--fs-h3); }
h4 { font-size: 1.125rem; letter-spacing: 0; }

p { max-width: 46em; }

strong, b { font-weight: 700; }

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

a:not([class]) {
  text-decoration: underline;
  text-underline-offset: 0.18em;
  text-decoration-thickness: 1px;
  text-decoration-color: var(--line);
  transition: color var(--dur) var(--ease), text-decoration-color var(--dur) var(--ease);
}

a:not([class]):hover {
  color: var(--cyan-500);
  text-decoration-color: var(--cyan-400);
}

:focus-visible {
  outline: 2px solid var(--cyan-400);
  outline-offset: 2px;
  border-radius: 1px;
}

::selection {
  background: var(--orange-500);
  color: var(--navy-900);
}

/* 4. 跳转链接 -------------------------------------------------------------- */
.skip-link {
  position: absolute;
  left: var(--sp-4);
  top: -120px;
  z-index: 120;
  display: inline-block;
  padding: 0.6rem 1rem;
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--navy-900);
  background: var(--cyan-400);
  border-radius: var(--radius);
  transition: top var(--dur) var(--ease);
}

.skip-link:focus {
  top: 0.5rem;
}

/* 5. 页头 ------------------------------------------------------------------ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background: var(--navy-800);
  color: var(--white);
  border-bottom: 1px solid var(--line-on-dark);
}

.site-header::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  height: 2px;
  width: calc(var(--scroll-progress) * 100%);
  background: linear-gradient(90deg, var(--cyan-400), var(--orange-500));
  pointer-events: none;
}

.site-header__inner {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 var(--gutter);
  min-height: var(--hdr-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-5);
}

/* 品牌块 */
.brand-block {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  min-width: 0;
}

.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 0.5rem;
  color: var(--white);
}

.brand__mark {
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 1.375rem;
  letter-spacing: -0.02em;
  line-height: 1.2;
  transition: font-size var(--dur) var(--ease);
}

.brand__sub {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--cyan-400);
  transition: opacity var(--dur) var(--ease);
}

.version-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.18rem 0.5rem;
  border: 1px solid var(--line-on-dark);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  white-space: nowrap;
}

.version-badge__label { color: rgba(255, 255, 255, 0.55); }

.version-badge__num {
  color: var(--orange-500);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.site-header[data-condensed] {
  border-bottom-color: var(--line-on-dark-strong);
}

.site-header[data-condensed] .brand__mark { font-size: 1rem; }

.site-header[data-condensed] .brand__sub { opacity: 0; }

/* 移动端菜单按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.6rem;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--line-on-dark);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--white);
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.nav-toggle:hover {
  border-color: var(--cyan-400);
  color: var(--cyan-400);
}

.nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  gap: 5px;
  width: 20px;
}

.nav-toggle__bar {
  display: block;
  width: 100%;
  height: 1px;
  background: currentColor;
  transition: transform var(--dur) var(--ease);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:first-child {
  transform: translateY(3px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:last-child {
  transform: translateY(-3px) rotate(-45deg);
}

.nav-toggle__label { text-transform: uppercase; }

/* 导航 */
.site-nav {
  display: flex;
  align-items: center;
  gap: var(--sp-5);
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--sp-5);
  list-style: none;
}

.site-nav__item { display: flex; }

.site-nav__link {
  position: relative;
  display: inline-block;
  padding: 0.4rem 0;
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  font-weight: 500;
  letter-spacing: 0.06em;
  color: rgba(255, 255, 255, 0.78);
  transition: color var(--dur) var(--ease);
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0.1rem;
  height: 1px;
  background: var(--cyan-400);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}

.site-nav__link:hover,
.site-nav__link:focus-visible { color: var(--white); }

.site-nav__link:hover::after,
.site-nav__link:focus-visible::after { transform: scaleX(1); }

.site-nav__link[aria-current="page"] { color: var(--white); font-weight: 700; }

.site-nav__link[aria-current="page"]::after {
  height: 2px;
  background: var(--orange-500);
  transform: scaleX(1);
}

.site-nav__drawer-extra { display: none; }

.site-nav__meta-link {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.55);
  transition: color var(--dur) var(--ease);
}

.site-nav__meta-link:hover,
.site-nav__meta-link:focus-visible { color: var(--cyan-400); }

.site-nav__cta { margin-left: var(--sp-2); }

/* 6. 按钮 ------------------------------------------------------------------ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.65rem 1.15rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  font-weight: 700;
  letter-spacing: 0.06em;
  text-align: center;
  transition: background-color var(--dur) var(--ease),
              color var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              transform var(--dur) var(--ease);
}

.btn:hover { transform: translateY(-2px); }

.btn--solid {
  background: var(--orange-500);
  border-color: var(--orange-500);
  color: var(--navy-900);
}

.btn--solid:hover,
.btn--solid:focus-visible {
  background: var(--orange-400);
  border-color: var(--orange-400);
}

.btn--line {
  background: transparent;
  border-color: var(--line-on-dark);
  color: var(--white);
}

.btn--line:hover,
.btn--line:focus-visible {
  border-color: var(--cyan-400);
  color: var(--cyan-400);
}

.btn--ghost {
  background: transparent;
  border-color: var(--navy-700);
  color: var(--navy-800);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  background: var(--navy-800);
  border-color: var(--navy-800);
  color: var(--white);
}

/* 7. 页脚 ------------------------------------------------------------------ */
.site-footer {
  background: var(--navy-800);
  color: rgba(255, 255, 255, 0.72);
  border-top: 1px solid var(--line-on-dark);
}

.site-footer__inner {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: var(--sp-8) var(--gutter) var(--sp-6);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 1px solid var(--line-on-dark);
}

.footer-col {
  padding: var(--sp-6) var(--sp-5) var(--sp-6) 0;
  border-right: 1px solid var(--line-on-dark);
  min-width: 0;
}

.footer-col:last-child {
  border-right: 0;
  padding-right: 0;
}

.footer-col__title {
  margin: 0 0 var(--sp-4);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--white);
}

.footer-col__lead {
  margin: 0 0 var(--sp-2);
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--white);
}

.footer-col__text {
  margin: 0 0 var(--sp-4);
  font-size: 0.875rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.6);
}

.footer-version {
  margin: 0 0 var(--sp-4);
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  letter-spacing: 0.04em;
  color: rgba(255, 255, 255, 0.7);
}

.footer-version__num {
  color: var(--orange-500);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.footer-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  font-size: 0.9375rem;
  line-height: 1.6;
}

.footer-list__item a {
  color: rgba(255, 255, 255, 0.72);
  transition: color var(--dur) var(--ease);
}

.footer-list__item a:hover,
.footer-list__item a:focus-visible { color: var(--cyan-400); }

.footer-contact {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--sp-4);
}

.footer-contact__row {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.footer-contact__label {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--cyan-500);
}

.footer-contact__value {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.9);
  overflow-wrap: break-word;
  word-break: break-word;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--sp-3) var(--sp-5);
  margin-top: var(--sp-6);
  padding-top: var(--sp-4);
  border-top: 1px solid var(--line-on-dark);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  color: rgba(255, 255, 255, 0.5);
}

.footer-legal__icp { color: rgba(255, 255, 255, 0.66); }

.footer-legal__copy { font-variant-numeric: tabular-nums; }

.footer-legal__note {
  flex: 1 1 100%;
  margin: 0;
  max-width: 60em;
  font-family: var(--font-sans);
  font-size: var(--fs-sm);
  line-height: 1.7;
  letter-spacing: 0.01em;
  color: rgba(255, 255, 255, 0.52);
}

/* 8. 布局骨架 -------------------------------------------------------------- */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.wrap--narrow { max-width: 860px; }

.section { padding: var(--sp-9) 0; }

.section--paper { background: var(--paper); }

.section--white { background: var(--white); }

.section--dark {
  background: var(--navy-800);
  color: rgba(255, 255, 255, 0.8);
}

.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark .section__title { color: var(--white); }

.section__head {
  display: grid;
  gap: var(--sp-4);
  max-width: 52rem;
  margin-bottom: var(--sp-7);
}

.section__index {
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--orange-500);
  font-variant-numeric: tabular-nums;
}

.section__title {
  font-family: var(--font-mono);
  font-size: var(--fs-section);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--navy-800);
}

.section__lede {
  margin: 0;
  max-width: 44rem;
  font-size: var(--fs-body);
  color: var(--ink-muted);
}

.section--dark .section__lede { color: rgba(255, 255, 255, 0.68); }

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan-500);
}

.grid {
  display: grid;
  gap: var(--sp-6);
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }

.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

.grid--split { grid-template-columns: minmax(0, 2fr) minmax(0, 1fr); }

.grid--split-rev { grid-template-columns: minmax(0, 1fr) minmax(0, 2fr); }

/* 9. 正文排版 -------------------------------------------------------------- */
.prose { max-width: 46rem; }

.prose > * + * { margin-top: var(--sp-4); }

.prose h2 { margin-top: var(--sp-7); font-size: var(--fs-h3); }

.prose h3 { margin-top: var(--sp-6); }

.prose ul,
.prose ol { padding-left: 1.25rem; }

.prose li + li { margin-top: 0.35rem; }

.prose strong { color: var(--navy-800); }

.prose code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  padding: 0.1em 0.35em;
  border: 1px solid var(--line);
  background: var(--white);
  color: var(--navy-800);
}

/* 10. 面包屑 --------------------------------------------------------------- */
.breadcrumb {
  background: var(--white);
  border-bottom: 1px solid var(--line);
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  list-style: none;
  padding: var(--sp-4) 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
}

.breadcrumb__item {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.breadcrumb__item:not(:last-child)::after {
  content: "/";
  color: var(--line);
}

.breadcrumb__link {
  color: var(--ink-muted);
  transition: color var(--dur) var(--ease);
}

.breadcrumb__link:hover,
.breadcrumb__link:focus-visible { color: var(--cyan-500); }

.breadcrumb__current {
  color: var(--navy-800);
  font-weight: 700;
}

/* 11. 卡片 ---------------------------------------------------------------- */
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  padding: var(--sp-5);
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: box-shadow var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.card::before {
  content: "";
  position: absolute;
  top: -1px;
  left: -1px;
  right: -1px;
  height: 2px;
  background: var(--orange-500);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 26px rgba(10, 37, 64, 0.12);
}

.card:hover::before { transform: scaleX(1); }

.card__index {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--orange-500);
  font-variant-numeric: tabular-nums;
}

.card__title {
  font-family: var(--font-mono);
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--navy-800);
}

.card__meta {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}

.card__text {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--ink-muted);
}

/* 12. 统计数字 ------------------------------------------------------------- */
.metric {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: var(--sp-4) 0;
  border-top: 1px solid var(--line);
}

.metric__value {
  font-family: var(--font-mono);
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--navy-800);
  font-variant-numeric: tabular-nums;
}

.metric__label {
  font-size: var(--fs-sm);
  color: var(--ink-muted);
}

.section--dark .metric { border-top-color: var(--line-on-dark); }

.section--dark .metric__value { color: var(--white); }

.section--dark .metric__label { color: rgba(255, 255, 255, 0.6); }

/* 13. 标签 ---------------------------------------------------------------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.18rem 0.45rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--white);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
  white-space: nowrap;
}

.tag--orange {
  border-color: var(--orange-500);
  color: var(--orange-500);
  background: transparent;
}

.tag--cyan {
  border-color: var(--cyan-400);
  color: var(--cyan-500);
  background: transparent;
}

/* 14. 旁注 ---------------------------------------------------------------- */
.aside-note {
  padding: var(--sp-2) 0 var(--sp-2) var(--sp-4);
  border-left: 2px solid var(--cyan-400);
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--ink-muted);
}

.aside-note__label {
  display: block;
  margin-bottom: 0.35rem;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan-500);
}

.section--dark .aside-note { color: rgba(255, 255, 255, 0.68); }

/* 15. 数据表 -------------------------------------------------------------- */
.data-table {
  width: 100%;
  background: var(--white);
  font-size: 0.9375rem;
  line-height: 1.5;
  border: 1px solid var(--line);
}

.data-table caption {
  caption-side: top;
  padding: 0 0 var(--sp-3);
  text-align: left;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

.data-table th {
  padding: 0.7rem var(--sp-4);
  background: var(--navy-800);
  color: var(--white);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-align: left;
  white-space: nowrap;
  border-right: 1px solid var(--navy-700);
}

.data-table th:last-child { border-right: 0; }

.data-table td {
  padding: 0.7rem var(--sp-4);
  border-bottom: 1px solid var(--line);
  color: var(--ink);
  vertical-align: top;
}

.data-table tbody tr { transition: background-color var(--dur) var(--ease); }

.data-table tbody tr:hover { background: var(--hover-tint); }

.data-table tbody tr:last-child td { border-bottom: 0; }

.data-table__num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--navy-800);
  white-space: nowrap;
}

/* 16. 折叠面板 ------------------------------------------------------------ */
.disclosure {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.disclosure + .disclosure { margin-top: var(--sp-3); }

.disclosure__summary {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  padding: var(--sp-4) var(--sp-5);
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--navy-800);
  cursor: pointer;
  list-style: none;
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.disclosure__summary::-webkit-details-marker { display: none; }

.disclosure__summary::after {
  content: "＋";
  margin-left: auto;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--orange-500);
  transition: transform var(--dur) var(--ease);
}

.disclosure__summary:hover { background: var(--hover-tint); }

.disclosure[open] .disclosure__summary::after { transform: rotate(45deg); }

.disclosure__body {
  padding: 0 var(--sp-5) var(--sp-5);
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--ink-muted);
}

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

/* 17. 图形容器（经纬网格占位） ------------------------------------------- */
.figure {
  margin: 0;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.figure__frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background-color: var(--navy-800);
  background-image:
    linear-gradient(rgba(0, 229, 255, 0.16) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 229, 255, 0.16) 1px, transparent 1px);
  background-size: 32px 32px;
}

.figure__frame::after {
  content: "";
  position: absolute;
  top: 12px;
  left: 12px;
  width: 14px;
  height: 14px;
  border-top: 1px solid var(--orange-500);
  border-left: 1px solid var(--orange-500);
  pointer-events: none;
}

.figure__frame img,
.figure__frame svg,
.figure__frame video {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.figure--wide .figure__frame { aspect-ratio: 21 / 9; }

.figure--tall .figure__frame { aspect-ratio: 4 / 5; }

.figure--square .figure__frame { aspect-ratio: 1 / 1; }

.figure__caption {
  padding: var(--sp-3) var(--sp-4);
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  color: var(--ink-muted);
}

/* 18. 刻度带 -------------------------------------------------------------- */
.rule-scale {
  display: flex;
  align-items: stretch;
  border-top: 1px solid var(--line);
  padding-top: var(--sp-3);
  overflow-x: auto;
}

.rule-scale__tick {
  flex: 1 1 0;
  min-width: 64px;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  padding: 0 var(--sp-2);
  border-left: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}

.rule-scale__tick--active {
  border-left: 2px solid var(--orange-500);
  color: var(--orange-500);
  font-weight: 700;
}

.section--dark .rule-scale { border-top-color: var(--line-on-dark); }

.section--dark .rule-scale__tick {
  border-left-color: var(--line-on-dark);
  color: rgba(255, 255, 255, 0.55);
}

.section--dark .rule-scale__tick--active {
  border-left-color: var(--orange-500);
  color: var(--orange-500);
}

/* 19. 章节高亮状态（由共享脚本写入） -------------------------------------- */
[data-section-link] {
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

[data-section-link][data-active] {
  color: var(--orange-500);
  font-weight: 700;
}

/* 20. 响应式 -------------------------------------------------------------- */
@media (max-width: 1100px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-col { padding-right: var(--sp-5); }
  .footer-col:nth-child(2n) { border-right: 0; padding-right: 0; }
  .footer-col:nth-child(n + 3) { border-top: 1px solid var(--line-on-dark); }
}

@media (max-width: 960px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--hdr-h);
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 85;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    padding: var(--sp-5) var(--gutter) var(--sp-8);
    background: var(--navy-900);
    border-top: 1px solid var(--line-on-dark);
    overflow-y: auto;
    visibility: hidden;
    transform: translateX(100%);
    transition: transform var(--dur) var(--ease), visibility var(--dur) var(--ease);
  }

  .site-nav[data-open] {
    visibility: visible;
    transform: translateX(0);
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
  }

  .site-nav__item {
    width: 100%;
    border-bottom: 1px solid var(--line-on-dark);
  }

  .site-nav__link {
    display: block;
    width: 100%;
    padding: 0.95rem 0;
    font-size: 1rem;
  }

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

  .site-nav__link[aria-current="page"] { color: var(--orange-500); }

  .site-nav__drawer-extra {
    display: flex;
    flex-wrap: wrap;
    gap: var(--sp-5);
    margin-top: var(--sp-5);
  }

  .site-nav__cta {
    margin: var(--sp-6) 0 0;
    width: 100%;
  }

  body[data-nav-open] { overflow: hidden; }

  .grid--2,
  .grid--3,
  .grid--split,
  .grid--split-rev { grid-template-columns: minmax(0, 1fr); }

  .section { padding: var(--sp-8) 0; }
}

@media (max-width: 620px) {
  :root { --hdr-h: 64px; }

  .brand__sub { display: none; }

  .version-badge { display: none; }

  .footer-grid { grid-template-columns: minmax(0, 1fr); }

  .footer-col {
    border-right: 0;
    padding-right: 0;
    padding-left: 0;
  }

  .footer-col:nth-child(n + 2) { border-top: 1px solid var(--line-on-dark); }

  .footer-legal { flex-direction: column; align-items: flex-start; }
}

/* 21. 动效降级 ------------------------------------------------------------ */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .btn:hover,
  .card:hover { transform: none; }
}