.page-about {
  --about-rail: 1px;
  --about-node-size: 11px;
  --about-head-gap: 22px;
  background: var(--ink-900);
  color: var(--text-primary);
}

/* ================= 首屏 ================= */

.page-about .about-hero {
  padding-top: clamp(22px, 4.2vw, 46px);
}

.page-about .about-hero__grid {
  margin-top: 26px;
  row-gap: 34px;
}

.page-about .about-hero__lead .bvt-h1 {
  margin: 12px 0 0;
  max-width: 22ch;
}

.page-about .about-hero__lead .bvt-lede {
  margin: 18px 0 0;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-hero__facts {
  align-self: start;
}

.page-about .about-hero__facts-title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.page-about .about-facts {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-facts__item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding: 13px 0;
  border-bottom: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-facts__key {
  font-size: 13px;
  color: var(--text-muted);
  letter-spacing: 0.02em;
}

.page-about .about-facts__val {
  font-family: var(--font-mono);
  font-size: 19px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  color: var(--orange-500);
  white-space: nowrap;
}

.page-about .about-facts__unit {
  margin-left: 4px;
  font-family: var(--font-body);
  font-size: 12px;
  font-weight: 400;
  color: var(--text-muted);
}

/* ================= 内容边界 ================= */

.page-about #scope .bvt-h2 {
  margin-top: 12px;
  max-width: 18ch;
}

.page-about .about-scope__body {
  display: grid;
  gap: 16px;
}

.page-about .about-scope__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
  max-width: 68ch;
}

.page-about .about-scope__body p:last-child {
  padding-left: 16px;
  border-left: 2px solid var(--orange-500);
  color: var(--text-muted);
}

/* ================= 记录来源 ================= */

.page-about #sources .bvt-h2 {
  margin-top: 12px;
  max-width: 22ch;
}

.page-about .about-sources {
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-sources__item {
  padding: 24px 0;
  border-bottom: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-sources__num {
  display: inline-block;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--legacy-blue);
}

.page-about .about-sources__title {
  margin: 10px 0 10px;
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--text-primary);
}

.page-about .about-sources__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-muted);
  max-width: 68ch;
}

.page-about .about-sources__note {
  margin: 28px 0 0;
  padding: 16px 18px;
  border-radius: var(--r-md);
  border: var(--about-rail) solid var(--surface-line-soft);
  background: var(--ink-800);
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-muted);
  max-width: 68ch;
}

/* ================= 版本演进 ================= */

.page-about .about-versions__head {
  row-gap: 30px;
}

.page-about .about-versions__intro .bvt-h2 {
  margin-top: 12px;
  max-width: 20ch;
}

.page-about .about-versions__intro .bvt-lede {
  margin-top: 16px;
}

.page-about .about-versions__figure {
  margin: 0;
}

.page-about .about-versions__figure img,
.page-about .about-versions__plan img,
.page-about .about-workflow__figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  border-radius: var(--r-md);
  border: var(--about-rail) solid var(--blueprint-line);
  background: var(--charcoal-700);
}

.page-about .about-versions__plan {
  margin: 40px 0 0;
}

.page-about .about-timeline {
  margin-top: 44px;
  display: grid;
  gap: 30px;
}

.page-about .about-timeline__index {
  padding: 16px 18px;
  border-radius: var(--r-md);
  border: var(--about-rail) solid var(--surface-line-soft);
  background: var(--ink-800);
}

.page-about .about-timeline__index-title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.page-about .about-timeline__index-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-timeline__index-list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 10px;
  border-radius: var(--r-sm);
  font-size: 14px;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 240ms var(--ease), background-color 240ms var(--ease);
}

.page-about .about-timeline__index-list a .bvt-mono {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--legacy-blue);
}

.page-about .about-timeline__index-list a:hover {
  color: var(--text-primary);
  background: rgba(34, 48, 63, 0.5);
}

.page-about .about-timeline__track {
  list-style: none;
  margin: 0;
  padding: 0 0 0 28px;
  position: relative;
}

.page-about .about-timeline__track::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: var(--blueprint-line);
}

.page-about .about-timeline__node {
  position: relative;
  padding-bottom: 18px;
}

.page-about .about-timeline__node::before {
  content: "";
  position: absolute;
  left: -26.5px;
  top: 19px;
  width: var(--about-node-size);
  height: var(--about-node-size);
  border-radius: 50%;
  box-sizing: border-box;
  background: var(--ink-900);
  border: 1px solid var(--blueprint-line);
  z-index: 1;
}

.page-about .about-timeline__node:last-child {
  padding-bottom: 0;
}

.page-about .about-version {
  border-radius: var(--r-md);
  border: var(--about-rail) solid var(--surface-line-soft);
  background: var(--ink-800);
  overflow: hidden;
}

.page-about .about-version[open] {
  border-color: rgba(53, 242, 192, 0.28);
  background: var(--charcoal-700);
}

.page-about .about-version__summary {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}

.page-about .about-version__summary::-webkit-details-marker {
  display: none;
}

.page-about .about-version__summary:focus-visible {
  outline: 2px solid var(--acid-cyan);
  outline-offset: -4px;
}

.page-about .about-version__tag {
  display: inline-block;
  padding: 5px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--ink-900);
  background: var(--legacy-blue);
  white-space: nowrap;
}

.page-about .about-version[open] .about-version__tag {
  background: var(--acid-cyan);
}

.page-about .about-version__heading {
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-width: 0;
}

.page-about .about-version__title {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 600;
  letter-spacing: 0.01em;
  line-height: 1.35;
  color: var(--text-primary);
}

.page-about .about-version__period {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--text-faint);
}

.page-about .about-version__chevron {
  width: 9px;
  height: 9px;
  border-right: 1.5px solid var(--text-muted);
  border-bottom: 1.5px solid var(--text-muted);
  transform: rotate(45deg);
  transition: transform 240ms var(--ease);
}

.page-about .about-version[open] .about-version__chevron {
  transform: rotate(-135deg);
}

.page-about .about-version__body {
  padding: 0 18px 20px;
  border-top: var(--about-rail) solid var(--surface-line-soft);
  margin-top: 2px;
  padding-top: 18px;
}

.page-about .about-version__body p {
  margin: 0 0 12px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
  max-width: 68ch;
}

.page-about .about-version__body p:last-child {
  margin-bottom: 0;
}

.page-about .about-version__hint {
  font-size: 14px;
  color: var(--text-muted);
}

.page-about .about-version__hint a {
  color: var(--acid-cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ================= 数据维度 ================= */

.page-about #dimensions .bvt-h2 {
  margin-top: 12px;
  max-width: 18ch;
}

.page-about #dimensions .bvt-lede {
  margin-top: 16px;
}

.page-about .about-tabs {
  margin-top: 32px;
}

.page-about .about-tabs .bvt-tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  padding-bottom: 10px;
  border-bottom: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-tabs .bvt-tabs__tab {
  appearance: none;
  border: 0;
  background: transparent;
  padding: 10px 16px;
  border-radius: 999px;
  font-family: var(--font-body);
  font-size: 14px;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  cursor: pointer;
  transition: color 240ms var(--ease), background-color 240ms var(--ease);
}

.page-about .about-tabs .bvt-tabs__tab:hover {
  color: var(--text-primary);
  background: rgba(34, 48, 63, 0.5);
}

.page-about .about-tabs .bvt-tabs__tab[aria-selected="true"] {
  color: var(--acid-cyan);
  box-shadow: inset 0 -2px 0 var(--acid-cyan);
  border-radius: var(--r-sm) var(--r-sm) 0 0;
  background: rgba(53, 242, 192, 0.07);
}

.page-about .about-tabs .bvt-tabs__tab:focus-visible {
  outline: 2px solid var(--acid-cyan);
  outline-offset: 3px;
}

.page-about .about-tabs__panel {
  margin-top: 24px;
}

.page-about .about-tabs__panel:focus-visible {
  outline: 2px solid var(--acid-cyan);
  outline-offset: 4px;
}

.page-about .about-fields {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-fields__row {
  display: grid;
  gap: 4px;
  padding: 14px 0;
  border-bottom: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-fields__name {
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--text-primary);
}

.page-about .about-fields__detail {
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-muted);
}

.page-about .about-fields--legacy .about-fields__name {
  color: var(--legacy-blue);
}

/* ================= 整理流程 ================= */

.page-about .about-workflow__figure {
  margin: 0 0 40px;
}

.page-about #workflow .bvt-h2 {
  margin-top: 12px;
  max-width: 16ch;
}

.page-about #workflow .bvt-lede {
  margin-top: 16px;
}

.page-about .about-flow {
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
  display: grid;
  gap: 24px;
}

.page-about .about-flow__step {
  position: relative;
  padding: 22px 0 0;
  border-top: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-flow__step::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--orange-500);
}

.page-about .about-flow__num {
  display: block;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--orange-500);
}

.page-about .about-flow__title {
  margin: 10px 0 10px;
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--text-primary);
}

.page-about .about-flow__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.85;
  color: var(--text-muted);
  max-width: 40ch;
}

/* ================= 团队与协作 ================= */

.page-about .about-team__grid {
  row-gap: 34px;
}

.page-about .about-team__intro .bvt-h2 {
  margin-top: 12px;
  max-width: 20ch;
}

.page-about .about-team__intro p {
  margin: 16px 0 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-primary);
  max-width: 68ch;
}

.page-about .about-team__intro p + p {
  color: var(--text-muted);
}

.page-about .about-team__side {
  display: grid;
  gap: 22px;
}

.page-about .about-team__chart-wrap {
  margin: 0;
  display: flex;
  justify-content: center;
}

.page-about .about-team__chart {
  width: min(230px, 68vw);
  height: auto;
  display: block;
}

.page-about .about-team__chart-num {
  fill: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 27px;
  font-weight: 600;
}

.page-about .about-team__chart-cap {
  fill: var(--text-muted);
  font-family: var(--font-body);
  font-size: 11px;
  letter-spacing: 0.08em;
}

.page-about .about-team__legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-team__legend-item {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 12px;
  padding: 12px 0;
  border-bottom: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-team__swatch {
  width: 10px;
  height: 10px;
  border-radius: 2px;
  display: inline-block;
}

.page-about .about-team__swatch--calibration {
  background: var(--acid-cyan);
}

.page-about .about-team__swatch--editorial {
  background: var(--orange-500);
}

.page-about .about-team__swatch--frontend {
  background: var(--legacy-blue);
}

.page-about .about-team__swatch--operation {
  background: var(--cyan-dim);
}

.page-about .about-team__legend-name {
  font-size: 14px;
  color: var(--text-muted);
}

.page-about .about-team__legend-val {
  font-family: var(--font-mono);
  font-size: 17px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  color: var(--text-primary);
}

.page-about .about-team__meta {
  margin-top: 40px;
  display: grid;
  gap: 0;
  border-top: var(--about-rail) solid var(--blueprint-line);
  border-bottom: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-team__meta-cell {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 16px 0;
  border-bottom: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-team__meta-cell:last-child {
  border-bottom: 0;
}

.page-about .about-team__meta-key {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-faint);
}

.page-about .about-team__meta-val {
  font-size: 15px;
  color: var(--text-primary);
}

/* ================= 继续阅读 ================= */

.page-about .about-next {
  border-top: var(--about-rail) solid var(--blueprint-line);
}

.page-about .about-next .bvt-h2 {
  margin-top: 12px;
  max-width: 16ch;
}

.page-about .about-next__list {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-next__item {
  border-bottom: var(--about-rail) solid var(--surface-line-soft);
}

.page-about .about-next__link {
  display: grid;
  gap: 8px;
  padding: 20px 4px 20px 0;
  text-decoration: none;
  transition: background-color 240ms var(--ease), padding-left 240ms var(--ease);
}

.page-about .about-next__link:hover {
  background: rgba(34, 48, 63, 0.32);
  padding-left: 12px;
}

.page-about .about-next__link:focus-visible {
  outline: 2px solid var(--acid-cyan);
  outline-offset: 2px;
}

.page-about .about-next__title {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--text-primary);
}

.page-about .about-next__link:hover .about-next__title {
  color: var(--orange-500);
}

.page-about .about-next__desc {
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-muted);
  max-width: 68ch;
}

/* ================= 响应式 ================= */

@media (min-width: 768px) {
  .page-about .about-fields__row {
    grid-template-columns: 200px 1fr;
    align-items: baseline;
    gap: 24px;
  }

  .page-about .about-team__meta {
    grid-template-columns: repeat(3, 1fr);
  }

  .page-about .about-team__meta-cell {
    padding: 18px 20px;
    border-bottom: 0;
    border-right: var(--about-rail) solid var(--surface-line-soft);
  }

  .page-about .about-team__meta-cell:first-child {
    padding-left: 0;
  }

  .page-about .about-team__meta-cell:last-child {
    border-right: 0;
  }

  .page-about .about-next__list {
    grid-template-columns: repeat(2, 1fr);
    column-gap: 40px;
  }
}

@media (min-width: 900px) {
  .page-about .about-sources {
    grid-template-columns: repeat(3, 1fr);
    column-gap: 32px;
    border-top: var(--about-rail) solid var(--blueprint-line);
  }

  .page-about .about-sources__item {
    border-bottom: 0;
    border-top: var(--about-rail) solid var(--surface-line-soft);
    margin-top: -1px;
    padding: 26px 0 8px;
  }

  .page-about .about-flow {
    grid-template-columns: repeat(4, 1fr);
    gap: 0;
  }

  .page-about .about-flow__step {
    padding-right: 22px;
  }

  .page-about .about-flow__step + .about-flow__step {
    padding-left: 22px;
  }

  .page-about .about-flow__step + .about-flow__step::before {
    left: 22px;
  }
}

@media (min-width: 1024px) {
  .page-about .about-hero__grid {
    row-gap: 0;
    column-gap: 56px;
    align-items: start;
  }

  .page-about .about-timeline {
    grid-template-columns: 236px 1fr;
    column-gap: 40px;
    align-items: start;
  }

  .page-about .about-timeline__index {
    position: sticky;
    top: calc(var(--header-h) + 20px);
  }

  .page-about .about-versions__head {
    column-gap: 48px;
    align-items: end;
  }

  .page-about .about-team__grid {
    column-gap: 48px;
  }

  .page-about .about-next__list {
    grid-template-columns: repeat(3, 1fr);
    column-gap: 36px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-version__chevron,
  .page-about .about-timeline__index-list a,
  .page-about .about-tabs .bvt-tabs__tab,
  .page-about .about-next__link {
    transition: none;
  }
}
<<<END>>>