/* ============================================================
   9393网页版中国站 · /assets/site.css
   共享层：reset / 变量 / 中文排版 / 头部 / 页脚 / 通用组件
   页面特色布局由各页面专属 CSS 承接
   ============================================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: 118px;
}

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

ul, ol { list-style: none; }

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

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%; }

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

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

/* ---------- 2. 设计变量 ---------- */
:root {
  /* 色彩 */
  --c-ink: #0E1B33;
  --c-ink-2: #182A4D;
  --c-ink-3: #2C3E63;
  --c-orange: #FF7A3D;
  --c-orange-soft: rgba(255, 122, 61, 0.14);
  --c-sand: #E3B45C;
  --c-jade: #3FBF9F;
  --c-mist: #F2F5FA;
  --c-gray: #B9C3D6;
  --c-black: #101422;
  --c-white: #FFFFFF;

  /* 字体 */
  --font-title: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  --font-body: "Inter", "Noto Sans SC", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --fs-h1: clamp(38px, 5vw, 64px);
  --fs-h2: clamp(26px, 3vw, 40px);
  --fs-h3: 20px;
  --fs-body: 16px;
  --fs-small: 14px;
  --fs-index: 13px;
  --lh-body: 1.75;
  --track: 0.08em;

  /* 网格与节奏 */
  --w-max: 1240px;
  --gutter: 24px;
  --cut: 18px;
  --line: 1px solid rgba(185, 195, 214, 0.22);

  /* 动效 */
  --dur: 0.32s;
  --dur-slow: 0.42s;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 中文排版基线 ---------- */
body {
  background: var(--c-ink);
  color: #DCE4F2;
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  font-weight: 400;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: clip;
}

/* 卫星网格 + 等高线底纹：抽象数据纹理层 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(0deg, rgba(185, 195, 214, 0.055) 0 1px, transparent 1px 88px),
    repeating-linear-gradient(90deg, rgba(185, 195, 214, 0.055) 0 1px, transparent 1px 88px);
  -webkit-mask-image: radial-gradient(125% 90% at 72% -10%, #000 0%, transparent 74%);
  mask-image: radial-gradient(125% 90% at 72% -10%, #000 0%, transparent 74%);
}

main { position: relative; z-index: 1; }

h1, h2, h3, h4 {
  font-family: var(--font-title);
  font-weight: 700;
  line-height: 1.2;
  color: var(--c-white);
  letter-spacing: 0.01em;
}

h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); line-height: 1.4; }

p { max-width: 74ch; }

::selection {
  background: var(--c-orange);
  color: var(--c-black);
}

/* ---------- 4. 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: 50%;
  top: -120px;
  transform: translateX(-50%);
  z-index: 200;
  padding: 12px 22px;
  border-radius: 999px;
  background: var(--c-orange);
  color: var(--c-black);
  font-size: var(--fs-small);
  font-weight: 600;
  white-space: nowrap;
  transition: top var(--dur) var(--ease);
}

.skip-link:focus {
  top: 16px;
}

/* ---------- 5. 头部：悬浮胶囊导航 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  padding: 16px var(--gutter) 10px;
  background: linear-gradient(180deg,
    rgba(14, 27, 51, 0.96) 0%,
    rgba(14, 27, 51, 0.62) 62%,
    rgba(14, 27, 51, 0) 100%);
  transition: padding var(--dur) var(--ease);
}

.header-capsule {
  position: relative;
  max-width: var(--w-max);
  margin: 0 auto;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px 18px;
  padding: 10px 12px 10px 16px;
  border: 1px solid rgba(185, 195, 214, 0.22);
  border-radius: 999px;
  background: linear-gradient(120deg, rgba(24, 42, 77, 0.93), rgba(16, 29, 52, 0.88));
  box-shadow:
    0 26px 54px -36px rgba(0, 0, 0, 1),
    inset 0 1px 0 rgba(255, 255, 255, 0.05);
  -webkit-backdrop-filter: blur(16px);
  backdrop-filter: blur(16px);
  transition: padding var(--dur) var(--ease), background var(--dur) var(--ease),
    border-radius var(--dur) var(--ease);
}

.site-header[data-scrolled="true"] { padding-top: 8px; padding-bottom: 6px; }

.site-header[data-scrolled="true"] .header-capsule {
  padding: 6px 10px 6px 12px;
  background: linear-gradient(120deg, rgba(24, 42, 77, 0.98), rgba(16, 29, 52, 0.96));
}

.site-header[data-open="true"] .header-capsule,
.site-header[data-open="true"][data-scrolled="true"] .header-capsule {
  border-radius: 26px;
}

/* 品牌 */
.brand {
  order: 1;
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 4px 8px 4px 4px;
  border-radius: 999px;
}

.brand-mark {
  width: 26px;
  height: 26px;
  flex: 0 0 auto;
  border: 1px solid rgba(227, 180, 92, 0.55);
  background-image:
    linear-gradient(135deg, var(--c-orange) 0 44%, transparent 44%),
    linear-gradient(315deg, var(--c-sand) 0 26%, transparent 26%);
  background-color: rgba(14, 27, 51, 0.6);
  transition: transform var(--dur-slow) var(--ease);
}

.brand:hover .brand-mark { transform: rotate(-8deg); }

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

.brand-name {
  font-family: var(--font-title);
  font-size: 17px;
  font-weight: 700;
  color: var(--c-white);
}

.brand-line {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--c-sand);
}

/* 主导航 */
.site-nav {
  order: 2;
  margin-inline: auto;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-item { flex: 0 0 auto; }

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 9px 13px;
  border-radius: 999px;
  font-size: 14.5px;
  font-weight: 500;
  color: var(--c-gray);
  white-space: nowrap;
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.nav-link::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--c-orange);
  opacity: 0;
  transform: scale(0.3);
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.nav-link:hover {
  color: var(--c-white);
  background: rgba(255, 122, 61, 0.10);
}

.nav-link[aria-current="page"] {
  color: var(--c-white);
  background: rgba(255, 122, 61, 0.16);
}

.nav-link[aria-current="page"]::before {
  opacity: 1;
  transform: scale(1);
}

/* 右侧工具区 */
.header-utility {
  order: 3;
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  gap: 12px;
}

.utility-hours {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  max-width: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--c-jade);
  white-space: nowrap;
}

.utility-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--c-jade);
  box-shadow: 0 0 0 4px rgba(63, 191, 159, 0.16);
}

/* 移动导航按钮 */
.nav-toggle {
  order: 4;
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 15px 9px 13px;
  border-radius: 999px;
  border: 1px solid rgba(185, 195, 214, 0.28);
  color: var(--c-mist);
  font-size: var(--fs-small);
  font-weight: 600;
  transition: border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.nav-toggle:hover { background: rgba(255, 122, 61, 0.10); }

.nav-toggle-lines {
  position: relative;
  display: block;
  width: 16px;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: background var(--dur) var(--ease);
}

.nav-toggle-lines::before,
.nav-toggle-lines::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}

.nav-toggle-lines::before { top: -5px; }
.nav-toggle-lines::after { top: 5px; }

.nav-toggle[aria-expanded="true"] {
  border-color: rgba(255, 122, 61, 0.6);
  background: rgba(255, 122, 61, 0.14);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-lines { background: transparent; }
.nav-toggle[aria-expanded="true"] .nav-toggle-lines::before { transform: translateY(5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-lines::after { transform: translateY(-5px) rotate(-45deg); }

/* 头部响应式 */
@media (max-width: 1280px) {
  .utility-hours { display: none; }
}

@media (max-width: 1080px) {
  .site-header { padding-top: 12px; }

  .header-capsule {
    row-gap: 0;
    padding: 8px 10px 8px 14px;
  }

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

  .header-utility { order: 2; margin-left: auto; }

  .site-nav {
    order: 4;
    flex-basis: 100%;
    margin: 10px 0 0;
    padding-top: 10px;
    border-top: 1px solid rgba(185, 195, 214, 0.18);
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
  }

  .nav-link {
    justify-content: flex-start;
    padding: 13px 16px;
    border-radius: 14px;
    font-size: 16px;
  }

  .nav-link::before { order: -1; }

  .js .site-nav { display: none; }

  .js .site-nav[data-open="true"] {
    display: block;
    animation: navDrop var(--dur) var(--ease) both;
  }
}

@keyframes navDrop {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: none; }
}

@media (max-width: 640px) {
  .header-capsule { gap: 10px; border-radius: 22px; }
  .brand-line { display: none; }
  .btn { padding: 10px 15px; font-size: 13px; }
  .nav-toggle-label { display: none; }
  .nav-toggle { padding: 10px 12px; }
}

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: var(--fs-small);
  font-weight: 600;
  letter-spacing: 0.02em;
  white-space: nowrap;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease),
    border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.btn--primary {
  background: var(--c-orange);
  color: var(--c-black);
  box-shadow: 0 12px 28px -16px rgba(255, 122, 61, 0.95);
}

.btn--primary:hover {
  background: #FF8F5C;
  transform: translateY(-1px);
}

.btn--ghost {
  border-color: rgba(185, 195, 214, 0.34);
  color: var(--c-mist);
}

.btn--ghost:hover {
  border-color: var(--c-orange);
  color: var(--c-white);
  background: rgba(255, 122, 61, 0.10);
}

.btn--quiet {
  border-color: rgba(227, 180, 92, 0.42);
  color: var(--c-sand);
}

.btn--quiet:hover {
  background: rgba(227, 180, 92, 0.12);
  color: var(--c-white);
}

/* ---------- 7. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: clamp(64px, 9vw, 120px);
  padding: clamp(46px, 6vw, 74px) 0 28px;
  border-top: 1px solid rgba(185, 195, 214, 0.14);
  background: linear-gradient(180deg,
    rgba(15, 28, 52, 0.0) 0%,
    rgba(15, 28, 52, 0.78) 34%,
    #0B1526 100%);
}

.site-footer::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 1px;
  background: linear-gradient(90deg,
    transparent 0%,
    var(--c-sand) 20%,
    var(--c-orange) 50%,
    var(--c-sand) 80%,
    transparent 100%);
  opacity: 0.7;
}

.footer-inner {
  width: 100%;
  max-width: var(--w-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 4fr) minmax(0, 5fr) minmax(0, 3.4fr);
  gap: clamp(26px, 4vw, 56px);
}

.footer-brand-link {
  display: inline-block;
  font-family: var(--font-title);
  font-size: clamp(22px, 2.4vw, 28px);
  font-weight: 700;
  color: var(--c-white);
  transition: color var(--dur) var(--ease);
}

.footer-brand-link:hover { color: var(--c-orange); }

.footer-brand-line {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--c-sand);
}

.footer-signature {
  margin-top: 18px;
  max-width: 32ch;
  font-size: var(--fs-small);
  line-height: 1.8;
  color: var(--c-gray);
}

.footer-columns {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.footer-heading {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--c-mist);
}

.footer-column .footer-heading::after,
.footer-contact .footer-heading::after {
  content: "";
  display: block;
  width: 22px;
  height: 2px;
  margin-top: 8px;
  background: var(--c-sand);
}

.footer-links { display: grid; gap: 9px; }

.footer-link {
  display: inline-block;
  font-size: var(--fs-small);
  color: var(--c-gray);
  transition: color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

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

.footer-contact .footer-heading { margin-bottom: 14px; }

.contact-list {
  display: grid;
  gap: 13px;
  font-style: normal;
}

.contact-item { display: grid; gap: 2px; }

.contact-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--c-sand);
}

.contact-value {
  font-size: var(--fs-small);
  color: var(--c-mist);
  overflow-wrap: anywhere;
}

.contact-value--mono {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.01em;
  font-variant-numeric: tabular-nums;
}

.footer-bottom {
  margin-top: clamp(34px, 5vw, 58px);
  padding-top: 20px;
  border-top: 1px solid rgba(185, 195, 214, 0.14);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
}

.footer-legal,
.footer-icp {
  max-width: none;
  font-size: var(--fs-index);
  color: var(--c-gray);
}

.footer-icp {
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
  color: var(--c-sand);
}

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

@media (max-width: 640px) {
  .footer-top { grid-template-columns: 1fr; }
  .footer-columns { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-signature { max-width: none; }
}

/* ---------- 8. 通用容器与排版组件 ---------- */
.container {
  width: 100%;
  max-width: var(--w-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.section-head { display: grid; gap: 14px; margin-bottom: clamp(26px, 3vw, 42px); }

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-sand);
}

.section-title { font-size: var(--fs-h2); }

.section-lead {
  font-size: var(--fs-body);
  color: var(--c-gray);
  max-width: 62ch;
}

.rule {
  height: 1px;
  border: 0;
  background: linear-gradient(90deg, var(--c-sand), rgba(227, 180, 92, 0));
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

.status {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  letter-spacing: 0.05em;
  color: var(--c-jade);
}

.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: currentColor;
  box-shadow: 0 0 0 4px rgba(63, 191, 159, 0.16);
}

/* 非对称 3 / 9 分栏骨架 */
.rail {
  display: grid;
  grid-template-columns: minmax(0, 3fr) minmax(0, 9fr);
  gap: clamp(20px, 3.6vw, 56px);
}

.rail-label {
  position: sticky;
  top: 118px;
  align-self: start;
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  letter-spacing: 0.14em;
  color: var(--c-sand);
}

.rail-label::after {
  content: "";
  display: block;
  width: 1px;
  height: 56px;
  margin-top: 14px;
  background: linear-gradient(180deg, var(--c-sand), transparent);
}

@media (max-width: 900px) {
  .rail { grid-template-columns: 1fr; gap: 16px; }
  .rail-label { position: static; }
  .rail-label::after { display: none; }
}

/* 切角面板 */
.panel-cut {
  position: relative;
  padding: clamp(22px, 3vw, 34px);
  background: linear-gradient(160deg, rgba(24, 42, 77, 0.95), rgba(24, 42, 77, 0.68));
  border: 1px solid rgba(185, 195, 214, 0.18);
  -webkit-clip-path: polygon(0 0, calc(100% - var(--cut)) 0, 100% var(--cut), 100% 100%, var(--cut) 100%, 0 calc(100% - var(--cut)));
  clip-path: polygon(0 0, calc(100% - var(--cut)) 0, 100% var(--cut), 100% 100%, var(--cut) 100%, 0 calc(100% - var(--cut)));
  transition: background var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.panel-cut::after {
  content: "";
  position: absolute;
  left: clamp(22px, 3vw, 34px);
  top: 0;
  width: 34px;
  height: 2px;
  background: var(--c-orange);
}

/* 面包屑 */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 9px;
  padding-block: 20px 0;
  font-size: var(--fs-small);
  color: var(--c-gray);
}

.breadcrumb a {
  color: var(--c-gray);
  transition: color var(--dur) var(--ease);
}

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

.breadcrumb-sep {
  font-family: var(--font-mono);
  color: var(--c-ink-3);
}

/* 正文长文 */
.prose { max-width: 72ch; }

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

.prose p { color: var(--c-gray); }

.prose h2, .prose h3 { margin-top: 1.7em; color: var(--c-white); }

.prose ul, .prose ol { display: grid; gap: 0.5em; }

.prose li {
  position: relative;
  padding-left: 22px;
  color: var(--c-gray);
}

.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.78em;
  width: 10px;
  height: 1px;
  background: var(--c-sand);
}

.prose strong { color: var(--c-white); }

.prose a {
  color: var(--c-orange);
  border-bottom: 1px solid rgba(255, 122, 61, 0.42);
}

.prose a:hover { border-bottom-color: var(--c-orange); }

/* ---------- 9. 图片容器（供页面阶段放占位） ---------- */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  border: 1px solid rgba(185, 195, 214, 0.18);
  background-color: var(--c-ink-2);
  background-image:
    radial-gradient(120% 120% at 18% 6%, rgba(63, 191, 159, 0.16), transparent 62%),
    radial-gradient(90% 90% at 88% 92%, rgba(255, 122, 61, 0.14), transparent 60%),
    repeating-linear-gradient(135deg, rgba(185, 195, 214, 0.07) 0 1px, transparent 1px 14px);
  -webkit-clip-path: polygon(0 0, calc(100% - 24px) 0, 100% 24px, 100% 100%, 24px 100%, 0 calc(100% - 24px));
  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;
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(180deg, rgba(14, 27, 51, 0) 42%, rgba(14, 27, 51, 0.72) 100%);
}

.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--tall { aspect-ratio: 4 / 5; }

.media-caption {
  margin-top: 10px;
  max-width: none;
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  letter-spacing: 0.04em;
  color: var(--c-gray);
}

/* ---------- 10. 索引带 ---------- */
.index-band {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 1px solid rgba(185, 195, 214, 0.16);
  border-left: 1px solid rgba(185, 195, 214, 0.16);
}

.index-item {
  display: block;
  padding: 16px 18px;
  border-right: 1px solid rgba(185, 195, 214, 0.16);
  border-bottom: 1px solid rgba(185, 195, 214, 0.16);
  transition: background var(--dur) var(--ease);
}

.index-item:hover,
.index-item:focus-visible { background: rgba(255, 122, 61, 0.09); }

.index-num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  letter-spacing: 0.12em;
  color: var(--c-sand);
}

.index-name {
  display: block;
  margin-top: 6px;
  font-size: 15px;
  font-weight: 600;
  color: var(--c-mist);
}

.index-desc {
  display: block;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  font-size: var(--fs-small);
  line-height: 1.65;
  color: var(--c-gray);
  transition: max-height var(--dur-slow) var(--ease), opacity var(--dur) var(--ease),
    margin-top var(--dur) var(--ease);
}

.index-item:hover .index-desc,
.index-item:focus-visible .index-desc {
  max-height: 72px;
  margin-top: 8px;
  opacity: 1;
}

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

@media (max-width: 640px) {
  .index-band { grid-template-columns: 1fr; }
  .index-desc { max-height: none; opacity: 1; margin-top: 6px; }
}

/* ---------- 11. 分段切换（标签页） ---------- */
.tabs {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  padding: 6px;
  border: 1px solid rgba(185, 195, 214, 0.22);
  border-radius: 999px;
  background: rgba(24, 42, 77, 0.6);
}

.tabs-indicator {
  position: absolute;
  top: 6px;
  bottom: 6px;
  left: 0;
  width: 0;
  border-radius: 999px;
  background: var(--c-orange);
  opacity: 0;
  z-index: 0;
  transition: transform var(--dur) var(--ease), width var(--dur) var(--ease),
    opacity var(--dur) var(--ease);
}

.tabs-indicator[data-ready="true"] { opacity: 1; }

.tab {
  position: relative;
  z-index: 1;
  padding: 10px 20px;
  border-radius: 999px;
  font-size: 14.5px;
  font-weight: 600;
  color: var(--c-gray);
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.tab:hover { color: var(--c-white); }

.tab[aria-selected="true"] { color: var(--c-black); }

.tab-panels { margin-top: clamp(20px, 2.6vw, 32px); }

.tab-panel[hidden] { display: none; }

.tab-panel { animation: panelIn var(--dur-slow) var(--ease) both; }

@keyframes panelIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: none; }
}

/* ---------- 12. 回到顶部 ---------- */
.to-top {
  position: fixed;
  right: clamp(16px, 3vw, 34px);
  bottom: clamp(16px, 3vw, 34px);
  z-index: 70;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 17px;
  border: 1px solid rgba(185, 195, 214, 0.28);
  border-radius: 999px;
  background: rgba(24, 42, 77, 0.92);
  color: var(--c-mist);
  font-family: var(--font-mono);
  font-size: var(--fs-index);
  letter-spacing: 0.08em;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease),
    background var(--dur) var(--ease), color var(--dur) var(--ease);
}

.to-top[data-visible="true"] {
  opacity: 1;
  transform: none;
  pointer-events: auto;
}

.to-top:hover {
  background: var(--c-orange);
  border-color: transparent;
  color: var(--c-black);
}

/* ---------- 13. 网格与显现 ---------- */
.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)); }

@media (max-width: 900px) {
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 640px) {
  .grid--2,
  .grid--3 { grid-template-columns: 1fr; }
}

.js [data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s var(--ease), transform 0.6s var(--ease);
}

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

/* ---------- 14. 减动效 ---------- */
@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;
  }

  .js [data-reveal],
  .js [data-reveal][data-revealed="true"] {
    opacity: 1;
    transform: none;
  }

  .tabs-indicator { transition: none; }
  .index-desc { transition: none; }
  .brand:hover .brand-mark { transform: none; }
}