/* ============================================================
   优乐在线 · 共享样式表  /assets/site.css
   坐标网格体系：深空蓝基底 / 信号橙焦点 / 坐标青描边 / 直角细线
   ============================================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 130px;
}

body {
  margin: 0;
  background: #F5F7FB;
  color: #0A0E18;
  font-family: "Source Han Sans SC", "PingFang SC", "HarmonyOS Sans SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

main { display: block; }

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

h1, h2, h3, h4, p, ul, ol, dl, figure, blockquote { margin: 0; }

ul, ol { padding: 0; }

a { color: inherit; }

button { font: inherit; color: inherit; }

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

hr { border: 0; }

/* ---------- 2. 变量 ---------- */
:root {
  --ink: #0B1B3A;
  --ink-2: #16295C;
  --signal: #FF6B35;
  --cyan: #2EC4B6;
  --cyan-deep: #0E7C72;
  --wine: #7A1F3D;
  --violet: #3B2E7E;
  --grid: #C7D0E0;
  --paper: #F5F7FB;
  --black: #0A0E18;
  --amber: #F2B441;

  --muted: rgba(11, 27, 58, 0.62);
  --hairline: rgba(11, 27, 58, 0.14);
  --hairline-dark: rgba(199, 208, 224, 0.24);

  --font-display: "Noto Sans SC", "HarmonyOS Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Source Han Sans SC", "PingFang SC", "HarmonyOS Sans SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", "SFMono-Regular", "Consolas", "Menlo", "Liberation Mono", monospace;

  --shell-max: 1360px;
  --shell-pad: clamp(18px, 4vw, 56px);
  --radius: 2px;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --speed-fast: 120ms;
  --speed: 240ms;
}

/* ---------- 3. 工具类 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding-inline: var(--shell-pad);
}

.shell--tight { max-width: 1000px; }

.prose {
  max-width: 720px;
  font-size: 17px;
  line-height: 1.75;
  color: var(--black);
}

.prose p + p { margin-top: 1.1em; }

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
}

.label-caps {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan-deep);
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: currentColor;
  flex: none;
}

.section-index {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--signal);
  margin-bottom: 10px;
}

.h-display {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(44px, 7.6vw, 132px);
  line-height: 1.02;
  letter-spacing: -0.02em;
  margin: 0;
  color: var(--ink);
}

.h-section {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(24px, 3.2vw, 40px);
  line-height: 1.22;
  letter-spacing: 0;
  margin: 0;
  color: var(--ink);
}

.h-sub {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.4;
  margin: 0;
  color: var(--ink);
}

.lead {
  font-size: clamp(16px, 1.5vw, 19px);
  line-height: 1.8;
  color: var(--muted);
  max-width: 720px;
}

.divider {
  height: 1px;
  background: var(--hairline);
  border: 0;
  margin: 0;
}

.divider--dark { background: var(--hairline-dark); }

/* ---------- 4. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  background: transparent;
  transition: background-color var(--speed-fast) var(--ease),
              color var(--speed-fast) var(--ease),
              border-color var(--speed-fast) var(--ease);
}

.btn--signal {
  background: var(--signal);
  border-color: var(--signal);
  color: #FFFFFF;
}

.btn--signal:hover { background: #FF8355; border-color: #FF8355; }

.btn--outline {
  border-color: rgba(199, 208, 224, 0.55);
  color: var(--paper);
}

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

.btn--ink {
  border-color: rgba(11, 27, 58, 0.3);
  color: var(--ink);
}

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

.btn--sm { padding: 8px 15px; font-size: 13px; }

/* ---------- 5. 面包屑 ---------- */
.breadcrumb { padding: clamp(18px, 3vw, 34px) 0 0; }

.breadcrumb ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

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

.breadcrumb li + li::before {
  content: "›";
  margin: 0 10px;
  color: rgba(11, 27, 58, 0.32);
}

.breadcrumb a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--speed-fast) var(--ease), border-color var(--speed-fast) var(--ease);
}

.breadcrumb a:hover { color: var(--ink); border-bottom-color: var(--cyan); }

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

/* ---------- 6. 区块与网格 ---------- */
.section { padding: clamp(56px, 8vw, 120px) 0; }

.section--tight { padding: clamp(36px, 5vw, 72px) 0; }

.section--paper { background: var(--paper); }

.section--ink {
  background: var(--ink);
  color: rgba(199, 208, 224, 0.86);
  border-top: 1px solid var(--hairline-dark);
  border-bottom: 1px solid var(--hairline-dark);
}

.section--ink .h-section,
.section--ink .h-display,
.section--ink .h-sub { color: var(--paper); }

.section--ink .eyebrow { color: var(--cyan); }

.section--ink .lead { color: rgba(199, 208, 224, 0.8); }

.section--ink .divider { background: var(--hairline-dark); }

.section-head {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: clamp(28px, 4vw, 52px);
  max-width: 860px;
}

.section-head--split {
  flex-direction: row;
  align-items: flex-end;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 22px;
  max-width: none;
}

.grid {
  display: grid;
  gap: clamp(16px, 2.4vw, 32px);
}

.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)); }

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(14px, 2vw, 28px);
}

/* ---------- 7. 面板与档案卡 ---------- */
.panel {
  position: relative;
  background: #FFFFFF;
  border: 1px solid var(--hairline);
  border-radius: var(--radius);
  padding: clamp(18px, 2.2vw, 30px);
  color: var(--black);
}

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

.panel--ink {
  background: var(--ink);
  border-color: var(--hairline-dark);
  color: rgba(199, 208, 224, 0.88);
}

.panel--wine {
  background: var(--wine);
  border-color: rgba(242, 180, 65, 0.3);
  color: #F6E1E8;
}

.panel--violet {
  background: var(--violet);
  border-color: rgba(46, 196, 182, 0.34);
  color: #DEDAF6;
}

.panel--paper { background: var(--paper); }

.panel--amber {
  background: #FFF6E4;
  border-color: rgba(242, 180, 65, 0.62);
}

.panel--ink h2, .panel--ink h3, .panel--ink h4,
.panel--wine h2, .panel--wine h3, .panel--wine h4,
.panel--violet h2, .panel--violet h3, .panel--violet h4 {
  color: #FFFFFF;
}

.panel--ink .mono, .panel--wine .mono, .panel--violet .mono { color: inherit; }

.file-card { position: relative; }

.file-card__tab {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 13px;
  background: var(--ink);
  color: var(--paper);
  border-radius: var(--radius) var(--radius) 0 0;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.file-card__body {
  border: 1px solid var(--hairline);
  background: #FFFFFF;
  border-radius: 0 var(--radius) var(--radius) var(--radius);
  padding: clamp(18px, 2vw, 28px);
}

.file-card__body > * + * { margin-top: 12px; }

/* ---------- 8. 标签与徽章 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border: 1px solid rgba(11, 27, 58, 0.22);
  border-radius: var(--radius);
  background: transparent;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-decoration: none;
  transition: border-color var(--speed-fast) var(--ease), color var(--speed-fast) var(--ease);
}

.tag--cyan { border-color: rgba(46, 196, 182, 0.62); color: var(--cyan-deep); }
.tag--cyan:hover { border-color: var(--cyan-deep); }

.tag--amber {
  border-color: rgba(242, 180, 65, 0.7);
  background: rgba(242, 180, 65, 0.14);
  color: #7A5209;
}

.tag--signal {
  background: var(--signal);
  border-color: var(--signal);
  color: #FFFFFF;
}

.batch-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 3px 10px;
  border: 1px solid rgba(242, 180, 65, 0.5);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--amber);
}

.batch-badge::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--amber);
  flex: none;
}

/* ---------- 9. 数据块 ---------- */
.stat { display: flex; flex-direction: column; gap: 8px; }

.stat__value {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: clamp(28px, 4vw, 46px);
  line-height: 1;
  letter-spacing: 0;
  color: var(--signal);
  font-variant-numeric: tabular-nums;
}

.stat__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.panel--ink .stat__label,
.section--ink .stat__label { color: rgba(199, 208, 224, 0.62); }

/* ---------- 10. 提示块 ---------- */
.notice {
  padding: 14px 18px;
  border-left: 3px solid var(--cyan);
  background: rgba(46, 196, 182, 0.08);
  font-size: 15px;
  line-height: 1.7;
  color: var(--black);
}

.section--ink .notice {
  background: rgba(46, 196, 182, 0.14);
  color: rgba(199, 208, 224, 0.9);
}

/* ---------- 11. 图片容器（页面阶段使用） ---------- */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 10;
  background: var(--ink-2);
  border: 1px solid var(--hairline-dark);
  border-radius: var(--radius);
  overflow: hidden;
}

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

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(199, 208, 224, 0.09) 1px, transparent 1px),
    linear-gradient(90deg, rgba(199, 208, 224, 0.09) 1px, transparent 1px);
  background-size: 40px 40px;
}

.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }

.media-frame__caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.section--ink .media-frame__caption { color: rgba(199, 208, 224, 0.62); }

/* ---------- 12. 滚动显现 ---------- */
html.js .reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 480ms var(--ease), transform 480ms var(--ease);
}

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

/* ---------- 13. 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: 14px;
  top: -120px;
  z-index: 200;
  padding: 10px 18px;
  background: var(--signal);
  color: #FFFFFF;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  text-decoration: none;
  border-radius: var(--radius);
  transition: top 150ms var(--ease);
}

.skip-link:focus { top: 14px; }

#main-content { scroll-margin-top: 130px; }

/* ---------- 14. 页头 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background-color: var(--ink);
  background-image:
    linear-gradient(rgba(199, 208, 224, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(199, 208, 224, 0.055) 1px, transparent 1px);
  background-size: 72px 72px;
  color: var(--paper);
  border-bottom: 1px solid var(--hairline-dark);
}

.header-grid {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding: 0 var(--shell-pad);
  min-height: 106px;
  display: grid;
  grid-template-columns: minmax(180px, 256px) 1px minmax(0, 1fr) minmax(186px, 236px);
  column-gap: clamp(20px, 3vw, 56px);
  align-items: stretch;
}

/* 品牌坐标块 */
.brand-block {
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 20px 0;
  min-width: 0;
}

.brand-mark {
  display: block;
  text-decoration: none;
  color: inherit;
}

.brand-coord {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.brand-name {
  display: block;
  margin-top: 5px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(24px, 2.4vw, 32px);
  line-height: 1.04;
  letter-spacing: -0.02em;
  color: #FFFFFF;
}

.brand-sub {
  display: block;
  margin-top: 7px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: rgba(199, 208, 224, 0.72);
}

.brand-tagline {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--amber);
}

/* 纵向坐标轴 */
.header-axis {
  position: relative;
  width: 1px;
  justify-self: center;
  align-self: stretch;
  margin: 16px 0;
  background: linear-gradient(
    180deg,
    rgba(199, 208, 224, 0) 0%,
    rgba(199, 208, 224, 0.45) 18%,
    rgba(199, 208, 224, 0.45) 82%,
    rgba(199, 208, 224, 0) 100%
  );
}

.header-axis .axis-tick {
  position: absolute;
  left: -5px;
  width: 11px;
  height: 1px;
  background: var(--cyan);
  opacity: 0.85;
}

.header-axis .axis-tick:nth-child(1) { top: 16%; }
.header-axis .axis-tick:nth-child(2) { top: 50%; }
.header-axis .axis-tick:nth-child(3) { top: 84%; }

/* 导航 */
.site-nav {
  align-self: center;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px clamp(18px, 2.4vw, 40px);
  padding: 20px 0;
  min-width: 0;
}

.nav-column { min-width: 0; }

.nav-column-label {
  display: block;
  margin-bottom: 9px;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan);
}

.nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 2px 20px;
}

.nav-list a {
  display: inline-block;
  padding: 5px 0;
  font-size: 14px;
  color: var(--grid);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--speed-fast) var(--ease), border-color var(--speed-fast) var(--ease);
}

.nav-list a:hover {
  color: #FFFFFF;
  border-bottom-color: var(--signal);
}

.nav-list a[aria-current="page"] {
  color: #FFFFFF;
  border-bottom-color: var(--cyan);
}

.nav-list a[aria-current="page"]::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  margin-right: 7px;
  background: var(--signal);
  transform: translateY(-1px);
}

/* 页头 CTA */
.header-cta {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  gap: 11px;
  padding: 20px 0;
  min-width: 0;
}

.input-hint {
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.65;
  letter-spacing: 0.06em;
  color: rgba(199, 208, 224, 0.78);
}

/* 移动开关 */
.nav-toggle {
  display: none;
  align-self: center;
  align-items: center;
  gap: 10px;
  padding: 10px 15px;
  border: 1px solid rgba(199, 208, 224, 0.5);
  border-radius: var(--radius);
  background: transparent;
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  cursor: pointer;
  transition: border-color var(--speed-fast) var(--ease), color var(--speed-fast) var(--ease);
}

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

.nav-toggle-bars {
  display: inline-flex;
  flex-direction: column;
  gap: 3px;
  width: 15px;
}

.nav-toggle-bars span {
  display: block;
  height: 1px;
  background: currentColor;
}

.nav-toggle-bars span:nth-child(2) { width: 68%; }

/* 滚动进度 */
.scroll-progress {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  pointer-events: none;
  background: rgba(199, 208, 224, 0.12);
}

.scroll-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--cyan), var(--signal));
  transition: width 80ms linear;
}

/* ---------- 15. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(72px, 9vw, 140px);
  background: var(--ink);
  color: var(--grid);
  border-top: 1px solid var(--hairline-dark);
}

.footer-inner {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding: clamp(48px, 6vw, 84px) var(--shell-pad) 0;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.05fr 1.6fr 1.05fr 1.25fr;
  gap: clamp(24px, 3vw, 48px);
  padding-bottom: clamp(38px, 5vw, 64px);
}

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

.footer-title {
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--hairline-dark);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan);
}

.footer-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-list a {
  font-size: 14px;
  color: rgba(199, 208, 224, 0.82);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--speed-fast) var(--ease), border-color var(--speed-fast) var(--ease);
}

.footer-list a:hover {
  color: var(--amber);
  border-bottom-color: var(--amber);
}

.footer-tags {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.footer-tags a {
  display: inline-block;
  padding: 4px 10px;
  border: 1px solid var(--hairline-dark);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: rgba(199, 208, 224, 0.86);
  text-decoration: none;
  transition: border-color var(--speed-fast) var(--ease), color var(--speed-fast) var(--ease);
}

.footer-tags a:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.footer-contact {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.footer-contact li {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.footer-contact .k {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: rgba(199, 208, 224, 0.54);
}

.footer-contact .v {
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.6;
  letter-spacing: 0.03em;
  color: var(--paper);
  word-break: break-word;
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px 30px;
  padding: 22px 0 28px;
  border-top: 1px solid var(--hairline-dark);
}

.footer-closing {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--paper);
}

.footer-legal {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 22px;
}

.footer-legal a {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: rgba(199, 208, 224, 0.74);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--speed-fast) var(--ease), border-color var(--speed-fast) var(--ease);
}

.footer-legal a:hover {
  color: var(--amber);
  border-bottom-color: var(--amber);
}

.footer-meta {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: rgba(199, 208, 224, 0.6);
}

.footer-strip {
  height: 64px;
  border-top: 1px solid rgba(199, 208, 224, 0.12);
  background-image:
    repeating-linear-gradient(90deg, rgba(199, 208, 224, 0.14) 0 1px, transparent 1px 8.3333%),
    repeating-linear-gradient(0deg, rgba(199, 208, 224, 0.09) 0 1px, transparent 1px 16px);
}

/* ---------- 16. 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: clamp(14px, 2vw, 30px);
  bottom: clamp(14px, 2vw, 30px);
  z-index: 70;
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  padding: 0;
  background: var(--ink);
  color: var(--cyan);
  border: 1px solid rgba(199, 208, 224, 0.45);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 15px;
  line-height: 1;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--speed) var(--ease), visibility var(--speed) var(--ease),
              border-color var(--speed-fast) var(--ease), color var(--speed-fast) var(--ease);
}

.to-top[data-visible] { opacity: 1; visibility: visible; }

.to-top:hover { border-color: var(--cyan); color: var(--amber); }

/* ---------- 17. 焦点可见 ---------- */
:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

.site-header :focus-visible,
.site-footer :focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

/* ---------- 18. 响应式 ---------- */
@media (max-width: 1180px) {
  .header-grid {
    grid-template-columns: minmax(170px, 220px) 1px minmax(0, 1fr);
  }
  .header-cta {
    grid-column: 1 / -1;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    padding: 0 0 18px;
  }
  .header-axis { grid-row: 1 / 2; }
  .footer-grid { grid-template-columns: 1fr 1.5fr; }
}

@media (max-width: 1024px) {
  .header-grid {
    grid-template-columns: minmax(0, 1fr) auto;
    grid-template-areas:
      "brand toggle"
      "nav nav"
      "cta cta";
    column-gap: 16px;
    min-height: 0;
    padding-top: 16px;
    padding-bottom: 16px;
  }

  .brand-block {
    grid-area: brand;
    padding: 0 0 6px;
  }

  .header-axis { display: none; }

  .site-nav {
    grid-area: nav;
    display: none;
    grid-template-columns: minmax(0, 1fr);
    gap: 18px;
    padding: 16px 0 4px;
    border-top: 1px solid var(--hairline-dark);
  }

  .site-nav[data-open] { display: grid; }

  .nav-list { gap: 4px 22px; }

  .header-cta {
    grid-area: cta;
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding: 12px 0 2px;
  }

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

@media (max-width: 900px) {
  .grid--3,
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  body { font-size: 16px; }

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

  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }

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

  .footer-base {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .brand-name { font-size: 26px; }

  .section-head--split { flex-direction: column; align-items: flex-start; }
}

/* ---------- 19. 减弱动效 ---------- */
@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;
  }

  html.js .reveal {
    opacity: 1 !important;
    transform: none !important;
  }

  .scroll-progress { display: none; }
}