/* =========================================================
   安博电竞站 · 共享外壳样式 /assets/site.css
   深空黑 · 指挥舱蓝黑 · 蓝图线 · 电竞紫 · 霓虹青 · 熔岩橙 · 暖纸
   ========================================================= */

/* ---------- 1. 设计变量 ---------- */
:root {
  --void: #070A12;
  --cabin: #0E1526;
  --line: #22304D;
  --line-soft: rgba(34, 48, 77, 0.62);
  --violet: #6C4CF1;
  --cyan: #35E6FF;
  --lava: #FF6A2A;
  --paper: #F2E9D8;
  --ink: #10131C;
  --mint: #5BE7A9;
  --alert: #FF4D6D;
  --mist: #9AA8C7;
  --text: #E8EDF7;

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

  --wrap: 1240px;
  --gutter: clamp(18px, 4vw, 40px);
  --radius: 2px;
  --ease: cubic-bezier(0.22, 0.85, 0.3, 1);
  --shadow-panel: 0 24px 60px -28px rgba(3, 6, 14, 0.92);
  --hud-h: 38px;
}

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

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

body {
  margin: 0;
  background-color: var(--void);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: 0.012em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; }
li { list-style: none; }
img, svg, video { max-width: 100%; height: auto; }
a { color: var(--cyan); text-decoration: none; }
button { font: inherit; color: inherit; }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.14;
  letter-spacing: 0.01em;
  word-break: break-word;
}
strong { font-weight: 700; }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: 1px;
}

::selection { background: var(--violet); color: #fff; }

/* ---------- 3. 通用工具 ---------- */
.visually-hidden {
  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;
}

.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; letter-spacing: 0.08em; }
.muted { color: var(--mist); }

.blueprint-bg {
  background-image:
    linear-gradient(to right, var(--line-soft) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line-soft) 1px, transparent 1px);
  background-size: 62px 62px;
  background-position: center top;
}

.rule {
  border: 0;
  border-top: 1px solid var(--line);
  margin-block: clamp(24px, 4vw, 48px);
}

/* ---------- 4. 布局容器 ---------- */
.container {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: clamp(48px, 7vw, 96px); position: relative; }

.section--band {
  background-color: var(--cabin);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.grid { display: grid; gap: clamp(14px, 2vw, 24px); }
.grid--2 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.grid--asym { grid-template-columns: minmax(220px, 0.78fr) minmax(300px, 1.62fr); }

/* ---------- 5. 排版组件 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 14px;
}
.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: currentColor;
  display: inline-block;
}

.section-title {
  font-size: clamp(28px, 4vw, 46px);
  margin-bottom: 14px;
}

.lede {
  font-size: clamp(16px, 1.5vw, 18.5px);
  color: var(--mist);
  max-width: 66ch;
  line-height: 1.8;
}

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 44px;
  padding: 12px 24px;
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  border: 1px solid transparent;
  border-radius: var(--radius);
  cursor: pointer;
  transition: transform 0.2s var(--ease), box-shadow 0.2s var(--ease),
              background-color 0.2s var(--ease), color 0.2s var(--ease),
              border-color 0.2s var(--ease);
}

.btn--primary {
  background-color: var(--violet);
  color: #fff;
  box-shadow: 0 0 0 1px rgba(108, 76, 241, 0.62), 0 16px 34px -20px rgba(108, 76, 241, 0.95);
}
.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 0 1px var(--cyan), 0 20px 40px -18px rgba(53, 230, 255, 0.55);
}

.btn--ghost {
  background-color: transparent;
  border-color: var(--line);
  color: var(--text);
}
.btn--ghost:hover {
  border-color: var(--cyan);
  color: var(--cyan);
  transform: translateY(-2px);
}

.btn--paper {
  background-color: var(--paper);
  color: var(--ink);
  border-color: var(--ink);
}
.btn--paper:hover {
  background-color: #fff8ea;
  transform: translateY(-2px);
}

/* ---------- 7. 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--mist);
  background-color: rgba(14, 21, 38, 0.72);
  border: 1px solid var(--line);
  border-radius: 999px;
  white-space: nowrap;
}
.tag--region {
  color: var(--cyan);
  border-color: rgba(53, 230, 255, 0.48);
  background-color: rgba(53, 230, 255, 0.1);
}
.tag--live {
  color: #1a0a03;
  background-color: var(--lava);
  border-color: var(--lava);
  font-weight: 700;
}
.tag--ok {
  color: #04231a;
  background-color: var(--mint);
  border-color: var(--mint);
  font-weight: 700;
}

/* ---------- 8. 内容层 ---------- */
.paper-panel {
  background-color: var(--paper);
  color: var(--ink);
  border: 1px solid #d8cbb2;
  border-radius: var(--radius);
  padding: clamp(20px, 3vw, 34px);
  box-shadow: var(--shadow-panel);
  line-height: 1.8;
}
.paper-panel a { color: #3a2bb5; text-decoration: underline; text-underline-offset: 3px; }
.paper-panel a:hover { color: #1d1470; }
.paper-panel :focus-visible { outline-color: #3a2bb5; }

.glass-panel {
  background-image: linear-gradient(158deg, rgba(14, 21, 38, 0.94), rgba(14, 21, 38, 0.62));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(18px, 3vw, 28px);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

/* ---------- 9. 面包屑与章节目录 ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding-block: 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--mist);
}
.breadcrumb li { display: flex; align-items: center; gap: 8px; }
.breadcrumb li + li::before { content: "/"; color: var(--line); }
.breadcrumb a { color: var(--mist); }
.breadcrumb a:hover { color: var(--cyan); }
.breadcrumb [aria-current="page"] { color: var(--cyan); }

.index-list {
  border-left: 1px solid var(--line);
}
.index-item a {
  display: block;
  padding: 9px 14px;
  margin-left: -1px;
  font-size: 14.5px;
  line-height: 1.5;
  color: var(--mist);
  border-left: 2px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease), background-color 0.18s var(--ease);
}
.index-item a:hover { color: var(--text); border-left-color: var(--violet); }
.index-item a[aria-current="true"] {
  color: var(--cyan);
  border-left-color: var(--cyan);
  background-color: rgba(53, 230, 255, 0.07);
}

/* ---------- 10. 图像容器基础规则 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background-color: var(--cabin);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}
.media-frame img,
.media-frame video {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: linear-gradient(198deg, rgba(108, 76, 241, 0.2), rgba(7, 10, 18, 0) 46%, rgba(7, 10, 18, 0.6));
  pointer-events: none;
}
.media-frame[data-empty]::before {
  content: attr(data-empty);
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 16px;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--line);
  background-image:
    linear-gradient(to right, rgba(34, 48, 77, 0.5) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(34, 48, 77, 0.5) 1px, transparent 1px);
  background-size: 34px 34px;
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--skew { clip-path: polygon(0 0, 100% 0, 100% 90%, 0 100%); }

.media-caption {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist);
}

/* =========================================================
   11. 页头
   ========================================================= */
.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 300;
  padding: 11px 20px;
  background-color: var(--cyan);
  color: #04121a;
  font-weight: 700;
  font-size: 14px;
  border-radius: var(--radius);
  transform: translateY(-180%);
  transition: transform 0.22s var(--ease);
}
.skip-link:focus,
.skip-link:focus-visible { transform: translateY(0); outline-color: #04121a; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  background-color: rgba(7, 10, 18, 0.95);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line);
  color: var(--text);
}
.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(34, 48, 77, 0.5) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(34, 48, 77, 0.5) 1px, transparent 1px);
  background-size: 56px 56px;
  opacity: 0.5;
  pointer-events: none;
}
.site-header[data-scrolled] {
  box-shadow: 0 22px 46px -34px #000, inset 0 -1px 0 rgba(53, 230, 255, 0.16);
}

/* HUD 状态条 */
.hud-bar {
  position: relative;
  z-index: 2;
  background-color: var(--cabin);
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
}
.hud-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  max-width: var(--wrap);
  min-height: var(--hud-h);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.hud-status {
  display: flex;
  align-items: center;
  gap: 14px;
  color: var(--mist);
  white-space: nowrap;
}
.hud-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--mint);
  box-shadow: 0 0 10px var(--mint);
  flex: none;
}
.hud-meta { text-transform: uppercase; }
.hud-meta--dim { color: rgba(154, 168, 199, 0.62); }

.hud-actions {
  display: flex;
  align-items: center;
  gap: 6px;
}
.hud-link {
  padding: 6px 10px;
  color: var(--mist);
  border: 1px solid transparent;
  border-radius: var(--radius);
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.hud-link:hover { color: var(--cyan); border-color: rgba(53, 230, 255, 0.38); }

.hud-account {
  padding: 4px 10px;
  color: var(--mist);
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  white-space: nowrap;
}

.hud-cta {
  display: inline-flex;
  align-items: center;
  padding: 7px 14px;
  background-color: var(--cyan);
  color: #04121a;
  font-family: var(--font-body);
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 0.06em;
  border-radius: var(--radius);
  transition: box-shadow 0.2s var(--ease), transform 0.2s var(--ease);
  white-space: nowrap;
}
.hud-cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 0 0 2px rgba(53, 230, 255, 0.25), 0 0 22px rgba(53, 230, 255, 0.5);
}

/* 移动菜单按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  min-height: 44px;
  min-width: 44px;
  padding: 8px 12px;
  background-color: rgba(7, 10, 18, 0.6);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  cursor: pointer;
  transition: border-color 0.2s var(--ease), color 0.2s var(--ease);
}
.nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }
.nav-toggle-bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 18px;
}
.nav-toggle-bars span {
  display: block;
  height: 2px;
  background-color: var(--cyan);
  transition: transform 0.26s var(--ease), opacity 0.2s var(--ease);
}
.site-header[data-open] .nav-toggle-bars span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.site-header[data-open] .nav-toggle-bars span:nth-child(2) { opacity: 0; }
.site-header[data-open] .nav-toggle-bars span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* 刊头 */
.masthead {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: end;
  gap: 18px;
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: clamp(14px, 2vw, 20px) var(--gutter) 12px;
}
.masthead-rail {
  display: flex;
  align-items: center;
  gap: 10px;
  padding-bottom: 6px;
  color: rgba(154, 168, 199, 0.55);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}
.masthead-rail--end { justify-content: flex-end; }
.rail-tick {
  flex: 1 1 auto;
  max-width: 120px;
  height: 1px;
  background-image: repeating-linear-gradient(to right, var(--line) 0 8px, transparent 8px 14px);
}
.rail-code { white-space: nowrap; }

.masthead-brand { text-align: center; }
.brand-link {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  color: var(--text);
}
.brand-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(24px, 3.2vw, 36px);
  line-height: 1.05;
  letter-spacing: 0.08em;
  text-shadow: 0 0 26px rgba(108, 76, 241, 0.5);
}
.brand-accent {
  position: relative;
  isolation: isolate;
  display: inline-block;
  margin-left: 0.08em;
  padding-inline: 0.14em;
  color: var(--cyan);
  font-style: normal;
}
.brand-accent::before {
  content: "";
  position: absolute;
  inset: 14% -3% 10%;
  z-index: -1;
  background-image: linear-gradient(105deg, rgba(108, 76, 241, 0.9), rgba(108, 76, 241, 0.24));
  transform: skewX(-9deg);
}
.brand-sub {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.18em;
  color: var(--mist);
}
.brand-link:hover .brand-title { text-shadow: 0 0 30px rgba(53, 230, 255, 0.55); }

/* 居中栏目导航 */
.masthead-nav {
  position: relative;
  z-index: 2;
  border-top: 1px solid var(--line-soft);
  background-color: rgba(7, 10, 18, 0.4);
}
.nav-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: clamp(2px, 0.8vw, 10px);
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 48px;
  padding: 12px clamp(10px, 1.2vw, 18px);
  color: var(--mist);
  font-size: 14.5px;
  letter-spacing: 0.06em;
  white-space: nowrap;
  transition: color 0.18s var(--ease), background-color 0.18s var(--ease);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: clamp(10px, 1.2vw, 18px);
  right: clamp(10px, 1.2vw, 18px);
  bottom: 7px;
  height: 2px;
  background-color: var(--cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.26s var(--ease);
}
.nav-link:hover { color: var(--text); background-color: rgba(108, 76, 241, 0.12); }
.nav-link:hover::after,
.nav-link:focus-visible::after { transform: scaleX(1); }
.nav-index {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--violet);
}
.nav-link[aria-current="page"] {
  color: var(--cyan);
  background-image: linear-gradient(180deg, rgba(53, 230, 255, 0.14), rgba(53, 230, 255, 0));
}
.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  background-color: var(--cyan);
  box-shadow: 0 0 12px rgba(53, 230, 255, 0.7);
}
.nav-link[aria-current="page"] .nav-index { color: var(--cyan); }

/* 滚动进度 */
.scroll-meter {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  z-index: 3;
  height: 2px;
  background-color: rgba(34, 48, 77, 0.5);
}
.scroll-meter-bar {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: left center;
  background-image: linear-gradient(90deg, var(--violet), var(--cyan));
  box-shadow: 0 0 12px rgba(53, 230, 255, 0.5);
}

/* =========================================================
   12. 页脚
   ========================================================= */
.site-footer {
  position: relative;
  overflow: hidden;
  background-color: var(--cabin);
  border-top: 1px solid var(--line);
  color: var(--text);
}
.site-footer::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(34, 48, 77, 0.55) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(34, 48, 77, 0.55) 1px, transparent 1px);
  background-size: 62px 62px;
  opacity: 0.7;
  pointer-events: none;
}
.site-footer::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background-image: linear-gradient(90deg, transparent, var(--violet) 28%, var(--cyan) 62%, transparent);
  opacity: 0.9;
}

.footer-top {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.3fr 1.6fr 0.95fr;
  gap: clamp(24px, 4vw, 52px);
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: clamp(36px, 6vw, 64px) var(--gutter) clamp(26px, 4vw, 40px);
}

.footer-brand { min-width: 0; }
.footer-title {
  font-family: var(--font-display);
  font-size: clamp(22px, 2.6vw, 30px);
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--text);
}
.footer-note {
  margin-top: 10px;
  max-width: 26ch;
  color: var(--mist);
  font-size: 14.5px;
  line-height: 1.7;
}
.footer-mono {
  margin-top: 18px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: rgba(154, 168, 199, 0.55);
  padding-top: 12px;
  border-top: 1px dashed var(--line);
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(18px, 3vw, 36px);
}
.footer-col-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--cyan);
}
.footer-list { display: grid; gap: 2px; }
.footer-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 40px;
  padding: 6px 0;
  color: var(--mist);
  font-size: 14.5px;
  transition: color 0.18s var(--ease), transform 0.18s var(--ease);
}
.footer-link::before {
  content: "";
  width: 0;
  height: 1px;
  background-color: var(--cyan);
  transition: width 0.22s var(--ease);
}
.footer-link:hover { color: var(--text); }
.footer-link:hover::before { width: 14px; }

.footer-contact { min-width: 0; }
.footer-contact-line {
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--text);
  word-break: break-all;
  margin-bottom: 10px;
}
.footer-contact-key {
  display: inline-block;
  min-width: 40px;
  margin-right: 6px;
  color: var(--violet);
  letter-spacing: 0.14em;
}
.footer-hours {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 4px;
  padding: 5px 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: #1a0a03;
  background-color: var(--lava);
  border-radius: var(--radius);
}

.footer-bottom {
  position: relative;
  z-index: 1;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: 16px var(--gutter) 22px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: rgba(154, 168, 199, 0.72);
}
.footer-legal { color: var(--mist); }
.footer-icp { color: var(--text); }
.footer-fine { max-width: 62ch; }

/* =========================================================
   13. 返回顶部
   ========================================================= */
.back-to-top {
  position: fixed;
  right: clamp(14px, 3vw, 28px);
  bottom: clamp(14px, 3vw, 28px);
  z-index: 130;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  padding: 0;
  font-family: var(--font-mono);
  font-size: 17px;
  line-height: 1;
  color: var(--cyan);
  background-color: rgba(14, 21, 38, 0.94);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transform: translateY(12px);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: opacity 0.24s var(--ease), transform 0.24s var(--ease),
              border-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}
.back-to-top.is-visible { opacity: 1; pointer-events: auto; transform: translateY(0); }
.back-to-top:hover {
  border-color: var(--cyan);
  box-shadow: 0 0 20px rgba(53, 230, 255, 0.4);
}

/* =========================================================
   14. 响应式
   ========================================================= */
@media (max-width: 1020px) {
  .footer-top { grid-template-columns: 1fr 1fr; }
  .footer-contact { grid-column: 1 / -1; }
  .grid--asym { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 900px) {
  .nav-toggle { display: inline-flex; }
  .masthead { grid-template-columns: minmax(0, 1fr); justify-items: center; gap: 0; }
  .masthead-rail { display: none; }

  .masthead-nav {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 0.36s var(--ease), opacity 0.24s var(--ease);
  }
  .site-header[data-open] .masthead-nav {
    max-height: calc(100vh - 150px);
    overflow-y: auto;
    opacity: 1;
    border-top-color: rgba(53, 230, 255, 0.35);
    background-color: rgba(7, 10, 18, 0.96);
  }
  .nav-list { flex-direction: column; align-items: stretch; gap: 0; padding: 8px var(--gutter) 18px; }
  .nav-link {
    justify-content: flex-start;
    min-height: 50px;
    padding: 13px 10px;
    font-size: 15.5px;
    border-bottom: 1px solid rgba(34, 48, 77, 0.6);
  }
  .nav-link::after { display: none; }
  .nav-link:hover { background-color: rgba(108, 76, 241, 0.16); }
  .nav-link[aria-current="page"] {
    color: var(--cyan);
    background-image: linear-gradient(90deg, rgba(53, 230, 255, 0.16), transparent 70%);
    box-shadow: inset 3px 0 0 var(--cyan);
  }
  .nav-index { font-size: 11px; }

  .footer-top { grid-template-columns: minmax(0, 1fr); gap: 28px; }
  .footer-contact { grid-column: auto; }
  .footer-note { max-width: none; }
}

@media (max-width: 760px) {
  body { font-size: 16px; }
  .hud-inner { min-height: 54px; padding-block: 5px; gap: 10px; flex-wrap: wrap; }
  .hud-link,
  .hud-account,
  .hud-meta--dim { display: none; }
  .hud-cta { padding: 9px 14px; min-height: 44px; }
  .footer-cols { grid-template-columns: minmax(0, 1fr); gap: 20px; }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
  .footer-fine { max-width: none; }
  .media-frame--wide { aspect-ratio: 16 / 9; }
}

@media (max-width: 420px) {
  .hud-status { font-size: 10.5px; letter-spacing: 0.1em; }
  .hud-cta { font-size: 12px; }
  .nav-toggle { padding-inline: 10px; }
  .nav-toggle-label { display: none; }
}

/* =========================================================
   15. 可访问性与打印
   ========================================================= */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  .nav-link:hover,
  .btn:hover,
  .back-to-top { transform: none !important; }
}

@media print {
  .site-header,
  .site-footer,
  .back-to-top,
  .skip-link,
  .scroll-meter { display: none !important; }
  body { background: #fff; color: #10131C; font-size: 12pt; }
  .paper-panel { box-shadow: none; border-color: #999; }
  a { color: #10131C; text-decoration: underline; }
}