/* ==========================================================================
   大厅游戏中心 · 共享站点样式 /assets/site.css
   深空档案室 · 左右分屏骨架 · 切角面板 · 等宽索引
   ========================================================================== */

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

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

body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: 1.78;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 { margin: 0; line-height: 1.26; font-weight: 700; }
p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
figure { margin: 0; }
img, svg, video { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; }
strong { font-weight: 700; }

/* ---------- 2. Tokens ---------- */
:root {
  --c-bg: #070B1A;
  --c-bg-2: #0E1630;
  --c-panel: #16203C;
  --c-cyan: #35E6D2;
  --c-magenta: #FF4FA3;
  --c-amber: #FFB347;
  --c-mint: #5EE6A8;
  --c-text: #E8EEF9;
  --c-text-2: #93A2C4;
  --c-line: #1E2B4A;
  --c-ink: #04121A;

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

  --fs-body: 16.5px;
  --shell: 1320px;
  --shell-mid: 1080px;
  --shell-narrow: 720px;
  --gap: 24px;
  --cut: 12px;
  --sec: 96px;

  --ease: cubic-bezier(.2, .7, .3, 1);
  --t-hover: 160ms;
  --t-state: 240ms;
}

/* ---------- 3. 背景网格底纹 ---------- */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: .75;
  background-image:
    repeating-linear-gradient(to right, rgba(30, 43, 74, .55) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(to bottom, rgba(30, 43, 74, .38) 0 1px, transparent 1px 96px);
  -webkit-mask-image: radial-gradient(120% 78% at 72% 0%, #000 0%, transparent 76%);
  mask-image: radial-gradient(120% 78% at 72% 0%, #000 0%, transparent 76%);
}

#main-content { position: relative; z-index: 1; display: block; }

/* ---------- 4. 通用排版 ---------- */
.mono { font-family: var(--font-mono); letter-spacing: .06em; }
.tnum { font-variant-numeric: tabular-nums; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-cyan);
  text-transform: uppercase;
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  flex: none;
  background: var(--c-cyan);
}

.label-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  line-height: 1.5;
  padding: 3px 9px 4px;
  color: var(--c-magenta);
  background: rgba(255, 79, 163, .14);
  clip-path: polygon(0 0, 100% 0, 100% 100%, 7px 100%, 0 calc(100% - 7px));
}
.label-tag--cyan { color: var(--c-cyan); background: rgba(53, 230, 210, .12); }
.label-tag--amber { color: var(--c-amber); background: rgba(255, 179, 71, .14); }

.prose { max-width: 68ch; }
.prose > * + * { margin-top: 1.05em; }
.prose h2 {
  font-size: clamp(22px, 2.2vw, 28px);
  font-weight: 800;
  letter-spacing: .02em;
  margin-top: 2em;
}
.prose h3 { font-size: 18px; font-weight: 700; margin-top: 1.7em; }
.prose p { color: var(--c-text); }
.prose a {
  color: var(--c-cyan);
  border-bottom: 1px solid rgba(53, 230, 210, .35);
  transition: border-color var(--t-hover) var(--ease);
}
.prose a:hover { border-bottom-color: var(--c-cyan); }
.prose li { position: relative; padding-left: 22px; }
.prose li + li { margin-top: .5em; }
.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .74em;
  width: 9px;
  height: 1px;
  background: var(--c-cyan);
}
.prose strong { color: #FFFFFF; }
.prose code {
  font-family: var(--font-mono);
  font-size: .9em;
  padding: 1px 6px;
  border-radius: 2px;
  background: rgba(53, 230, 210, .1);
  color: var(--c-cyan);
}

.sr-only {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* ---------- 5. 容器 / 网格 / 分屏 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: 24px;
}
.shell--mid { max-width: var(--shell-mid); }
.shell--narrow { max-width: var(--shell-narrow); }

.split {
  display: grid;
  grid-template-columns: minmax(0, 26fr) minmax(0, 74fr);
  gap: 48px;
  align-items: start;
}
.split__aside { position: relative; min-width: 0; }
.split__main { position: relative; min-width: 0; }

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gap);
}
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-7 { grid-column: span 7; }
.span-8 { grid-column: span 8; }

.stack > * + * { margin-top: 16px; }
.stack--sm > * + * { margin-top: 8px; }

.section { position: relative; padding-block: var(--sec); }
.section--tight { padding-block: 48px; }
.section--alt { background: var(--c-bg-2); }

/* ---------- 6. 装饰：斜线与扫描线 ---------- */
.slash {
  display: block;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(53, 230, 210, .55), transparent);
  transform: rotate(-8deg);
  transform-origin: left center;
}
.scanline {
  position: absolute;
  left: 0; right: 0;
  height: 1px;
  pointer-events: none;
  background: linear-gradient(90deg, transparent, rgba(53, 230, 210, .45), rgba(255, 79, 163, .3), transparent);
  animation: scan-drift 8s var(--ease) forwards;
}
@keyframes scan-drift {
  from { transform: translateY(0); opacity: 0; }
  20%  { opacity: .9; }
  to   { transform: translateY(12px); opacity: .55; }
}

/* ---------- 7. 面板 / 图像容器 ---------- */
.panel {
  position: relative;
  background: var(--c-panel);
  padding: 24px;
  min-width: 0;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut)),
                     calc(100% - var(--cut)) 100%, 0 100%);
}
.panel--flat {
  background: var(--c-bg-2);
  clip-path: none;
  padding: 20px 0;
}

.media-frame {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--c-line);
  background: linear-gradient(150deg, #101B36, #0A1226);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px),
                     calc(100% - 16px) 100%, 0 100%);
}
.media-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: .55;
  background-image:
    repeating-linear-gradient(to right, rgba(30, 43, 74, .6) 0 1px, transparent 1px 48px),
    repeating-linear-gradient(to bottom, rgba(30, 43, 74, .6) 0 1px, transparent 1px 48px);
}
.media-frame__body { position: relative; display: block; width: 100%; height: 100%; }
.media-frame img { width: 100%; height: 100%; object-fit: cover; }
.ratio-16-9 { aspect-ratio: 16 / 9; }
.ratio-4-3 { aspect-ratio: 4 / 3; }
.ratio-1-1 { aspect-ratio: 1 / 1; }
.media-cap {
  display: block;
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  color: var(--c-text-2);
}

/* ---------- 8. 面包屑 ---------- */
.breadcrumbs {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--c-text-2);
}
.breadcrumbs__list { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.breadcrumbs__item { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumbs__item + .breadcrumbs__item::before { content: "/"; color: rgba(147, 162, 196, .45); }
.breadcrumbs a { transition: color var(--t-hover) var(--ease); }
.breadcrumbs a:hover { color: var(--c-cyan); }
.breadcrumbs [aria-current="page"] { color: var(--c-text); }

/* ---------- 9. 状态点 ---------- */
.status-dot {
  width: 6px;
  height: 6px;
  flex: none;
  border-radius: 50%;
  background: var(--c-cyan);
  box-shadow: 0 0 0 3px rgba(53, 230, 210, .14);
}
.status-dot--cyan { background: var(--c-cyan); box-shadow: 0 0 0 3px rgba(53, 230, 210, .14); }
.status-dot--mint { background: var(--c-mint); box-shadow: 0 0 0 3px rgba(94, 230, 168, .14); }
.status-dot--amber { background: var(--c-amber); box-shadow: 0 0 0 3px rgba(255, 179, 71, .16); }

/* ---------- 10. 按钮 ---------- */
.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 18px 11px 22px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: .02em;
  line-height: 1.3;
  border-radius: 3px;
  cursor: pointer;
  transition: background-color var(--t-hover) var(--ease),
              color var(--t-hover) var(--ease),
              box-shadow var(--t-hover) var(--ease),
              transform var(--t-hover) var(--ease);
}
.btn::before {
  content: "";
  position: absolute;
  left: 10px;
  top: 20%;
  width: 2px;
  height: 60%;
  background: currentColor;
  opacity: .55;
  transform: skewX(-8deg);
}
.btn--primary { background: var(--c-cyan); color: var(--c-ink); }
.btn--primary::before { background: var(--c-ink); }
.btn--primary:hover { background: #5BF0DF; transform: translateY(-1px); }
.btn--ghost {
  background: rgba(53, 230, 210, .06);
  color: var(--c-text);
  box-shadow: inset 0 0 0 1px rgba(53, 230, 210, .38);
}
.btn--ghost:hover {
  background: rgba(53, 230, 210, .14);
  color: var(--c-cyan);
  transform: translateY(-1px);
}

/* ---------- 11. 焦点环 ---------- */
:focus-visible {
  outline: 2px solid var(--c-cyan);
  outline-offset: 2px;
  border-radius: 2px;
}

/* ---------- 12. 跳转链接 ---------- */
.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 200;
  padding: 10px 18px;
  border-radius: 4px;
  background: var(--c-cyan);
  color: var(--c-ink);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .02em;
  transform: translateY(-180%);
  transition: transform var(--t-hover) var(--ease);
}
.skip-link:focus { transform: translateY(0); }

/* ---------- 13. 页头 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: linear-gradient(180deg, rgba(7, 11, 26, .97), rgba(7, 11, 26, .88));
  border-bottom: 1px solid var(--c-line);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.header-rail {
  background: var(--c-bg-2);
  border-bottom: 1px solid var(--c-line);
}
.header-rail__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  min-height: 34px;
  padding-block: 6px;
}
.rail-list { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 22px; }
.rail-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .06em;
  font-variant-numeric: tabular-nums;
  color: var(--c-text-2);
}
.rail-note {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .06em;
  color: rgba(147, 162, 196, .72);
  white-space: nowrap;
}

.header-bar { position: relative; }
.header-bar::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 38%;
  height: 1px;
  background: linear-gradient(90deg, var(--c-cyan), transparent);
  opacity: .55;
  pointer-events: none;
}

.header-shell {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 78px;
  padding-block: 14px;
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
  border-radius: 4px;
}
.brand__glyph {
  width: 34px;
  height: 34px;
  flex: none;
  display: grid;
  align-content: center;
  justify-content: center;
  gap: 3px;
  background: linear-gradient(160deg, #1B2A4E, #0E1630);
  border-left: 2px solid var(--c-cyan);
  clip-path: polygon(0 0, 100% 0, 100% 68%, 68% 100%, 0 100%);
}
.brand__glyph i { display: block; height: 2px; background: var(--c-cyan); opacity: .85; }
.brand__glyph i:nth-child(1) { width: 18px; }
.brand__glyph i:nth-child(2) { width: 12px; background: var(--c-magenta); }
.brand__glyph i:nth-child(3) { width: 7px; background: var(--c-amber); }

.brand__text { display: block; min-width: 0; }
.brand__name {
  display: block;
  font-size: 19px;
  font-weight: 800;
  letter-spacing: .06em;
  line-height: 1.3;
  color: var(--c-text);
}
.brand__sub {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .08em;
  line-height: 1.5;
  color: var(--c-text-2);
}

/* 导航 */
.site-nav {
  display: flex;
  align-items: center;
  gap: 28px;
  margin-left: auto;
  min-width: 0;
}
.site-nav__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 2px;
}
.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 9px 12px;
  font-size: 14.5px;
  color: var(--c-text-2);
  border-radius: 3px;
  transition: color var(--t-hover) var(--ease),
              background-color var(--t-hover) var(--ease),
              transform var(--t-hover) var(--ease);
}
.site-nav__idx {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: .08em;
  font-variant-numeric: tabular-nums;
  color: rgba(147, 162, 196, .6);
  transition: color var(--t-hover) var(--ease);
}
.site-nav__link:hover {
  color: var(--c-text);
  background: rgba(53, 230, 210, .07);
  transform: translateY(-1px);
}
.site-nav__link:hover .site-nav__idx { color: var(--c-cyan); }
.site-nav__link[aria-current="page"] { color: var(--c-text); }
.site-nav__link[aria-current="page"] .site-nav__idx { color: var(--c-cyan); }
.site-nav__link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 2px;
  height: 2px;
  background: var(--c-cyan);
  box-shadow: 0 0 10px rgba(53, 230, 210, .6);
}
.site-nav__actions { display: flex; align-items: center; gap: 10px; flex: none; }

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border: 1px solid rgba(53, 230, 210, .35);
  border-radius: 3px;
  background: rgba(22, 32, 60, .9);
  color: var(--c-text);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  cursor: pointer;
  transition: background-color var(--t-hover) var(--ease),
              color var(--t-hover) var(--ease);
}
.nav-toggle:hover { background: rgba(53, 230, 210, .12); color: var(--c-cyan); }
.nav-toggle__bars { position: relative; width: 18px; height: 10px; flex: none; }
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  height: 2px;
  background: currentColor;
  transition: transform var(--t-state) var(--ease), width var(--t-state) var(--ease);
}
.nav-toggle__bars::before { top: 0; width: 18px; }
.nav-toggle__bars::after { bottom: 0; width: 12px; background: var(--c-cyan); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { transform: translateY(4px) rotate(-8deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { transform: translateY(-4px) rotate(-8deg); width: 18px; }

/* ---------- 14. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  background: var(--c-bg-2);
  border-top: 1px solid var(--c-line);
}
.footer-rail {
  height: 3px;
  background: linear-gradient(90deg,
    var(--c-cyan) 0 16%,
    var(--c-magenta) 16% 26%,
    var(--c-amber) 26% 30%,
    transparent 30%);
}
.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: 48px;
  padding-block: 72px 48px;
}
.footer-brand { min-width: 0; }
.brand--footer { margin-bottom: 18px; }
.footer-summary {
  max-width: 46ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--c-text-2);
}
.footer-availability {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-top: 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--c-text-2);
}
.footer-cols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 32px;
}
.footer-col__title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .16em;
  color: var(--c-cyan);
}
.footer-col__title::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 1px;
  margin-right: 8px;
  vertical-align: middle;
  background: var(--c-magenta);
}
.footer-links li + li { margin-top: 9px; }
.footer-links a {
  font-size: 14.5px;
  color: var(--c-text-2);
  transition: color var(--t-hover) var(--ease), padding-left var(--t-hover) var(--ease);
}
.footer-links a:hover { color: var(--c-cyan); padding-left: 4px; }

.footer-contact {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 40px;
  padding-block: 26px;
  border-top: 1px solid var(--c-line);
  border-bottom: 1px solid var(--c-line);
}
.contact-item { display: inline-flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.contact-item__key {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .14em;
  color: var(--c-text-2);
}
.contact-item__val {
  font-family: var(--font-mono);
  font-size: 13.5px;
  font-variant-numeric: tabular-nums;
  color: var(--c-text);
}
.copy-btn {
  padding: 3px 9px;
  border: 1px solid rgba(53, 230, 210, .3);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--c-cyan);
  cursor: pointer;
  transition: background-color var(--t-hover) var(--ease),
              color var(--t-hover) var(--ease),
              border-color var(--t-hover) var(--ease);
}
.copy-btn:hover { background: rgba(53, 230, 210, .14); }
.copy-btn.is-copied {
  color: var(--c-mint);
  border-color: rgba(94, 230, 168, .55);
  background: rgba(94, 230, 168, .12);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 28px;
  padding-block: 22px 44px;
}
.footer-legal,
.footer-icp {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .05em;
  color: var(--c-text-2);
}
.footer-legal a { color: var(--c-text-2); transition: color var(--t-hover) var(--ease); }
.footer-legal a:hover { color: var(--c-cyan); }

/* ---------- 15. 滚动进度与回到顶部 ---------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  z-index: 120;
  pointer-events: none;
}
.scroll-progress__bar {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--c-cyan), var(--c-magenta));
  transition: width 120ms linear;
}
.to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 110;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(53, 230, 210, .35);
  border-radius: 3px;
  background: rgba(22, 32, 60, .94);
  color: var(--c-cyan);
  font-family: var(--font-mono);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(6px);
  transition: opacity var(--t-state) var(--ease),
              transform var(--t-state) var(--ease),
              visibility var(--t-state) var(--ease),
              background-color var(--t-hover) var(--ease);
}
.to-top:hover { background: rgba(53, 230, 210, .16); }
.to-top.is-active { opacity: 1; visibility: visible; transform: translateY(0); }

/* ---------- 16. 滚动显现 ---------- */
[data-reveal] {
  transition: opacity 320ms var(--ease), transform 320ms var(--ease);
}
[data-reveal].is-hidden { opacity: 0; transform: translateY(8px); }

/* ---------- 17. 响应式 ---------- */
@media (max-width: 1160px) {
  .header-shell {
    flex-wrap: wrap;
    gap: 0 16px;
    min-height: 64px;
    padding-block: 12px;
  }
  .nav-toggle { display: inline-flex; }
  .site-nav {
    display: none;
    flex: 1 1 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 16px;
    margin-left: 0;
    padding: 16px 0 20px;
    border-top: 1px solid var(--c-line);
  }
  .site-nav[data-open] { display: flex; }
  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 2px;
  }
  .site-nav__link {
    padding: 12px 10px;
    font-size: 16px;
    border-left: 2px solid transparent;
  }
  .site-nav__link:hover { transform: none; }
  .site-nav__link[aria-current="page"] {
    background: rgba(53, 230, 210, .07);
    border-left-color: var(--c-cyan);
  }
  .site-nav__link[aria-current="page"]::after { display: none; }
  .site-nav__actions { flex-direction: column; align-items: stretch; }
  .site-nav__actions .btn { width: 100%; }
}

@media (max-width: 1080px) {
  :root { --sec: 76px; }
  .split { grid-template-columns: minmax(0, 1fr); gap: 32px; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: 40px; padding-block: 56px 40px; }
  .footer-contact { padding-block: 22px; }
}

@media (max-width: 900px) {
  .span-4, .span-5, .span-7, .span-8 { grid-column: 1 / -1; }
  .rail-note { display: none; }
  .rail-list { gap: 6px 16px; }
  .rail-item { font-size: 11px; }
}

@media (max-width: 640px) {
  :root { --fs-body: 16px; --gap: 16px; --sec: 60px; }
  .shell { padding-inline: 18px; }
  .grid-12 { gap: 16px; }
  .header-rail__inner { min-height: 30px; }
  .rail-list { flex-direction: column; align-items: flex-start; gap: 4px; padding-block: 6px; }
  .brand__name { font-size: 17px; }
  .brand__sub { font-size: 10px; letter-spacing: .04em; }
  .footer-cols { grid-template-columns: 1fr 1fr; gap: 26px 20px; }
  .footer-bottom { padding-block: 20px 34px; }
  .to-top { right: 16px; bottom: 16px; }
  .panel { padding: 18px; }
}

/* ---------- 18. 减少动态 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .scanline { animation: none; opacity: 0; }
  [data-reveal],
  [data-reveal].is-hidden { opacity: 1; transform: none; transition: none; }
  .site-nav__link:hover,
  .btn:hover { transform: none; }
  .scroll-progress__bar { transition: none; }
  .to-top { transform: none; transition: opacity var(--t-state) var(--ease), visibility var(--t-state) var(--ease); }
}