/* ==========================================================================
   欧博体育服务中心 · 共享站点样式 /assets/site.css
   夜间数字赛场 + 服务控制台：深海底、1px 网格、直角块面、荧光青单点强调
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-bottom: 9rem;
}

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

ul, ol { margin: 0; padding: 0; list-style: none; }

img, picture, svg, video {
  display: block;
  max-width: 100%;
  height: auto;
}

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

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

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

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

/* ---------- 2. 变量 ---------- */
:root {
  --void: #050B1A;
  --console: #0A1730;
  --grid: #102A4C;
  --steel: #1E4E7A;
  --cyan: #23F0D0;
  --cyan-bright: #63F9E0;
  --violet: #7B4DFF;
  --violet-soft: #B9A2FF;
  --amber: #F2B33D;
  --ink: #E8F1FF;
  --body-ink: #CBDCF2;
  --muted: #9FB3CC;

  --cyan-a08: rgba(35, 240, 208, .08);
  --cyan-a16: rgba(35, 240, 208, .16);
  --cyan-a34: rgba(35, 240, 208, .34);
  --violet-a12: rgba(123, 77, 255, .12);
  --amber-a12: rgba(242, 179, 61, .12);

  --font-display: "PingFang SC", "Noto Sans SC", "Source Han Sans SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-body: "PingFang SC", "Noto Sans SC", "Source Han Sans SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", Menlo, Consolas, "Liberation Mono", monospace;

  --shell: 1280px;
  --gutter: clamp(1rem, 3vw, 2.5rem);
  --gap: clamp(10px, 1.1vw, 16px);
  --pad-block: clamp(3.25rem, 6.5vw, 6rem);
  --header-space: 9.5rem;
}

/* ---------- 3. 基础与中文排版 ---------- */
body {
  min-height: 100vh;
  padding-bottom: var(--header-space);
  background-color: var(--void);
  background-image:
    linear-gradient(rgba(16, 42, 76, .42) 1px, transparent 1px),
    linear-gradient(90deg, rgba(16, 42, 76, .42) 1px, transparent 1px);
  background-size: 96px 96px;
  background-attachment: fixed;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: clamp(15px, .35vw + 14.2px, 17px);
  font-weight: 400;
  line-height: 1.75;
  letter-spacing: .01em;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 900;
  font-stretch: 92%;
  letter-spacing: -.02em;
  line-height: 1.12;
  color: var(--ink);
  text-wrap: balance;
}

h1 { font-size: clamp(2.1rem, 5vw, 4.2rem); }
h2 { font-size: clamp(1.6rem, 3vw, 2.6rem); }
h3 { font-size: clamp(1.15rem, 1.6vw, 1.5rem); font-weight: 800; letter-spacing: -.005em; }
h4 { font-size: 1.02rem; font-weight: 800; letter-spacing: 0; line-height: 1.4; }

p { max-width: 38em; }

strong, b { font-weight: 800; color: #FFFFFF; }

::selection { background: var(--cyan); color: var(--void); }

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

/* ---------- 4. 布局工具 ---------- */
.container {
  width: min(var(--shell), 100% - var(--gutter) * 2);
  margin-inline: auto;
}

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

.span-2  { grid-column: span 2; }
.span-3  { grid-column: span 3; }
.span-4  { grid-column: span 4; }
.span-5  { grid-column: span 5; }
.span-6  { grid-column: span 6; }
.span-7  { grid-column: span 7; }
.span-8  { grid-column: span 8; }
.span-12 { grid-column: span 12; }

.stack > * + * { margin-top: 1rem; }

.mono {
  font-family: var(--font-mono);
  letter-spacing: .05em;
}

/* ---------- 5. 跳过链接 ---------- */
.skip-link {
  position: fixed;
  top: 0;
  left: 50%;
  z-index: 300;
  transform: translate(-50%, -140%);
  padding: .75rem 1.15rem;
  background: var(--cyan);
  color: var(--void);
  font-family: var(--font-mono);
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .1em;
  transition: transform .2s ease;
}

.skip-link:focus,
.skip-link:focus-visible {
  transform: translate(-50%, 0);
}

/* ---------- 6. 头部：底部悬浮控制条 ---------- */
.site-header {
  position: fixed;
  left: 0;
  right: 0;
  bottom: clamp(.75rem, 2vh, 1.6rem);
  z-index: 120;
  display: flex;
  justify-content: center;
  padding-inline: var(--gutter);
  pointer-events: none;
}

.scroll-meter {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  z-index: 140;
  background: rgba(16, 42, 76, .55);
}

.scroll-meter__fill {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--cyan), var(--violet));
}

.header-pod {
  pointer-events: auto;
  position: relative;
  display: flex;
  align-items: center;
  gap: clamp(.4rem, 1.2vw, 1rem);
  width: min(1220px, 100%);
  padding: .5rem .6rem;
  background: rgba(10, 23, 48, .9);
  border: 1px solid var(--grid);
  box-shadow: 0 22px 60px rgba(3, 7, 18, .78);
  -webkit-backdrop-filter: blur(18px) saturate(150%);
  backdrop-filter: blur(18px) saturate(150%);
  transition: padding .3s ease, background-color .3s ease, box-shadow .3s ease;
}

.header-pod::before,
.header-pod::after {
  content: "";
  position: absolute;
  width: 10px;
  height: 10px;
  border-style: solid;
  border-color: var(--cyan);
  transition: border-color .28s ease;
}

.header-pod::before { top: -1px; left: -1px; border-width: 1px 0 0 1px; }
.header-pod::after { bottom: -1px; right: -1px; border-width: 0 1px 1px 0; }

.site-header[data-scrolled="true"] .header-pod {
  padding-top: .28rem;
  padding-bottom: .28rem;
  background: rgba(10, 23, 48, .97);
  box-shadow: 0 14px 34px rgba(3, 7, 18, .88);
}

/* 品牌浮岛 */
.brand {
  display: flex;
  align-items: center;
  gap: .6rem;
  flex: 0 0 auto;
  min-width: 0;
  padding: .22rem .45rem .22rem .25rem;
  border: 1px solid transparent;
  transition: border-color .25s ease, background-color .25s ease;
}

.brand:hover,
.brand:focus-visible {
  border-color: var(--grid);
  background-color: rgba(16, 42, 76, .45);
}

.brand__mark {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 34px;
  height: 34px;
  background: var(--cyan);
  color: var(--void);
  font-family: var(--font-mono);
  font-size: .76rem;
  font-weight: 700;
  letter-spacing: .04em;
}

.brand__text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.brand__name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: .95rem;
  letter-spacing: -.01em;
  line-height: 1.25;
  white-space: nowrap;
}

.brand__tag {
  font-family: var(--font-mono);
  font-size: .6rem;
  font-weight: 500;
  letter-spacing: .14em;
  color: var(--muted);
  white-space: nowrap;
}

.brand__version {
  flex: 0 0 auto;
  padding: .18rem .42rem;
  border: 1px solid var(--cyan-a34);
  background: var(--cyan-a08);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: .7rem;
  font-weight: 700;
  letter-spacing: .08em;
}

/* 导航 */
.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(.5rem, 1.4vw, 1.6rem);
  flex: 1 1 auto;
  min-width: 0;
}

.nav-list {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 1 1 auto;
  gap: .12rem;
  min-width: 0;
}

.nav-link {
  display: inline-flex;
  align-items: baseline;
  gap: .35rem;
  padding: .55rem .6rem;
  border: 1px solid transparent;
  color: var(--muted);
  font-size: .86rem;
  font-weight: 500;
  white-space: nowrap;
  transition: color .22s ease, border-color .22s ease, background-color .22s ease;
}

.nav-link__index {
  font-family: var(--font-mono);
  font-size: .6rem;
  font-weight: 500;
  letter-spacing: .08em;
  color: var(--steel);
  transition: color .22s ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--ink);
  border-color: var(--cyan);
  background-color: var(--cyan-a08);
}

.nav-link:hover .nav-link__index,
.nav-link:focus-visible .nav-link__index { color: var(--cyan); }

.nav-link[aria-current="page"] {
  color: var(--cyan);
  border-color: var(--cyan-a34);
  background-color: var(--cyan-a08);
}

.nav-link[aria-current="page"] .nav-link__index { color: var(--cyan); }

.nav-actions {
  display: flex;
  align-items: center;
  gap: .4rem;
  flex: 0 0 auto;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  padding: .6rem .95rem;
  background: var(--cyan);
  border: 1px solid var(--cyan);
  color: var(--void);
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .08em;
  white-space: nowrap;
  transition: background-color .22s ease, border-color .22s ease;
}

.nav-cta:hover,
.nav-cta:focus-visible {
  background: var(--cyan-bright);
  border-color: var(--cyan-bright);
}

.nav-ghost {
  display: inline-flex;
  align-items: center;
  padding: .6rem .85rem;
  background: transparent;
  border: 1px solid var(--grid);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 500;
  letter-spacing: .08em;
  white-space: nowrap;
  transition: color .22s ease, border-color .22s ease, background-color .22s ease;
}

.nav-ghost:hover,
.nav-ghost:focus-visible {
  color: var(--ink);
  border-color: var(--violet);
  background: var(--violet-a12);
}

/* 移动端开关 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: .55rem;
  flex: 0 0 auto;
  padding: .55rem .8rem;
  border: 1px solid var(--grid);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: .7rem;
  font-weight: 500;
  letter-spacing: .12em;
  transition: border-color .22s ease, background-color .22s ease;
}

.nav-toggle:hover,
.nav-toggle:focus-visible {
  border-color: var(--cyan);
  background-color: var(--cyan-a08);
}

.nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  gap: 3px;
  width: 14px;
}

.nav-toggle__bars i {
  display: block;
  height: 1px;
  background: var(--cyan);
  transition: transform .25s ease, opacity .25s ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(4px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3) { transform: translateY(-4px) rotate(-45deg); }

/* ---------- 7. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(3rem, 6vw, 5.5rem);
  border-top: 1px solid var(--grid);
  background: linear-gradient(180deg, rgba(10, 23, 48, .9), rgba(5, 11, 26, 1));
  padding-block: clamp(2.5rem, 5vw, 4rem) clamp(5rem, 10vw, 8rem);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: clamp(60px, 12vw, 160px);
  height: 2px;
  background: var(--cyan);
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1.6fr);
  gap: clamp(1.75rem, 4vw, 3.5rem);
  align-items: start;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: .8rem;
  max-width: 26rem;
}

.footer-brand__mark {
  align-self: flex-start;
  padding: .28rem .55rem;
  border: 1px solid var(--grid);
  background: rgba(5, 11, 26, .7);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: .68rem;
  font-weight: 700;
  letter-spacing: .14em;
}

.footer-brand__line {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.05rem;
  line-height: 1.45;
  letter-spacing: -.01em;
}

.footer-brand__note {
  max-width: 32ch;
  color: var(--muted);
  font-size: .85rem;
  line-height: 1.7;
}

.footer-nav {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(1rem, 2.5vw, 2rem);
}

.footer-col__title {
  display: flex;
  align-items: center;
  gap: .5rem;
  margin-bottom: .95rem;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: .68rem;
  font-weight: 500;
  letter-spacing: .18em;
}

.footer-col__title::before {
  content: "";
  width: 14px;
  height: 1px;
  background: var(--cyan);
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: .55rem;
}

.footer-link {
  display: inline-block;
  padding-left: 0;
  border-bottom: 1px solid transparent;
  color: var(--muted);
  font-size: .9rem;
  transition: color .22s ease, border-color .22s ease, padding-left .22s ease;
}

.footer-link:hover,
.footer-link:focus-visible {
  color: var(--ink);
  border-color: var(--cyan);
  padding-left: .3rem;
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem 1.5rem;
  justify-content: space-between;
  align-items: baseline;
  margin-top: clamp(2rem, 4vw, 3rem);
  padding-top: 1.25rem;
  border-top: 1px solid var(--grid);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
}

.footer-meta__contact { word-break: break-word; }
.footer-meta__legal { color: var(--steel); }

/* ---------- 8. 章节与编号体系 ---------- */
.section {
  position: relative;
  padding-block: var(--pad-block);
}

.section + .section { border-top: 1px solid var(--grid); }

.section-head {
  display: flex;
  flex-direction: column;
  gap: .7rem;
  margin-bottom: clamp(1.5rem, 3vw, 2.75rem);
}

.section-num {
  display: inline-flex;
  align-items: center;
  gap: .65rem;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: clamp(1.05rem, 2vw, 1.55rem);
  font-weight: 500;
  letter-spacing: .08em;
  line-height: 1;
}

.section-num::before {
  content: "";
  width: clamp(20px, 4vw, 46px);
  height: 1px;
  background: var(--cyan);
}

.section-title { font-size: clamp(1.7rem, 3.4vw, 2.9rem); }

.section-lead {
  max-width: 38em;
  color: var(--muted);
  font-size: 1rem;
}

/* ---------- 9. Bento 信息块 ---------- */
.panel {
  position: relative;
  padding: clamp(1.25rem, 2vw, 1.9rem);
  background: var(--console);
  border: 1px solid var(--grid);
}

.panel::after {
  content: "";
  position: absolute;
  top: -1px;
  right: -1px;
  width: 13px;
  height: 13px;
  border-top: 1px solid var(--steel);
  border-right: 1px solid var(--steel);
  transition: border-color .25s ease;
}

.panel:hover::after { border-color: var(--cyan); }

.panel--focus {
  background:
    linear-gradient(158deg, rgba(35, 240, 208, .1), rgba(10, 23, 48, .15) 46%),
    var(--console);
  border-color: var(--cyan-a34);
}

.panel--quiet {
  background: transparent;
}

.panel-link {
  display: block;
  transition: border-color .25s ease, background-color .25s ease;
}

.panel-link:hover,
.panel-link:focus-visible {
  border-color: var(--cyan);
  background-color: var(--cyan-a08);
}

/* ---------- 10. 标签、徽标、按钮 ---------- */
.chip {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  padding: .28rem .55rem;
  border: 1px solid var(--grid);
  background: rgba(5, 11, 26, .6);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: .68rem;
  font-weight: 500;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.chip--cyan {
  color: var(--cyan);
  border-color: var(--cyan-a34);
  background: var(--cyan-a08);
}

.chip--violet {
  color: var(--violet-soft);
  border-color: rgba(123, 77, 255, .45);
  background: var(--violet-a12);
}

.chip--amber {
  color: var(--amber);
  border-color: rgba(242, 179, 61, .42);
  background: var(--amber-a12);
}

.num-badge {
  display: inline-grid;
  place-items: center;
  min-width: 2.2rem;
  height: 1.5rem;
  padding: 0 .45rem;
  background: var(--cyan);
  color: var(--void);
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .14em;
}

.num-badge--steel {
  background: var(--steel);
  color: var(--ink);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .85rem 1.2rem;
  border: 1px solid var(--grid);
  background: transparent;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: .78rem;
  font-weight: 500;
  letter-spacing: .1em;
  transition: border-color .22s ease, background-color .22s ease, color .22s ease;
}

.btn:hover,
.btn:focus-visible {
  border-color: var(--cyan);
  background-color: var(--cyan-a08);
  color: var(--ink);
}

.btn--primary {
  background: var(--cyan);
  border-color: var(--cyan);
  color: var(--void);
  font-weight: 700;
}

.btn--primary:hover,
.btn--primary:focus-visible {
  background: var(--cyan-bright);
  border-color: var(--cyan-bright);
  color: var(--void);
}

.btn--ghost {
  border-color: var(--steel);
  color: var(--muted);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  color: var(--ink);
  border-color: var(--violet);
  background-color: var(--violet-a12);
}

/* ---------- 11. 面包屑 ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .5rem;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .08em;
}

.breadcrumb li {
  display: flex;
  align-items: center;
  gap: .5rem;
}

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

.breadcrumb a {
  border-bottom: 1px solid transparent;
  transition: color .22s ease, border-color .22s ease;
}

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

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

/* ---------- 12. 正文容器 ---------- */
.prose { max-width: 46rem; }

.prose p {
  max-width: 38em;
  color: var(--body-ink);
}

.prose p + p { margin-top: 1rem; }

.prose h2 { margin-top: 2.6rem; }
.prose h3 { margin-top: 1.9rem; margin-bottom: .55rem; }
.prose h4 { margin-top: 1.4rem; margin-bottom: .4rem; }

.prose ul,
.prose ol {
  margin-top: .9rem;
  padding-left: 0;
}

.prose li {
  position: relative;
  padding-left: 1.5rem;
  color: var(--body-ink);
}

.prose li + li { margin-top: .45rem; }

.prose ul > li::before {
  content: "";
  position: absolute;
  top: .72em;
  left: 0;
  width: 7px;
  height: 1px;
  background: var(--cyan);
}

.prose ol { counter-reset: prose-ol; }

.prose ol > li { counter-increment: prose-ol; }

.prose ol > li::before {
  content: counter(prose-ol, decimal-leading-zero);
  position: absolute;
  top: 0;
  left: 0;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: .74rem;
  font-weight: 500;
  letter-spacing: .06em;
}

.prose a {
  color: var(--cyan);
  border-bottom: 1px solid rgba(35, 240, 208, .4);
  transition: border-color .2s ease;
}

.prose a:hover,
.prose a:focus-visible { border-color: var(--cyan); }

/* ---------- 13. 图片容器（页面阶段填充） ---------- */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border: 1px solid var(--grid);
  background-color: #071021;
  background-image:
    linear-gradient(rgba(16, 42, 76, .85) 1px, transparent 1px),
    linear-gradient(90deg, rgba(16, 42, 76, .85) 1px, transparent 1px);
  background-size: 28px 28px;
}

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

.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--tall { aspect-ratio: 4 / 5; }

.media-frame__tag {
  position: absolute;
  left: 0;
  bottom: 0;
  padding: .3rem .6rem;
  border-top: 1px solid var(--grid);
  border-right: 1px solid var(--grid);
  background: rgba(5, 11, 26, .88);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: .66rem;
  letter-spacing: .14em;
  text-transform: uppercase;
}

/* ---------- 14. 索引条 ---------- */
.index-rail {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .5rem .95rem;
  padding: .7rem .95rem;
  border: 1px solid var(--grid);
  background: rgba(10, 23, 48, .72);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .12em;
}

.index-rail__item {
  display: inline-flex;
  align-items: center;
  gap: .45rem;
}

.index-rail__item::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--steel);
}

.index-rail__item--active { color: var(--cyan); }
.index-rail__item--active::before { background: var(--cyan); }

/* ---------- 15. 滚动显现 ---------- */
[data-reveal] {
  opacity: 1;
  transform: none;
}

html.js [data-reveal] {
  opacity: 0;
  transform: translateY(4px);
  transition: opacity .5s ease, transform .5s ease;
}

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

/* ---------- 16. 响应式 ---------- */
@media (max-width: 1080px) {
  :root { --header-space: 8.75rem; }

  .header-pod { justify-content: space-between; }

  .brand__tag { display: none; }

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

  .site-nav {
    position: fixed;
    left: var(--gutter);
    right: var(--gutter);
    bottom: clamp(4.4rem, 11vh, 5.6rem);
    max-height: min(66vh, 500px);
    overflow-y: auto;
    display: none;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: .4rem;
    padding: .9rem;
    background: rgba(10, 23, 48, .98);
    border: 1px solid var(--grid);
    box-shadow: 0 -22px 50px rgba(3, 7, 18, .85);
    -webkit-backdrop-filter: blur(18px);
    backdrop-filter: blur(18px);
  }

  .site-nav[data-open="true"] { display: flex; }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 1px;
    flex: 0 0 auto;
  }

  .nav-link {
    justify-content: flex-start;
    padding: .8rem .75rem;
    border-color: transparent;
    border-bottom: 1px solid var(--grid);
  }

  .nav-link__index { font-size: .68rem; color: var(--steel); }

  .nav-actions {
    flex-direction: column;
    align-items: stretch;
    gap: .45rem;
    margin-top: .35rem;
    padding-top: .8rem;
    border-top: 1px solid var(--grid);
  }

  .nav-cta,
  .nav-ghost {
    justify-content: center;
    padding: .85rem 1rem;
  }

  .nav-cta::before,
  .nav-ghost::before {
    content: attr(data-index);
    margin-right: .5rem;
    font-family: var(--font-mono);
    font-size: .66rem;
    font-weight: 500;
    opacity: .7;
  }

  .span-2,
  .span-3,
  .span-4 { grid-column: span 6; }

  .span-5,
  .span-7,
  .span-8 { grid-column: span 12; }

  .footer-top { grid-template-columns: 1fr; }
}

@media (max-width: 720px) {
  :root {
    --gutter: 1rem;
    --header-space: 8rem;
    --pad-block: clamp(2.75rem, 9vw, 4rem);
  }

  .brand__mark { width: 30px; height: 30px; font-size: .7rem; }
  .brand__name { font-size: .88rem; }

  .footer-nav { grid-template-columns: 1fr 1fr; }

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

@media (max-width: 640px) {
  .layout-12 { grid-template-columns: 1fr; }
  .layout-12 > * { grid-column: auto; }

  .footer-nav { grid-template-columns: 1fr; }
}

/* ---------- 17. 无障碍与动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }

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

  .footer-link:hover,
  .footer-link:focus-visible { padding-left: 0; }
}