.page-about {
  --about-gap: clamp(3.5rem, 8vw, 6.5rem);
  --p-dim: rgba(20, 24, 26, .72);
  --p-line: rgba(20, 24, 26, .13);

  position: relative;
  background: var(--ink-deep);
  color: var(--paper);
  overflow-x: clip;
}

/* ============ 首屏 ============ */
.page-about .about-hero {
  position: relative;
  padding: clamp(7rem, 15vw, 10.5rem) 0 clamp(2.5rem, 6vw, 4rem);
  background:
    radial-gradient(90% 110% at 88% -10%, rgba(53, 240, 200, .16), transparent 60%),
    linear-gradient(180deg, var(--ink-mid) 0%, var(--ink-deep) 78%);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(90deg, rgba(94, 122, 114, .13) 0 1px, transparent 1px 12.5%);
  pointer-events: none;
}

.page-about .about-hero > .wrap {
  position: relative;
  z-index: 1;
}

.page-about .about-hero__eyebrow {
  margin: 1.5rem 0 0;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-hero__title {
  margin: 1.1rem 0 1.4rem;
  max-width: 13em;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2.4rem, 8.4vw, 5.4rem);
  line-height: 1.02;
  letter-spacing: -.02em;
  color: var(--paper);
}

.page-about .about-hero__span {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin: 0 0 1.75rem;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.35rem, 4.4vw, 2.2rem);
  font-weight: 500;
  letter-spacing: .08em;
  color: var(--cyan);
}

.page-about .about-hero__rule {
  flex: 1 1 auto;
  max-width: 9rem;
  height: 1px;
  background: linear-gradient(90deg, var(--cyan), transparent);
}

.page-about .about-hero__lede {
  max-width: 60ch;
  color: var(--txt-dim);
}

.page-about .about-hero__stats {
  list-style: none;
  margin: 2.75rem 0 0;
  padding: 1.5rem 0 0;
  border-top: var(--hair);
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.page-about .about-hero__stats li {
  display: flex;
  flex-direction: column;
  gap: .35rem;
}

.page-about .about-hero__stats .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.5rem, 4.6vw, 2.3rem);
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-hero__stats small {
  font-size: .78rem;
  letter-spacing: .06em;
  color: var(--txt-faint);
}

/* 区间导航胶囊 */
.page-about .about-eranav {
  display: flex;
  gap: .6rem;
  margin-top: 2.75rem;
  padding-bottom: .4rem;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-eranav a {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  gap: .18rem;
  min-height: 44px;
  padding: .7rem 1.15rem;
  border: var(--hair-cyan);
  border-radius: var(--pill);
  text-decoration: none;
  color: var(--cyan-mist);
  font-size: .82rem;
  transition: background .2s var(--ease), color .2s var(--ease), border-color .2s var(--ease);
}

.page-about .about-eranav a:hover,
.page-about .about-eranav a:focus-visible {
  background: rgba(53, 240, 200, .13);
  border-color: var(--cyan);
  color: var(--cyan);
  outline: none;
}

.page-about .about-eranav .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  letter-spacing: .06em;
}

.page-about .about-eranav small {
  font-size: .72rem;
  letter-spacing: .08em;
  color: var(--txt-faint);
}

/* ============ 档案起点 ============ */
.page-about .about-origin {
  position: relative;
  padding: var(--about-gap) 0;
  background: var(--ink-deep);
}

.page-about .about-origin__grid {
  display: grid;
  gap: 2.5rem;
}

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

.page-about .about-origin__text .sec-head {
  margin-bottom: 1.5rem;
}

.page-about .about-origin__text .prose + .prose {
  margin-top: 1.1rem;
}

.page-about .prose {
  max-width: 68ch;
  color: var(--txt-dim);
}

/* ============ 三区间长卷 ============ */
.page-about .about-era {
  position: relative;
  padding: var(--about-gap) 0;
}

.page-about .about-era--wine {
  background: linear-gradient(180deg, var(--ink-deep) 0, var(--wine) 180px, var(--wine) 100%);
}

.page-about .about-era--mid {
  background: linear-gradient(180deg, var(--wine) 0, var(--ink-mid) 180px, var(--ink-mid) 100%);
}

.page-about .about-era--indigo {
  background: linear-gradient(180deg, var(--ink-mid) 0, var(--indigo) 180px, var(--indigo) 100%);
}

.page-about .about-era__grid {
  display: grid;
  gap: 1.75rem;
}

.page-about .about-era__rail {
  order: 0;
  display: flex;
  align-items: center;
  gap: .9rem;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.05rem, 3.4vw, 1.35rem);
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--cyan);
}

.page-about .about-era__rail-line {
  flex: 1 1 auto;
  max-width: 2.5rem;
  height: 1px;
  background: linear-gradient(90deg, var(--cyan), transparent);
}

.page-about .about-era__body { order: 1; }
.page-about .about-era__media { order: 2; }

.page-about .about-era__tag {
  display: inline-block;
  margin: 0 0 .9rem;
  padding: .32rem .75rem;
  border: var(--hair-cyan);
  border-radius: var(--pill);
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .14em;
  color: var(--cyan-mist);
}

.page-about .about-era__title {
  margin: 0 0 1.1rem;
  padding-bottom: .85rem;
  border-bottom: var(--hair-cyan);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.8rem, 5.6vw, 3.1rem);
  line-height: 1.08;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .about-era__lead {
  margin: 0;
  max-width: 54ch;
  font-size: 1rem;
  line-height: 1.78;
  color: rgba(245, 241, 232, .8);
}

.page-about .about-era__nodes {
  list-style: none;
  margin: 1.9rem 0 0;
  padding: 0;
  display: grid;
  gap: 1rem;
}

.page-about .about-era__nodes li {
  display: grid;
  grid-template-columns: 2.6rem minmax(0, 1fr);
  gap: .9rem;
  padding-top: .95rem;
  border-top: 1px solid rgba(245, 241, 232, .18);
}

.page-about .about-era__nodes .n {
  padding-top: .2rem;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: .84rem;
  letter-spacing: .08em;
  color: var(--cyan);
}

.page-about .about-era__nodes p {
  margin: 0;
  font-size: .95rem;
  line-height: 1.76;
  color: rgba(245, 241, 232, .84);
}

.page-about .about-era__media {
  margin: 0;
  border: var(--hair-cyan);
  border-radius: var(--radius);
  overflow: hidden;
}

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

.page-about .about-era__media .frame__caption {
  padding: .75rem 1rem;
  font-size: .78rem;
  line-height: 1.6;
  color: rgba(245, 241, 232, .6);
}

/* ============ 暖白工作区 ============ */
.page-about .about-paper {
  position: relative;
  padding: var(--about-gap) 0;
  background:
    radial-gradient(90% 60% at 100% 0%, rgba(53, 240, 200, .09), transparent 60%),
    var(--paper);
  color: var(--char);
}

.page-about .about-paper__stack {
  display: grid;
  gap: clamp(3rem, 7vw, 5rem);
}

.page-about .about-block {
  position: relative;
}

.page-about .about-block + .about-block {
  padding-top: clamp(3rem, 7vw, 5rem);
  border-top: 1px solid var(--p-line);
}

.page-about .about-paper .prose {
  color: var(--p-dim);
}

.page-about .about-paper .sec-head {
  margin-bottom: 1.35rem;
}

.page-about .about-paper .sec-head__num {
  color: var(--wine);
}

.page-about .about-paper .sec-head__title {
  color: var(--char);
}

.page-about .about-paper__lede {
  max-width: 60ch;
  color: var(--p-dim);
}

.page-about .about-block__intro {
  margin-bottom: 0;
}

/* 工作四步 */
.page-about .about-steps {
  display: grid;
  gap: 1rem;
  margin-top: 2.4rem;
  padding-bottom: 1.5rem;
}

.page-about .step-card {
  background: #fff;
  border: 1px solid var(--p-line);
  border-radius: var(--radius);
  padding: 1.2rem 1.2rem 1rem;
  box-shadow: 0 18px 34px -34px rgba(0, 0, 0, .7);
  transition: border-color .22s var(--ease), box-shadow .22s var(--ease);
}

.page-about .step-card:hover {
  border-color: rgba(11, 42, 38, .38);
}

.page-about .step-card[open] {
  border-color: rgba(11, 42, 38, .5);
  box-shadow: 0 22px 40px -34px rgba(11, 42, 38, .85);
}

.page-about .step-card > summary {
  display: flex;
  align-items: center;
  gap: .7rem;
  min-height: 44px;
  list-style: none;
  cursor: pointer;
  font-weight: 700;
  font-size: 1.02rem;
  color: var(--char);
}

.page-about .step-card > summary::-webkit-details-marker { display: none; }

.page-about .step-card > summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: rgba(20, 24, 26, .42);
}

.page-about .step-card[open] > summary::after { content: "–"; }

.page-about .step-card__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: .84rem;
  letter-spacing: .08em;
  color: var(--wine);
}

.page-about .step-card__body {
  margin: .9rem 0 0;
  padding-top: .9rem;
  border-top: 1px solid var(--p-line);
  font-size: .94rem;
  line-height: 1.78;
  color: var(--p-dim);
}

/* 团队 */
.page-about .about-team {
  display: grid;
  gap: 1.5rem;
}

/* 覆盖范围数字 */
.page-about .about-stats {
  margin-top: 2.4rem;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--p-line);
  border: 1px solid var(--p-line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .about-stats > div {
  display: flex;
  flex-direction: column;
  gap: .4rem;
  padding: 1.25rem 1.1rem;
  background: var(--paper);
}

.page-about .about-stats .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.65rem, 5vw, 2.3rem);
  font-weight: 700;
  line-height: 1;
  color: var(--ink-deep);
}

.page-about .about-stats span:last-child {
  font-size: .82rem;
  line-height: 1.55;
  color: var(--p-dim);
}

/* 维护节奏 */
.page-about .about-rhythm {
  margin-top: 2.5rem;
}

.page-about .about-rhythm__title {
  margin: 0 0 1.25rem;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.15rem, 3.4vw, 1.5rem);
  letter-spacing: .01em;
  color: var(--char);
}

.page-about .about-rhythm__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1rem;
}

.page-about .about-rhythm__list li {
  display: grid;
  grid-template-columns: 5.5rem minmax(0, 1fr);
  gap: 1rem;
  align-items: baseline;
  padding-top: .9rem;
  border-top: 1px solid var(--p-line);
}

.page-about .about-rhythm__list .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: .95rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--wine);
}

.page-about .about-rhythm__list p {
  margin: 0;
  font-size: .95rem;
  line-height: 1.75;
  color: var(--p-dim);
}

/* 版本演进 */
.page-about .about-versions {
  list-style: none;
  margin: 2.2rem 0 0;
  padding: 0 0 0 1.4rem;
  border-left: 1px solid var(--p-line);
}

.page-about .about-versions li {
  position: relative;
  display: grid;
  grid-template-columns: 4.2rem minmax(0, 1fr);
  gap: 1.1rem;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--p-line);
}

.page-about .about-versions li:last-child { border-bottom: none; }

.page-about .about-versions li::before {
  content: "";
  position: absolute;
  left: -1.4rem;
  top: 1.7rem;
  width: 7px;
  height: 7px;
  margin-left: -4px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 4px var(--paper), 0 0 0 5px rgba(11, 42, 38, .18);
}

.page-about .about-versions .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--wine);
  line-height: 1.4;
}

.page-about .about-versions p {
  margin: 0;
  font-size: .95rem;
  line-height: 1.78;
  color: var(--p-dim);
}

.page-about .about-versions strong {
  color: var(--char);
  font-weight: 700;
}

/* 收尾 */
.page-about .about-cta {
  margin-top: clamp(3rem, 7vw, 5rem);
  padding: clamp(1.75rem, 5vw, 3rem);
  border-radius: var(--radius);
  background:
    radial-gradient(90% 120% at 92% 0%, rgba(53, 240, 200, .18), transparent 58%),
    var(--ink-deep);
  color: var(--paper);
  box-shadow: var(--shadow);
}

.page-about .about-cta__title {
  margin: 0 0 .9rem;
  max-width: 22ch;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.5rem, 4.6vw, 2.3rem);
  line-height: 1.12;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .about-cta__text {
  margin: 0 0 1.75rem;
  max-width: 58ch;
  font-size: .98rem;
  line-height: 1.78;
  color: var(--txt-dim);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
}

.page-about .about-cta__actions .btn {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  text-decoration: none;
}

/* ============ 响应式 ============ */
@media (min-width: 640px) {
  .page-about .about-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1.1rem;
  }

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

  .page-about .about-team {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 2.5rem;
  }
}

@media (min-width: 900px) {
  .page-about .about-origin__grid {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
    gap: 4rem;
    align-items: start;
  }

  .page-about .about-era__grid {
    grid-template-columns: 5rem minmax(0, 1fr);
    gap: 3rem;
    align-items: start;
  }

  .page-about .about-era__rail {
    position: sticky;
    top: 8rem;
    align-self: start;
    flex-direction: column;
    align-items: flex-start;
    gap: 1.4rem;
    padding-top: .5rem;
  }

  .page-about .about-era__rail-line {
    flex: 0 0 auto;
    width: 1px;
    max-width: none;
    height: 5rem;
    background: linear-gradient(180deg, var(--cyan), transparent);
  }

  .page-about .about-era--media-right .about-era__grid {
    grid-template-columns: 5rem minmax(0, 1.35fr) minmax(0, .95fr);
    gap: 2.5rem;
  }

  .page-about .about-era--media-left .about-era__grid {
    grid-template-columns: 5rem minmax(0, .95fr) minmax(0, 1.35fr);
    gap: 2.5rem;
  }

  .page-about .about-era--media-right .about-era__rail,
  .page-about .about-era--media-left .about-era__rail {
    grid-column: 1;
    grid-row: 1;
  }

  .page-about .about-era--media-right .about-era__body {
    grid-column: 2;
    grid-row: 1;
    order: 0;
  }

  .page-about .about-era--media-right .about-era__media {
    grid-column: 3;
    grid-row: 1;
    order: 0;
    margin-top: 2.5rem;
  }

  .page-about .about-era--media-left .about-era__media {
    grid-column: 2;
    grid-row: 1;
    order: 0;
    margin-top: 4rem;
  }

  .page-about .about-era--media-left .about-era__body {
    grid-column: 3;
    grid-row: 1;
    order: 0;
  }

  .page-about .about-rhythm__list li {
    grid-template-columns: 6.5rem minmax(0, 1fr);
    gap: 1.5rem;
  }
}

@media (min-width: 1080px) {
  .page-about .about-steps {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1.25rem;
    padding-bottom: 2.75rem;
  }

  .page-about .about-steps > .step-card:nth-child(2) { transform: translateY(1.75rem); }
  .page-about .about-steps > .step-card:nth-child(3) { transform: translateY(.6rem); }
  .page-about .about-steps > .step-card:nth-child(4) { transform: translateY(2.4rem); }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .step-card,
  .page-about .about-eranav a {
    transition: none;
  }
}