.page-about {
  --about-rail: 240px;
  background: var(--ink);
  color: var(--text);
}

/* ---------- 首屏框景 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
  background: var(--ink);
}

.page-about .about-hero__bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.page-about .about-hero__bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.42;
  filter: saturate(0.75) contrast(1.08);
}

.page-about .about-hero__bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 80% 12%, rgba(255, 90, 42, 0.16), transparent 58%),
    linear-gradient(180deg, rgba(14, 16, 19, 0.6) 0%, rgba(14, 16, 19, 0.88) 62%, var(--ink) 100%);
}

.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
  padding-top: clamp(32px, 5vw, 48px);
  padding-bottom: clamp(40px, 6vw, 72px);
}

.page-about .about-hero__frame {
  margin-top: clamp(24px, 4vw, 40px);
  padding: clamp(20px, 3.5vw, 36px);
  border: 1px solid var(--line);
  background: linear-gradient(160deg, rgba(23, 26, 31, 0.72), rgba(14, 16, 19, 0.32));
  box-shadow: inset 0 0 0 1px rgba(127, 166, 201, 0.08);
}

.page-about .about-hero__label {
  margin: 0 0 16px;
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--data);
}

.page-about .about-hero h1 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(32px, 7vw, 62px);
  line-height: 1.06;
  letter-spacing: 0.01em;
  color: var(--paper);
  max-width: 18em;
}

.page-about .about-hero__lede {
  margin: clamp(16px, 2.6vw, 24px) 0 0;
  max-width: 46em;
  font-size: clamp(15px, 1.4vw, 19px);
  line-height: 1.75;
  color: var(--text-dim);
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(24px, 4vw, 40px) 0 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-hero__stat {
  background: var(--stand);
  padding: 14px 16px;
}

.page-about .about-hero__stat dt {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--text-dim);
}

.page-about .about-hero__stat dd {
  margin: 6px 0 0;
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 700;
  color: var(--paper);
  line-height: 1.1;
}

.page-about .about-hero__stat dd span {
  font-size: 12px;
  font-weight: 400;
  color: var(--data);
  margin-left: 4px;
}

/* ---------- 侧轨 + 正文 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 56px);
  padding-top: clamp(32px, 5vw, 64px);
  padding-bottom: clamp(48px, 7vw, 96px);
}

.page-about .about-rail {
  min-width: 0;
}

.page-about .chapter-nav {
  border-top: 1px solid var(--line);
  padding-top: 16px;
}

.page-about .chapter-nav__title {
  margin: 0 0 12px;
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.page-about .chapter-nav__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px 8px;
}

.page-about .chapter-nav__link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 6px 0;
  color: var(--text-dim);
  text-decoration: none;
  font-size: 14px;
  border-bottom: 1px solid transparent;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .chapter-nav__num {
  font-size: 11px;
  color: var(--data-deep);
  letter-spacing: 0.04em;
}

.page-about .chapter-nav__link:hover,
.page-about .chapter-nav__link:focus-visible {
  color: var(--paper);
  border-bottom-color: var(--flare);
}

.page-about .chapter-nav__link:hover .chapter-nav__num,
.page-about .chapter-nav__link:focus-visible .chapter-nav__num {
  color: var(--flare);
}

/* ---------- 章节 ---------- */
.page-about .about-body {
  min-width: 0;
  display: grid;
  gap: clamp(20px, 3vw, 32px);
}

.page-about .chapter {
  border-top: 1px solid var(--line);
  padding-top: clamp(24px, 3.5vw, 40px);
  display: grid;
  gap: clamp(16px, 2.4vw, 24px);
}

.page-about .chapter__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px 18px;
  align-items: start;
}

.page-about .chapter__num {
  font-size: clamp(34px, 7vw, 64px);
  font-weight: 700;
  line-height: 0.8;
  color: var(--line);
  letter-spacing: -0.02em;
}

.page-about .chapter__kicker {
  margin: 0 0 8px;
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--flare);
}

.page-about .chapter__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(21px, 3.4vw, 32px);
  line-height: 1.24;
  color: var(--paper);
}

.page-about .chapter__body {
  display: grid;
  gap: 14px;
  min-width: 0;
}

.page-about .chapter__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .chapter__body p strong {
  color: var(--text);
}

.page-about .chapter__after {
  padding-top: 4px;
  border-top: 1px solid var(--line-soft);
}

.page-about .chapter__note {
  border-left: 2px solid var(--data-deep);
  padding: 10px 0 10px 14px;
  background: linear-gradient(90deg, rgba(64, 86, 107, 0.14), transparent 70%);
}

.page-about .chapter__note-label {
  display: inline-block;
  margin-bottom: 6px;
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--data);
}

.page-about .chapter__note p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.75;
  color: var(--text-dim);
}

.page-about .chapter__note--inline {
  margin-top: 4px;
}

/* 纸色章节 */
.page-about .chapter--paper {
  background: var(--paper);
  color: #1B1E24;
  border-top-color: var(--paper);
  padding: clamp(22px, 3.5vw, 40px);
}

.page-about .chapter--paper .chapter__num {
  color: var(--paper-shadow);
}

.page-about .chapter--paper .chapter__title {
  color: #14171C;
}

.page-about .chapter--paper .chapter__kicker {
  color: var(--flare-deep);
}

.page-about .chapter--paper .chapter__body p,
.page-about .chapter--paper .chapter__after {
  color: #3C434D;
}

/* ---------- 服务对象 ---------- */
.page-about .aud-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
}

.page-about .aud-card {
  border: 1px solid var(--paper-shadow);
  border-left: 3px solid var(--flare);
  background: rgba(255, 255, 255, 0.42);
  padding: 16px 16px 14px;
}

.page-about .aud-card__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 700;
  color: #14171C;
  letter-spacing: 0.01em;
}

.page-about .aud-card p {
  margin: 0 0 10px;
  font-size: 14px;
  line-height: 1.8;
  color: #3C434D;
}

.page-about .aud-card__tag {
  margin: 0;
  font-size: 11.5px;
  letter-spacing: 0.04em;
  color: var(--flare-deep);
}

/* ---------- 生产流程 ---------- */
.page-about .flow {
  border: 1px solid var(--line);
  background: var(--stand);
  padding: clamp(16px, 2.5vw, 24px);
}

.page-about .flow__line {
  display: block;
  width: 100%;
  height: 36px;
  margin-bottom: 16px;
}

.page-about .flow__steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  counter-reset: none;
}

.page-about .flow__step {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 4px 10px;
  align-items: baseline;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line-soft);
}

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

.page-about .flow__num {
  grid-row: span 2;
  font-size: 12px;
  color: var(--data);
  padding-top: 2px;
}

.page-about .flow__step strong {
  font-size: 14.5px;
  color: var(--paper);
  font-weight: 600;
}

.page-about .flow__step span:last-child {
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--text-dim);
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

/* ---------- 设计原则 ---------- */
.page-about .principle-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .principle {
  background: var(--stand);
  padding: 16px clamp(14px, 2.4vw, 22px);
  transition: background 0.2s var(--ease);
}

.page-about .principle:hover {
  background: #1B1F26;
}

.page-about .principle__title {
  margin: 0 0 8px;
  font-size: 15.5px;
  font-weight: 600;
  color: var(--paper);
  position: relative;
  padding-left: 14px;
}

.page-about .principle__title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 6px;
  height: 1px;
  background: var(--flare);
}

.page-about .principle p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-dim);
}

/* ---------- 时间轴 ---------- */
.page-about .track-block {
  border-top: 1px solid var(--line);
  padding-top: clamp(24px, 3.5vw, 40px);
  display: grid;
  gap: clamp(18px, 2.6vw, 26px);
}

.page-about .track-block__lede {
  margin: 10px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--text-dim);
  max-width: 44em;
}

.page-about .track {
  list-style: none;
  margin: 0;
  padding: 0 0 0 22px;
  border-left: 1px solid var(--line);
  display: grid;
  gap: 18px;
}

.page-about .track__item {
  position: relative;
  outline: none;
}

.page-about .track__item::before {
  content: "";
  position: absolute;
  left: -27px;
  top: 7px;
  width: 9px;
  height: 9px;
  background: var(--line);
  transition: background 0.2s var(--ease), transform 0.2s var(--ease);
}

.page-about .track__item:hover::before,
.page-about .track__item:focus-visible::before {
  background: var(--flare);
  transform: scale(1.25);
}

.page-about .track__stage {
  margin: 0 0 4px;
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--data);
}

.page-about .track__title {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
  color: var(--paper);
  line-height: 1.4;
  transition: color 0.2s var(--ease);
}

.page-about .track__item:hover .track__title,
.page-about .track__item:focus-visible .track__title {
  color: var(--flare);
}

.page-about .track__note {
  margin: 0;
  overflow: hidden;
  max-height: 0;
  opacity: 0;
  font-size: 13.5px;
  line-height: 1.8;
  color: var(--text-dim);
  transition: max-height 0.28s var(--ease), opacity 0.2s var(--ease), margin-top 0.28s var(--ease);
}

.page-about .track__item:hover .track__note,
.page-about .track__item:focus-visible .track__note,
.page-about .track__item:focus-within .track__note {
  max-height: 200px;
  opacity: 1;
  margin-top: 8px;
}

/* ---------- 覆盖与合作 ---------- */
.page-about .reach-band {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .reach-band__item {
  background: var(--stand);
  padding: 14px 16px;
  display: grid;
  gap: 4px;
}

.page-about .reach-band__value {
  font-size: clamp(24px, 4vw, 34px);
  font-weight: 700;
  line-height: 1;
  color: var(--data);
}

.page-about .reach-band__label {
  font-size: 12px;
  line-height: 1.5;
  color: var(--text-dim);
}

/* ---------- 下一步 ---------- */
.page-about .next-block {
  border-top: 1px solid var(--line);
  padding-top: clamp(24px, 3.5vw, 40px);
  display: grid;
  gap: 14px;
}

.page-about .next-block__lede {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--text-dim);
  max-width: 46em;
}

.page-about .next-block .btn-row {
  margin-top: 6px;
  flex-wrap: wrap;
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 640px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .aud-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .flow__steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px 22px;
  }

  .page-about .flow__step {
    border-bottom: 0;
    padding-bottom: 0;
  }

  .page-about .principle-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .reach-band {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* ---------- 桌面：侧轨常驻 ---------- */
@media (min-width: 960px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 96px;
    align-self: start;
  }

  .page-about .chapter-nav__list {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 0;
    border-left: 1px solid var(--line);
    padding-left: 0;
  }

  .page-about .chapter-nav__link {
    display: flex;
    padding: 8px 0 8px 14px;
    margin-left: -1px;
    border-bottom: 0;
    border-left: 1px solid transparent;
    font-size: 13.5px;
  }

  .page-about .chapter-nav__link:hover,
  .page-about .chapter-nav__link:focus-visible {
    border-bottom-color: transparent;
    border-left-color: var(--flare);
    color: var(--paper);
  }

  .page-about .aud-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .flow__steps {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 12px;
  }

  .page-about .flow__step {
    grid-template-columns: minmax(0, 1fr);
    gap: 6px;
  }

  .page-about .flow__num {
    grid-row: auto;
  }

  .page-about .track {
    padding-left: 28px;
    gap: 22px;
  }

  .page-about .track__item::before {
    left: -33px;
    width: 11px;
    height: 11px;
  }

  .page-about .track-block__head {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 8px 40px;
    align-items: end;
  }

  .page-about .track-block__head .chapter__kicker {
    grid-column: 1 / -1;
  }

  .page-about .track-block__lede {
    margin: 0;
    align-self: end;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .chapter-nav__link,
  .page-about .track__note,
  .page-about .track__title,
  .page-about .track__item::before,
  .page-about .principle {
    transition: none;
  }
}
<<<END>>>