/* ==========================================================================
   贝斯特2255 官方服务中心 · 共享站点样式 /assets/site.css
   基调：深空蓝 + 暖橙 + 青玉 · 胶囊几何 · 编辑感标题 · 目录型内容地图
   ========================================================================== */

/* ---------- 1. 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 124px;
}
body, h1, h2, h3, h4, p, figure, blockquote, dl, dd, ul, ol { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
img { height: auto; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; padding: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
summary { cursor: pointer; }
summary::-webkit-details-marker { display: none; }
[hidden] { display: none !important; }

/* ---------- 2. 变量 ---------- */
:root {
  --bs-ink: #0B2036;
  --bs-blue: #14406E;
  --bs-blue-lift: #2E6FA8;
  --bs-mist: #E8F0F7;
  --bs-orange: #E4762A;
  --bs-orange-soft: #FBE4D0;
  --bs-jade: #2FA39A;
  --bs-jade-soft: #DFF2F0;
  --bs-text: #33475B;
  --bs-muted: #5C7791;
  --bs-paper: #FBFCFE;
  --bs-line: rgba(20, 64, 110, .12);
  --bs-line-soft: rgba(20, 64, 110, .08);

  --bs-font-display: "Source Han Sans SC", "HarmonyOS Sans SC", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --bs-font-body: "Source Han Serif SC", "Noto Serif SC", "Songti SC", "SimSun", Georgia, serif;
  --bs-font-mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, "Courier New", monospace;

  --bs-r-card: 24px;
  --bs-r-lg: 32px;
  --bs-r-pill: 999px;

  --bs-gap: 32px;
  --bs-ease: cubic-bezier(.22, .61, .36, 1);
  --bs-shadow-soft: 0 18px 44px -30px rgba(11, 32, 54, .55);
  --bs-header-space: 104px;
}

/* ---------- 3. 中文排版与基础 ---------- */
body {
  padding-top: var(--bs-header-space);
  font-family: var(--bs-font-body);
  font-size: 17px;
  line-height: 1.85;
  color: var(--bs-text);
  background: var(--bs-mist);
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3, h4 {
  font-family: var(--bs-font-display);
  font-weight: 800;
  color: var(--bs-ink);
  line-height: 1.28;
  letter-spacing: -.02em;
}
h1 { font-size: clamp(30px, 4vw, 52px); }
h2 { font-size: clamp(24px, 2.6vw, 34px); }
h3 { font-size: clamp(19px, 1.6vw, 22px); }
h4 { font-size: 17px; line-height: 1.5; }
p { text-wrap: pretty; }
strong { color: var(--bs-ink); font-weight: 700; }
:focus-visible { outline: 2px solid var(--bs-orange); outline-offset: 2px; border-radius: 6px; }

/* ---------- 4. 布局骨架 ---------- */
.bs-shell { width: 100%; max-width: 1200px; margin-inline: auto; padding-inline: 22px; }
.bs-section { padding-block: clamp(48px, 7vw, 88px); }
.bs-section--mist { background: var(--bs-mist); }
.bs-section--paper { background: var(--bs-paper); }
.bs-section--ink {
  background: linear-gradient(158deg, var(--bs-ink) 0%, var(--bs-blue) 58%, var(--bs-blue-lift) 100%);
  color: #D8E7F4;
}
.bs-section--ink h1, .bs-section--ink h2, .bs-section--ink h3 { color: #FFFFFF; }
.bs-section--ink .bs-lede, .bs-section--ink p { color: #C6DBEC; }

.bs-grid { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: var(--bs-gap); }
.bs-grid--cards { display: grid; gap: 20px; grid-template-columns: repeat(auto-fill, minmax(238px, 1fr)); }
.bs-split { display: grid; gap: var(--bs-gap); grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); align-items: start; }
.bs-split--reverse { grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); }

.bs-eyebrow {
  font-family: var(--bs-font-mono);
  font-size: 12.5px;
  letter-spacing: .18em;
  color: var(--bs-jade);
  margin-bottom: 10px;
}
.bs-section__title { margin-bottom: 12px; }
.bs-lede { font-size: 17px; line-height: 1.85; color: var(--bs-muted); max-width: 62ch; }
.bs-muted { color: var(--bs-muted); }
.bs-mono { font-family: var(--bs-font-mono); font-variant-numeric: tabular-nums; letter-spacing: .01em; }
.bs-num { font-family: var(--bs-font-mono); font-variant-numeric: tabular-nums; text-align: right; }
.bs-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;
}

/* ---------- 5. 按钮 ---------- */
.bs-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 22px;
  border: 1px solid transparent;
  border-radius: var(--bs-r-pill);
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 15px;
  line-height: 1.3;
  letter-spacing: .01em;
  transition: background-color .22s var(--bs-ease), color .22s var(--bs-ease),
              border-color .22s var(--bs-ease), transform .22s var(--bs-ease),
              box-shadow .22s var(--bs-ease);
}
.bs-btn--primary { background: var(--bs-blue); color: var(--bs-paper); box-shadow: 0 12px 26px -18px rgba(11, 32, 54, .9); }
.bs-btn--primary:hover { background: var(--bs-blue-lift); transform: translateY(-2px); }
.bs-btn--accent { background: var(--bs-orange); color: #FFFFFF; box-shadow: 0 12px 26px -16px rgba(228, 118, 42, .85); }
.bs-btn--accent:hover { background: #C9621C; transform: translateY(-2px); }
.bs-btn--ghost { background: var(--bs-paper); color: var(--bs-blue); border-color: var(--bs-line); }
.bs-btn--ghost:hover { border-color: var(--bs-blue); background: var(--bs-mist); transform: translateY(-2px); }
.bs-btn--sm { padding: 8px 16px; font-size: 14px; }

/* ---------- 6. 头部与胶囊导航 ---------- */
.bs-skip {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 140;
  padding: 10px 18px;
  border-radius: var(--bs-r-pill);
  background: var(--bs-ink);
  color: #FFFFFF;
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 14px;
  transform: translateY(-200%);
  transition: transform .22s var(--bs-ease);
}
.bs-skip:focus { transform: translateY(0); }

.bs-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 80;
  padding: 16px 0;
  transition: padding .22s var(--bs-ease);
}
.bs-header[data-scrolled="true"] { padding: 9px 0; }
.bs-header__bar {
  position: relative;
  display: flex;
  align-items: center;
  gap: 16px;
  width: min(1200px, calc(100% - 28px));
  margin-inline: auto;
  padding: 8px 10px 8px 16px;
  border: 1px solid var(--bs-line);
  border-radius: var(--bs-r-pill);
  background: rgba(251, 252, 254, .88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 12px 32px -22px rgba(11, 32, 54, .7);
  transition: box-shadow .22s var(--bs-ease), padding .22s var(--bs-ease), background-color .22s var(--bs-ease);
}
.bs-header[data-scrolled="true"] .bs-header__bar {
  padding: 5px 8px 5px 14px;
  background: rgba(251, 252, 254, .96);
  box-shadow: 0 20px 44px -24px rgba(11, 32, 54, .75);
}
.bs-header__actions { display: flex; align-items: center; gap: 10px; flex: 0 0 auto; }

.bs-brand { display: inline-flex; align-items: center; gap: 10px; flex: 0 0 auto; }
.bs-brand__mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 14px;
  background: linear-gradient(140deg, var(--bs-blue-lift), var(--bs-blue) 55%, var(--bs-ink));
  color: #FFFFFF;
  font-family: var(--bs-font-display);
  font-weight: 800;
  font-size: 19px;
  line-height: 1;
}
.bs-brand__text { display: flex; flex-direction: column; line-height: 1.16; }
.bs-brand__name { font-family: var(--bs-font-display); font-weight: 800; font-size: 16px; color: var(--bs-ink); letter-spacing: -.01em; }
.bs-brand__sub { font-size: 11.5px; letter-spacing: .09em; color: var(--bs-blue-lift); }
.bs-brand__badge {
  padding: 3px 10px;
  border-radius: var(--bs-r-pill);
  border: 1px solid rgba(228, 118, 42, .3);
  background: var(--bs-orange-soft);
  color: #9E4A0F;
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 11px;
  line-height: 1.6;
}

.bs-nav { margin-inline: auto; }
.bs-nav__list {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px;
  border-radius: var(--bs-r-pill);
  background: var(--bs-mist);
}
.bs-nav__link {
  display: block;
  padding: 8px 16px;
  border-radius: var(--bs-r-pill);
  font-family: var(--bs-font-display);
  font-weight: 600;
  font-size: 15px;
  color: var(--bs-blue);
  white-space: nowrap;
  transition: background-color .22s var(--bs-ease), color .22s var(--bs-ease),
              transform .22s var(--bs-ease), box-shadow .22s var(--bs-ease);
}
.bs-nav__link:hover {
  background: var(--bs-paper);
  transform: translateY(-2px);
  box-shadow: 0 8px 18px -14px rgba(11, 32, 54, .9);
}
.bs-nav__link[aria-current="page"] {
  background: var(--bs-blue);
  color: var(--bs-paper);
  box-shadow: 0 10px 20px -14px rgba(11, 32, 54, .95);
}

.bs-navtoggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 9px 15px;
  border: 1px solid var(--bs-line);
  border-radius: var(--bs-r-pill);
  background: var(--bs-mist);
  color: var(--bs-blue);
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 14px;
  transition: border-color .22s var(--bs-ease), background-color .22s var(--bs-ease);
}
.bs-navtoggle__bars { display: grid; gap: 3px; width: 16px; }
.bs-navtoggle__bars span {
  display: block;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform .22s var(--bs-ease), opacity .22s var(--bs-ease);
}
.bs-navtoggle[aria-expanded="true"] .bs-navtoggle__bars span:nth-child(1) { transform: translateY(5px) rotate(45deg); }
.bs-navtoggle[aria-expanded="true"] .bs-navtoggle__bars span:nth-child(2) { opacity: 0; }
.bs-navtoggle[aria-expanded="true"] .bs-navtoggle__bars span:nth-child(3) { transform: translateY(-5px) rotate(-45deg); }

/* ---------- 7. 面包屑 / 正文容器 ---------- */
.bs-breadcrumb { font-size: 13.5px; padding-block: 6px 0; }
.bs-breadcrumb__list { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; color: var(--bs-muted); }
.bs-breadcrumb__item + .bs-breadcrumb__item::before { content: "/"; margin-right: 8px; color: #9CB2C6; }
.bs-breadcrumb__item[aria-current="page"] { color: var(--bs-ink); font-weight: 700; }

.bs-prose { max-width: 68ch; font-size: 17px; line-height: 1.85; }
.bs-prose p + p { margin-top: 1.2em; }
.bs-prose h2 { margin: 1.7em 0 .55em; }
.bs-prose h3 { margin: 1.4em 0 .5em; }
.bs-prose ul, .bs-prose ol { margin: 1em 0; padding-left: 1.15em; list-style: disc; }
.bs-prose li + li { margin-top: .4em; }
.bs-prose blockquote {
  margin: 1.4em 0;
  padding: 16px 20px;
  border-left: 4px solid var(--bs-jade);
  border-radius: 0 18px 18px 0;
  background: var(--bs-jade-soft);
  font-family: var(--bs-font-body);
  color: var(--bs-blue);
}

/* ---------- 8. 卡片 / 索引 / 步骤 ---------- */
.bs-card {
  padding: 24px;
  border: 1px solid var(--bs-line);
  border-radius: var(--bs-r-card);
  background: var(--bs-paper);
  transition: border-color .22s var(--bs-ease), transform .22s var(--bs-ease), box-shadow .22s var(--bs-ease);
}
.bs-card:hover { border-color: var(--bs-blue); transform: translateY(-2px); box-shadow: var(--bs-shadow-soft); }
.bs-card--accent { background: var(--bs-orange-soft); border-color: rgba(228, 118, 42, .26); }
.bs-card--jade { background: var(--bs-jade-soft); border-color: rgba(47, 163, 154, .28); }
.bs-card__title { font-family: var(--bs-font-display); font-weight: 800; font-size: 20px; color: var(--bs-ink); margin-bottom: 8px; }
.bs-card__meta { font-family: var(--bs-font-mono); font-size: 13px; color: var(--bs-muted); margin-bottom: 10px; }
.bs-card__body { font-size: 16px; line-height: 1.8; }

.bs-index { display: grid; gap: 12px; }
.bs-index__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  border: 1px solid var(--bs-line);
  border-radius: 20px;
  background: var(--bs-paper);
  transition: border-color .22s var(--bs-ease), transform .22s var(--bs-ease), background-color .22s var(--bs-ease);
}
.bs-index__item:hover { border-color: var(--bs-blue); background: var(--bs-mist); transform: translateX(4px); }
.bs-index__num { font-family: var(--bs-font-mono); font-size: 13px; font-weight: 700; color: var(--bs-orange); transition: transform .22s var(--bs-ease); }
.bs-index__item:hover .bs-index__num { transform: scale(1.04); }
.bs-index__label { font-family: var(--bs-font-display); font-weight: 700; font-size: 17px; color: var(--bs-ink); }
.bs-index__desc { font-size: 14px; line-height: 1.7; color: var(--bs-muted); }

.bs-steps { display: grid; gap: 20px; grid-template-columns: repeat(auto-fit, minmax(258px, 1fr)); }
.bs-step {
  padding: 26px 24px 24px;
  border: 1px solid var(--bs-line);
  border-radius: var(--bs-r-card);
  background: var(--bs-paper);
  transition: border-color .22s var(--bs-ease), transform .22s var(--bs-ease), box-shadow .22s var(--bs-ease);
}
.bs-step:hover { border-color: var(--bs-blue); transform: translateY(-2px); box-shadow: var(--bs-shadow-soft); }
.bs-step__num {
  font-family: var(--bs-font-display);
  font-weight: 800;
  font-size: clamp(56px, 7vw, 88px);
  line-height: .92;
  color: var(--bs-orange);
  letter-spacing: -.03em;
  transition: transform .22s var(--bs-ease);
}
.bs-step:hover .bs-step__num { transform: scale(1.04); }
.bs-step__title { font-family: var(--bs-font-display); font-weight: 800; font-size: 20px; color: var(--bs-ink); margin-top: 12px; }
.bs-step__body { font-size: 15.5px; line-height: 1.8; margin-top: 8px; }

/* ---------- 9. 表格 ---------- */
.bs-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--bs-line);
  border-radius: 22px;
  background: var(--bs-paper);
}
.bs-table { min-width: 520px; font-size: 14.5px; }
.bs-table th {
  padding: 13px 16px;
  background: var(--bs-mist);
  color: var(--bs-blue);
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 14px;
  text-align: left;
  white-space: nowrap;
}
.bs-table td { padding: 12px 16px; border-top: 1px solid var(--bs-line-soft); color: var(--bs-text); }
.bs-table tbody tr:nth-child(even) { background: var(--bs-jade-soft); }
.bs-table tbody tr { transition: background-color .22s var(--bs-ease); }
.bs-table tbody tr:hover { background: var(--bs-mist); }

/* ---------- 10. 胶囊标签页 / 折叠 ---------- */
.bs-tabs__list {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 4px;
  padding: 5px;
  border-radius: var(--bs-r-pill);
  background: var(--bs-mist);
}
.bs-tabs__btn {
  padding: 9px 18px;
  border-radius: var(--bs-r-pill);
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 15px;
  color: var(--bs-blue);
  transition: background-color .22s var(--bs-ease), color .22s var(--bs-ease), box-shadow .22s var(--bs-ease);
}
.bs-tabs__btn:hover { background: var(--bs-paper); }
.bs-tabs__btn[aria-selected="true"] {
  background: var(--bs-blue);
  color: var(--bs-paper);
  box-shadow: 0 10px 22px -16px rgba(11, 32, 54, .95);
}
.bs-tabs__panel { margin-top: 22px; }

.bs-details {
  padding: 0 20px;
  border: 1px solid var(--bs-line);
  border-radius: 20px;
  background: var(--bs-paper);
}
.bs-details + .bs-details { margin-top: 12px; }
.bs-details > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 17px 0;
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 17px;
  color: var(--bs-ink);
}
.bs-details__icon {
  flex: 0 0 auto;
  color: var(--bs-orange);
  font-size: 20px;
  line-height: 1;
  transition: transform .22s var(--bs-ease);
}
.bs-details[open] .bs-details__icon { transform: rotate(90deg); }
.bs-details__body {
  padding: 16px 0 20px;
  border-top: 1px solid var(--bs-line-soft);
  font-size: 16px;
  line-height: 1.85;
}

/* ---------- 11. 标签 / 图片容器 ---------- */
.bs-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border: 1px solid rgba(228, 118, 42, .28);
  border-radius: var(--bs-r-pill);
  background: var(--bs-orange-soft);
  color: #9E4A0F;
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 12.5px;
  line-height: 1.7;
}
.bs-tag--jade { background: var(--bs-jade-soft); border-color: rgba(47, 163, 154, .32); color: #1B7A72; }
.bs-tag--blue { background: var(--bs-mist); border-color: var(--bs-line); color: var(--bs-blue); }

.bs-media {
  display: block;
  overflow: hidden;
  border: 1px solid var(--bs-line);
  border-radius: var(--bs-r-card);
  background: var(--bs-paper);
}
.bs-media__frame {
  position: relative;
  aspect-ratio: 16 / 9;
  background: linear-gradient(140deg, #DCE9F4 0%, #F7FBFE 52%, #E6F3F1 100%);
}
.bs-media__frame img { width: 100%; height: 100%; object-fit: cover; }
.bs-media__caption { padding: 12px 16px; border-top: 1px solid var(--bs-line-soft); font-size: 13px; color: var(--bs-muted); }
.bs-media--wide .bs-media__frame { aspect-ratio: 21 / 9; }
.bs-media--tall .bs-media__frame { aspect-ratio: 3 / 4; }

/* ---------- 12. 页脚 ---------- */
.bs-footer {
  margin-top: clamp(40px, 6vw, 72px);
  padding-top: clamp(44px, 6vw, 72px);
  border-radius: 40px 40px 0 0;
  background: linear-gradient(166deg, var(--bs-ink) 0%, #0D2C4D 52%, #123A63 100%);
  color: #C7DDEE;
}
.bs-footer__grid {
  display: grid;
  gap: var(--bs-gap);
  grid-template-columns: 1.45fr 1fr 1.35fr 1fr;
}
.bs-footer__col { min-width: 0; }
.bs-footer__brand {
  font-family: var(--bs-font-display);
  font-weight: 800;
  font-size: 24px;
  color: #FFFFFF;
  letter-spacing: -.01em;
  margin-bottom: 12px;
}
.bs-footer__tagline { font-size: 15.5px; line-height: 1.85; color: #C7DDEE; max-width: 34ch; }
.bs-footer__since {
  margin-top: 12px;
  font-family: var(--bs-font-mono);
  font-size: 12.5px;
  letter-spacing: .04em;
  color: #8FB4D4;
}
.bs-footer__title {
  font-family: var(--bs-font-display);
  font-weight: 700;
  font-size: 13px;
  letter-spacing: .16em;
  color: #8FB4D4;
  margin-bottom: 14px;
}
.bs-footer__links { display: grid; gap: 4px; }
.bs-footer__links a {
  display: inline-block;
  padding: 5px 0;
  border-bottom: 1px solid transparent;
  font-size: 15px;
  color: #DCEAF6;
  transition: color .22s var(--bs-ease), border-color .22s var(--bs-ease);
}
.bs-footer__links a:hover { color: #FFFFFF; border-bottom-color: var(--bs-orange); }
.bs-footer__meta { display: grid; gap: 2px; }
.bs-footer__meta li {
  display: grid;
  gap: 2px;
  padding: 9px 0;
  border-bottom: 1px dashed rgba(255, 255, 255, .14);
}
.bs-footer__key { font-size: 12.5px; letter-spacing: .08em; color: #8FB4D4; }
.bs-footer__val { font-size: 15px; color: #EAF4FC; word-break: break-word; }
.bs-footer__note { margin-top: 10px; font-size: 12.5px; line-height: 1.75; color: #8FB4D4; }
.bs-footer__icp { margin-top: 14px; font-size: 13px; color: #9DBDD8; }
.bs-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-top: clamp(34px, 5vw, 48px);
  padding: 18px 0 22px;
  border-top: 1px solid rgba(255, 255, 255, .14);
  font-size: 12.5px;
  line-height: 1.7;
  color: #9DBDD8;
}
.bs-footer__legal { font-family: var(--bs-font-mono); letter-spacing: .01em; }
.bs-footer__copy { color: #8FB4D4; }

/* ---------- 13. 滚动反馈 ---------- */
.bs-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 130;
  height: 3px;
  width: 0;
  pointer-events: none;
  background: linear-gradient(90deg, var(--bs-jade) 0%, var(--bs-blue-lift) 48%, var(--bs-orange) 100%);
}
.bs-js [data-reveal] { opacity: 0; transform: translateY(12px); transition: opacity .5s var(--bs-ease), transform .5s var(--bs-ease); }
.bs-js [data-reveal="1"] { transition-delay: .07s; }
.bs-js [data-reveal="2"] { transition-delay: .14s; }
.bs-js [data-reveal].is-visible { opacity: 1; transform: none; }

/* ---------- 14. 响应式 ---------- */
@media (max-width: 1080px) {
  .bs-nav__link { padding: 8px 12px; font-size: 14.5px; }
  .bs-brand__sub { display: none; }
}
@media (max-width: 980px) {
  :root { --bs-header-space: 92px; --bs-gap: 22px; }
  .bs-split, .bs-split--reverse { grid-template-columns: minmax(0, 1fr); }
  .bs-grid { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .bs-navtoggle { display: inline-flex; }
  .bs-nav {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    right: 0;
    display: none;
    margin: 0;
    padding: 10px;
    border: 1px solid var(--bs-line);
    border-radius: 26px;
    background: var(--bs-paper);
    box-shadow: 0 26px 54px -28px rgba(11, 32, 54, .8);
  }
  .bs-nav[data-open="true"] { display: block; }
  .bs-nav__list { display: grid; gap: 4px; padding: 0; background: transparent; }
  .bs-nav__link { padding: 12px 16px; border-radius: 18px; font-size: 16px; }
  .bs-nav__link:hover { transform: none; background: var(--bs-mist); }
  .bs-footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 620px) {
  :root { --bs-header-space: 86px; }
  body { font-size: 16.5px; }
  .bs-shell { padding-inline: 16px; }
  .bs-header__bar { width: calc(100% - 20px); padding: 7px 8px 7px 12px; gap: 10px; }
  .bs-brand__badge { display: none; }
  .bs-btn--sm { padding: 7px 13px; font-size: 13px; }
  .bs-navtoggle { padding: 8px 12px; }
  .bs-navtoggle__label { display: none; }
  .bs-footer__grid { grid-template-columns: minmax(0, 1fr); gap: 26px; }
  .bs-footer__bottom { flex-direction: column; align-items: flex-start; gap: 6px; }
  .bs-index__item { grid-template-columns: auto minmax(0, 1fr); }
  .bs-index__desc { grid-column: 2; }
}

/* ---------- 15. 无障碍与减弱动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition-duration: .16s !important; }
  .bs-js [data-reveal] { opacity: 1 !important; transform: none !important; }
  .bs-btn:hover,
  .bs-nav__link:hover,
  .bs-card:hover,
  .bs-step:hover,
  .bs-step:hover .bs-step__num,
  .bs-index__item:hover,
  .bs-index__item:hover .bs-index__num { transform: none !important; }
  .bs-progress { display: none; }
}