/* ==========================================================================
   B体育主站 — 共享外壳样式 /assets/site.css
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  --progress: 0;
}

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

ul, ol { margin: 0; padding: 0; }

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

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

a { color: inherit; }

:root {
  /* 色彩 */
  --ink-900: #070B14;
  --ink-800: #0E1524;
  --ink-700: #16233C;
  --line: #22304C;
  --line-soft: #1A2740;
  --cyan: #00E5D4;
  --cyan-ink: #04120F;
  --orange: #FF7A1A;
  --orange-ink: #180800;
  --amber: #FFC24B;
  --paper: #F4EFE6;
  --paper-ink: #14181D;
  --paper-line: #D8CFC0;
  --muted: #9AA7BF;
  --text: #C8D2E0;

  /* 尺度 */
  --wrap: 1200px;
  --wrap-wide: 1480px;
  --gut: clamp(18px, 4vw, 44px);
  --rail-h: 30px;
  --header-h: 62px;

  --fs-88: clamp(40px, 6vw, 88px);
  --fs-56: clamp(30px, 4.2vw, 56px);
  --fs-32: clamp(23px, 2.6vw, 32px);
  --fs-22: 22px;
  --fs-17: 17px;
  --fs-13: 13px;

  /* 形状 */
  --r-sm: 4px;
  --r-md: 10px;
  --r-lg: 20px;

  /* 动效 */
  --ease: cubic-bezier(.22, .61, .36, 1);
  --t: 220ms;

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

/* --- 2. 中文正文节奏 ----------------------------------------------------- */
body {
  min-height: 100vh;
  background: var(--ink-900);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: var(--fs-17);
  font-weight: 500;
  line-height: 1.75;
  letter-spacing: .005em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -.012em;
  color: #fff;
}

h1 { font-size: var(--fs-56); }
h2 { font-size: var(--fs-32); }
h3 { font-size: var(--fs-22); }
h4 { font-size: var(--fs-17); font-weight: 700; }

p { text-wrap: pretty; }

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

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

[id] { scroll-margin-top: calc(var(--header-h) + var(--rail-h) + 18px); }

/* --- 3. 通用工具 --------------------------------------------------------- */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gut);
}

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

.t-display {
  font-size: var(--fs-88);
  font-weight: 800;
  line-height: 1.02;
  letter-spacing: -.03em;
  color: #fff;
}

.t-h1 { font-size: var(--fs-56); font-weight: 800; line-height: 1.04; letter-spacing: -.02em; color: #fff; }
.t-h2 { font-size: var(--fs-32); font-weight: 800; line-height: 1.1; color: #fff; }
.t-h3 { font-size: var(--fs-22); font-weight: 800; line-height: 1.2; color: #fff; }

.lead {
  font-size: clamp(17px, 1.5vw, 20px);
  line-height: 1.7;
  color: var(--text);
  max-width: 40ch;
}

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

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
}

.stack > * + * { margin-top: clamp(14px, 2vw, 24px); }
.stack-sm > * + * { margin-top: 10px; }

.rule {
  height: 1px;
  background: var(--line);
  border: 0;
}

.index-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--cyan);
  line-height: 1.4;
}

.index-label::before {
  content: "";
  width: 18px;
  height: 1px;
  background: currentColor;
  flex: none;
}

.index-label-plain::before { display: none; }

/* --- 4. 按钮体系 --------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1px solid transparent;
  border-radius: var(--r-sm);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .01em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--t) var(--ease), color var(--t) var(--ease),
    border-color var(--t) var(--ease), transform var(--t) var(--ease);
}

.btn-primary {
  background: var(--orange);
  color: var(--orange-ink);
  border-color: var(--orange);
}

.btn-primary:hover { background: #FF9046; border-color: #FF9046; transform: translateY(-1px); }

.btn-ghost {
  background: transparent;
  color: var(--cyan);
  border-color: rgba(0, 229, 212, .45);
}

.btn-ghost:hover { border-color: var(--cyan); background: rgba(0, 229, 212, .09); }

.btn-quiet {
  background: var(--ink-800);
  color: var(--text);
  border-color: var(--line);
}

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

.to-top {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 16px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .14em;
  cursor: pointer;
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease);
}

.to-top:hover { color: var(--cyan); border-color: var(--cyan); }

/* --- 5. 标签与芯片 ------------------------------------------------------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(14, 21, 36, .85);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  line-height: 1.5;
}

.tag-cyan { color: var(--cyan); border-color: rgba(0, 229, 212, .4); }
.tag-orange { color: var(--orange); border-color: rgba(255, 122, 26, .42); }
.tag-amber { color: var(--amber); border-color: rgba(255, 194, 75, .4); }

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chip {
  padding: 7px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: transparent;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .12em;
  cursor: pointer;
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease),
    background var(--t) var(--ease);
}

.chip:hover { color: var(--text); border-color: #34456B; }

.chip[aria-pressed="true"],
.chip[data-active="true"] {
  color: var(--cyan-ink);
  background: var(--cyan);
  border-color: var(--cyan);
}

/* --- 6. 面板卡片 --------------------------------------------------------- */
.panel {
  position: relative;
  display: block;
  background: var(--ink-800);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  padding: clamp(18px, 2.4vw, 28px);
  transition: transform var(--t) var(--ease), border-color var(--t) var(--ease),
    background var(--t) var(--ease);
}

.panel:hover,
.panel:focus-within {
  transform: translateY(-4px);
  border-color: var(--cyan);
}

.panel-quiet { background: var(--ink-700); }

.panel-title {
  font-size: var(--fs-22);
  font-weight: 800;
  line-height: 1.2;
  color: #fff;
  margin-bottom: 10px;
}

.panel-text {
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
}

.panel-foot {
  margin-top: 18px;
  padding-top: 14px;
  border-top: 1px solid var(--line-soft);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .12em;
  color: var(--muted);
}

.panel-link {
  display: inline-block;
  text-decoration: none;
  color: var(--muted);
  transition: color var(--t) var(--ease);
}

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

/* --- 7. 图文容器 --------------------------------------------------------- */
.media {
  position: relative;
  display: block;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--ink-800);
}

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

.media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(158deg, rgba(0, 229, 212, .10), transparent 52%, rgba(7, 11, 20, .55));
}

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

.media-caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  color: var(--muted);
}

/* --- 8. 长文排版 --------------------------------------------------------- */
.prose {
  max-width: 68ch;
  color: var(--text);
  font-size: var(--fs-17);
  line-height: 1.75;
}

.prose > * + * { margin-top: 1.05em; }

.prose h2 { font-size: var(--fs-32); margin-top: 1.9em; }
.prose h3 { font-size: var(--fs-22); margin-top: 1.6em; }

.prose ul, .prose ol { padding-left: 1.2em; }
.prose ul { list-style: none; }
.prose ul li { position: relative; padding-left: 16px; }
.prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .74em;
  width: 7px;
  height: 1px;
  background: var(--cyan);
}
.prose ol { list-style: decimal; }
.prose li + li { margin-top: .45em; }

.prose a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 229, 212, .38);
  transition: border-color var(--t) var(--ease);
}
.prose a:hover { border-bottom-color: var(--cyan); }

.prose strong { color: #fff; font-weight: 700; }

.prose code {
  font-family: var(--font-mono);
  font-size: .92em;
  color: var(--amber);
  background: rgba(255, 194, 75, .09);
  padding: 1px 6px;
  border-radius: 3px;
}

/* --- 9. 暖纸色阅读区 ----------------------------------------------------- */
.paper {
  background: var(--paper);
  color: var(--paper-ink);
  border-radius: var(--r-lg);
  padding: clamp(24px, 4vw, 56px);
}

.paper h1, .paper h2, .paper h3, .paper h4 { color: var(--paper-ink); }
.paper .muted { color: #5C5A55; }
.paper .index-label { color: #0A5D57; }
.paper .prose { color: var(--paper-ink); }
.paper .prose a { color: #0A5D57; border-bottom-color: rgba(10, 93, 87, .4); }
.paper .prose strong { color: #000; }
.paper .prose code { color: #8A4A00; background: rgba(138, 74, 0, .09); }
.paper .rule { background: var(--paper-line); }
.paper .panel {
  background: #FFFDF8;
  border-color: var(--paper-line);
  color: var(--paper-ink);
}
.paper .panel-title { color: var(--paper-ink); }
.paper .panel-text { color: #4C4A46; }
.paper .panel-foot { border-top-color: var(--paper-line); color: #6C6A65; }
.paper .panel-link { color: #0A5D57; }
.paper .media { border-color: var(--paper-line); }
.paper .media-caption { color: #6C6A65; }
.paper .tag { background: rgba(255, 255, 255, .8); border-color: var(--paper-line); color: #57544F; }
.paper .tag-cyan { color: #0A5D57; border-color: rgba(10, 93, 87, .4); }

/* --- 10. 面包屑 ---------------------------------------------------------- */
.crumbs { font-family: var(--font-mono); font-size: 11.5px; letter-spacing: .1em; }

.crumbs-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  list-style: none;
}

.crumbs-item { color: var(--muted); }

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

.crumbs a {
  text-decoration: none;
  color: var(--muted);
  transition: color var(--t) var(--ease);
}

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

.crumbs-item[aria-current="page"] { color: var(--text); }

/* --- 11. 章节构件 -------------------------------------------------------- */
.chapter-head {
  position: relative;
  display: grid;
  gap: 6px;
  padding-top: clamp(10px, 2vw, 22px);
}

.chapter-num {
  font-size: clamp(56px, 10vw, 132px);
  font-weight: 200;
  line-height: .86;
  letter-spacing: -.05em;
  color: rgba(200, 210, 224, .12);
  font-variant-numeric: tabular-nums;
  user-select: none;
}

.chapter-title {
  font-size: var(--fs-56);
  font-weight: 800;
  line-height: 1.02;
  letter-spacing: -.022em;
  color: #fff;
}

.chapter-note {
  max-width: 52ch;
  font-size: 16px;
  line-height: 1.75;
  color: var(--muted);
}

.chapter-nav {
  position: sticky;
  top: calc(var(--header-h) + var(--rail-h) + 20px);
  display: grid;
  gap: 2px;
  border-left: 1px solid var(--line);
  padding-left: 0;
}

.chapter-nav a {
  display: block;
  padding: 8px 14px;
  border-left: 2px solid transparent;
  margin-left: -1px;
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--muted);
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease);
}

.chapter-nav a:hover { color: var(--text); }

.chapter-nav a[data-active="true"] {
  color: var(--cyan);
  border-left-color: var(--cyan);
}

/* --- 12. 网格 ------------------------------------------------------------ */
.grid { display: grid; gap: clamp(16px, 2vw, 26px); }

.grid-3 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }

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

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

@media (max-width: 960px) {
  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .span-4, .span-5, .span-7, .span-8 { grid-column: span 6; }
}

/* --- 13. 折叠与表格 ------------------------------------------------------ */
.accordion {
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--ink-800);
  overflow: hidden;
}

.accordion + .accordion { margin-top: 12px; }

.accordion summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  list-style: none;
  cursor: pointer;
  font-size: 16px;
  font-weight: 700;
  color: var(--text);
  transition: color var(--t) var(--ease);
}

.accordion summary::-webkit-details-marker { display: none; }

.accordion summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--cyan);
}

.accordion[open] summary::after { content: "–"; }

.accordion summary:hover { color: #fff; }

.accordion[open] summary { border-bottom: 1px solid var(--line-soft); }

.accordion-body {
  padding: 16px 20px 20px;
  font-size: 15px;
  line-height: 1.78;
  color: var(--muted);
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
}

.table th,
.table td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.table th {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--muted);
}

.table td.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
}

/* --- 14. 显现 ------------------------------------------------------------ */
html.js [data-reveal] {
  opacity: 0;
  transform: translateY(6px);
  transition: opacity 420ms var(--ease), transform 420ms var(--ease);
}

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

/* --- 15. 页头 ------------------------------------------------------------ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background 260ms var(--ease), border-color 260ms var(--ease),
    box-shadow 260ms var(--ease);
}

.site-header[data-scrolled="true"],
.site-header[data-nav-open] {
  background: rgba(7, 11, 20, .95);
  border-bottom-color: var(--line);
  box-shadow: 0 18px 40px -32px rgba(0, 0, 0, .95);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

.skip-link {
  position: absolute;
  left: 14px;
  top: -70px;
  z-index: 200;
  padding: 10px 16px;
  border-radius: var(--r-sm);
  background: var(--cyan);
  color: var(--cyan-ink);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  transition: top 160ms var(--ease);
}

.skip-link:focus { top: 12px; }

.header-rail { height: var(--rail-h); overflow: hidden; }

.rail-inner {
  height: var(--rail-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.rail-note,
.rail-clock {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 10.5px;
  font-weight: 500;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}

.rail-clock { font-variant-numeric: tabular-nums; color: #6E7C96; }

.rail-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 3px rgba(0, 229, 212, .14);
  flex: none;
}

.header-bar { border-top: 1px solid rgba(34, 48, 76, .55); }

.site-header[data-scrolled="true"] .header-bar,
.site-header[data-nav-open] .header-bar { border-top-color: transparent; }

.header-inner {
  display: flex;
  align-items: center;
  gap: clamp(14px, 2.4vw, 34px);
  min-height: var(--header-h);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
  text-decoration: none;
}

.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  background: var(--cyan);
  color: var(--cyan-ink);
  font-size: 18px;
  font-weight: 900;
  letter-spacing: -.03em;
  line-height: 1;
  clip-path: polygon(0 0, 100% 0, 100% 70%, 86% 100%, 0 100%);
}

.brand-text { display: grid; gap: 1px; }

.brand-name {
  font-size: 16.5px;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: .01em;
  color: #fff;
}

.brand-tag {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: .15em;
  text-transform: uppercase;
  color: var(--muted);
  line-height: 1.3;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1.6vw, 22px);
  margin-left: auto;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
  list-style: none;
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: 10px 12px;
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--t) var(--ease);
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 3px;
  height: 2px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--t) var(--ease);
}

.nav-link:hover,
.nav-link:focus-visible { color: #fff; }

.nav-link:hover::after,
.nav-link:focus-visible::after,
.nav-link[aria-current="page"]::after { transform: scaleX(1); }

.nav-link[aria-current="page"] { color: #fff; }

.nav-index {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: .08em;
  color: #64748E;
  transition: color var(--t) var(--ease);
}

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

.nav-cta { flex: none; }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  margin-left: auto;
  padding: 9px 14px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .16em;
  cursor: pointer;
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease);
}

.nav-toggle:hover { border-color: var(--cyan); color: #fff; }

.nav-toggle-lines {
  position: relative;
  display: block;
  width: 18px;
  height: 11px;
  flex: none;
}

.nav-toggle-lines::before,
.nav-toggle-lines::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 1.5px;
  background: var(--cyan);
  transition: transform var(--t) var(--ease), top var(--t) var(--ease),
    bottom var(--t) var(--ease);
}

.nav-toggle-lines::before { top: 0; }
.nav-toggle-lines::after { bottom: 0; }

.site-header[data-nav-open] .nav-toggle-lines::before { top: 4.5px; transform: rotate(45deg); }
.site-header[data-nav-open] .nav-toggle-lines::after { bottom: 5px; transform: rotate(-45deg); }

.scroll-progress {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  transform: scaleX(var(--progress, 0));
  transform-origin: left center;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
  pointer-events: none;
}

/* --- 16. 页脚 ------------------------------------------------------------ */
.site-footer {
  position: relative;
  margin-top: clamp(64px, 10vw, 140px);
  background: var(--ink-900);
  border-top: 1px solid var(--line);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  width: min(340px, 42%);
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
}

.footer-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.7fr);
  gap: clamp(28px, 5vw, 76px);
  padding-top: clamp(40px, 6vw, 74px);
  padding-bottom: clamp(32px, 5vw, 58px);
}

.footer-intro { max-width: 40ch; }

.footer-kicker {
  font-size: var(--fs-22);
  font-weight: 800;
  letter-spacing: -.01em;
  color: #fff;
  margin-bottom: 12px;
}

.footer-lede {
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
  margin-bottom: 24px;
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(18px, 3vw, 40px);
}

.footer-col-title {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 14px;
}

.footer-links {
  display: grid;
  gap: 10px;
  list-style: none;
}

.footer-links a {
  display: inline-block;
  font-size: 15px;
  color: var(--text);
  text-decoration: none;
  transition: color var(--t) var(--ease), transform var(--t) var(--ease);
}

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

.footer-contact {
  background: var(--ink-800);
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
}

.contact-inner {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: clamp(18px, 3vw, 36px);
  padding-top: clamp(22px, 3vw, 34px);
  padding-bottom: clamp(22px, 3vw, 34px);
}

.contact-value {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: .02em;
  color: var(--text);
  word-break: break-word;
}

.contact-value-address {
  font-family: var(--font-sans);
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--muted);
  max-width: 34ch;
}

.copy-btn {
  flex: none;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: 3px;
  background: transparent;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: .14em;
  cursor: pointer;
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease),
    background var(--t) var(--ease);
}

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

.copy-btn[data-state="ok"] {
  color: var(--cyan-ink);
  background: var(--cyan);
  border-color: var(--cyan);
}

.copy-btn[data-state="fail"] { color: var(--amber); border-color: var(--amber); }

.footer-base { padding: 18px 0 30px; }

.base-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 28px;
  font-size: 12.5px;
  color: var(--muted);
}

.footer-legal,
.footer-copy {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  white-space: nowrap;
}

.footer-note {
  max-width: 62ch;
  line-height: 1.7;
}

/* --- 17. 响应式 ---------------------------------------------------------- */
@media (max-width: 1024px) {
  .nav-link { padding: 10px 9px; font-size: 14.5px; }
  .nav-index { display: none; }
}

@media (max-width: 960px) {
  .header-inner { gap: 12px; }

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

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    margin-left: 0;
    padding: 6px var(--gut) 22px;
    background: rgba(7, 11, 20, .985);
    border-bottom: 1px solid var(--line);
    box-shadow: 0 30px 50px -34px rgba(0, 0, 0, .95);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: opacity 200ms var(--ease), transform 200ms var(--ease),
      visibility 200ms var(--ease);
  }

  .site-nav[data-open] {
    opacity: 1;
    visibility: visible;
    transform: none;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .nav-link {
    width: 100%;
    padding: 15px 4px;
    font-size: 17px;
    border-bottom: 1px solid var(--line-soft);
  }

  .nav-index { display: inline; color: var(--cyan); }

  .nav-link::after { display: none; }

  .nav-cta {
    width: 100%;
    margin-top: 18px;
    padding: 14px 20px;
  }

  .footer-wrap { grid-template-columns: 1fr; }
  .footer-cols { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 760px) {
  .header-rail { display: none; }
  [id] { scroll-margin-top: calc(var(--header-h) + 18px); }
  .chapter-nav { position: static; display: flex; flex-wrap: wrap; border-left: 0; gap: 6px; }
  .chapter-nav a { border: 1px solid var(--line); border-radius: 999px; margin-left: 0; }
}

@media (max-width: 620px) {
  :root { --fs-17: 16px; }
  .footer-cols { grid-template-columns: 1fr; }
  .base-inner { flex-direction: column; align-items: flex-start; }
  .footer-legal, .footer-copy { white-space: normal; }
}

/* --- 18. 减弱动效 -------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

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

  html.js [data-reveal] { opacity: 1; transform: none; }
  .panel:hover, .panel:focus-within { transform: none; }
  .footer-links a:hover { transform: none; }
}