/* =========================================================
   爱游指南 · 共享站点样式 /assets/site.css
   深海蓝底 · 珊瑚橙信号 · 薄荷绿状态 · 切角画册语言
   ========================================================= */

/* ---------- 1. Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
body, h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, ul, ol { margin: 0; }
ul, ol { padding: 0; }
img, svg, video { max-width: 100%; display: block; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; }
a { color: inherit; }
table { border-collapse: collapse; width: 100%; }

/* ---------- 2. 变量 ---------- */
:root {
  --abyss-900: #061726;
  --abyss-800: #0A2439;
  --abyss-700: #123A57;
  --abyss-600: #1B4E73;
  --coral-500: #FF6B4A;
  --coral-300: #FF9E80;
  --mint-400: #45D6B0;
  --mint-700: #12705E;
  --fog-050: #F2F7FB;
  --fog-200: #C3D3E0;
  --fog-400: #7E93A6;
  --sand-100: #FFE9C7;
  --ink-900: #0A1520;

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

  --fs-100: 12px;
  --fs-200: 14px;
  --fs-300: 16px;
  --fs-400: 17px;
  --fs-500: 20px;
  --fs-600: 26px;
  --fs-700: 34px;
  --fs-800: 48px;
  --fs-900: clamp(42px, 5.6vw, 68px);

  --header-h: 76px;
  --page-max: 1240px;
  --gutter: clamp(18px, 4vw, 48px);

  --line-soft: rgba(27, 78, 115, 0.55);
  --line-mid: rgba(27, 78, 115, 0.85);
  --line-strong: rgba(27, 78, 115, 1);

  --ease: cubic-bezier(0.22, 0.72, 0.28, 1);
}

@media (max-width: 720px) {
  :root { --header-h: 64px; }
}

/* ---------- 3. 基础排版 ---------- */
html {
  scroll-padding-top: calc(var(--header-h) + 20px);
  background: var(--abyss-900);
}
@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}
body {
  background-color: var(--abyss-900);
  background-image:
    radial-gradient(900px 620px at 12% -6%, rgba(27, 78, 115, 0.42), transparent 68%),
    radial-gradient(760px 560px at 96% 8%, rgba(69, 214, 176, 0.10), transparent 70%),
    radial-gradient(900px 700px at 62% 108%, rgba(255, 107, 74, 0.08), transparent 72%);
  background-attachment: fixed;
  color: var(--fog-050);
  font-family: var(--font-body);
  font-size: var(--fs-400);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.14;
  color: var(--fog-050);
}
h1 { font-size: var(--fs-900); line-height: 1.06; }
h2 { font-size: clamp(26px, 3.1vw, 34px); }
h3 { font-size: var(--fs-500); line-height: 1.3; }
h4 { font-size: var(--fs-300); letter-spacing: 0; }
p { max-width: 68ch; margin-bottom: 1em; }
p:last-child { margin-bottom: 0; }
a { color: var(--coral-300); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--coral-500); }
strong, b { font-weight: 700; color: var(--fog-050); }
code, kbd, samp, pre { font-family: var(--font-mono); font-size: 0.92em; }

:focus-visible {
  outline: 2px solid var(--coral-500);
  outline-offset: 3px;
  border-radius: 1px;
}
::selection { background: var(--coral-500); color: var(--abyss-900); }

/* ---------- 4. 版心与章节 ---------- */
main { display: block; padding-top: var(--header-h); }

.container {
  width: 100%;
  max-width: var(--page-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.container--wide { max-width: 1420px; }
.container--narrow { max-width: 820px; }

.section { position: relative; padding-block: clamp(56px, 8vw, 118px); }
.section--tight { padding-block: clamp(34px, 4.4vw, 58px); }

.section--light {
  background: var(--fog-050);
  color: var(--ink-900);
}
.section--light h1,
.section--light h2,
.section--light h3,
.section--light h4 { color: var(--ink-900); }
.section--light p { color: #33475A; }
.section--light strong { color: var(--ink-900); }
.section--light .eyebrow { color: var(--mint-700); }
.section--light .eyebrow::before { background: var(--mint-700); }
.section--light .lede { color: #33475A; }
.section--light .aside-note { color: #4A5F73; border-left-color: var(--mint-700); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 16px 28px;
  margin-bottom: clamp(24px, 3.2vw, 46px);
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--fog-400);
  margin-bottom: 10px;
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  flex: 0 0 auto;
  background: var(--coral-500);
}

.lede {
  font-size: var(--fs-500);
  line-height: 1.68;
  color: var(--fog-200);
  max-width: 44ch;
}

.aside-note {
  border-left: 2px solid var(--mint-400);
  padding: 4px 0 4px 16px;
  font-size: var(--fs-300);
  line-height: 1.7;
  color: var(--fog-400);
  max-width: 46ch;
}

.rule { border: 0; height: 1px; background: var(--line-mid); margin: 0; }
.rule--slash {
  height: 10px;
  background: repeating-linear-gradient(115deg, rgba(27, 78, 115, 0.95) 0 2px, transparent 2px 9px);
}

/* ---------- 5. 网格 ---------- */
.grid { display: grid; gap: clamp(18px, 2.4vw, 32px); align-items: start; }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--main-side { grid-template-columns: minmax(0, 1fr) 268px; }

@media (max-width: 980px) {
  .grid--2, .grid--3, .grid--main-side { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 22px;
  font-family: var(--font-body);
  font-size: var(--fs-300);
  font-weight: 600;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  color: var(--abyss-900);
  background: var(--coral-500);
  border: 1px solid transparent;
  border-radius: 0;
  clip-path: polygon(10px 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%, 0 10px);
  transition: background-color 0.22s var(--ease), color 0.22s var(--ease), transform 0.18s var(--ease), border-color 0.22s var(--ease);
}
.btn:hover { background: #FF8465; color: var(--abyss-900); }
.btn:active { transform: translateY(1px); }
.btn--primary { background: var(--coral-500); color: var(--abyss-900); }
.btn--ghost {
  background: transparent;
  color: var(--fog-050);
  border-color: rgba(195, 211, 224, 0.34);
}
.btn--ghost:hover {
  background: rgba(255, 107, 74, 0.10);
  border-color: var(--coral-500);
  color: var(--coral-300);
}
.btn--sm { padding: 9px 15px; font-size: var(--fs-200); }
.btn--quiet {
  background: transparent;
  color: var(--coral-300);
  padding: 4px 0;
  clip-path: none;
  border: 0;
}
.btn--quiet:hover { background: transparent; color: var(--coral-500); }

/* ---------- 7. 面包屑 ---------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: var(--fs-200);
  letter-spacing: 0.04em;
  color: var(--fog-400);
  padding-block: 16px;
}
.breadcrumb__list { display: flex; flex-wrap: wrap; gap: 8px; list-style: none; }
.breadcrumb__item { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumb__item + .breadcrumb__item::before { content: "/"; color: var(--abyss-600); }
.breadcrumb__link { color: var(--fog-200); text-decoration: none; }
.breadcrumb__link:hover { color: var(--coral-300); }
.breadcrumb__item[aria-current="page"] { color: var(--fog-050); }

/* ---------- 8. 卡片 ---------- */
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
  overflow: hidden;
  padding: clamp(20px, 2.2vw, 28px);
  background: linear-gradient(158deg, rgba(18, 58, 87, 0.72), rgba(10, 36, 57, 0.72));
  border: 1px solid var(--line-mid);
}
.card--cut {
  clip-path: polygon(0 0, calc(100% - 22px) 0, 100% 22px, 100% 100%, 0 100%);
}
.card__num {
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  letter-spacing: 0.14em;
  color: var(--fog-400);
}
.card__title {
  font-family: var(--font-display);
  font-size: var(--fs-500);
  font-weight: 700;
  line-height: 1.3;
  margin: 0;
}
.card__text { margin: 0; font-size: var(--fs-300); color: var(--fog-200); }
.card__more {
  margin-top: auto;
  padding-top: 8px;
  font-family: var(--font-mono);
  font-size: var(--fs-200);
  letter-spacing: 0.04em;
  color: var(--coral-300);
  text-decoration: none;
}
.card__more:hover { color: var(--coral-500); }
.card__extra {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 12px 20px;
  font-size: var(--fs-200);
  line-height: 1.6;
  color: var(--fog-200);
  background: linear-gradient(to top, rgba(6, 23, 38, 0.97), rgba(6, 23, 38, 0.78));
  border-top: 1px solid var(--line-mid);
  transform: translateY(100%);
  opacity: 0;
  pointer-events: none;
  transition: transform 0.28s var(--ease), opacity 0.28s var(--ease);
}
.card:hover .card__extra,
.card:focus-within .card__extra { transform: translateY(0); opacity: 1; }

/* ---------- 9. 标签 / 提示 / 芯片 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  padding: 5px 11px;
  border-radius: 999px;
  white-space: nowrap;
}
.tag--mint { background: rgba(69, 214, 176, 0.14); color: var(--mint-400); }
.tag--coral { background: rgba(255, 107, 74, 0.15); color: var(--coral-300); }
.tag--sand { background: var(--sand-100); color: #7A4A12; }

.notice {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  padding: 16px 20px;
  background: var(--sand-100);
  color: #6B4310;
  border-left: 4px solid var(--coral-500);
  font-size: var(--fs-300);
  line-height: 1.7;
}

.chip-row { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  padding: 8px 13px;
  color: var(--fog-200);
  background: rgba(18, 58, 87, 0.42);
  border: 1px solid var(--line-mid);
  cursor: pointer;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}
.chip:hover { border-color: var(--coral-300); color: var(--fog-050); }
.chip[aria-pressed="true"] {
  color: var(--coral-300);
  border-color: var(--coral-500);
  background: rgba(255, 107, 74, 0.12);
}

/* ---------- 10. 索引列表 ---------- */
.index-list { list-style: none; }
.index-list__item {
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr) auto;
  gap: 6px 14px;
  align-items: baseline;
  padding: 15px 0;
  border-bottom: 1px solid var(--line-soft);
}
.index-list__item:first-child { border-top: 1px solid var(--line-soft); }
.index-list__num {
  font-family: var(--font-mono);
  font-size: var(--fs-200);
  color: var(--fog-400);
  letter-spacing: 0.06em;
}
.index-list__label {
  font-size: var(--fs-400);
  color: var(--fog-050);
  text-decoration: none;
}
.index-list__label:hover { color: var(--coral-300); }
.index-list__meta {
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  color: var(--mint-400);
  letter-spacing: 0.05em;
}
@media (max-width: 560px) {
  .index-list__item { grid-template-columns: 42px minmax(0, 1fr); }
  .index-list__meta { grid-column: 2; }
}

/* ---------- 11. 折叠块 ---------- */
.fold { border-top: 1px solid var(--line-mid); }
.fold:last-of-type { border-bottom: 1px solid var(--line-mid); }
.fold__summary {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 18px;
  padding: 18px 0;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-display);
  font-size: var(--fs-500);
  font-weight: 600;
  line-height: 1.4;
  color: var(--fog-050);
}
.fold__summary::-webkit-details-marker { display: none; }
.fold__summary::after {
  content: "+";
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--fs-500);
  color: var(--coral-500);
  line-height: 1;
}
.fold[open] .fold__summary::after { content: "−"; }
.fold__summary:hover { color: var(--coral-300); }
.fold__body { padding: 0 0 22px; color: var(--fog-200); font-size: var(--fs-300); }

/* ---------- 12. 时间轴 ---------- */
.timeline {
  display: flex;
  gap: 0;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  padding-bottom: 14px;
  -webkit-overflow-scrolling: touch;
}
.timeline__item {
  position: relative;
  flex: 0 0 min(272px, 74vw);
  padding: 0 26px 0 0;
  scroll-snap-align: start;
}
.timeline__node {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--abyss-900);
  border: 2px solid var(--abyss-600);
  margin-bottom: 16px;
}
.timeline__item::before {
  content: "";
  position: absolute;
  top: 5px;
  left: 12px;
  right: 0;
  height: 1px;
  background: var(--line-mid);
}
.timeline__item:last-child::before { right: 100%; }
.timeline__item[data-state="current"] .timeline__node {
  background: var(--coral-500);
  border-color: var(--coral-500);
  box-shadow: 0 0 0 5px rgba(255, 107, 74, 0.16);
}
.timeline__label {
  font-family: var(--font-display);
  font-size: var(--fs-500);
  font-weight: 600;
  margin-bottom: 6px;
}
.timeline__meta {
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  letter-spacing: 0.06em;
  color: var(--fog-400);
  margin: 0;
}

/* ---------- 13. 图片容器 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  background: linear-gradient(150deg, var(--abyss-700), var(--abyss-900));
  border: 1px solid var(--line-mid);
  clip-path: polygon(0 0, calc(100% - 24px) 0, 100% 24px, 100% 100%, 24px 100%, 0 calc(100% - 24px));
}
.media-frame__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.media-frame--16x9 { aspect-ratio: 16 / 9; }
.media-frame--4x3 { aspect-ratio: 4 / 3; }
.media-frame--1x1 { aspect-ratio: 1 / 1; }
.media-frame__caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 12px 18px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--fog-200);
  background: linear-gradient(to top, rgba(6, 23, 38, 0.92), rgba(6, 23, 38, 0));
}

/* ---------- 14. 显现动效 ---------- */
.js-ready .reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}
.js-ready .reveal.is-visible { opacity: 1; transform: none; }

/* ---------- 15. 头部 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 80;
  background: linear-gradient(
    180deg,
    rgba(6, 23, 38, 0.96) 0%,
    rgba(6, 23, 38, 0.86) 58%,
    rgba(6, 23, 38, 0.40) 88%,
    rgba(6, 23, 38, 0) 100%
  );
  -webkit-backdrop-filter: blur(12px) saturate(120%);
  backdrop-filter: blur(12px) saturate(120%);
}
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: rgba(27, 78, 115, 0.45);
  z-index: 90;
}
.progress-bar__fill {
  display: block;
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--mint-400), var(--coral-500));
}
.skip-link {
  position: fixed;
  left: 50%;
  top: -120px;
  transform: translateX(-50%);
  z-index: 120;
  padding: 12px 22px;
  background: var(--coral-500);
  color: var(--abyss-900);
  font-weight: 700;
  text-decoration: none;
  transition: top 0.2s var(--ease);
}
.skip-link:focus { top: 12px; color: var(--abyss-900); }

.site-header__inner {
  display: flex;
  align-items: center;
  gap: clamp(14px, 2.4vw, 40px);
  height: var(--header-h);
  max-width: 1420px;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 13px;
  flex: 0 0 auto;
  text-decoration: none;
  color: var(--fog-050);
}
.brand__mark {
  position: relative;
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  flex: 0 0 auto;
  background: linear-gradient(150deg, var(--abyss-700), var(--abyss-900));
  border: 1px solid rgba(69, 214, 176, 0.34);
  clip-path: polygon(12px 0, 100% 0, 100% 100%, 0 100%, 0 12px);
}
.brand__mark::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 12px;
  height: 12px;
  background: var(--coral-500);
  clip-path: polygon(0 0, 100% 0, 0 100%);
}
.brand__mark-text {
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--mint-400);
}
.brand__text { display: flex; flex-direction: column; gap: 1px; }
.brand__name {
  font-family: var(--font-display);
  font-size: var(--fs-400);
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.2;
  color: var(--fog-050);
}
.brand__tagline {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--fog-400);
  line-height: 1.3;
}

/* 导航 */
.site-nav { margin-left: auto; }
.site-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(2px, 1.1vw, 14px);
  list-style: none;
}
.site-nav__item { display: block; }
.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: 10px 9px 12px;
  font-size: var(--fs-300);
  color: var(--fog-200);
  text-decoration: none;
  transition: color 0.22s var(--ease);
}
.site-nav__num {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.05em;
  color: var(--fog-400);
  transition: color 0.22s var(--ease);
}
.site-nav__link::after {
  content: "";
  position: absolute;
  left: 9px;
  right: 9px;
  bottom: 5px;
  height: 2px;
  background: var(--coral-500);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform 0.26s var(--ease), background-color 0.26s var(--ease);
}
.site-nav__link:hover { color: var(--fog-050); }
.site-nav__link:hover::after { transform: scaleX(1); }
.site-nav__link:hover .site-nav__num { color: var(--coral-300); }
.site-nav__link[aria-current="page"],
.site-nav__link.is-current { color: var(--fog-050); }
.site-nav__link[aria-current="page"]::after,
.site-nav__link.is-current::after {
  transform: scaleX(1);
  background: var(--mint-400);
}
.site-nav__link[aria-current="page"] .site-nav__num,
.site-nav__link.is-current .site-nav__num { color: var(--mint-400); }

.site-nav__foot { display: none; }
.site-nav__hint {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--fog-400);
  margin-bottom: 14px;
}

/* 头部右侧工具区 */
.site-header__meta {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
}
.version-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 13px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  white-space: nowrap;
  color: var(--mint-400);
  background: rgba(69, 214, 176, 0.07);
  border: 1px solid rgba(69, 214, 176, 0.34);
  clip-path: polygon(8px 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%, 0 8px);
}
.version-chip__dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--mint-400);
  box-shadow: 0 0 0 3px rgba(69, 214, 176, 0.18);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 14px;
  color: var(--fog-050);
  background: rgba(18, 58, 87, 0.62);
  border: 1px solid var(--line-strong);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  cursor: pointer;
  clip-path: polygon(8px 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%, 0 8px);
}
.nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 3px;
  width: 16px;
}
.nav-toggle__bars i {
  display: block;
  height: 1.5px;
  background: currentColor;
  transition: transform 0.24s var(--ease), opacity 0.24s var(--ease);
}
.nav-toggle__bars i:nth-child(2) { width: 68%; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(4.5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3) { transform: translateY(-4.5px) rotate(-45deg); }

/* 头部断点 */
@media (max-width: 1180px) {
  .version-chip { display: none; }
}
@media (max-width: 1024px) {
  .site-header__inner { gap: 12px; }
  .site-header__meta .btn { display: none; }
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    margin-left: 0;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    padding: 20px var(--gutter) 34px;
    background: linear-gradient(180deg, rgba(6, 23, 38, 0.995), rgba(10, 36, 57, 0.995));
    border-top: 1px solid var(--line-mid);
    border-bottom: 1px solid var(--line-mid);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-12px);
    transition: opacity 0.26s var(--ease), transform 0.26s var(--ease), visibility 0.26s linear;
  }
  .site-nav[data-open="true"] {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }
  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }
  .site-nav__item { border-bottom: 1px solid var(--line-soft); }
  .site-nav__link {
    width: 100%;
    justify-content: flex-start;
    gap: 12px;
    padding: 16px 2px;
    font-size: var(--fs-500);
  }
  .site-nav__link::after { display: none; }
  .site-nav__num { font-size: var(--fs-100); }
  .site-nav__foot { display: block; margin-top: 24px; }
  .site-nav__foot .btn { width: 100%; }
}
@media (max-width: 640px) {
  .brand__tagline { display: none; }
}

/* ---------- 16. 页脚 ---------- */
.site-footer {
  position: relative;
  padding: clamp(48px, 6vw, 86px) 0 30px;
  background: linear-gradient(180deg, var(--abyss-900) 0%, #04101C 100%);
  border-top: 1px solid var(--line-mid);
  color: var(--fog-200);
}
.site-footer::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.55;
  background-image:
    linear-gradient(rgba(27, 78, 115, 0.22) 1px, transparent 1px),
    linear-gradient(90deg, rgba(27, 78, 115, 0.22) 1px, transparent 1px);
  background-size: 74px 74px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 76%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 76%);
}
.site-footer__inner { position: relative; }

.site-footer__top {
  display: grid;
  grid-template-columns: minmax(240px, 1fr) minmax(0, 1.4fr);
  gap: clamp(28px, 4vw, 68px);
}
.footer-brand { display: flex; flex-direction: column; gap: 12px; }
.footer-brand__link {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--fog-050);
}
.footer-brand__name {
  font-family: var(--font-display);
  font-size: var(--fs-500);
  font-weight: 700;
  letter-spacing: -0.01em;
}
.footer-brand__desc {
  font-size: var(--fs-300);
  line-height: 1.75;
  color: var(--fog-200);
  max-width: 42ch;
}
.footer-brand__note {
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  letter-spacing: 0.05em;
  color: var(--fog-400);
  max-width: 42ch;
  margin: 0;
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(18px, 2.4vw, 34px);
}
.footer-col__title {
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  letter-spacing: 0.14em;
  color: var(--fog-400);
  padding-bottom: 12px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--line-soft);
}
.footer-col__list { list-style: none; display: flex; flex-direction: column; gap: 9px; }
.footer-col__link {
  font-size: var(--fs-300);
  color: var(--fog-200);
  text-decoration: none;
  transition: color 0.2s var(--ease), padding-left 0.2s var(--ease);
}
.footer-col__link:hover {
  color: var(--coral-300);
  padding-left: 5px;
}

.site-footer__contact {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 28px;
  margin-top: clamp(34px, 4vw, 56px);
  padding-top: 24px;
  border-top: 1px solid var(--line-mid);
}
.footer-contact__line { margin: 0; font-size: var(--fs-300); color: var(--fog-200); }
.footer-contact__note { margin: 0; font-size: var(--fs-200); color: var(--fog-400); }

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 10px 24px;
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line-soft);
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  letter-spacing: 0.06em;
  color: var(--fog-400);
}
.footer-legal, .footer-copy { margin: 0; }
.footer-copy__year { color: var(--mint-400); }
.footer-footnote {
  margin: 14px 0 0;
  font-family: var(--font-mono);
  font-size: var(--fs-100);
  letter-spacing: 0.05em;
  color: rgba(126, 147, 166, 0.78);
}

@media (max-width: 900px) {
  .site-footer__top { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 560px) {
  .footer-cols { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 22px 18px; }
  .site-footer__bottom { flex-direction: column; }
}

/* ---------- 17. 返回顶部（JS 生成） ---------- */
.to-top {
  position: fixed;
  right: clamp(14px, 2vw, 30px);
  bottom: clamp(14px, 2vw, 30px);
  z-index: 70;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 16px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--fog-050);
  background: rgba(18, 58, 87, 0.88);
  border: 1px solid var(--line-strong);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.24s var(--ease), transform 0.24s var(--ease), visibility 0.24s linear, border-color 0.2s var(--ease);
  clip-path: polygon(8px 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%, 0 8px);
}
.to-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.to-top:hover { border-color: var(--coral-500); color: var(--coral-300); }
.to-top__text { display: inline; }

/* ---------- 18. 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  html { scroll-behavior: auto; }
  .js-ready .reveal { opacity: 1; transform: none; }
  .card__extra { transform: translateY(0); opacity: 1; pointer-events: auto; }
  .to-top { transform: none; }
}