/* ==========================================================================
   伟德CN中文站 · /assets/site.css
   骨架：悬浮胶囊导航 + 编号色带长卷 + 双口径对照网格 + 档案柜页脚
   ========================================================================== */

/* ---------- 1. 变量 ---------- */
:root {
  /* 主色板 */
  --vd-indigo: #14213D;
  --vd-slate: #333A45;
  --vd-steel: #4C5C7A;
  --vd-mist: #A7B0BF;
  --vd-bone: #F4F1EA;
  --vd-teal: #1F8A8A;
  --vd-teal-deep: #0F5F5C;
  --vd-clay: #D97742;
  --vd-clay-soft: #F6D9BC;
  --vd-ink: #0B1220;

  /* 语义色 */
  --vd-fg: var(--vd-indigo);
  --vd-muted: var(--vd-steel);
  --vd-line: rgba(20, 33, 61, 0.14);
  --vd-line-strong: rgba(20, 33, 61, 0.32);
  --vd-line-invert: rgba(167, 176, 191, 0.2);

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

  /* 九级字号阶梯 */
  --vd-t12: 0.75rem;
  --vd-t14: 0.875rem;
  --vd-t16: 1rem;
  --vd-t18: 1.125rem;
  --vd-t24: 1.5rem;
  --vd-t32: 2rem;
  --vd-t44: 2.75rem;
  --vd-t64: 4rem;
  --vd-t88: 5.5rem;

  /* 间距与骨架 */
  --vd-s1: 4px;
  --vd-s2: 8px;
  --vd-s3: 12px;
  --vd-s4: 16px;
  --vd-s5: 24px;
  --vd-s6: 32px;
  --vd-s7: 48px;
  --vd-s8: 64px;
  --vd-s9: 96px;
  --vd-shell: 1280px;
  --vd-cut: 18px;
  --vd-cut-sm: 10px;
  --vd-clearance: clamp(96px, 12vw, 124px);
}

/* ---------- 2. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

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

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

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

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

a { color: inherit; }

/* ---------- 3. 中文排版基础 ---------- */
body {
  font-family: var(--vd-sans);
  font-size: var(--vd-t16);
  font-weight: 400;
  line-height: 1.75;
  color: var(--vd-fg);
  background: var(--vd-bone);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(var(--vd-t44), 7vw, var(--vd-t88)); }
h2 { font-size: clamp(var(--vd-t24), 3.6vw, var(--vd-t44)); }
h3 { font-size: var(--vd-t24); }
h4 { font-size: var(--vd-t18); }

p { text-wrap: pretty; }

strong, b { font-weight: 700; }

::selection {
  background: var(--vd-clay-soft);
  color: #5A2A0E;
}

:focus-visible {
  outline: 2px solid var(--vd-clay);
  outline-offset: 3px;
}

#main-content {
  padding-top: var(--vd-clearance);
  scroll-margin-top: var(--vd-clearance);
}

/* ---------- 4. 跳过链接 ---------- */
.vd-skip {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 999;
  padding: 10px 20px;
  border-radius: 999px;
  background: var(--vd-clay);
  color: #20100A;
  font-size: var(--vd-t14);
  font-weight: 700;
  text-decoration: none;
  transform: translateY(-180%);
  transition: transform 0.16s ease;
}

.vd-skip:focus,
.vd-skip:focus-visible {
  transform: translateY(0);
}

/* ---------- 5. 悬浮胶囊头部 ---------- */
.vd-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 80;
  padding: clamp(10px, 1.6vw, 16px) clamp(10px, 2.6vw, 28px) 0;
  pointer-events: none;
}

.vd-header__rail {
  position: relative;
  max-width: var(--vd-shell);
  margin: 0 auto;
  pointer-events: auto;
}

.vd-capsule {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1.4vw, 20px);
  min-height: 64px;
  padding: 8px 10px 8px 14px;
  border: 1px solid var(--vd-line-invert);
  border-radius: 999px;
  background: rgba(20, 33, 61, 0.94);
  box-shadow: 0 14px 34px rgba(11, 18, 32, 0.26);
  transition: min-height 0.24s ease, background-color 0.24s ease, border-color 0.24s ease;
}

.vd-header[data-scrolled="true"] .vd-capsule {
  min-height: 54px;
  background: rgba(11, 18, 32, 0.97);
  border-color: rgba(167, 176, 191, 0.3);
}

/* 品牌 */
.vd-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: none;
  text-decoration: none;
  color: var(--vd-bone);
}

.vd-brand__mark {
  position: relative;
  width: 30px;
  height: 30px;
  flex: none;
  background: var(--vd-clay);
  clip-path: polygon(0 0, 100% 0, 100% 68%, 68% 100%, 0 100%);
  transition: transform 0.16s ease;
}

.vd-brand__mark::before {
  content: "";
  position: absolute;
  top: 9px;
  left: 9px;
  width: 12px;
  height: 12px;
  background: var(--vd-indigo);
  clip-path: polygon(0 0, 100% 0, 100% 68%, 68% 100%, 0 100%);
}

.vd-brand:hover .vd-brand__mark { transform: translateY(-2px); }

.vd-brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
}

.vd-brand__name {
  font-size: var(--vd-t16);
  font-weight: 800;
  letter-spacing: 0.02em;
}

.vd-brand__sub {
  font-size: var(--vd-t12);
  font-family: var(--vd-mono);
  letter-spacing: 0.06em;
  color: var(--vd-mist);
  transition: opacity 0.2s ease;
}

.vd-header[data-scrolled="true"] .vd-brand__sub { opacity: 0; }

/* 收缩态当前栏目 */
.vd-header__current {
  display: none;
  flex: none;
  padding-left: 12px;
  border-left: 1px solid var(--vd-line-invert);
  font-family: var(--vd-mono);
  font-size: var(--vd-t12);
  letter-spacing: 0.08em;
  color: var(--vd-teal);
  white-space: nowrap;
}

.vd-header__current:empty { display: none; }

.vd-header[data-scrolled="true"] .vd-header__current { display: inline-block; }

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

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

.vd-nav__link {
  position: relative;
  display: block;
  padding: 8px 12px;
  border-radius: 999px;
  font-size: var(--vd-t14);
  font-weight: 500;
  color: rgba(244, 241, 234, 0.76);
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.16s ease, background-color 0.16s ease, box-shadow 0.16s ease;
}

.vd-nav__link::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 4px;
  height: 1px;
  background: var(--vd-clay);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.12s ease;
}

.vd-nav__link:hover {
  color: var(--vd-bone);
  background: rgba(167, 176, 191, 0.12);
}

.vd-nav__link:hover::after { transform: scaleX(1); }

.vd-nav__link[aria-current="page"] {
  color: var(--vd-bone);
  background: linear-gradient(180deg, rgba(31, 138, 138, 0.34), rgba(31, 138, 138, 0.14));
  box-shadow: inset 0 0 0 1px rgba(31, 138, 138, 0.55);
}

.vd-nav__link[aria-current="page"]::after { transform: scaleX(1); }

/* 行动区 */
.vd-header__actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: none;
  margin-left: auto;
}

.vd-nav + .vd-header__actions { margin-left: 0; }

/* 移动菜单按钮 */
.vd-burger {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 14px 9px 12px;
  border: 1px solid rgba(167, 176, 191, 0.34);
  border-radius: 999px;
  background: transparent;
  color: var(--vd-bone);
  font-size: var(--vd-t12);
  font-weight: 700;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: border-color 0.16s ease, background-color 0.16s ease;
}

.vd-burger:hover { border-color: var(--vd-clay); }

.vd-burger__bars {
  display: grid;
  gap: 4px;
  width: 18px;
}

.vd-burger__bars i {
  display: block;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.18s ease, opacity 0.18s ease;
}

.vd-header[data-open="true"] .vd-burger__bars i:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.vd-header[data-open="true"] .vd-burger__bars i:nth-child(2) { opacity: 0; }

.vd-header[data-open="true"] .vd-burger__bars i:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* 阅读进度 */
.vd-header__meter {
  height: 2px;
  margin-top: 6px;
  border-radius: 2px;
  background: rgba(76, 92, 122, 0.22);
  overflow: hidden;
  opacity: 0.9;
}

.vd-header__meter-fill {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--vd-teal), var(--vd-clay));
  transition: width 0.12s linear;
}

/* ---------- 6. 通用按钮 ---------- */
.vd-btn {
  --vd-btn-bg: var(--vd-clay);
  --vd-btn-fg: #20100A;
  --vd-btn-bd: transparent;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 24px;
  border: 1px solid var(--vd-btn-bd);
  border-radius: 999px;
  background: var(--vd-btn-bg);
  color: var(--vd-btn-fg);
  font-size: var(--vd-t14);
  font-weight: 700;
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.16s ease, color 0.16s ease,
    border-color 0.16s ease, transform 0.16s ease;
}

.vd-btn:hover { transform: translateY(-2px); }
.vd-btn:active { transform: translateY(0); }

.vd-btn--clay {
  --vd-btn-bg: var(--vd-clay);
  --vd-btn-fg: #20100A;
}

.vd-btn--teal {
  --vd-btn-bg: var(--vd-teal);
  --vd-btn-fg: #F4F1EA;
}

.vd-btn--teal:hover { --vd-btn-bg: var(--vd-teal-deep); }

.vd-btn--solid {
  --vd-btn-bg: var(--vd-indigo);
  --vd-btn-fg: var(--vd-bone);
}

.vd-btn--ghost {
  --vd-btn-bg: transparent;
  --vd-btn-fg: var(--vd-bone);
  --vd-btn-bd: rgba(167, 176, 191, 0.42);
}

.vd-btn--ghost:hover {
  --vd-btn-bd: var(--vd-clay);
  --vd-btn-fg: #FFFFFF;
}

.vd-btn--sm {
  padding: 9px 18px;
  font-size: var(--vd-t12);
}

.vd-btn--block {
  width: 100%;
}

/* ---------- 7. 容器与正文 ---------- */
.vd-shell {
  width: 100%;
  max-width: var(--vd-shell);
  margin: 0 auto;
  padding-inline: clamp(18px, 4vw, 40px);
}

.vd-topspace {
  padding-top: var(--vd-clearance);
}

.vd-prose {
  max-width: 34em;
  font-size: var(--vd-t18);
  line-height: 1.75;
  color: var(--vd-fg);
}

.vd-prose > * + * { margin-top: 1.1em; }

.vd-prose h2 {
  margin-top: 2em;
  font-size: var(--vd-t32);
  font-weight: 800;
  line-height: 1.25;
}

.vd-prose h3 {
  margin-top: 1.7em;
  font-size: var(--vd-t24);
  font-weight: 800;
}

.vd-prose ul li {
  position: relative;
  padding-left: 1.4em;
  margin-top: 0.5em;
}

.vd-prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 9px;
  height: 2px;
  background: var(--vd-clay);
}

.vd-prose a {
  color: var(--vd-teal-deep);
  text-decoration: none;
  border-bottom: 1px solid rgba(15, 95, 92, 0.4);
  transition: border-color 0.16s ease, color 0.16s ease;
}

.vd-prose a:hover {
  color: var(--vd-clay);
  border-color: var(--vd-clay);
}

.vd-prose--invert { color: rgba(244, 241, 234, 0.86); }
.vd-prose--invert a { color: var(--vd-clay-soft); }

/* ---------- 8. 面包屑 ---------- */
.vd-crumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--vd-mono);
  font-size: var(--vd-t12);
  letter-spacing: 0.04em;
  color: var(--vd-muted);
}

.vd-crumb a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.16s ease, border-color 0.16s ease;
}

.vd-crumb a:hover {
  color: var(--vd-indigo);
  border-color: var(--vd-clay);
}

.vd-crumb__sep {
  color: var(--vd-steel);
  opacity: 0.55;
}

.vd-crumb [aria-current="page"] {
  color: var(--vd-indigo);
  font-weight: 600;
}

/* ---------- 9. 编号色带 ---------- */
.vd-band {
  display: flex;
  align-items: baseline;
  gap: var(--vd-s4);
  padding: var(--vd-s3) 0 var(--vd-s4);
  border-top: 2px solid var(--vd-indigo);
}

.vd-band__no {
  font-family: var(--vd-mono);
  font-size: var(--vd-t14);
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--vd-clay);
}

.vd-band__title {
  font-size: var(--vd-t24);
  font-weight: 800;
  letter-spacing: -0.01em;
}

.vd-band--invert {
  border-top-color: var(--vd-mist);
}

.vd-band--invert .vd-band__title { color: var(--vd-bone); }

/* ---------- 10. 切角面板 ---------- */
.vd-panel {
  position: relative;
  padding: var(--vd-s6);
  background: #FFFFFF;
  clip-path: polygon(0 0, calc(100% - var(--vd-cut)) 0, 100% var(--vd-cut), 100% 100%, 0 100%);
}

.vd-panel::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 46px;
  height: 3px;
  background: var(--vd-clay);
}

.vd-panel--deep {
  background: var(--vd-indigo);
  color: var(--vd-bone);
}

.vd-panel--deep::before { background: var(--vd-teal); }

/* ---------- 11. 标签与数字块 ---------- */
.vd-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border: 1px solid rgba(217, 119, 66, 0.35);
  border-radius: 999px;
  background: var(--vd-clay-soft);
  color: #7A3A14;
  font-size: var(--vd-t12);
  font-weight: 600;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

.vd-tag--teal {
  border-color: rgba(15, 95, 92, 0.32);
  background: rgba(31, 138, 138, 0.14);
  color: var(--vd-teal-deep);
}

.vd-stat {
  display: block;
}

.vd-stat__num {
  font-family: var(--vd-mono);
  font-size: clamp(var(--vd-t32), 5vw, var(--vd-t64));
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--vd-clay);
  font-variant-numeric: tabular-nums;
}

.vd-stat__unit {
  margin-left: 6px;
  font-size: var(--vd-t14);
  font-weight: 500;
  letter-spacing: 0.04em;
  color: var(--vd-muted);
}

.vd-stat__label {
  margin-top: 10px;
  font-size: var(--vd-t14);
  color: var(--vd-muted);
}

.vd-stat--teal .vd-stat__num { color: var(--vd-teal); }
.vd-stat--invert .vd-stat__label { color: var(--vd-mist); }

/* ---------- 12. 网格 ---------- */
.vd-grid {
  display: grid;
  gap: clamp(16px, 2.4vw, 28px);
}

.vd-grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.vd-grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.vd-grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.vd-grid--sidebar { grid-template-columns: minmax(0, 1.65fr) minmax(0, 1fr); }
.vd-grid--duo { grid-template-columns: repeat(2, minmax(0, 1fr)); }

@media (max-width: 1024px) {
  .vd-grid--3,
  .vd-grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 760px) {
  .vd-grid--2,
  .vd-grid--3,
  .vd-grid--4,
  .vd-grid--sidebar,
  .vd-grid--duo { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- 13. 斜线分隔 ---------- */
.vd-rule {
  height: 10px;
  border: 0;
  background: repeating-linear-gradient(
    -45deg,
    var(--vd-line-strong) 0 1px,
    transparent 1px 9px
  );
}

.vd-rule--invert {
  background: repeating-linear-gradient(
    -45deg,
    rgba(167, 176, 191, 0.34) 0 1px,
    transparent 1px 9px
  );
}

/* ---------- 14. 图片容器（页面阶段放 img / picture） ---------- */
.vd-media {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background-color: var(--vd-indigo);
  background-image:
    linear-gradient(135deg, rgba(76, 92, 122, 0.35), rgba(31, 138, 138, 0.2)),
    repeating-linear-gradient(90deg, rgba(167, 176, 191, 0.22) 0 1px, transparent 1px 32px),
    repeating-linear-gradient(0deg, rgba(167, 176, 191, 0.22) 0 1px, transparent 1px 32px);
  clip-path: polygon(0 0, calc(100% - 22px) 0, 100% 22px, 100% 100%, 0 100%);
}

.vd-media > img,
.vd-media > picture > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

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

.vd-media__cap {
  margin-top: var(--vd-s2);
  font-family: var(--vd-mono);
  font-size: var(--vd-t12);
  letter-spacing: 0.04em;
  color: var(--vd-muted);
}

/* ---------- 15. 显现 ---------- */
html[data-reveal-ready="true"] .vd-reveal {
  opacity: 0;
  transform: translateY(10px);
}

html[data-reveal-ready="true"] .vd-reveal[data-revealed="true"] {
  opacity: 1;
  transform: none;
  transition: opacity 0.18s ease, transform 0.18s ease;
}

/* ---------- 16. 页脚（档案柜抽屉） ---------- */
.vd-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 120px);
  background: var(--vd-ink);
  color: var(--vd-bone);
  overflow: hidden;
}

.vd-footer::before {
  content: "";
  display: block;
  height: 8px;
  background: repeating-linear-gradient(
    -45deg,
    rgba(31, 138, 138, 0.7) 0 2px,
    transparent 2px 12px
  );
}

.vd-footer__rail {
  max-width: var(--vd-shell);
  margin: 0 auto;
  padding: clamp(40px, 6vw, 76px) clamp(18px, 4vw, 40px) 0;
}

.vd-footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 2.2fr);
  gap: clamp(32px, 5vw, 64px);
}

.vd-footer__identity { max-width: 30em; }

.vd-footer__mark {
  display: inline-grid;
  place-items: center;
  width: 46px;
  height: 46px;
  margin-bottom: 18px;
  background: var(--vd-clay);
  color: #20100A;
  font-size: var(--vd-t18);
  font-weight: 900;
  clip-path: polygon(0 0, 100% 0, 100% 70%, 70% 100%, 0 100%);
}

.vd-footer__name {
  font-size: var(--vd-t18);
  font-weight: 800;
  letter-spacing: 0.02em;
}

.vd-footer__domain {
  margin-top: 4px;
  font-family: var(--vd-mono);
  font-size: var(--vd-t12);
  letter-spacing: 0.06em;
  color: var(--vd-teal);
}

.vd-footer__note {
  margin-top: 16px;
  font-size: var(--vd-t14);
  line-height: 1.75;
  color: rgba(244, 241, 234, 0.66);
}

.vd-footer__drawers {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: clamp(22px, 3vw, 36px);
}

.vd-drawer__title {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding-bottom: 12px;
  margin-bottom: 14px;
  border-bottom: 1px solid var(--vd-line-invert);
  font-size: var(--vd-t12);
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--vd-mist);
}

.vd-drawer__no {
  font-family: var(--vd-mono);
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--vd-teal);
}

.vd-drawer__link {
  display: inline-block;
  padding: 5px 0;
  font-size: var(--vd-t14);
  color: rgba(244, 241, 234, 0.72);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.16s ease, border-color 0.16s ease;
}

.vd-drawer__link:hover {
  color: var(--vd-bone);
  border-color: var(--vd-clay);
}

.vd-drawer__item {
  padding: 5px 0;
  font-size: var(--vd-t14);
  line-height: 1.7;
  color: rgba(244, 241, 234, 0.62);
}

.vd-drawer__item:first-child { color: rgba(244, 241, 234, 0.82); }

.vd-footer__base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  margin-top: clamp(36px, 5vw, 64px);
  padding: 22px 0 30px;
  border-top: 1px solid var(--vd-line-invert);
}

.vd-footer__copy {
  font-size: var(--vd-t12);
  font-family: var(--vd-mono);
  letter-spacing: 0.04em;
  color: rgba(244, 241, 234, 0.58);
}

.vd-footer__legal {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 20px;
}

.vd-footer__legal .vd-drawer__link { font-size: var(--vd-t12); }

/* ---------- 17. 返回顶部 ---------- */
.vd-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 70;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  border: 1px solid rgba(167, 176, 191, 0.35);
  border-radius: 999px;
  background: rgba(11, 18, 32, 0.94);
  color: var(--vd-bone);
  font-size: var(--vd-t12);
  font-weight: 700;
  letter-spacing: 0.08em;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.18s ease, transform 0.18s ease,
    visibility 0.18s ease, border-color 0.16s ease;
}

.vd-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.vd-top:hover {
  border-color: var(--vd-clay);
  transform: translateY(-2px);
}

/* ---------- 18. 响应式：头部 ---------- */
@media (max-width: 1180px) and (min-width: 901px) {
  .vd-nav__link {
    padding: 8px 9px;
    font-size: var(--vd-t12);
  }
  .vd-nav__link::after { left: 9px; right: 9px; }
  .vd-brand__sub { display: none; }
}

@media (max-width: 900px) {
  .vd-capsule { border-radius: 24px; }

  .vd-brand__sub { font-size: 0.6875rem; }

  .vd-nav {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    right: 0;
    margin-left: 0;
    padding: 10px;
    border: 1px solid rgba(167, 176, 191, 0.24);
    border-radius: 22px;
    background: rgba(11, 18, 32, 0.98);
    box-shadow: 0 20px 44px rgba(11, 18, 32, 0.4);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: opacity 0.18s ease, transform 0.18s ease, visibility 0.18s ease;
    counter-reset: vdnav;
    max-height: min(72vh, 520px);
    overflow-y: auto;
  }

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

  .vd-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .vd-nav__link {
    display: flex;
    align-items: center;
    padding: 13px 14px;
    border-radius: 14px;
    font-size: var(--vd-t16);
    font-weight: 600;
  }

  .vd-nav__link::before {
    counter-increment: vdnav;
    content: counter(vdnav, decimal-leading-zero);
    margin-right: 12px;
    font-family: var(--vd-mono);
    font-size: var(--vd-t12);
    font-weight: 600;
    color: var(--vd-steel);
  }

  .vd-nav__link::after { display: none; }

  .vd-nav__link[aria-current="page"]::before { color: var(--vd-teal); }

  .vd-burger { display: inline-flex; }

  .vd-header[data-scrolled="true"] .vd-current,
  .vd-header[data-scrolled="true"] .vd-header__current {
    display: none;
  }

  .vd-header__actions { margin-left: auto; }
}

@media (max-width: 560px) {
  .vd-capsule { padding: 7px 8px 7px 11px; gap: 8px; }

  .vd-brand__sub { display: none; }

  .vd-brand__name { font-size: var(--vd-t14); }

  .vd-header__cta {
    padding: 8px 12px;
    font-size: 0.6875rem;
    letter-spacing: 0;
  }

  .vd-burger__label { display: none; }

  .vd-footer__note { font-size: var(--vd-t12); }

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

  .vd-footer__base { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 1000px) {
  .vd-footer__top { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 760px) and (min-width: 561px) {
  .vd-footer__drawers { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ---------- 19. 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  html[data-reveal-ready="true"] .vd-reveal {
    opacity: 1;
    transform: none;
  }

  .vd-btn:hover,
  .vd-top:hover,
  .vd-brand:hover .vd-brand__mark {
    transform: none;
  }
}