.page-about {
  --about-rail: 216px;
  --about-text: #D3CCC1;
  background: var(--sky-900);
  color: var(--paper);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-top {
  padding-top: 36px;
}

.page-about .about-top__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
  margin-top: 26px;
}

.page-about .about-top__eyebrow {
  margin: 0 0 12px;
  font-size: var(--fs-data);
  letter-spacing: .18em;
  color: var(--neon);
}

.page-about .about-top__main .h-hero {
  margin: 0 0 18px;
  color: var(--paper);
}

.page-about .about-top__main .prose__lead {
  margin: 0;
  max-width: 34em;
  color: var(--about-text);
  line-height: 1.75;
}

.page-about .about-top__meta {
  margin: 22px 0 0;
  padding-left: 12px;
  border-left: 3px solid var(--neon);
  font-size: var(--fs-data);
  letter-spacing: .04em;
  color: var(--gray);
}

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

.page-about .about-strip {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 40px 0 0;
  padding: 0;
  background: var(--line-soft);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-strip__item {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 16px 18px;
  background: var(--sky-900);
}

.page-about .about-strip__num {
  font-family: var(--font-mono);
  font-size: clamp(1.2rem, 2.6vw, 1.75rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--neon);
}

.page-about .about-strip__key {
  font-size: var(--fs-data);
  color: var(--gray);
}

/* ---------- 骨架：左索引栏 + 右内容流 ---------- */
.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  padding-top: 64px;
  padding-bottom: 56px;
}

.page-about .about-rail__cap {
  margin: 0 0 14px;
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--gray);
}

.page-about .about-rail__list {
  list-style: none;
  display: flex;
  gap: 10px;
  margin: 0;
  padding: 0 0 4px;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .about-rail__list::-webkit-scrollbar {
  display: none;
}

.page-about .about-rail__link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--line);
  font-size: var(--fs-data);
  color: var(--paper);
  text-decoration: none;
  white-space: nowrap;
  transition: color .18s ease, border-color .18s ease;
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--neon);
  border-color: var(--clay-lite);
}

.page-about .about-rail__num {
  color: var(--clay-lite);
  font-size: 11px;
}

.page-about .about-rail__link:hover .about-rail__num,
.page-about .about-rail__link:focus-visible .about-rail__num {
  color: var(--neon);
}

.page-about .about-flow {
  display: flex;
  flex-direction: column;
  gap: 64px;
  min-width: 0;
}

.page-about .about-phase {
  min-width: 0;
  scroll-margin-top: calc(var(--bar-h) + 32px);
}

.page-about .about-phase__body {
  margin-top: 20px;
}

.page-about .about-phase__body > p {
  max-width: 40em;
  margin: 0 0 18px;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

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

.page-about .about-phase__figure {
  margin: 0 0 26px;
}

/* ---------- 引用块 ---------- */
.page-about .about-quote {
  margin: 30px 0 0;
  padding: 26px 24px;
  background: var(--indigo);
  border-left: 4px solid var(--clay-lite);
}

.page-about .about-quote p {
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(1.15rem, 2.6vw, 1.5rem);
  font-weight: 700;
  line-height: 1.55;
  letter-spacing: -.01em;
  color: var(--paper);
}

/* ---------- 字段分组 ---------- */
.page-about .field-group {
  margin-bottom: 10px;
  background: var(--sky-700);
  border-left: 3px solid var(--clay-deep);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%);
  transition: border-color .18s ease;
}

.page-about .field-group[open] {
  border-left-color: var(--neon);
}

.page-about .field-group__head {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 15px 18px;
  cursor: pointer;
  list-style: none;
  color: var(--paper);
  transition: color .18s ease;
}

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

.page-about .field-group__head:hover {
  color: var(--neon);
}

.page-about .field-group__mark {
  position: relative;
  width: 12px;
  height: 12px;
  flex: none;
}

.page-about .field-group__mark::before,
.page-about .field-group__mark::after {
  content: "";
  position: absolute;
  background: currentColor;
  transition: transform .22s ease-out;
}

.page-about .field-group__mark::before {
  left: 0;
  top: 5px;
  width: 12px;
  height: 2px;
}

.page-about .field-group__mark::after {
  left: 5px;
  top: 0;
  width: 2px;
  height: 12px;
}

.page-about .field-group[open] .field-group__mark::after {
  transform: scaleY(0);
}

.page-about .field-group__name {
  flex: 1 1 auto;
  font-size: .9375rem;
  font-weight: 700;
}

.page-about .field-group__count {
  flex: none;
  font-size: var(--fs-data);
  color: var(--neon);
}

.page-about .field-group__body {
  padding: 0 18px 18px;
}

.page-about .field-group__body p {
  margin: 0;
  max-width: 40em;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

/* ---------- 溯源分区 ---------- */
.page-about .about-phase--indigo {
  background: var(--indigo);
  padding: 30px 22px 34px;
}

.page-about .about-phase--indigo .about-phase__body > p {
  color: var(--paper);
}

.page-about .about-source-line {
  margin: 26px 0 0;
  padding: 10px 0 10px 14px;
  border-left: 3px solid var(--neon);
  font-size: var(--fs-data);
  letter-spacing: .06em;
  color: var(--gray);
}

/* ---------- 工作室 ---------- */
.page-about .about-phase__body--split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 24px;
}

.page-about .about-phase__figure--side {
  margin: 0;
}

.page-about .about-phase__column > p {
  margin: 0 0 18px;
  max-width: 40em;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

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

.page-about .about-roles__item {
  display: grid;
  gap: 6px;
  padding: 16px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-roles__key {
  font-family: var(--font-mono);
  font-size: var(--fs-data);
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--neon);
}

.page-about .about-roles__val {
  margin: 0;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

.page-about .about-cadence {
  margin: 28px 0 0;
  max-width: 40em;
  padding-left: 16px;
  border-left: 2px solid var(--clay);
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

/* ---------- 阶段线 ---------- */
.page-about .about-stages {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-stages__item {
  position: relative;
  padding: 0 0 30px 26px;
  border-left: 2px solid var(--clay-deep);
}

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

.page-about .about-stages__item::before {
  content: "";
  position: absolute;
  left: -6px;
  top: 7px;
  width: 10px;
  height: 10px;
  background: var(--clay);
  transform: rotate(45deg);
}

.page-about .about-stages__num {
  display: block;
  margin-bottom: 6px;
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--neon);
}

.page-about .about-stages__title {
  margin: 0 0 8px;
  font-family: var(--font-serif);
  font-size: var(--fs-sub);
  font-weight: 700;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .about-stages__item p {
  margin: 0;
  max-width: 38em;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--about-text);
}

/* ---------- 边界（纸面） ---------- */
.page-about .about-phase--paper {
  background: var(--paper);
  color: var(--ink);
  padding: 30px 22px 34px;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%);
}

.page-about .about-phase--paper .section-index__name {
  color: var(--ink);
}

.page-about .about-nots {
  list-style: none;
  display: grid;
  gap: 14px;
  margin: 0;
  padding: 0;
}

.page-about .about-nots li {
  position: relative;
  padding-left: 22px;
  font-size: .9375rem;
  line-height: 1.8;
  color: rgba(20, 18, 16, .84);
}

.page-about .about-nots li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .68em;
  width: 12px;
  height: 2px;
  background: var(--clay);
}

.page-about .about-nots a {
  color: var(--clay-deep);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-nots a:hover,
.page-about .about-nots a:focus-visible {
  color: var(--clay);
}

/* ---------- 收束 ---------- */
.page-about .about-outro {
  padding-top: 12px;
  padding-bottom: 60px;
}

.page-about .about-outro__text {
  margin: 0 0 20px;
  font-family: var(--font-serif);
  font-size: clamp(1.2rem, 2.6vw, 1.6rem);
  font-weight: 700;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .about-outro__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .about-contour {
  margin-top: 46px;
  color: var(--teal-deep);
}

.page-about .about-contour svg {
  display: block;
  width: 100%;
  height: 84px;
}

.page-about .about-contour path {
  fill: none;
  stroke: currentColor;
  stroke-width: 1;
  vector-effect: non-scaling-stroke;
}

/* ---------- 响应式 ---------- */
@media (min-width: 620px) {
  .page-about .about-roles__item {
    grid-template-columns: 168px minmax(0, 1fr);
    gap: 20px;
    align-items: baseline;
  }
}

@media (min-width: 760px) {
  .page-about .about-strip {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-phase__body--split {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: 32px;
    align-items: start;
  }

  .page-about .about-phase--indigo,
  .page-about .about-phase--paper {
    padding: 38px 34px 42px;
  }
}

@media (min-width: 1000px) {
  .page-about .about-top {
    padding-top: 52px;
  }

  .page-about .about-top__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 56px;
    margin-top: 34px;
  }

  .page-about .about-top__fig {
    margin-top: 34px;
  }

  .page-about .about-shell {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 56px;
    padding-top: 88px;
    padding-bottom: 72px;
  }

  .page-about .about-rail__inner {
    position: sticky;
    top: calc(var(--bar-h) + 28px);
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding: 2px 0 2px 20px;
    border-left: 2px solid var(--clay);
  }

  .page-about .about-rail__link {
    position: relative;
    border: 0;
    padding: 9px 0;
    white-space: normal;
  }

  .page-about .about-rail__link::before {
    content: "";
    position: absolute;
    left: -22px;
    top: 50%;
    width: 12px;
    height: 2px;
    background: var(--clay);
    transform: translateY(-50%);
    transition: width .18s ease, background-color .18s ease;
  }

  .page-about .about-rail__link:hover::before,
  .page-about .about-rail__link:focus-visible::before {
    width: 16px;
    background: var(--neon);
  }

  .page-about .about-flow {
    gap: 80px;
  }

  .page-about .about-quote {
    padding: 32px 34px;
  }
}

@media (min-width: 1280px) {
  .page-about .about-strip {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }

  .page-about .about-strip__item {
    padding: 18px 20px 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__link,
  .page-about .field-group,
  .page-about .field-group__head,
  .page-about .field-group__mark::before,
  .page-about .field-group__mark::after,
  .page-about .about-rail__link::before {
    transition: none;
  }
}
<<<END>>>