/* ==========================================================================
   FB体育中心 · /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 头部 / 页脚 / 通用组件
   ========================================================================== */

/* ---------- 01. reset ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 110px;
}

body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, table, fieldset {
  margin: 0;
}

ul, ol { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
table { border-collapse: collapse; border-spacing: 0; }
hr { border: 0; margin: 0; }

/* ---------- 02. 设计令牌 ---------- */
:root {
  /* 看台深蓝体系 */
  --ink: #0A1A2B;
  --ink-2: #12293F;
  --turf: #1E7A50;
  --turf-deep: #14563A;
  --cyan: #2ED3C6;
  --signal: #FF6A2B;
  --signal-soft: #FFB37A;
  --paper: #F4F1EA;
  --chalk: #E8EEF4;
  --carbon: #0A0F16;
  --grey: #8B9AA8;

  --line-dark: rgba(232, 238, 244, 0.12);
  --line-dark-strong: rgba(232, 238, 244, 0.26);
  --line-light: rgba(10, 15, 22, 0.14);
  --glass-bg: rgba(18, 41, 63, 0.55);
  --glass-brd: rgba(232, 238, 244, 0.18);

  /* 字体：窄体大写标题 / 等宽数字 / 高可读正文 */
  --font-display: "Barlow Condensed", "Oswald", "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "Roboto Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Courier New", monospace;

  /* 尺度 */
  --container: 1240px;
  --container-wide: 1440px;
  --gutter: clamp(20px, 5vw, 64px);

  --sp-1: clamp(56px, 7vw, 96px);
  --sp-2: clamp(88px, 12vw, 160px);
  --sp-3: clamp(120px, 16vw, 240px);

  --radius: 4px;
  --ease-out: cubic-bezier(0.22, 0.61, 0.36, 1);
  --header-h: 84px;
}

/* ---------- 03. 基础排版 ---------- */
body {
  background-color: var(--ink);
  color: var(--chalk);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  min-height: 100%;
}

body.is-nav-open { overflow: hidden; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.06;
  letter-spacing: 0.02em;
  text-wrap: balance;
}

h1 {
  font-size: clamp(48px, 9vw, 140px);
  line-height: 0.92;
  letter-spacing: 0.01em;
  text-transform: uppercase;
}

h2 { font-size: clamp(30px, 4vw, 64px); }
h3 { font-size: clamp(20px, 1.8vw, 28px); letter-spacing: 0.04em; }
h4 { font-size: 18px; letter-spacing: 0.06em; }

p { text-wrap: pretty; }

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

::selection { background: var(--signal); color: var(--carbon); }

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

/* 数字一律等宽并放大一号 */
.num, .mono, [data-num] {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1.08em;
  letter-spacing: 0;
}

.eyebrow {
  display: inline-block;
  font-family: var(--font-body);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--cyan);
}

.eyebrow--warm { color: var(--signal-soft); }
.eyebrow--muted { color: var(--grey); }

/* ---------- 04. 布局工具 ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.container--narrow { max-width: 860px; }
.container--wide { max-width: var(--container-wide); }

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 40px);
}

.stack > * + * { margin-top: var(--stack-gap, 20px); }

/* ---------- 05. 看台栏杆分割线 ---------- */
.rail {
  height: 1px;
  width: 100%;
  background: linear-gradient(90deg, var(--line-dark-strong), rgba(232, 238, 244, 0.02));
}

.rail--turf {
  background: linear-gradient(90deg, var(--turf), rgba(30, 122, 80, 0.05));
}

.rail--warm {
  background: linear-gradient(90deg, var(--signal), rgba(255, 106, 43, 0.05));
}

/* ---------- 06. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 24px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  line-height: 1.2;
  transition: background-color 0.24s var(--ease-out), color 0.24s var(--ease-out),
              border-color 0.24s var(--ease-out), transform 0.24s var(--ease-out);
}

.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }

.btn--signal {
  background-color: var(--signal);
  border-color: var(--signal);
  color: var(--carbon);
}
.btn--signal:hover { background-color: var(--signal-soft); border-color: var(--signal-soft); }

.btn--ghost {
  border-color: var(--line-dark-strong);
  color: var(--chalk);
  background-color: transparent;
}
.btn--ghost:hover { border-color: var(--cyan); color: var(--cyan); }

.btn--cyan {
  border-color: var(--cyan);
  color: var(--cyan);
  background-color: transparent;
}
.btn--cyan:hover { background-color: var(--cyan); color: var(--ink); }

.btn--paper {
  background-color: var(--paper);
  border-color: var(--paper);
  color: var(--carbon);
}
.btn--paper:hover { background-color: #fff; }

.btn--sm { padding: 10px 16px; font-size: 12.5px; letter-spacing: 0.06em; }
.btn--lg { padding: 18px 32px; font-size: 15px; }

/* ---------- 07. 头部 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 80;
}

.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-color: rgba(10, 26, 43, 0.55);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  transition: background-color 0.36s var(--ease-out);
  pointer-events: none;
}

.site-header[data-scrolled="true"]::before {
  background-color: rgba(18, 41, 63, 0.96);
}

.site-header[data-scrolled="true"] {
  box-shadow: 0 1px 0 var(--line-dark), 0 14px 36px rgba(4, 9, 16, 0.45);
}

.site-header__inner {
  display: flex;
  align-items: center;
  gap: clamp(16px, 3vw, 40px);
  width: 100%;
  max-width: var(--container-wide);
  margin-inline: auto;
  padding-inline: var(--gutter);
  height: var(--header-h);
  transition: height 0.36s var(--ease-out);
}

.site-header[data-scrolled="true"] .site-header__inner { height: 64px; }

.skip-link {
  position: fixed;
  top: -80px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 200;
  padding: 10px 20px;
  background-color: var(--signal);
  color: var(--carbon);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  border-radius: var(--radius);
  transition: top 0.24s var(--ease-out);
}

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

/* 品牌字标 */
.brand {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1px;
  line-height: 1;
  padding-block: 6px;
  border-left: 2px solid var(--signal);
  padding-left: 12px;
}

.brand__mark {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--chalk);
}

.brand__sub {
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.24em;
  color: var(--grey);
  transition: opacity 0.3s var(--ease-out);
}

.site-header[data-scrolled="true"] .brand__sub { opacity: 0.55; }

/* 主导航 */
.site-header__nav {
  flex: 1 1 auto;
  display: flex;
  justify-content: center;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1.6vw, 28px);
}

.nav-list__item { display: block; }

.nav-link {
  position: relative;
  display: inline-block;
  padding: 8px 2px;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: rgba(232, 238, 244, 0.76);
  transition: color 0.2s var(--ease-out);
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 100%;
  bottom: 1px;
  height: 2px;
  background-color: var(--turf);
  transition: right 0.28s var(--ease-out);
}

.nav-link:hover { color: var(--chalk); }
.nav-link:hover::after { right: 0; }

.nav-link[aria-current="page"] { color: var(--chalk); font-weight: 700; }
.nav-link[aria-current="page"]::after { right: 0; }

/* 移动端面板底部联系入口 */
.nav-panel__foot { display: none; }

/* 动作区 */
.site-header__actions {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  gap: 10px;
}

/* 汉堡（看台栏杆）按钮 */
.nav-toggle {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line-dark-strong);
  border-radius: var(--radius);
  transition: border-color 0.24s var(--ease-out), background-color 0.24s var(--ease-out);
}

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

.nav-toggle__rail {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background-color: var(--chalk);
  transition: transform 0.28s var(--ease-out), opacity 0.2s var(--ease-out);
}

.site-header[data-open="true"] .nav-toggle__rail:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.site-header[data-open="true"] .nav-toggle__rail:nth-child(2) { opacity: 0; }
.site-header[data-open="true"] .nav-toggle__rail:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ---------- 08. 页脚 ---------- */
.site-footer {
  position: relative;
  background-color: var(--ink-2);
  border-top: 1px solid var(--line-dark);
  color: var(--chalk);
  padding-block: clamp(56px, 8vw, 120px) 36px;
}

.site-footer__inner {
  width: 100%;
  max-width: var(--container-wide);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(4, minmax(0, 1fr));
  gap: clamp(28px, 3.4vw, 56px);
}

.footer-brand { display: flex; flex-direction: column; gap: 18px; }

.footer-brand__glass {
  padding: 22px 20px;
  border: 1px solid var(--glass-brd);
  border-radius: var(--radius);
  background-color: var(--glass-bg);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}

.footer-brand__name {
  font-family: var(--font-display);
  font-size: 26px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  line-height: 1.1;
}

.footer-brand__sub {
  margin-top: 6px;
  font-size: 11px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--cyan);
}

.footer-brand__note {
  font-size: 13.5px;
  line-height: 1.8;
  color: var(--grey);
  max-width: 30ch;
}

.footer-col__title {
  font-family: var(--font-body);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--grey);
  margin-bottom: 16px;
}

.footer-list { display: flex; flex-direction: column; gap: 2px; }

.footer-link {
  display: inline-block;
  padding: 6px 0;
  font-size: 14px;
  line-height: 1.6;
  color: rgba(232, 238, 244, 0.78);
  transition: color 0.22s var(--ease-out), transform 0.22s var(--ease-out);
}

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

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 28px;
  margin-top: clamp(48px, 7vw, 96px);
  padding-top: 20px;
  border-top: 1px solid var(--line-dark);
  font-size: 12.5px;
  letter-spacing: 0.05em;
  color: var(--grey);
}

.footer-legal__line { color: var(--grey); }

.footer-legal__links { display: flex; flex-wrap: wrap; gap: 8px 20px; }

.footer-legal__link {
  display: inline-block;
  padding: 4px 0;
  color: rgba(232, 238, 244, 0.72);
  border-bottom: 1px solid transparent;
  transition: color 0.22s var(--ease-out), border-color 0.22s var(--ease-out);
}

.footer-legal__link:hover { color: var(--chalk); border-bottom-color: var(--signal); }

.footer-year {
  margin-top: 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--grey);
}

/* ---------- 09. 章节体系 ---------- */
.section {
  position: relative;
  padding-block: var(--sp-1);
}

.section--tight { padding-block: clamp(40px, 5vw, 72px); }
.section--deep { padding-block: var(--sp-2); }
.section--deeper { padding-block: var(--sp-3); }

.section--paper { background-color: var(--paper); color: var(--carbon); }
.section--paper h1, .section--paper h2, .section--paper h3 { color: var(--carbon); }
.section--paper .eyebrow { color: var(--turf-deep); }
.section--paper p { color: #2B333B; }

.section--turf {
  background-image: linear-gradient(160deg, var(--turf) 0%, var(--turf-deep) 100%);
  color: var(--chalk);
}

.section__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(56px, 9vw, 132px);
  font-weight: 700;
  line-height: 0.78;
  letter-spacing: -0.03em;
  color: rgba(232, 238, 244, 0.1);
  user-select: none;
}

.section--paper .section__num { color: rgba(10, 15, 22, 0.1); }

.section__title {
  margin-top: 12px;
  margin-left: clamp(0px, 3vw, 48px);
  max-width: 22ch;
}

.section__lede {
  margin-left: clamp(0px, 3vw, 48px);
  margin-top: 20px;
  max-width: 56ch;
  font-size: clamp(16px, 1.1vw, 18px);
  line-height: 1.75;
  color: rgba(232, 238, 244, 0.76);
}

.section--paper .section__lede { color: #3C454E; }

/* ---------- 10. 卡片 ---------- */
.glass-card {
  padding: clamp(20px, 3vw, 36px);
  border: 1px solid var(--glass-brd);
  border-radius: var(--radius);
  background-color: var(--glass-bg);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}

.solid-card {
  padding: clamp(20px, 3vw, 36px);
  border: 1px solid var(--line-dark);
  border-radius: var(--radius);
  background-color: var(--ink-2);
}

.solid-card--paper {
  background-color: var(--paper);
  border-color: var(--line-light);
  color: var(--carbon);
}

.solid-card--turf {
  background-color: var(--turf-deep);
  border-color: rgba(46, 211, 198, 0.28);
}

.pulse-card { position: relative; }

.pulse-card::after {
  content: "";
  position: absolute;
  inset: -1px;
  border: 1px solid var(--signal);
  border-radius: var(--radius);
  pointer-events: none;
  animation: kt-pulse 2.4s ease-in-out infinite;
}

@keyframes kt-pulse {
  0%, 100% { opacity: 0.22; box-shadow: 0 0 0 0 rgba(255, 106, 43, 0); }
  50% { opacity: 0.7; box-shadow: 0 0 0 6px rgba(255, 106, 43, 0.12); }
}

/* ---------- 11. 面包屑 ---------- */
.breadcrumbs { font-size: 12px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--grey); }

.breadcrumb-list { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }

.breadcrumb-item { display: flex; align-items: center; gap: 8px; }

.breadcrumb-item + .breadcrumb-item::before {
  content: "／";
  color: rgba(139, 154, 168, 0.6);
}

.breadcrumb-link { transition: color 0.2s var(--ease-out); }
.breadcrumb-link:hover { color: var(--cyan); }

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

/* ---------- 12. 正文容器 ---------- */
.prose {
  font-size: clamp(16px, 1.1vw, 18px);
  line-height: 1.75;
  color: var(--chalk);
}

.prose > * + * { margin-top: 1.15em; }
.prose h2 { margin-top: 2em; font-size: clamp(26px, 2.6vw, 40px); }
.prose h3 { margin-top: 1.6em; }
.prose ul, .prose ol { padding-left: 1.4em; }
.prose ul { list-style: square; }
.prose ol { list-style: decimal; }
.prose li + li { margin-top: 0.5em; }
.prose li::marker { color: var(--cyan); }
.prose a { color: var(--cyan); border-bottom: 1px solid rgba(46, 211, 198, 0.4); }
.prose a:hover { border-bottom-color: var(--cyan); }
.prose blockquote {
  padding: 4px 0 4px 22px;
  border-left: 2px solid var(--signal);
  color: rgba(232, 238, 244, 0.8);
}

.prose--light { color: #2B333B; }
.prose--light h1, .prose--light h2, .prose--light h3 { color: var(--carbon); }
.prose--light a { color: var(--turf-deep); border-bottom-color: rgba(20, 86, 58, 0.35); }
.prose--light li::marker { color: var(--turf-deep); }

/* ---------- 13. 图片容器基础 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line-dark);
  border-radius: var(--radius);
  background-color: var(--ink-2);
}

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

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

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.media-frame--turf::after {
  background-image: repeating-linear-gradient(115deg, rgba(20, 86, 58, 0.42) 0 6px, rgba(30, 122, 80, 0.12) 6px 13px);
  mix-blend-mode: multiply;
}

.media-frame--screen::after {
  background-image: repeating-linear-gradient(0deg, rgba(46, 211, 198, 0.12) 0 1px, rgba(46, 211, 198, 0) 1px 5px);
}

.media-frame--stand::after {
  background-image: linear-gradient(180deg, rgba(10, 26, 43, 0) 38%, rgba(10, 26, 43, 0.72) 100%);
}

/* ---------- 14. 数据表 ---------- */
.data-table {
  width: 100%;
  font-size: 14px;
  line-height: 1.5;
  color: var(--carbon);
}

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

.data-table thead th {
  font-family: var(--font-body);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: #6C7A86;
  border-bottom-color: rgba(10, 15, 22, 0.28);
}

.data-table tbody tr:hover { background-color: rgba(30, 122, 80, 0.07); }

.data-table td.num,
.data-table th.num { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

.data-table--dark { color: var(--chalk); }
.data-table--dark th, .data-table--dark td { border-bottom-color: var(--line-dark); }
.data-table--dark thead th { color: var(--grey); border-bottom-color: var(--line-dark-strong); }
.data-table--dark tbody tr:hover { background-color: rgba(46, 211, 198, 0.06); }

.table-scroll { width: 100%; overflow-x: auto; }

/* ---------- 15. 筛选芯片 ---------- */
.chip-row { display: flex; flex-wrap: wrap; gap: 10px; }

.chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 15px;
  border: 1px solid var(--line-dark-strong);
  border-radius: var(--radius);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: rgba(232, 238, 244, 0.8);
  transition: color 0.22s var(--ease-out), border-color 0.22s var(--ease-out),
              background-color 0.22s var(--ease-out);
}

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

.chip[aria-pressed="true"] {
  background-color: var(--turf);
  border-color: var(--turf);
  color: #fff;
}

.chip--light { border-color: var(--line-light); color: #3C454E; }
.chip--light:hover { border-color: var(--turf-deep); color: var(--turf-deep); }
.chip--light[aria-pressed="true"] { background-color: var(--turf-deep); border-color: var(--turf-deep); color: var(--paper); }

/* ---------- 16. 联赛订阅带 ---------- */
.subscribe-band {
  display: flex;
  gap: 16px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding: 6px var(--gutter) 22px;
  scrollbar-width: thin;
  scrollbar-color: var(--cyan) transparent;
}

.subscribe-band::-webkit-scrollbar { height: 6px; }
.subscribe-band::-webkit-scrollbar-track { background-color: var(--line-dark); }
.subscribe-band::-webkit-scrollbar-thumb { background-color: var(--cyan); border-radius: 3px; }

.subscribe-card {
  flex: 0 0 clamp(220px, 26vw, 296px);
  scroll-snap-align: start;
  padding: 20px;
  border: 1px solid var(--line-dark);
  border-radius: var(--radius);
  background-color: var(--ink-2);
  transition: border-color 0.24s var(--ease-out), transform 0.24s var(--ease-out);
}

.subscribe-card:hover { border-color: var(--cyan); transform: translateY(-3px); }

.subscribe-card--more {
  display: flex;
  align-items: center;
  justify-content: center;
  border-color: var(--signal);
  color: var(--signal-soft);
  font-weight: 700;
  letter-spacing: 0.08em;
  background-color: transparent;
}

/* ---------- 17. 章节目录 ---------- */
.chapter-index {
  display: flex;
  flex-direction: column;
  gap: 4px;
  position: sticky;
  top: 120px;
}

.chapter-index__link {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 6px 0 6px 14px;
  border-left: 2px solid var(--line-dark);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--grey);
  transition: color 0.22s var(--ease-out), border-color 0.22s var(--ease-out);
}

.chapter-index__link:hover { color: var(--chalk); }

.chapter-index__link[aria-current="true"] {
  color: var(--chalk);
  border-left-color: var(--signal);
}

.chapter-index__num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--cyan);
}

/* ---------- 18. 滚动进度条 ---------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  z-index: 90;
  pointer-events: none;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background-image: linear-gradient(90deg, var(--turf) 0%, var(--cyan) 55%, var(--signal) 100%);
}

/* ---------- 19. 返回顶部 ---------- */
.back-to-top {
  position: fixed;
  right: clamp(16px, 3vw, 32px);
  bottom: clamp(16px, 3vw, 32px);
  z-index: 60;
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border: 1px solid var(--line-dark-strong);
  border-radius: var(--radius);
  background-color: rgba(18, 41, 63, 0.92);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  color: var(--chalk);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 0.32s var(--ease-out), transform 0.32s var(--ease-out),
              visibility 0.32s var(--ease-out), border-color 0.24s var(--ease-out);
}

.back-to-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

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

.back-to-top__bars {
  display: flex;
  flex-direction: column;
  gap: 3px;
  width: 18px;
}

.back-to-top__bars span {
  display: block;
  height: 2px;
  border-radius: 2px;
  background-color: currentColor;
}

.back-to-top__bars span:nth-child(1) { width: 100%; }
.back-to-top__bars span:nth-child(2) { width: 68%; }
.back-to-top__bars span:nth-child(3) { width: 100%; }

/* ---------- 20. 入场显现 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.52s var(--ease-out), transform 0.52s var(--ease-out);
}

.reveal.is-visible { opacity: 1; transform: none; }

/* ---------- 21. 玻璃导航层辅助 ---------- */
.glass-layer {
  background-color: var(--glass-bg);
  border: 1px solid var(--glass-brd);
  border-radius: var(--radius);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
}

/* ---------- 22. 平板 ---------- */
@media (max-width: 1080px) {
  :root { --gutter: clamp(20px, 4vw, 40px); }

  .nav-link { font-size: 13px; letter-spacing: 0.03em; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-brand { grid-column: 1 / -1; }
  .footer-col { transform: none !important; }
}

/* ---------- 23. 移动端 ---------- */
@media (max-width: 900px) {
  :root { --header-h: 66px; }

  .site-header__inner { height: var(--header-h); gap: 12px; }
  .site-header[data-scrolled="true"] .site-header__inner { height: 58px; }

  .brand { padding-left: 10px; }
  .brand__mark { font-size: 18px; }
  .brand__sub { font-size: 9px; letter-spacing: 0.2em; }

  .site-header__nav {
    position: fixed;
    inset: 0;
    z-index: 70;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    gap: 0;
    padding: 104px var(--gutter) 120px;
    background-color: var(--ink);
    overflow-y: auto;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.28s var(--ease-out), transform 0.28s var(--ease-out),
                visibility 0.28s var(--ease-out);
  }

  .site-header[data-open="true"] .site-header__nav {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

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

  .nav-link {
    display: block;
    padding: 18px 0;
    font-family: var(--font-display);
    font-size: 26px;
    font-weight: 800;
    letter-spacing: 0.05em;
    color: var(--chalk);
    border-bottom: 1px solid var(--line-dark);
  }

  .nav-link::after { display: none; }
  .nav-link[aria-current="page"] { color: var(--cyan); }

  .nav-panel__foot {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-top: auto;
    padding-top: 28px;
    border-top: 1px solid var(--line-dark);
  }

  .nav-panel__eyebrow {
    font-size: 11px;
    letter-spacing: 0.22em;
    text-transform: uppercase;
    color: var(--grey);
  }

  .nav-panel__contact {
    font-family: var(--font-mono);
    font-size: 14px;
    color: var(--cyan);
  }

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

  .section__title,
  .section__lede { margin-left: 0; }

  .chapter-index {
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 8px;
  }

  .chapter-index__link { border-left: 0; border-bottom: 2px solid var(--line-dark); padding: 6px 10px; }
  .chapter-index__link[aria-current="true"] { border-left: 0; border-bottom-color: var(--signal); }
}

/* ---------- 24. 小屏 ---------- */
@media (max-width: 620px) {
  .site-header__cta { display: none; }
  .slide-header__actions { gap: 0; }

  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-legal { flex-direction: column; align-items: flex-start; }

  .btn { padding: 13px 20px; font-size: 13px; width: 100%; }
  .btn--inline { width: auto; }

  .back-to-top { width: 44px; height: 44px; }
}

/* ---------- 25. 动效降级 ---------- */
@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;
  }

  .reveal { opacity: 1; transform: none; }

  .pulse-card::after { animation: none; opacity: 0.45; }

  .btn:hover,
  .subscribe-card:hover,
  .footer-link:hover { transform: none; }
}