/* ==========================================================================
   启博中心 · 共享样式表 /assets/site.css
   坐标地图视觉系统：透明叠加页头 · 左右分屏 · 复古出版色 · 等宽索引入
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: calc(var(--header-h) + 16px);
}

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

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

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

button, input, select, textarea {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
}

button { cursor: pointer; }

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

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

::selection { background: var(--orange); color: #fff; }

/* --------------------------------------------------------------------------
   2. 设计令牌
   -------------------------------------------------------------------------- */
:root {
  /* 色彩 */
  --blue: #0B3B5A;
  --blue-deep: #062B42;
  --orange: #FF6B35;
  --paper: #FDFBF7;
  --cream: #F4EFE6;
  --mint: #3FBF9F;
  --blue-light: #DCE8EF;
  --grid: #E3E6E8;
  --gray: #6B7780;
  --ink: #241C16;

  /* 页头/页脚色彩上下文 */
  --hdr-fg: var(--ink);
  --hdr-muted: var(--gray);

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

  /* 尺度 */
  --header-h: 72px;
  --gutter: clamp(20px, 4vw, 56px);
  --maxw: 1440px;
  --radius: 14px;
  --radius-lg: 26px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);

  /* 网格底纹 */
  --grid-line: rgba(11, 59, 90, 0.06);
}

@media (max-width: 640px) {
  :root { --header-h: 62px; }
}

/* --------------------------------------------------------------------------
   3. 基础排版
   -------------------------------------------------------------------------- */
body {
  font-family: var(--font-sans);
  font-size: 16.5px;
  line-height: 1.75;
  color: var(--ink);
  background-color: var(--paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

body.nav-open { overflow: hidden; }

h1, h2, h3, h4, h5, h6 {
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--blue);
}

h1 { font-size: clamp(34px, 5vw, 60px); }
h2 { font-size: clamp(26px, 3.2vw, 40px); }
h3 { font-size: clamp(20px, 2.2vw, 26px); }
h4 { font-size: clamp(17px, 1.6vw, 20px); }

p { line-height: 1.75; }

.on-dark h1,
.on-dark h2,
.on-dark h3,
.on-dark h4 { color: var(--paper); }

/* 等宽索引标签 */
.label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--gray);
}

.label::before {
  content: "";
  width: 18px;
  height: 1px;
  background: var(--orange);
  flex: 0 0 auto;
}

/* --------------------------------------------------------------------------
   4. 焦点与动效降级
   -------------------------------------------------------------------------- */
:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 3px;
}

@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;
  }
}

/* --------------------------------------------------------------------------
   5. 布局容器与分屏
   -------------------------------------------------------------------------- */
.wrap {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: clamp(48px, 7vw, 104px); }
.section--tight { padding-block: clamp(28px, 4vw, 56px); }

.section-head { margin-bottom: clamp(24px, 3vw, 44px); }

.split {
  display: grid;
  grid-template-columns: minmax(250px, 34%) minmax(0, 1fr);
  gap: clamp(24px, 4vw, 72px);
  align-items: start;
}

.split--reverse {
  grid-template-columns: minmax(0, 1fr) minmax(250px, 34%);
}

.split--reverse > .pane-index { order: 2; }

.pane-index {
  position: relative;
  min-width: 0;
}

.pane-index--panel {
  background: var(--cream);
  border-radius: var(--radius-lg);
  padding: clamp(20px, 2.4vw, 32px);
}

.pane-main { min-width: 0; }

@media (min-width: 901px) {
  .pane-index--sticky {
    position: sticky;
    top: calc(var(--header-h) + 28px);
  }
}

@media (max-width: 900px) {
  .split,
  .split--reverse {
    grid-template-columns: minmax(0, 1fr);
    gap: 28px;
  }
  .split--reverse > .pane-index { order: 0; }
}

/* --------------------------------------------------------------------------
   6. 正文与栅格
   -------------------------------------------------------------------------- */
.prose { max-width: 68ch; }
.prose > * + * { margin-top: 1.2em; }
.prose ul,
.prose ol { padding-left: 1.3em; }
.prose li + li { margin-top: 0.5em; }
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose strong { color: var(--blue); font-weight: 900; }

.grid {
  display: grid;
  gap: clamp(18px, 2.4vw, 30px);
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

@media (max-width: 980px) {
  .grid--3,
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 620px) {
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }
}

/* --------------------------------------------------------------------------
   7. 跳过链接
   -------------------------------------------------------------------------- */
.skip-link {
  position: fixed;
  left: 50%;
  top: 0;
  z-index: 200;
  transform: translate(-50%, -110%);
  background: var(--blue);
  color: var(--paper);
  font-size: 14px;
  font-weight: 700;
  padding: 12px 22px;
  border-radius: 0 0 12px 12px;
  transition: transform 0.2s var(--ease);
}

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

/* --------------------------------------------------------------------------
   8. 品牌标识
   -------------------------------------------------------------------------- */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  flex: 0 0 auto;
}

.brand__mark {
  position: relative;
  width: 26px;
  height: 26px;
  flex: 0 0 auto;
  border: 1.5px solid var(--orange);
  border-radius: 50%;
  display: grid;
  place-items: center;
}

.brand__mark::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--orange);
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand__name {
  font-size: 17px;
  font-weight: 900;
  letter-spacing: -0.01em;
  color: var(--hdr-fg);
}

.brand__tagline {
  margin-top: 2px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--hdr-muted);
  white-space: nowrap;
}

@media (max-width: 460px) {
  .brand__tagline { display: none; }
}

/* --------------------------------------------------------------------------
   9. 页头
   -------------------------------------------------------------------------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 90;
  background: transparent;
  border-bottom: 1px solid transparent;
  color: var(--hdr-fg);
  transition: background-color 0.28s var(--ease),
              border-color 0.28s var(--ease);
}

.site-header[data-scrolled="true"] {
  --hdr-fg: var(--paper);
  --hdr-muted: rgba(253, 251, 247, 0.62);
  background: var(--blue);
  border-bottom-color: rgba(253, 251, 247, 0.18);
}

.header-grid {
  position: relative;
  display: flex;
  align-items: center;
  gap: clamp(14px, 2.4vw, 36px);
  max-width: var(--maxw);
  min-height: var(--header-h);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: auto;
  flex: 0 0 auto;
}

/* --- 主导航 --- */
.site-nav {
  margin-left: auto;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.site-nav__link {
  position: relative;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 13px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 500;
  color: var(--hdr-fg);
  transition: color 0.18s var(--ease);
}

.site-nav__idx {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  color: var(--hdr-muted);
  transition: color 0.18s var(--ease);
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 13px;
  right: 13px;
  bottom: 5px;
  height: 1.5px;
  background: var(--orange);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.18s var(--ease);
}

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

.site-nav__link:hover .site-nav__idx,
.site-nav__link[aria-current="page"] .site-nav__idx {
  color: var(--orange);
}

.site-nav__link[aria-current="page"] { font-weight: 700; }

/* --- 移动端开关 --- */
.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  border: 1.5px solid currentColor;
  border-radius: 12px;
  color: var(--hdr-fg);
  transition: border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

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

.nav-toggle__pin {
  position: relative;
  width: 19px;
  height: 19px;
  border: 1.5px solid currentColor;
  border-radius: 50%;
}

.nav-toggle__pin::before {
  content: "";
  position: absolute;
  inset: 0;
  margin: auto;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--orange);
}

/* --- 阅读进度游标 --- */
.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background: var(--orange);
  transform: scaleX(0);
  transform-origin: left center;
  opacity: 0;
  transition: transform 0.1s linear, opacity 0.24s var(--ease);
}

.site-header[data-scrolled="true"] .scroll-progress { opacity: 1; }

/* --- 页头移动端抽屉 --- */
@media (max-width: 960px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 85;
    margin-left: 0;
    padding: 26px var(--gutter) 48px;
    background: var(--blue-deep);
    background-image:
      linear-gradient(to right, rgba(253, 251, 247, 0.05) 1px, transparent 1px),
      linear-gradient(to bottom, rgba(253, 251, 247, 0.05) 1px, transparent 1px);
    background-size: 44px 44px;
    overflow-y: auto;
    transform: translateX(100%);
    transition: transform 0.28s var(--ease);
    -webkit-overflow-scrolling: touch;
  }

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

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav__item + .site-nav__item {
    border-top: 1px solid rgba(253, 251, 247, 0.14);
  }

  .site-nav__link {
    justify-content: flex-start;
    gap: 18px;
    padding: 18px 4px;
    border-radius: 0;
    font-size: 19px;
    font-weight: 700;
    color: var(--paper);
  }

  .site-nav__idx {
    font-size: 12px;
    color: var(--orange);
  }

  .site-nav__link::after {
    left: 4px;
    right: 4px;
    bottom: 10px;
  }
}

@media (max-width: 520px) {
  .header-actions .btn { display: none; }
}

/* --------------------------------------------------------------------------
   10. 按钮
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1.5px solid transparent;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.01em;
  line-height: 1.3;
  cursor: pointer;
  transition: background-color 0.2s var(--ease), color 0.2s var(--ease),
              border-color 0.2s var(--ease);
}

.btn--sm {
  padding: 9px 16px;
  font-size: 13px;
}

.btn--coord {
  background: var(--orange);
  color: #fff;
}

.btn--coord:hover { background: #e8561f; }

.btn--coord:active { background: #cf4a18; }

.btn--ghost {
  border-color: var(--grid);
  color: var(--blue);
  background: transparent;
}

.btn--ghost:hover {
  border-color: var(--orange);
  color: var(--orange);
}

.on-dark .btn--ghost {
  border-color: rgba(253, 251, 247, 0.3);
  color: var(--paper);
}

/* --------------------------------------------------------------------------
   11. 面包屑
   -------------------------------------------------------------------------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gray);
}

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

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

.breadcrumb li + li::before {
  content: "›";
  color: var(--gray);
  opacity: 0.7;
}

.breadcrumb a {
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.breadcrumb a:hover {
  color: var(--blue);
  border-bottom-color: var(--orange);
}

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

/* --------------------------------------------------------------------------
   12. 卡片 · 面板 · 标签
   -------------------------------------------------------------------------- */
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: clamp(18px, 2.2vw, 28px);
  background: var(--paper);
  border: 1px solid var(--grid);
  border-radius: var(--radius);
  transition: border-color 0.22s var(--ease), background-color 0.22s var(--ease);
}

.card:hover,
.card:focus-within { border-color: var(--orange); }

.card--cream { background: var(--cream); }

.card__index {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--orange);
}

.card__title {
  font-size: clamp(17px, 1.6vw, 20px);
  font-weight: 900;
  color: var(--blue);
  letter-spacing: -0.01em;
}

.card__text {
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--gray);
}

/* 折叠面板 */
.panel {
  background: var(--cream);
  border: 1px solid var(--grid);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.22s var(--ease);
}

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

.panel:hover { border-color: rgba(255, 107, 53, 0.55); }

.panel__head {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 18px 20px;
  text-align: left;
  font-size: 16px;
  font-weight: 700;
  color: var(--blue);
}

.panel__mark {
  position: relative;
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
  border: 1.5px solid var(--orange);
  border-radius: 50%;
  transition: transform 0.26s var(--ease);
}

.panel__mark::before,
.panel__mark::after {
  content: "";
  position: absolute;
  background: var(--orange);
}

.panel__mark::before {
  left: 50%; top: 3px; bottom: 3px; width: 1.5px;
  transform: translateX(-50%);
}

.panel__mark::after {
  top: 50%; left: 3px; right: 3px; height: 1.5px;
  transform: translateY(-50%);
}

.panel[data-open="true"] .panel__mark { transform: rotate(90deg); }

.panel__label {
  flex: 1 1 auto;
  min-width: 0;
}

.panel__body {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.26s ease-out;
}

.panel__body > * {
  overflow: hidden;
  min-height: 0;
}

.panel[data-open="true"] .panel__body { grid-template-rows: 1fr; }

.panel__body > * > * {
  padding: 0 20px 20px 50px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--ink);
}

.panel__body > * > * + * { margin-top: 0.9em; }

/* 标签 */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border-radius: 999px;
  background: var(--blue-light);
  color: var(--blue);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  white-space: nowrap;
}

.tag--accent { background: var(--orange); color: #fff; }
.tag--mint { background: rgba(63, 191, 159, 0.16); color: #1d7d66; }

/* --------------------------------------------------------------------------
   13. 图例 · 刻度 · 坐标胶囊
   -------------------------------------------------------------------------- */
.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--gray);
}

.legend__item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.legend__dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--orange);
  flex: 0 0 auto;
}

.legend__dot--blue { background: var(--blue); }
.legend__dot--mint { background: var(--mint); }

.legend__dot--line {
  width: 22px;
  height: 0;
  border-radius: 0;
  background: none;
  border-top: 1.5px dashed var(--gray);
}

.coord-rule {
  height: 14px;
  border-bottom: 1px solid rgba(11, 59, 90, 0.22);
  background-image: repeating-linear-gradient(
    to right,
    rgba(11, 59, 90, 0.22) 0 1px,
    transparent 1px 32px
  );
  background-repeat: no-repeat;
  background-size: 100% 8px;
  background-position: left bottom;
}

.on-dark .coord-rule {
  border-bottom-color: rgba(253, 251, 247, 0.24);
  background-image: repeating-linear-gradient(
    to right,
    rgba(253, 251, 247, 0.24) 0 1px,
    transparent 1px 32px
  );
}

.coord-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border: 1px solid var(--grid);
  border-radius: 6px;
  background: var(--paper);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gray);
}

.coord-chip__dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--orange);
  flex: 0 0 auto;
}

/* --------------------------------------------------------------------------
   14. 图片容器
   -------------------------------------------------------------------------- */
.figure { margin: 0; }

.figure__media {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border: 1px solid var(--grid);
  border-radius: var(--radius);
  background-color: var(--blue-light);
  background-image:
    linear-gradient(to right, var(--grid-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid-line) 1px, transparent 1px);
  background-size: 32px 32px;
}

.figure__media--wide { aspect-ratio: 21 / 9; }
.figure__media--square { aspect-ratio: 1 / 1; }
.figure__media--map { aspect-ratio: 4 / 3; }

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

.figure__cap {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  line-height: 1.6;
  color: var(--gray);
}

/* --------------------------------------------------------------------------
   15. 页脚
   -------------------------------------------------------------------------- */
.site-footer {
  position: relative;
  --hdr-fg: var(--paper);
  --hdr-muted: rgba(253, 251, 247, 0.6);
  margin-top: clamp(64px, 8vw, 132px);
  background: var(--blue);
  color: rgba(253, 251, 247, 0.78);
  overflow: hidden;
}

.site-footer::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(253, 251, 247, 0.06) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(253, 251, 247, 0.06) 1px, transparent 1px);
  background-size: 48px 48px;
  pointer-events: none;
}

.footer-inner {
  position: relative;
  max-width: var(--maxw);
  margin-inline: auto;
  padding: clamp(44px, 5vw, 82px) var(--gutter) 30px;
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(240px, 1fr) minmax(0, 2fr);
  gap: clamp(28px, 4vw, 72px);
  padding-bottom: clamp(28px, 3vw, 46px);
  border-bottom: 1px solid rgba(253, 251, 247, 0.16);
}

.footer-brand { min-width: 0; }

.footer-origin {
  display: flex;
  flex-direction: column;
  gap: 5px;
  margin: 20px 0 22px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.footer-origin__k { color: var(--orange); }
.footer-origin__v { color: rgba(253, 251, 247, 0.7); }

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 44px);
}

.footer-col { min-width: 0; }

.footer-col__title {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
  font-size: 13px;
  font-weight: 900;
  letter-spacing: 0.06em;
  color: var(--paper);
}

.footer-col__title::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--orange);
  flex: 0 0 auto;
}

.footer-col__list li + li { margin-top: 10px; }

.footer-col__list a {
  display: inline-block;
  font-size: 14.5px;
  color: rgba(253, 251, 247, 0.72);
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.footer-col__list a:hover,
.footer-col__list a:focus-visible {
  color: #fff;
  border-bottom-color: var(--orange);
}

.footer-contact {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(18px, 3vw, 44px);
  padding: clamp(24px, 3vw, 38px) 0;
  border-bottom: 1px solid rgba(253, 251, 247, 0.16);
}

.footer-contact__item { min-width: 0; }

.footer-contact__k {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--orange);
}

.footer-contact__v {
  display: block;
  font-size: 14.5px;
  color: var(--paper);
  word-break: break-word;
}

.footer-note {
  max-width: 82ch;
  padding-top: 22px;
  font-size: 13px;
  line-height: 1.7;
  color: rgba(253, 251, 247, 0.56);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px;
  margin-top: 22px;
  padding-top: 20px;
  border-top: 1px solid rgba(253, 251, 247, 0.16);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: rgba(253, 251, 247, 0.55);
}

@media (max-width: 900px) {
  .footer-top { grid-template-columns: minmax(0, 1fr); }
  .footer-contact { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 620px) {
  .footer-cols { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-contact { grid-template-columns: minmax(0, 1fr); }
  .footer-legal { flex-direction: column; }
}

/* --------------------------------------------------------------------------
   16. 无障碍辅助
   -------------------------------------------------------------------------- */
[hidden] { display: none !important; }

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