/* ==========================================================================
   星空赛场 · 共享样式 /assets/site.css
   深空底 + 星轨边 + 荧光青导航 + 暖橙 CTA + 星尘紫氛围
   ========================================================================== */

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

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

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

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

img, svg, video, canvas {
  display: block;
  max-width: 100%;
}

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

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

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

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

/* 2. 变量 ---------------------------------------------------------------- */
:root {
  --ink-900: #05070F;
  --ink-800: #0C1220;
  --ink-700: #101A2E;
  --line: #1B2438;

  --moon: #E9EEF7;
  --dust: #9BA7BF;

  --cyan: #3DE3CE;
  --amber: #FF8A3D;
  --violet: #7C5CFF;
  --score: #F2C14E;
  --clay: #C96F4A;
  --rock: #6E7480;

  --t-1: 1;
  --t-2: .72;
  --t-3: .52;
  --t-4: .4;

  --shell: 1200px;
  --gutter: clamp(20px, 5vw, 64px);
  --header-h: 138px;
  --radius: 14px;
  --radius-lg: 22px;
  --ease: cubic-bezier(.22, .61, .36, 1);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

/* 3. 基础 ---------------------------------------------------------------- */
body {
  min-height: 100vh;
  background-color: var(--ink-900);
  color: var(--moon);
  font-family: var(--font-sans);
  font-size: 17px;
  font-weight: 300;
  line-height: 1.75;
  letter-spacing: .005em;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(62% 48% at 84% -12%, rgba(124, 92, 255, .17), transparent 70%),
    radial-gradient(46% 40% at 2% 6%, rgba(61, 227, 206, .07), transparent 72%),
    radial-gradient(72% 55% at 50% 118%, rgba(255, 138, 61, .06), transparent 72%);
}

main { position: relative; z-index: 1; }

h1, h2, h3, h4 {
  color: var(--moon);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -.01em;
}

h1 { font-size: clamp(40px, 7vw, 72px); font-weight: 900; line-height: 1.06; }
h2 { font-size: clamp(28px, 4.4vw, 48px); }
h3 { font-size: clamp(21px, 2.4vw, 32px); }
h4 { font-size: 18px; font-weight: 700; line-height: 1.4; }

p { max-width: 68ch; }

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

small { font-size: 13px; color: var(--dust); }

::selection { background: rgba(61, 227, 206, .28); color: var(--moon); }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: 4px;
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* 4. 布局工具 ------------------------------------------------------------ */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { position: relative; padding-block: clamp(56px, 8vw, 110px); }
.section--tight { padding-block: clamp(36px, 5vw, 64px); }

.main-offset { padding-top: var(--header-h); }

.stack { display: grid; gap: clamp(14px, 2.2vw, 26px); }
.stack--lg { gap: clamp(28px, 4vw, 56px); }

.grid { display: grid; gap: clamp(18px, 2.6vw, 32px); }
.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, 1.15fr) minmax(0, .85fr); }
.grid--offset > *:nth-child(even) { margin-top: clamp(16px, 3vw, 44px); }

/* 5. 文字建筑 ------------------------------------------------------------ */
.display {
  font-size: clamp(44px, 8.6vw, 96px);
  font-weight: 900;
  line-height: 1.02;
  letter-spacing: -.02em;
}

.display--step {
  display: block;
  padding-left: .42em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--cyan);
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: currentColor;
  opacity: .85;
}

.cut-rule {
  display: block;
  width: 72px;
  height: 6px;
  background: var(--cyan);
  clip-path: polygon(0 0, 100% 0, 100% 55%, calc(100% - 18px) 100%, 0 100%);
}

.cut-rule--amber { background: var(--amber); }

.chapter-num {
  position: absolute;
  top: clamp(-16px, -1vw, 0px);
  left: 0;
  z-index: 0;
  pointer-events: none;
  font-family: var(--font-mono);
  font-size: clamp(72px, 14vw, 180px);
  font-weight: 700;
  line-height: .8;
  color: rgba(233, 238, 247, .05);
  -webkit-text-stroke: 1px rgba(233, 238, 247, .08);
}

.hud-line {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--dust);
}

.hud-line::after {
  content: "";
  flex: 1 1 auto;
  height: 1px;
  background: linear-gradient(90deg, var(--line), transparent);
}

.num,
.num--sm,
.score {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
  font-weight: 700;
  letter-spacing: -.01em;
}

.score {
  display: block;
  font-size: clamp(48px, 7vw, 96px);
  line-height: 1;
  color: var(--score);
}

.num--sm {
  font-size: 13px;
  font-weight: 400;
  letter-spacing: .1em;
  color: var(--dust);
}

.is-flash { animation: scoreFlash .2s ease; }

@keyframes scoreFlash { 50% { opacity: .35; } }

/* 6. 按钮 ---------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: .06em;
  white-space: nowrap;
  transition: background-color .25s var(--ease), border-color .25s var(--ease),
    color .25s var(--ease), transform .25s var(--ease);
}

.btn--primary {
  background: var(--amber);
  color: #1A0C02;
}

.btn--primary:hover {
  background: #FFA063;
  transform: translateY(-2px);
}

.btn--ghost {
  border-color: var(--line);
  background: rgba(233, 238, 247, .03);
  color: var(--moon);
}

.btn--ghost:hover {
  border-color: rgba(61, 227, 206, .6);
  color: var(--cyan);
  transform: translateY(-2px);
}

.btn--quiet {
  padding: 6px 4px;
  color: var(--dust);
}

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

.btn[disabled],
.btn[aria-disabled="true"] {
  opacity: .42;
  pointer-events: none;
}

/* 7. 头部 ---------------------------------------------------------------- */
.site-header {
  --progress: 0;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color .35s var(--ease), border-color .35s var(--ease);
}

.site-header[data-scrolled="true"] {
  background: rgba(12, 18, 32, .93);
  border-bottom-color: var(--line);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}

.skip-link {
  position: absolute;
  top: -120px;
  left: 16px;
  z-index: 120;
  padding: 10px 18px;
  background: var(--cyan);
  color: #04121A;
  font-size: 14px;
  font-weight: 500;
  border-radius: 0 0 10px 10px;
  transition: top .2s var(--ease);
}

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

.scroll-progress {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--cyan), var(--violet));
  opacity: .9;
}

.header-shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.header-bar {
  display: flex;
  align-items: center;
  gap: clamp(14px, 2.4vw, 34px);
  padding: 18px 0 14px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 14px;
  margin-right: auto;
  flex: 0 0 auto;
}

.brand-mark {
  position: relative;
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: radial-gradient(circle at 32% 30%, rgba(61, 227, 206, .26), transparent 66%);
}

.brand-mark::after {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1px dashed rgba(61, 227, 206, .45);
  border-radius: 50%;
}

.brand-mark__dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 10px var(--amber);
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.28;
}

.brand-name {
  font-size: 19px;
  font-weight: 800;
  letter-spacing: .05em;
}

.brand-tagline {
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--dust);
}

.header-hud {
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--dust);
}

.header-hud::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--cyan);
  animation: hudPulse 2.6s var(--ease) infinite;
}

@keyframes hudPulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(61, 227, 206, .45); }
  55% { box-shadow: 0 0 0 7px rgba(61, 227, 206, 0); }
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 9px 14px 9px 13px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(233, 238, 247, .04);
  color: var(--moon);
  font-size: 13px;
  letter-spacing: .12em;
  transition: border-color .25s var(--ease), color .25s var(--ease);
}

.nav-toggle:hover { border-color: rgba(61, 227, 206, .55); color: var(--cyan); }

.nav-toggle__bars {
  display: grid;
  gap: 5px;
  width: 18px;
}

.nav-toggle__bars > span {
  display: block;
  height: 1.5px;
  background: currentColor;
  transition: transform .3s var(--ease), opacity .3s var(--ease);
}

.site-header[data-open="true"] .nav-toggle {
  border-color: rgba(61, 227, 206, .6);
  color: var(--cyan);
}

.site-header[data-open="true"] .nav-toggle__bars > span:first-child {
  transform: translateY(3.25px) rotate(45deg);
}

.site-header[data-open="true"] .nav-toggle__bars > span:last-child {
  transform: translateY(-3.25px) rotate(-45deg);
}

/* 星轨式栏目索引 */
.nav-scroll {
  position: relative;
  overflow-x: auto;
  overflow-y: hidden;
  padding-bottom: 12px;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  -ms-overflow-style: none;
  -webkit-mask-image: none;
  mask-image: none;
}

.nav-scroll::-webkit-scrollbar { display: none; }

.nav-scroll[data-edge="start"] {
  -webkit-mask-image: linear-gradient(90deg, #000 0, #000 calc(100% - 36px), transparent 100%);
  mask-image: linear-gradient(90deg, #000 0, #000 calc(100% - 36px), transparent 100%);
}

.nav-scroll[data-edge="end"] {
  -webkit-mask-image: linear-gradient(90deg, transparent 0, #000 36px, #000 100%);
  mask-image: linear-gradient(90deg, transparent 0, #000 36px, #000 100%);
}

.nav-scroll[data-edge="both"] {
  -webkit-mask-image: linear-gradient(90deg, transparent 0, #000 36px, #000 calc(100% - 36px), transparent 100%);
  mask-image: linear-gradient(90deg, transparent 0, #000 36px, #000 calc(100% - 36px), transparent 100%);
}

.nav-track {
  position: relative;
  display: flex;
  align-items: center;
  gap: 6px;
  min-width: max-content;
}

.nav-track::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line) 6%, var(--line) 94%, transparent);
}

.nav-link {
  position: relative;
  z-index: 1;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: 14px;
  letter-spacing: .08em;
  color: var(--dust);
  white-space: nowrap;
  scroll-snap-align: center;
  transition: color .25s var(--ease), background-color .25s var(--ease),
    border-color .25s var(--ease);
}

.nav-link::before {
  content: "";
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--rock);
  transition: background-color .25s var(--ease), box-shadow .25s var(--ease);
}

.nav-link:hover {
  color: var(--moon);
  background: rgba(233, 238, 247, .05);
}

.nav-link:hover::before { background: var(--cyan); }

.nav-link[aria-current="page"] {
  color: var(--cyan);
  border-color: rgba(61, 227, 206, .35);
  background: rgba(61, 227, 206, .08);
}

.nav-link[aria-current="page"]::before {
  background: var(--cyan);
  box-shadow: 0 0 10px var(--cyan);
}

/* 8. 页脚 ---------------------------------------------------------------- */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: clamp(64px, 9vw, 130px);
  padding: clamp(48px, 7vw, 88px) 0 36px;
  background: var(--ink-900);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line) 12%,
    rgba(61, 227, 206, .3) 50%, var(--line) 88%, transparent);
}

.footer-shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.5fr);
  gap: clamp(32px, 5vw, 72px);
  padding-bottom: clamp(28px, 4vw, 44px);
  border-bottom: 1px solid var(--line);
}

.footer-brand__name {
  display: block;
  font-size: clamp(22px, 2.6vw, 28px);
  font-weight: 900;
  letter-spacing: .04em;
}

.footer-brand__tagline {
  margin-top: 10px;
  font-size: 14px;
  letter-spacing: .16em;
  color: var(--dust);
}

.footer-brand__note {
  margin-top: 18px;
  max-width: 36ch;
  font-size: 14px;
  line-height: 1.85;
  color: var(--dust);
  opacity: var(--t-2);
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 40px);
}

.footer-col__heading {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: .22em;
  color: var(--rock);
}

.footer-list { display: grid; gap: 10px; }

.footer-list a {
  display: inline-block;
  font-size: 14px;
  color: var(--dust);
  transition: color .2s var(--ease), transform .2s var(--ease);
}

.footer-list a:hover {
  color: var(--cyan);
  transform: translateX(3px);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 22px 40px;
  padding-top: clamp(22px, 3vw, 32px);
}

.footer-contact {
  display: grid;
  gap: 8px;
  max-width: 52ch;
}

.footer-contact__item {
  display: flex;
  align-items: baseline;
  gap: 12px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--dust);
  opacity: var(--t-2);
}

.footer-contact__label {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--rock);
}

.footer-meta {
  display: grid;
  gap: 8px;
  justify-items: end;
  text-align: right;
}

.footer-update {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--dust);
}

.footer-update::before {
  content: "";
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--cyan);
}

.footer-legal {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--rock);
}

/* 9. 通用组件 ------------------------------------------------------------ */
.card {
  position: relative;
  padding: clamp(20px, 2.6vw, 30px);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--ink-800);
  transition: border-color .3s var(--ease), transform .3s var(--ease),
    box-shadow .3s var(--ease);
}

.card:hover {
  border-color: rgba(61, 227, 206, .5);
  transform: translateY(-2px);
  box-shadow: 0 18px 40px -28px rgba(61, 227, 206, .5);
}

.card--flat { background: transparent; }

.card--amber:hover {
  border-color: rgba(255, 138, 61, .5);
  box-shadow: 0 18px 40px -28px rgba(255, 138, 61, .5);
}

.band {
  position: relative;
  overflow: hidden;
  padding-block: clamp(26px, 4vw, 46px);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: linear-gradient(90deg, rgba(124, 92, 255, .14),
    rgba(61, 227, 206, .06) 55%, transparent);
}

.band__row {
  display: flex;
  gap: clamp(20px, 4vw, 56px);
  overflow-x: auto;
  scroll-snap-type: x proximity;
  scrollbar-width: none;
}

.band__row::-webkit-scrollbar { display: none; }

.band__item {
  flex: 0 0 auto;
  min-width: 180px;
  scroll-snap-align: start;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--dust);
}

.tag--cyan { border-color: rgba(61, 227, 206, .4); color: var(--cyan); }
.tag--clay { border-color: rgba(201, 111, 74, .45); color: var(--clay); }

.prose { max-width: 68ch; }

.prose > * + * { margin-top: 1.2em; }

.prose h2 { margin-top: 2.2em; font-size: clamp(24px, 3vw, 32px); }
.prose h3 { margin-top: 1.8em; font-size: clamp(19px, 2.2vw, 24px); }

.prose ul,
.prose ol {
  display: grid;
  gap: .6em;
  padding-left: 1.3em;
  list-style: disc;
}

.prose ol { list-style: decimal; }

.prose blockquote {
  padding-left: 18px;
  border-left: 2px solid var(--clay);
  color: var(--dust);
}

.prose a {
  color: var(--cyan);
  border-bottom: 1px solid rgba(61, 227, 206, .4);
}

.crumbs {
  padding-top: calc(var(--header-h) + 16px);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--rock);
}

.crumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.crumbs li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--line);
}

.crumbs a { color: var(--dust); }
.crumbs a:hover { color: var(--cyan); }
.crumbs [aria-current="page"] { color: var(--moon); }

/* 10. 图片容器基础 ------------------------------------------------------- */
.media {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(120% 120% at 18% 0%, rgba(124, 92, 255, .22), transparent 62%),
    linear-gradient(160deg, var(--ink-700), var(--ink-900));
}

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

.media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(180deg, transparent 46%, rgba(5, 7, 15, .74));
}

.media--21x9 { aspect-ratio: 21 / 9; }
.media--16x9 { aspect-ratio: 16 / 9; }
.media--4x3 { aspect-ratio: 4 / 3; }
.media--1x1 { aspect-ratio: 1 / 1; }
.media--3x4 { aspect-ratio: 3 / 4; }

.media__hud {
  position: absolute;
  left: 16px;
  bottom: 16px;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 6px 13px;
  border: 1px solid rgba(61, 227, 206, .35);
  border-radius: 999px;
  background: rgba(5, 7, 15, .62);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--cyan);
}

.media__credit {
  position: absolute;
  right: 14px;
  bottom: 14px;
  z-index: 2;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--dust);
  opacity: var(--t-4);
}

.media__placeholder {
  position: absolute;
  inset: 0;
  z-index: 1;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--rock);
}

/* 11. 显现动效 ----------------------------------------------------------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity .4s var(--ease), transform .4s var(--ease);
  will-change: opacity, transform;
}

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

/* 12. 响应式 ------------------------------------------------------------- */
@media (max-width: 1180px) {
  .header-hud { display: none; }
}

@media (max-width: 1024px) {
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  :root { --header-h: 74px; }

  .site-header {
    background: rgba(5, 7, 15, .9);
    border-bottom-color: var(--line);
    -webkit-backdrop-filter: blur(14px);
    backdrop-filter: blur(14px);
  }

  .header-bar { padding: 14px 0; }

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

  .nav-scroll { display: none; }

  .site-header[data-open="true"] .nav-scroll {
    display: block;
    margin-top: 6px;
    padding: 6px 0 18px;
    max-height: min(62vh, 460px);
    overflow-y: auto;
    border-top: 1px solid var(--line);
    -webkit-mask-image: none;
    mask-image: none;
  }

  .site-header[data-open="true"] .nav-track {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    min-width: 0;
  }

  .site-header[data-open="true"] .nav-track::before { display: none; }

  .site-header[data-open="true"] .nav-link {
    justify-content: flex-start;
    padding: 12px 14px;
    border-radius: 10px;
    font-size: 15px;
  }

  .footer-top { grid-template-columns: minmax(0, 1fr); }
  .footer-meta { justify-items: start; text-align: left; }
}

@media (max-width: 720px) {
  .grid--2,
  .grid--3,
  .grid--split { grid-template-columns: minmax(0, 1fr); }
  .grid--offset > *:nth-child(even) { margin-top: 0; }
  .footer-cols { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 560px) {
  .header-actions .btn--ghost { display: none; }
  .header-actions .btn--primary { padding: 10px 16px; font-size: 13px; }
  .brand-tagline { display: none; }
  .media__hud { left: 12px; bottom: 12px; font-size: 11px; }
}

@media (max-width: 420px) {
  .footer-cols { grid-template-columns: minmax(0, 1fr); }
}

/* 13. 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;
    transition-delay: 0ms !important;
  }

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

  .card:hover,
  .btn--primary:hover,
  .btn--ghost:hover,
  .footer-list a:hover { transform: none; }
}