/* ============================================================
   尊龙A9 · 品牌站 V3.1 — 共享样式表 /assets/site.css
   曜石黑舞台 + 鎏金铜铭牌 + 青玉信息分区
   ============================================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h, 72px) + 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, video, canvas { display: block; max-width: 100%; }

img { height: auto; }

a { color: inherit; text-decoration: none; }

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

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

table { border-collapse: collapse; }

/* ---------- 2. 变量 ---------- */
:root {
  /* 色彩 */
  --c-obsidian: #0B0E13;
  --c-deep: #101B2D;
  --c-midnight: #16243B;
  --c-gold: #C49A58;
  --c-gold-bright: #E4C078;
  --c-jade: #2F7A72;
  --c-jade-soft: #8FBDB4;
  --c-sand: #F5EFE3;
  --c-slate: #74839A;

  --metal-grad: linear-gradient(135deg, #3A2F1F 0%, #C49A58 52%, #E4C078 100%);
  --metal-line: linear-gradient(90deg, rgba(196, 154, 88, 0) 0%, #C49A58 24%, #E4C078 50%, #C49A58 76%, rgba(196, 154, 88, 0) 100%);

  /* 线框与透明层 */
  --line-gold: rgba(196, 154, 88, 0.24);
  --line-gold-soft: rgba(196, 154, 88, 0.14);
  --line-jade: rgba(143, 189, 180, 0.4);
  --surface-1: rgba(22, 36, 59, 0.88);
  --surface-2: rgba(16, 27, 45, 0.92);
  --text-soft: rgba(245, 239, 227, 0.72);
  --text-mute: rgba(245, 239, 227, 0.55);

  /* 字体 */
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", Georgia, serif;
  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: "IBM Plex Mono", "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  /* 尺度 */
  --header-h: 72px;
  --shell-max: 1320px;
  --gutter: clamp(1.25rem, 4vw, 3.5rem);
  --radius: 2px;
  --gap-lg: clamp(1.5rem, 3.4vw, 2.75rem);
  --gap-md: clamp(1rem, 2.4vw, 1.75rem);
  --section-y: clamp(3.5rem, 8vw, 6.5rem);

  /* 阴影 */
  --shadow-panel: 0 18px 44px rgba(0, 0, 0, 0.42);
  --shadow-gold: 0 8px 26px rgba(196, 154, 88, 0.2);
}

/* ---------- 3. 基础排版 ---------- */
body {
  position: relative;
  isolation: isolate;
  min-height: 100vh;
  background-color: var(--c-obsidian);
  color: var(--c-sand);
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.85;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(58rem 38rem at 10% -10%, rgba(16, 27, 45, 0.95), transparent 68%),
    radial-gradient(46rem 30rem at 94% 2%, rgba(196, 154, 88, 0.08), transparent 62%),
    radial-gradient(38rem 26rem at 50% 108%, rgba(47, 122, 114, 0.08), transparent 66%);
}

h1, h2, h3, h4, .t-display {
  font-family: var(--font-serif);
  font-weight: 900;
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--c-sand);
}

p { color: var(--text-soft); }

strong { color: var(--c-sand); font-weight: 600; }

a { transition: color 0.24s ease, border-color 0.24s ease, background-color 0.24s ease; }

::selection {
  background: rgba(196, 154, 88, 0.32);
  color: #fff;
}

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

/* ---------- 4. 工具类 ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.t-mono { font-family: var(--font-mono); letter-spacing: 0.08em; }
.t-serif { font-family: var(--font-serif); font-weight: 900; }
.t-soft { color: var(--text-soft); }
.t-mute { color: var(--c-slate); }
.t-gold { color: var(--c-gold); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--c-gold);
}

.eyebrow::before {
  content: "";
  width: 1.6rem;
  height: 1px;
  background: var(--c-gold);
  opacity: 0.7;
}

.lead {
  font-size: clamp(1rem, 1.5vw, 1.125rem);
  line-height: 1.9;
  color: var(--text-soft);
  max-width: 62ch;
}

.rule-gold {
  height: 1px;
  border: 0;
  background: var(--metal-line);
  opacity: 0.7;
}

/* ---------- 5. 布局 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.grid {
  display: grid;
  gap: var(--gap-md);
}

.grid--auto {
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 17rem), 1fr));
}

.grid--split {
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
}

.stack > * + * { margin-top: var(--gap-md); }
.stack--lg > * + * { margin-top: var(--gap-lg); }

.section {
  position: relative;
  padding-block: var(--section-y);
}

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.62rem 1.15rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: 0.9375rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  line-height: 1.4;
  white-space: nowrap;
  transition: background-color 0.24s ease, border-color 0.24s ease, color 0.24s ease, box-shadow 0.24s ease, filter 0.24s ease;
}

.btn--gold {
  background: var(--metal-grad);
  color: #0B0E13;
  font-weight: 600;
  box-shadow: var(--shadow-gold);
}

.btn--gold:hover { filter: brightness(1.08); }

.btn--ghost {
  border-color: rgba(196, 154, 88, 0.4);
  background: rgba(196, 154, 88, 0.06);
  color: var(--c-gold-bright);
}

.btn--ghost:hover {
  border-color: var(--c-gold);
  background: rgba(196, 154, 88, 0.14);
}

.btn--quiet {
  border-color: rgba(245, 239, 227, 0.18);
  color: var(--c-sand);
}

.btn--quiet:hover {
  border-color: rgba(196, 154, 88, 0.5);
  color: var(--c-gold-bright);
}

/* ---------- 7. 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.18rem 0.6rem;
  border: 1px solid rgba(196, 154, 88, 0.4);
  border-radius: 1px;
  background: rgba(196, 154, 88, 0.06);
  color: var(--c-gold);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  line-height: 1.6;
  white-space: nowrap;
}

.tag--jade {
  border-color: var(--line-jade);
  background: rgba(47, 122, 114, 0.16);
  color: var(--c-jade-soft);
}

.tag--sand {
  border-color: rgba(245, 239, 227, 0.24);
  background: rgba(245, 239, 227, 0.05);
  color: var(--c-sand);
}

/* ---------- 8. 面板与编号 ---------- */
.panel {
  position: relative;
  padding: clamp(1.25rem, 2.6vw, 2rem);
  background: linear-gradient(180deg, var(--surface-1) 0%, var(--surface-2) 100%);
  border: 1px solid var(--line-gold);
  border-radius: var(--radius);
}

.panel--stacked {
  isolation: isolate;
  margin-block-end: 0.85rem;
  margin-inline-end: 0.85rem;
}

.panel--stacked::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  transform: translate(0.85rem, 0.85rem);
  border: 1px solid var(--line-gold-soft);
  border-radius: var(--radius);
  pointer-events: none;
}

.panel__foot {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px dashed var(--line-gold-soft);
}

.index-num {
  font-family: var(--font-mono);
  font-size: clamp(1.4rem, 2.6vw, 2rem);
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px rgba(196, 154, 88, 0.62);
}

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem 1.25rem;
  margin-bottom: clamp(1.5rem, 3vw, 2.5rem);
}

.section-head__index {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.22em;
  color: var(--c-gold);
}

.section-head__title {
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: clamp(1.5rem, 3.4vw, 2.35rem);
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.section-head__note {
  flex: 1 1 16rem;
  font-size: 0.875rem;
  color: var(--c-slate);
}

/* ---------- 9. 图片容器基础规则 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  aspect-ratio: 16 / 10;
  border: 1px solid var(--line-gold);
  border-radius: var(--radius);
  background:
    radial-gradient(120% 92% at 50% 0%, rgba(22, 36, 59, 0.96), rgba(11, 14, 19, 1) 78%);
}

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

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(180deg, rgba(11, 14, 19, 0) 42%, rgba(11, 14, 19, 0.76) 100%),
    repeating-linear-gradient(0deg, rgba(245, 239, 227, 0.022) 0 1px, transparent 1px 3px);
}

.media-frame__caption {
  position: absolute;
  left: 1rem;
  right: 1rem;
  bottom: 0.8rem;
  z-index: 1;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  color: rgba(245, 239, 227, 0.7);
}

.media-frame__ph {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.2em;
  color: rgba(116, 131, 154, 0.9);
  background:
    linear-gradient(135deg, rgba(196, 154, 88, 0.06) 0 1px, transparent 1px 18px),
    linear-gradient(180deg, rgba(16, 27, 45, 0.7), rgba(11, 14, 19, 0.9));
}

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

/* ---------- 10. 面包屑 ---------- */
.breadcrumb {
  padding-block: 1.1rem;
  font-size: 0.8125rem;
  color: var(--c-slate);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
}

.breadcrumb li {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.breadcrumb li + li::before {
  content: "/";
  color: rgba(196, 154, 88, 0.5);
}

.breadcrumb a:hover { color: var(--c-gold-bright); }

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

/* ---------- 11. 跳转链接 ---------- */
.skip-link {
  position: fixed;
  top: 0;
  left: 50%;
  z-index: 200;
  padding: 0.7rem 1.3rem;
  transform: translate(-50%, -150%);
  background: var(--metal-grad);
  color: #0B0E13;
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  border-radius: 0 0 var(--radius) var(--radius);
  transition: transform 0.22s ease;
}

.skip-link:focus {
  transform: translate(-50%, 0);
}

/* ---------- 12. 页头 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: linear-gradient(180deg, rgba(11, 14, 19, 0.98) 0%, rgba(11, 14, 19, 0.9) 100%);
  border-bottom: 1px solid var(--line-gold);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: clamp(0.75rem, 2vw, 2rem);
  width: 100%;
  max-width: var(--shell-max);
  min-height: var(--header-h);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  flex: 0 0 auto;
  padding-block: 0.35rem;
}

.brand-mark__seal {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  flex: 0 0 auto;
  background: var(--metal-grad);
  border-radius: var(--radius);
  box-shadow: inset 0 0 0 1px rgba(245, 239, 227, 0.28), 0 0 18px rgba(196, 154, 88, 0.28);
  color: #0B0E13;
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 900;
  line-height: 1;
}

.brand-mark__text {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  line-height: 1.15;
}

.brand-mark__name {
  font-family: var(--font-serif);
  font-size: 1.0625rem;
  font-weight: 900;
  letter-spacing: 0.1em;
  color: var(--c-sand);
}

.brand-mark__ver {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.16em;
  color: var(--c-gold);
  text-transform: uppercase;
}

.site-nav { margin-inline-start: auto; }

.nav-list {
  display: flex;
  align-items: center;
  gap: clamp(0.2rem, 1.2vw, 0.9rem);
}

.nav-list a {
  position: relative;
  display: block;
  padding: 0.55rem 0.55rem 0.75rem;
  font-size: 0.9375rem;
  letter-spacing: 0.06em;
  color: var(--text-soft);
}

.nav-list a::after {
  content: "";
  position: absolute;
  left: 0.55rem;
  right: 0.55rem;
  bottom: 0.42rem;
  height: 1px;
  background: var(--metal-line);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.3s ease;
}

.nav-list a:hover { color: var(--c-sand); }
.nav-list a:hover::after { transform: scaleX(1); }

.nav-list a[aria-current="page"] {
  color: var(--c-gold-bright);
  font-weight: 500;
}

.nav-list a[aria-current="page"]::after { transform: scaleX(1); }

.nav-list a[aria-current="page"]::before {
  content: "";
  position: absolute;
  left: 0.55rem;
  top: 1.05rem;
  width: 3px;
  height: 3px;
  background: var(--c-gold-bright);
  box-shadow: 0 0 6px rgba(228, 192, 120, 0.8);
}

/* ---------- 13. 页头工具区 ---------- */
.header-tools {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  flex: 0 0 auto;
}

.site-search {
  position: relative;
  display: block;
}

.site-search::before {
  content: "";
  position: absolute;
  left: 0.78rem;
  top: 50%;
  width: 10px;
  height: 10px;
  margin-top: -7px;
  border: 1px solid rgba(196, 154, 88, 0.7);
  border-radius: 50%;
  pointer-events: none;
}

.site-search::after {
  content: "";
  position: absolute;
  left: 1.44rem;
  top: 50%;
  width: 5px;
  height: 1px;
  margin-top: 2px;
  background: rgba(196, 154, 88, 0.7);
  transform: rotate(45deg);
  transform-origin: left center;
  pointer-events: none;
}

.site-search__input {
  width: 12.5rem;
  padding: 0.5rem 0.8rem 0.5rem 2.1rem;
  background: rgba(22, 36, 59, 0.7);
  border: 1px solid var(--line-gold);
  border-radius: var(--radius);
  color: var(--c-sand);
  font-size: 0.875rem;
  letter-spacing: 0.02em;
  transition: border-color 0.24s ease, box-shadow 0.24s ease, background-color 0.24s ease;
}

.site-search__input::placeholder { color: rgba(116, 131, 154, 0.9); }

.site-search__input:focus {
  outline: none;
  border-color: var(--c-gold);
  background: rgba(22, 36, 59, 0.92);
  box-shadow: 0 0 0 3px rgba(196, 154, 88, 0.16);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.7rem;
  border: 1px solid rgba(196, 154, 88, 0.35);
  border-radius: var(--radius);
  color: var(--c-gold-bright);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
}

.nav-toggle__bars {
  position: relative;
  width: 16px;
  height: 10px;
  flex: 0 0 auto;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  transition: transform 0.26s ease, top 0.26s ease, bottom 0.26s ease;
}

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

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

/* ---------- 14. 阅读进度 ---------- */
.scroll-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: left center;
  background: linear-gradient(90deg, #C49A58 0%, #E4C078 100%);
  pointer-events: none;
}

/* ---------- 15. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: clamp(4rem, 10vw, 8rem);
  background:
    linear-gradient(180deg, rgba(16, 27, 45, 0.6) 0%, rgba(11, 14, 19, 1) 46%),
    var(--c-obsidian);
}

.site-footer::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 1px;
  background: var(--metal-line);
  opacity: 0.8;
}

.footer-inner {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding: clamp(3rem, 7vw, 5rem) var(--gutter) clamp(1.5rem, 3vw, 2.5rem);
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.85fr) minmax(0, 0.85fr) minmax(0, 1.1fr);
  gap: clamp(2rem, 4vw, 3.5rem);
}

.footer-col__title {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  margin-bottom: 1.15rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  color: var(--c-gold);
  text-transform: uppercase;
}

.footer-col__title::after {
  content: "";
  flex: 1 1 auto;
  height: 1px;
  background: linear-gradient(90deg, rgba(196, 154, 88, 0.55), transparent);
}

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  margin-bottom: 1rem;
}

.footer-brand__seal {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  background: var(--metal-grad);
  border-radius: var(--radius);
  box-shadow: inset 0 0 0 1px rgba(245, 239, 227, 0.26);
  color: #0B0E13;
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 900;
  line-height: 1;
}

.footer-brand__name {
  font-family: var(--font-serif);
  font-size: 1.375rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  color: var(--c-sand);
}

.footer-brand__desc {
  max-width: 34ch;
  font-size: 0.875rem;
  line-height: 1.9;
  color: var(--c-slate);
}

.footer-meta-line {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.2rem;
}

.footer-cta { margin-top: 1.4rem; }

.footer-links li + li { margin-top: 0.1rem; }

.footer-links a {
  position: relative;
  display: inline-block;
  padding: 0.3rem 0 0.3rem 0;
  font-size: 0.9rem;
  color: var(--text-soft);
  transition: color 0.24s ease, padding-left 0.24s ease;
}

.footer-links a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 0;
  height: 1px;
  background: var(--c-gold);
  transition: width 0.24s ease;
}

.footer-links a:hover {
  color: var(--c-gold-bright);
  padding-left: 1rem;
}

.footer-links a:hover::before { width: 0.7rem; }

.footer-contact li {
  display: grid;
  grid-template-columns: 2.9rem minmax(0, 1fr);
  gap: 0.6rem;
  padding: 0.5rem 0;
  border-bottom: 1px dashed var(--line-gold-soft);
  font-size: 0.875rem;
}

.footer-contact__k {
  padding-top: 0.15rem;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  color: var(--c-gold);
}

.footer-contact__v {
  color: var(--text-soft);
  word-break: break-word;
}

.footer-note {
  margin-top: 1rem;
  font-size: 0.8125rem;
  line-height: 1.8;
  color: var(--c-slate);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.9rem 2rem;
  margin-top: clamp(2.5rem, 5vw, 4rem);
  padding-top: 1.5rem;
  border-top: 1px solid var(--line-gold-soft);
  font-size: 0.8125rem;
  color: var(--c-slate);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem;
  color: var(--c-slate);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
}

.footer-dot {
  width: 3px;
  height: 3px;
  background: var(--c-gold);
  opacity: 0.7;
}

.footer-legal-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1.4rem;
}

.footer-legal-links a { color: var(--text-soft); }
.footer-legal-links a:hover { color: var(--c-gold-bright); }

/* ---------- 16. 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: clamp(1rem, 3vw, 2.25rem);
  bottom: clamp(1rem, 3vw, 2.25rem);
  z-index: 70;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border: 1px solid rgba(196, 154, 88, 0.45);
  border-radius: 50%;
  background: rgba(16, 27, 45, 0.92);
  color: var(--c-gold-bright);
  font-size: 1rem;
  line-height: 1;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s ease, background-color 0.24s ease, color 0.24s ease;
}

.to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.to-top:hover {
  background: var(--metal-grad);
  color: #0B0E13;
}

/* ---------- 17. 显现与状态 ---------- */
[data-reveal] { will-change: opacity, transform; }

.reveal-pending {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.68s ease, transform 0.68s ease;
}

[data-reveal].is-revealed {
  opacity: 1;
  transform: none;
  transition: opacity 0.68s ease, transform 0.68s ease;
}

[data-toc-link] {
  color: var(--text-mute);
  transition: color 0.24s ease, border-color 0.24s ease;
}

[data-toc-link].is-active {
  color: var(--c-gold-bright);
  border-color: var(--c-gold);
}

/* ---------- 18. 响应式 ---------- */
@media (max-width: 1279px) and (min-width: 1080px) {
  .site-search__input { width: 9.75rem; }
  .nav-list a { font-size: 0.875rem; padding-inline: 0.45rem; }
  .nav-list a::after { left: 0.45rem; right: 0.45rem; }
}

@media (max-width: 1079px) {
  :root { --header-h: 62px; }

  .brand-mark__seal { width: 32px; height: 32px; font-size: 1.0625rem; }
  .brand-mark__name { font-size: 0.9375rem; letter-spacing: 0.08em; }
  .brand-mark__ver { font-size: 0.625rem; }

  .site-search { display: none; }
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    padding: 0.75rem var(--gutter) 2rem;
    background: linear-gradient(180deg, rgba(16, 27, 45, 0.99) 0%, rgba(11, 14, 19, 0.99) 100%);
    border-bottom: 1px solid var(--line-gold);
    box-shadow: 0 26px 52px rgba(0, 0, 0, 0.55);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.26s ease, transform 0.26s ease, visibility 0.26s ease;
  }

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

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

  .nav-list li + li { border-top: 1px solid var(--line-gold-soft); }

  .nav-list a {
    padding: 0.95rem 0.25rem 0.95rem 1.1rem;
    font-size: 1.0625rem;
    letter-spacing: 0.08em;
    color: var(--text-soft);
  }

  .nav-list a::after {
    left: 0.25rem;
    right: auto;
    top: 50%;
    bottom: auto;
    width: 0.7rem;
    height: 1px;
    transform: scaleX(0);
    transform-origin: left center;
  }

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

  .nav-list a[aria-current="page"] { color: var(--c-gold-bright); }

  .nav-list a[aria-current="page"]::before { display: none; }

  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-col--brand { grid-column: 1 / -1; }
}

@media (max-width: 720px) {
  body { font-size: 15.5px; }

  .grid--split { grid-template-columns: minmax(0, 1fr); }
  .header-tools__help { display: none; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-col__title { margin-bottom: 0.9rem; }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
  }

  .to-top { width: 42px; height: 42px; }
}

@media (max-width: 420px) {
  .brand-mark__ver { display: none; }
  .nav-toggle__label { display: none; }
}

/* ---------- 19. 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;
    scroll-behavior: auto !important;
  }

  .reveal-pending {
    opacity: 1 !important;
    transform: none !important;
  }

  .scroll-progress { transform: scaleX(1) !important; opacity: 0.35; }
}

/* ---------- 20. 打印 ---------- */
@media print {
  .site-header,
  .to-top,
  .skip-link { display: none !important; }

  body {
    background: #fff;
    color: #111;
  }

  body::before { display: none; }
}