/* ==========================================================================
   贝博平台 · 共享样式表  /assets/site.css
   设计语言：技术蓝图网格 / 深海蓝与暖纸对照 / 荧光青描边 / 珊瑚橙行动点
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-total, 96px) + 16px);
}

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

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

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

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

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

a { color: inherit; }

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

/* ---------- 2. 设计令牌 ---------- */
:root {
  /* 色彩 */
  --abyss-900: #061A2E;
  --deep-800: #0E2C4A;
  --tide-700: #14456B;
  --cyan-400: #35E6D2;
  --coral-500: #FF6B4A;
  --coral-500-hover: #FF8163;
  --amber-400: #FFC24B;
  --paper-100: #F4EFE3;
  --paper-200: #E4DCCB;
  --ink-900: #14202B;
  --slate-500: #7C93A8;
  --mist-200: #C9D8E4;

  --line-cyan: rgba(53, 230, 210, 0.22);
  --line-soft: rgba(53, 230, 210, 0.12);
  --line-strong: rgba(53, 230, 210, 0.5);
  --line-paper: rgba(20, 32, 43, 0.12);

  /* 字体 */
  --font-display: "Noto Sans SC", "HarmonyOS Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-body: "Noto Sans SC", "HarmonyOS Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", "IBM Plex Mono", SFMono-Regular, Menlo, Consolas, "Courier New", monospace;

  /* 形状 */
  --r-sm: 12px;
  --r-md: 18px;
  --r-lg: 24px;
  --r-xl: 32px;
  --r-pill: 999px;

  /* 尺寸 */
  --wrap: 1320px;
  --gutter: 20px;
  --header-h: 62px;
  --rail-h: 0px;
  --header-total: calc(var(--header-h) + var(--rail-h));

  --shadow-float: 0 26px 50px -34px rgba(2, 10, 20, 0.95);
  --ease: cubic-bezier(0.22, 0.7, 0.3, 1);
}

@media (min-width: 768px) {
  :root { --gutter: 28px; --header-h: 70px; }
}

@media (min-width: 1024px) {
  :root { --gutter: 32px; --header-h: 80px; --rail-h: 34px; }
}

/* ---------- 3. 基础排版 ---------- */
body {
  min-height: 100vh;
  background-color: var(--abyss-900);
  color: var(--mist-200);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

@media (min-width: 768px) {
  body { font-size: 17px; }
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.012em;
}

h1 { font-size: clamp(2.2rem, 5vw, 4rem); }
h2 { font-size: clamp(1.55rem, 3vw, 2.25rem); }
h3 { font-size: clamp(1.15rem, 1.6vw, 1.35rem); line-height: 1.25; }
h4 { font-size: 1rem; line-height: 1.35; letter-spacing: 0; }

p { max-width: 40em; }

strong { font-weight: 700; color: var(--mist-200); }

::selection { background: var(--coral-500); color: #1a0d08; }

:focus-visible {
  outline: 2px solid var(--cyan-400);
  outline-offset: 3px;
  border-radius: 6px;
}

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

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

.grid-24 {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 20px;
}

.grid-24 > * { grid-column: 1 / -1; }

@media (min-width: 768px) {
  .grid-24 { grid-template-columns: repeat(12, minmax(0, 1fr)); gap: 24px; }
}

@media (min-width: 1024px) {
  .grid-24 { grid-template-columns: repeat(24, minmax(0, 1fr)); gap: 24px; }
}

.section { padding-block: clamp(3.25rem, 7vw, 6.5rem); }
.section--tight { padding-block: clamp(2rem, 4vw, 3.25rem); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 0.85rem 1.5rem;
  margin-bottom: clamp(1.25rem, 3vw, 2.25rem);
}

.section-head > * { min-width: 0; }

.eyebrow,
.index-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan-400);
}

.index-tag { color: var(--coral-500); }

.rule-line {
  height: 1px;
  border: 0;
  background-image: linear-gradient(90deg, var(--line-strong), rgba(53, 230, 210, 0.04));
}

.lede {
  font-size: 1.06rem;
  line-height: 1.7;
  color: var(--mist-200);
  max-width: 38em;
}

.muted { color: var(--slate-500); }

.mono,
.num {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
}

.blueprint {
  background-image:
    linear-gradient(var(--line-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-soft) 1px, transparent 1px);
  background-size: 48px 48px;
}

/* 框景与刻度 */
.frame {
  position: relative;
  border: 1px solid var(--line-cyan);
  border-radius: var(--r-xl);
  padding: clamp(1.25rem, 3vw, 2.5rem);
}

.frame::before,
.frame::after {
  content: "";
  position: absolute;
  width: 18px;
  height: 18px;
  border: 1.5px solid var(--cyan-400);
  pointer-events: none;
}

.frame::before {
  top: -1px; left: -1px;
  border-right: 0; border-bottom: 0;
  border-top-left-radius: var(--r-xl);
}

.frame::after {
  right: -1px; bottom: -1px;
  border-left: 0; border-top: 0;
  border-bottom-right-radius: var(--r-xl);
}

.frame-corner {
  position: absolute;
  width: 18px;
  height: 18px;
  border: 1.5px solid var(--cyan-400);
  pointer-events: none;
}

.frame-corner--tr { top: -1px; right: -1px; border-left: 0; border-bottom: 0; border-top-right-radius: var(--r-xl); }
.frame-corner--bl { bottom: -1px; left: -1px; border-right: 0; border-top: 0; border-bottom-left-radius: var(--r-xl); }

.ruler {
  height: 8px;
  border-top: 1px solid var(--line-cyan);
  background-image: repeating-linear-gradient(90deg, var(--line-strong) 0 1px, transparent 1px 24px);
  opacity: 0.75;
}

.hero-overlap { margin-top: calc(-1 * var(--header-total)); }

/* ---------- 5. 背景分区 ---------- */
.surface-deep {
  background-color: var(--abyss-900);
  color: var(--mist-200);
}

.surface-tide {
  background-color: var(--deep-800);
  color: var(--mist-200);
}

.surface-paper {
  background-color: var(--paper-100);
  color: var(--ink-900);
  background-image:
    linear-gradient(rgba(20, 32, 43, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(20, 32, 43, 0.045) 1px, transparent 1px);
  background-size: 56px 56px;
}

.surface-paper h1,
.surface-paper h2,
.surface-paper h3,
.surface-paper h4 { color: var(--ink-900); }

.surface-paper .muted { color: #5C6E7C; }
.surface-paper .lede { color: #2C3B47; }

/* ---------- 6. 按钮与胶囊 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: 46px;
  padding: 0.7rem 1.35rem;
  border: 1px solid transparent;
  border-radius: var(--r-pill);
  font-family: var(--font-body);
  font-size: 0.94rem;
  font-weight: 700;
  line-height: 1.2;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color 0.2s var(--ease), border-color 0.2s var(--ease), color 0.2s var(--ease), transform 0.2s var(--ease);
}

.btn-primary {
  background-color: var(--coral-500);
  color: #22100A;
}

.btn-primary:hover,
.btn-primary:focus-visible { background-color: var(--coral-500-hover); transform: translateY(-2px); }

.btn-outline {
  border-color: var(--line-strong);
  color: var(--mist-200);
  background-color: transparent;
}

.btn-outline:hover,
.btn-outline:focus-visible {
  border-color: var(--cyan-400);
  color: #EAFDF9;
  transform: translateY(-2px);
}

.btn-quiet {
  border-color: rgba(124, 147, 168, 0.4);
  color: var(--slate-500);
  background-color: transparent;
}

.btn-quiet:hover,
.btn-quiet:focus-visible { color: var(--mist-200); border-color: var(--line-cyan); }

.btn-block { width: 100%; }

.pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  min-height: 44px;
  padding: 0.55rem 1.05rem;
  border: 1px solid rgba(53, 230, 210, 0.35);
  border-radius: var(--r-pill);
  background-color: rgba(20, 69, 107, 0.35);
  color: var(--mist-200);
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.pill:hover,
.pill:focus-visible {
  transform: translateY(-2px);
  border-color: var(--cyan-400);
  background-color: rgba(53, 230, 210, 0.1);
}

.pill::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--cyan-400);
  flex: none;
}

.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

/* ---------- 7. 卡片 ---------- */
.card {
  position: relative;
  padding: clamp(1.1rem, 2vw, 1.6rem);
  border: 1px solid var(--line-paper);
  border-radius: var(--r-lg);
  background-color: #FBF8F0;
  color: var(--ink-900);
  box-shadow: var(--shadow-float);
}

.card--deep {
  border-color: var(--line-cyan);
  background-color: var(--tide-700);
  color: var(--mist-200);
  background-image: linear-gradient(150deg, rgba(53, 230, 210, 0.08), rgba(6, 26, 46, 0.5));
}

.card--deep h3,
.card--deep h4 { color: #EAFDF9; }

.card-index {
  display: block;
  margin-bottom: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  color: var(--coral-500);
}

.card--deep .card-index { color: var(--cyan-400); }

/* ---------- 8. 图片容器基础规则 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: 1px solid var(--line-cyan);
  border-radius: var(--r-xl);
  background-color: var(--deep-800);
  background-image: linear-gradient(145deg, var(--deep-800), var(--abyss-900));
}

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

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

.media-frame--empty {
  display: grid;
  place-items: center;
  background-image:
    linear-gradient(var(--line-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-soft) 1px, transparent 1px),
    linear-gradient(145deg, var(--deep-800), var(--abyss-900));
  background-size: 40px 40px, 40px 40px, 100% 100%;
}

.media-placeholder {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--slate-500);
  text-align: center;
  padding: 1rem;
}

.media-caption {
  margin-top: 0.6rem;
  font-size: 13px;
  line-height: 1.6;
  color: var(--slate-500);
  max-width: 40em;
}

.surface-paper .media-caption { color: #5C6E7C; }

/* ---------- 9. 面包屑 ---------- */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 0.6rem;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--slate-500);
}

.crumbs-item { display: inline-flex; align-items: center; gap: 0.6rem; }

.crumbs-item + .crumbs-item::before {
  content: "/";
  color: rgba(124, 147, 168, 0.6);
}

.crumbs a {
  text-decoration: none;
  color: var(--mist-200);
  border-bottom: 1px dashed var(--line-strong);
}

.crumbs a:hover { color: var(--cyan-400); }

.surface-paper .crumbs { color: #5C6E7C; }
.surface-paper .crumbs a { color: var(--ink-900); border-bottom-color: rgba(20, 32, 43, 0.25); }

/* ---------- 10. 正文容器 ---------- */
.prose {
  font-size: 17px;
  line-height: 1.75;
  max-width: 38em;
}

.prose > * + * { margin-top: 1.1em; }

.prose h2,
.prose h3 { margin-top: 1.9em; }

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

.prose ul { list-style: none; }

.prose ul > li { position: relative; padding-left: 0.9em; }

.prose ul > li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.7em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--cyan-400);
}

.prose ol { list-style: decimal; }

.prose a {
  color: var(--coral-500);
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 107, 74, 0.45);
}

.prose a:hover { border-bottom-color: var(--coral-500); }

.surface-paper .prose { color: var(--ink-900); }
.surface-paper .prose a { color: #C43C1C; border-bottom-color: rgba(196, 60, 28, 0.4); }

.prose blockquote {
  padding: 1rem 1.25rem;
  border-left: 3px solid var(--cyan-400);
  border-radius: 0 var(--r-md) var(--r-md) 0;
  background-color: rgba(20, 69, 107, 0.35);
}

.surface-paper .prose blockquote {
  background-color: var(--paper-200);
  border-left-color: var(--coral-500);
}

/* ---------- 11. 分段切换 ---------- */
.tabs { display: block; }

.tablist {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding-bottom: 0.65rem;
  border-bottom: 1px solid var(--line-cyan);
  margin-bottom: 1.5rem;
}

.tab {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0.55rem 1.1rem;
  border: 1px solid transparent;
  border-radius: var(--r-pill);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  color: var(--slate-500);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.tab:hover { color: var(--mist-200); border-color: var(--line-cyan); }

.tab[aria-selected="true"] {
  color: var(--abyss-900);
  background-color: var(--cyan-400);
  border-color: var(--cyan-400);
}

.tabpanel[hidden] { display: none; }

.tabpanel {
  animation: panel-in 0.2s var(--ease) both;
}

@keyframes panel-in {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: none; }
}

/* ---------- 12. 坐标索引跳转 ---------- */
.tick-nav {
  position: sticky;
  top: calc(var(--header-total) + 2rem);
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.tick-nav a {
  display: block;
  padding: 0.42rem 0 0.42rem 0.85rem;
  border-left: 1px solid var(--line-cyan);
  color: var(--slate-500);
  text-decoration: none;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), padding-left 0.2s var(--ease);
}

.tick-nav a:hover { color: var(--mist-200); border-left-color: var(--line-strong); }

.tick-nav a[aria-current="true"] {
  color: var(--cyan-400);
  border-left-color: var(--cyan-400);
  padding-left: 1.05rem;
}

/* ---------- 13. 跳转链接与滚动进度 ---------- */
.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 300;
  padding: 0.7rem 1.15rem;
  border-radius: var(--r-pill);
  background-color: var(--cyan-400);
  color: var(--abyss-900);
  font-weight: 700;
  font-size: 0.9rem;
  text-decoration: none;
  transform: translateY(-160%);
  transition: transform 0.2s var(--ease);
}

.skip-link:focus { transform: translateY(0); }

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 120;
  pointer-events: none;
  background-color: rgba(53, 230, 210, 0.08);
}

.scroll-progress span {
  display: block;
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background-image: linear-gradient(90deg, var(--cyan-400), var(--coral-500));
}

/* ---------- 14. 头部 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background-color: transparent;
  background-image: linear-gradient(180deg, rgba(6, 26, 46, 0.92) 0%, rgba(6, 26, 46, 0.6) 58%, rgba(6, 26, 46, 0) 100%);
  transition: background-color 0.24s var(--ease), box-shadow 0.24s var(--ease);
}

.site-header[data-state="scrolled"] {
  background-image: none;
  background-color: rgba(6, 26, 46, 0.97);
  box-shadow: 0 1px 0 var(--line-cyan), 0 22px 44px -40px #000;
}

.header-rail { display: none; }

.header-bar { width: 100%; }

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: var(--header-h);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  min-height: 44px;
  text-decoration: none;
  color: var(--mist-200);
  flex: none;
}

.brand-mark {
  position: relative;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  flex: none;
  border: 1.5px solid var(--cyan-400);
  border-radius: var(--r-sm);
  background-image: linear-gradient(150deg, rgba(53, 230, 210, 0.18), rgba(20, 69, 107, 0.5));
}

.brand-mark-line {
  width: 16px;
  height: 1.5px;
  border-radius: 2px;
  background-color: var(--cyan-400);
  box-shadow: 0 -5px 0 rgba(53, 230, 210, 0.55), 0 5px 0 rgba(53, 230, 210, 0.55);
}

.brand-mark-dot {
  position: absolute;
  right: 5px;
  bottom: 5px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--coral-500);
}

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

.brand-name {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.01em;
  color: #F1FBF9;
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 10px;
  line-height: 1.3;
  letter-spacing: 0.1em;
  color: var(--slate-500);
  white-space: nowrap;
}

/* 导航抽屉（移动优先） */
.site-nav {
  position: fixed;
  top: 0;
  right: 0;
  z-index: 90;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  width: min(90vw, 360px);
  height: 100dvh;
  padding: calc(var(--header-h) + 1.5rem) 1.25rem 2rem;
  overflow-y: auto;
  border-left: 1px solid var(--line-cyan);
  background-image: linear-gradient(180deg, rgba(14, 44, 74, 0.99), rgba(6, 26, 46, 0.99));
  transform: translateX(102%);
  transition: transform 0.28s var(--ease);
}

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

.nav-list {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  counter-reset: navidx;
  border-top: 1px solid var(--line-soft);
  padding-top: 0.75rem;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  counter-increment: navidx;
  border-bottom: 1px solid var(--line-soft);
}

.nav-item::before {
  content: "0" counter(navidx);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--slate-500);
  flex: none;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  flex: 1 1 auto;
  min-height: 52px;
  padding: 0.5rem 0.75rem;
  border: 1px solid transparent;
  border-radius: var(--r-md);
  color: var(--mist-200);
  font-size: 1.02rem;
  font-weight: 600;
  text-decoration: none;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease), transform 0.2s var(--ease);
}

.nav-link:hover,
.nav-link:focus-visible {
  color: #ffffff;
  border-color: var(--line-cyan);
  background-color: rgba(53, 230, 210, 0.06);
  transform: translateY(-2px);
}

.nav-link[aria-current="page"] {
  color: var(--cyan-400);
  border-color: var(--line-strong);
  background-color: rgba(53, 230, 210, 0.09);
}

.nav-foot {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: auto;
}

.nav-utility {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.nav-utility a {
  color: var(--slate-500);
  text-decoration: none;
  border-bottom: 1px dashed rgba(124, 147, 168, 0.45);
}

.nav-utility a:hover { color: var(--cyan-400); border-bottom-color: var(--line-strong); }

/* 头部右侧动作 */
.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex: none;
}

.header-cta { display: none; }

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  min-height: 44px;
  min-width: 44px;
  padding: 0.5rem 0.85rem;
  border: 1px solid var(--line-cyan);
  border-radius: var(--r-pill);
  color: var(--mist-200);
  font-size: 0.85rem;
  font-weight: 600;
  transition: border-color 0.2s var(--ease), color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.nav-toggle:hover { border-color: var(--cyan-400); color: #ffffff; background-color: rgba(53, 230, 210, 0.08); }

.nav-toggle-box {
  position: relative;
  display: block;
  width: 18px;
  height: 12px;
}

.nav-toggle-bar {
  position: absolute;
  left: 0;
  width: 100%;
  height: 1.5px;
  border-radius: 2px;
  background-color: var(--cyan-400);
  transition: transform 0.24s var(--ease), opacity 0.24s var(--ease);
}

.nav-toggle-bar:first-child { top: 0; }
.nav-toggle-bar:last-child { bottom: 0; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:first-child { transform: translateY(5.25px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:last-child { transform: translateY(-5.25px) rotate(-45deg); }

.nav-toggle-label { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.12em; }

/* 遮罩 */
.nav-scrim {
  position: fixed;
  inset: 0;
  z-index: 70;
  background-color: rgba(4, 16, 30, 0.68);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.24s var(--ease);
}

.nav-scrim[data-open] { opacity: 1; pointer-events: auto; }

/* 桌面导航 */
@media (min-width: 1024px) {
  .header-rail {
    display: block;
    border-bottom: 1px solid var(--line-soft);
  }

  .header-rail-inner {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    min-height: var(--rail-h);
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: 0.08em;
    color: var(--slate-500);
  }

  .rail-coord { display: inline-flex; align-items: center; gap: 0.5rem; margin: 0; max-width: none; }

  .rail-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background-color: var(--cyan-400);
    flex: none;
  }

  .rail-status { margin: 0; color: var(--mist-200); max-width: none; }

  .rail-sep { margin-inline: 0.6rem; color: var(--slate-500); }

  .rail-links {
    display: flex;
    gap: 1.5rem;
    margin-left: auto;
  }

  .rail-links a {
    color: var(--slate-500);
    text-decoration: none;
    transition: color 0.2s var(--ease);
  }

  .rail-links a:hover { color: var(--cyan-400); }

  .site-nav {
    position: static;
    z-index: auto;
    flex-direction: row;
    align-items: center;
    width: auto;
    height: auto;
    padding: 0;
    overflow: visible;
    border: 0;
    background-image: none;
    transform: none;
  }

  .nav-list {
    flex-direction: row;
    align-items: center;
    gap: 0.15rem;
    border-top: 0;
    padding-top: 0;
  }

  .nav-item { border-bottom: 0; gap: 0; }

  .nav-item::before { display: none; }

  .nav-link {
    flex: none;
    min-height: 44px;
    padding: 0.5rem 0.9rem;
    border-radius: var(--r-pill);
    font-size: 0.93rem;
  }

  .nav-foot { display: none; }

  .nav-toggle { display: none; }

  .header-cta { display: inline-flex; }

  .nav-scrim { display: none; }
}

/* ---------- 15. 页脚 ---------- */
.site-footer {
  position: relative;
  border-top: 1px solid var(--line-cyan);
  padding-block: clamp(2.5rem, 6vw, 4.5rem) 2rem;
  background-color: var(--abyss-900);
  background-image:
    linear-gradient(rgba(53, 230, 210, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(53, 230, 210, 0.055) 1px, transparent 1px);
  background-size: 64px 64px;
  color: var(--mist-200);
}

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

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.25rem;
}

@media (min-width: 640px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 2.25rem 1.75rem; }
}

@media (min-width: 1024px) {
  .footer-grid { grid-template-columns: 1.5fr 0.8fr 0.8fr 0.8fr 1.4fr; gap: 2.5rem; }
}

.footer-brand { display: flex; flex-direction: column; gap: 1rem; align-items: flex-start; }

.brand-footer .brand-name { font-size: 1.05rem; }

.footer-tagline {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--mist-200);
  max-width: 22em;
}

.footer-meta { display: flex; flex-wrap: wrap; gap: 0.5rem; }

.meta-chip {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 0.3rem 0.75rem;
  border: 1px solid var(--line-cyan);
  border-radius: var(--r-pill);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--slate-500);
}

.footer-col { display: flex; flex-direction: column; gap: 0.75rem; min-width: 0; }

.footer-col-title {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan-400);
}

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

.footer-links a {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  font-size: 0.94rem;
  color: var(--mist-200);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.footer-links a:hover,
.footer-links a:focus-visible { color: var(--cyan-400); border-bottom-color: var(--line-cyan); }

.contact-list { display: flex; flex-direction: column; gap: 0.85rem; }

.contact-item {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.35rem 0.6rem;
  font-size: 0.92rem;
  line-height: 1.6;
}

.contact-item-wide { align-items: flex-start; }

.contact-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--slate-500);
  flex: none;
  min-width: 4.5em;
}

.contact-value {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  letter-spacing: 0.02em;
  color: #EAFDF9;
  word-break: break-all;
}

.contact-item-wide .contact-value { font-family: var(--font-body); font-size: 0.92rem; letter-spacing: 0; }

.copy-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 30px;
  padding: 0.2rem 0.7rem;
  border: 1px solid var(--line-cyan);
  border-radius: var(--r-pill);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--slate-500);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

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

.copy-receipt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--amber-400);
  opacity: 0;
  transition: opacity 0.2s var(--ease);
}

.copy-receipt[data-visible] { opacity: 1; }

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1.5rem;
  margin-top: clamp(2rem, 5vw, 3.25rem);
  padding-top: 1.5rem;
  border-top: 1px solid var(--line-soft);
  font-size: 13px;
  color: var(--slate-500);
}

.footer-icp {
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
  color: var(--mist-200);
  max-width: none;
}

.footer-copy { font-family: var(--font-mono); letter-spacing: 0.04em; max-width: none; }

.footer-note {
  flex: 1 1 100%;
  font-size: 12.5px;
  line-height: 1.7;
  color: rgba(124, 147, 168, 0.9);
  max-width: 52em;
}

/* ---------- 16. 进场动效 ---------- */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}

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

/* ---------- 17. 降级与无障碍 ---------- */
@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;
  }

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

  .pill:hover,
  .btn:hover,
  .nav-link:hover { transform: none; }
}