.page-about {
  --about-rail: 72px;
  --about-flow-gap: clamp(1.75rem, 3vw, 3rem);
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumb {
  margin-top: clamp(1rem, 2vw, 1.75rem);
}

/* ---------- 图片容器统一 ---------- */
.page-about .media-frame img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page-about .media-frame__caption {
  position: static;
  inset: auto;
  margin: .75rem 0 0;
  padding: 0;
  font-size: var(--fs-sm);
  line-height: 1.65;
  color: var(--rock-300);
}

/* ---------- 开篇框景 ---------- */
.page-about .about-open {
  padding-top: clamp(1.5rem, 4vw, 3rem);
}

.page-about .about-open__frame {
  position: relative;
  margin: 0;
  padding: clamp(.4rem, .9vw, .75rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: linear-gradient(180deg, rgba(18, 38, 61, .92), rgba(8, 17, 31, .58));
  box-shadow: 0 50px 110px -60px rgba(0, 0, 0, .95);
}

.page-about .about-open__frame::before,
.page-about .about-open__frame::after {
  content: "";
  position: absolute;
  width: 26px;
  height: 26px;
  border: 1px solid var(--cyan-400);
  opacity: .6;
  pointer-events: none;
}

.page-about .about-open__frame::before {
  top: -1px;
  left: -1px;
  border-right: 0;
  border-bottom: 0;
  border-top-left-radius: var(--radius-lg);
}

.page-about .about-open__frame::after {
  right: -1px;
  bottom: -1px;
  border-top: 0;
  border-left: 0;
  border-bottom-right-radius: var(--radius-lg);
}

.page-about .about-open__frame .media-frame {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  border-radius: calc(var(--radius-lg) - 8px);
  background: var(--ink-900);
}

.page-about .about-open__copy {
  max-width: 44rem;
  margin-top: clamp(1.75rem, 4vw, 3rem);
}

.page-about .about-open__copy .eyebrow {
  color: var(--cyan-400);
}

.page-about .about-open__copy .display-title {
  margin: .7rem 0 1.15rem;
  font-family: var(--font-head);
  font-size: var(--fs-display);
  font-weight: 800;
  line-height: 1.06;
  letter-spacing: -.01em;
  color: var(--paper-50);
}

.page-about .about-open__copy .lede {
  margin: 0;
  font-size: clamp(1rem, 1.35vw, 1.1rem);
  line-height: 1.85;
  color: var(--rock-300);
}

.page-about .about-open__tags {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin: clamp(1.25rem, 3vw, 1.75rem) 0 0;
  padding: 0;
  list-style: none;
}

/* ---------- 索引轨 + 内容流 ---------- */
.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-flow-gap);
  margin-top: clamp(2.5rem, 6vw, 5rem);
}

.page-about .index-rail {
  display: flex;
  flex-direction: row;
  gap: .35rem;
  overflow-x: auto;
  padding: .35rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--glass);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  scrollbar-width: none;
}

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

.page-about .index-rail__item {
  display: inline-flex;
  align-items: center;
  gap: .45rem;
  flex: 0 0 auto;
  padding: .4rem .8rem;
  border-radius: 999px;
  color: var(--rock-300);
  font-size: var(--fs-sm);
  text-decoration: none;
  white-space: nowrap;
  transition: color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .index-rail__item:hover {
  color: var(--paper-50);
}

.page-about .index-rail__item[aria-current="true"],
.page-about .index-rail__item[aria-current="step"] {
  color: var(--ink-950);
  background: var(--cyan-400);
}

.page-about .index-rail__num {
  display: inline-grid;
  place-items: center;
  width: 1.55rem;
  height: 1.55rem;
  flex: 0 0 auto;
  border-radius: 50%;
  border: 1px solid var(--line-strong);
  background: var(--ink-900);
  font-family: var(--font-mono);
  font-size: .66rem;
  line-height: 1;
  color: var(--cyan-400);
  transition: background-color 180ms var(--ease), color 180ms var(--ease);
}

.page-about .index-rail__item[aria-current="true"] .index-rail__num,
.page-about .index-rail__item[aria-current="step"] .index-rail__num {
  background: var(--ink-950);
  color: var(--cyan-400);
}

.page-about .about-flow {
  display: grid;
  gap: clamp(3rem, 6vw, 5.5rem);
  min-width: 0;
}

.page-about .about-flow > .section {
  scroll-margin-top: 7rem;
}

/* ---------- 章节标题区 ---------- */
.page-about .section-head {
  display: flex;
  flex-direction: column;
  gap: .7rem;
  margin-bottom: clamp(1.5rem, 3vw, 2.25rem);
}

.page-about .section-head h2 {
  margin: 0;
  font-family: var(--font-head);
  font-size: var(--fs-h1);
  font-weight: 700;
  line-height: 1.18;
  letter-spacing: -.005em;
  color: var(--paper-50);
}

.page-about .section-head .eyebrow {
  color: var(--cyan-400);
}

/* ---------- 起点长文 ---------- */
.page-about .about-narrow {
  max-width: 42rem;
}

.page-about .about-narrow p {
  margin: 0;
  color: var(--rock-300);
  line-height: 1.9;
}

.page-about .about-narrow p + p {
  margin-top: 1.1rem;
}

/* ---------- 版本对照带 ---------- */
.page-about .about-versions__figure .media-frame {
  aspect-ratio: 3 / 2;
  overflow: hidden;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--ink-900);
}

.page-about .about-versions__rail {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: minmax(260px, 78vw);
  gap: 1rem;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding-bottom: .85rem;
  -webkit-overflow-scrolling: touch;
}

.page-about .version-card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: .55rem;
  scroll-snap-align: start;
  padding: clamp(1rem, 2vw, 1.4rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(18, 38, 61, .92), rgba(12, 27, 46, .78));
  overflow: hidden;
  transition: border-color 220ms var(--ease), transform 220ms var(--ease);
}

.page-about .version-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 42%;
  background: linear-gradient(180deg, var(--cyan-400), transparent);
  opacity: .55;
}

.page-about .version-card:hover {
  border-color: var(--line-strong);
  transform: translateY(-3px);
}

.page-about .version-card__num {
  font-family: var(--font-mono);
  font-size: clamp(1.6rem, 3.2vw, 2.1rem);
  font-weight: 700;
  line-height: 1;
  color: var(--cyan-400);
}

.page-about .version-card__when {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-tag);
  letter-spacing: .06em;
  color: var(--gold-400);
}

.page-about .version-card__title {
  margin: 0;
  font-family: var(--font-head);
  font-size: var(--fs-h3);
  font-weight: 700;
  line-height: 1.3;
  color: var(--paper-50);
}

.page-about .version-card__body {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.78;
  color: var(--rock-300);
}

.page-about .version-card__fix {
  margin: auto 0 0;
  padding-top: .7rem;
  border-top: 1px dashed var(--line);
  font-size: var(--fs-tag);
  letter-spacing: .04em;
  color: var(--gold-200);
}

/* ---------- 团队分工 ---------- */
.page-about .about-team__grid {
  gap: clamp(1rem, 2vw, 1.4rem);
}

.page-about .team-card {
  display: flex;
  flex-direction: column;
  gap: .6rem;
  padding: clamp(1.1rem, 2.2vw, 1.6rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(18, 38, 61, .9), rgba(12, 27, 46, .72));
  transition: border-color 220ms var(--ease), box-shadow 220ms var(--ease);
}

.page-about .team-card:hover,
.page-about .team-card:focus-within,
.page-about .team-card:focus {
  border-color: var(--line-strong);
  box-shadow: 0 26px 60px -46px rgba(63, 224, 208, .8);
  outline: none;
}

.page-about .team-card__tag {
  margin: 0;
  align-self: flex-start;
  padding: .25rem .6rem;
  border-radius: 999px;
  background: rgba(63, 224, 208, .12);
  border: 1px solid var(--line-strong);
  font-size: var(--fs-tag);
  letter-spacing: .06em;
  color: var(--cyan-200);
}

.page-about .team-card__title {
  margin: 0;
  font-family: var(--font-head);
  font-size: 1.2rem;
  font-weight: 700;
  line-height: 1.35;
  color: var(--paper-50);
}

.page-about .team-card__desc {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.78;
  color: var(--rock-300);
}

.page-about .team-card__more {
  display: grid;
  gap: .55rem;
  max-height: 26rem;
  opacity: 1;
  overflow: hidden;
  transition: max-height 340ms var(--ease), opacity 300ms var(--ease), margin-top 340ms var(--ease);
}

.page-about .team-card__more p {
  margin: 0;
  padding-left: .75rem;
  border-left: 2px solid rgba(63, 224, 208, .35);
  font-size: var(--fs-sm);
  line-height: 1.75;
  color: var(--rock-300);
}

.page-about .team-card__cadence {
  margin: auto 0 0;
  padding-top: .85rem;
  border-top: 1px dashed var(--line);
  font-size: var(--fs-sm);
  color: var(--gold-200);
}

/* ---------- 资料库积累 ---------- */
.page-about .about-library__figure {
  margin-bottom: clamp(1.5rem, 3vw, 2.25rem);
}

.page-about .about-library__figure .media-frame {
  aspect-ratio: 21 / 9;
  overflow: hidden;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--ink-900);
}

.page-about .about-metrics {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(.8rem, 1.6vw, 1.25rem);
}

.page-about .metric-card {
  padding: clamp(.9rem, 1.8vw, 1.3rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.page-about .metric-card__value {
  display: flex;
  align-items: baseline;
  gap: .25rem;
  margin: 0;
}

.page-about .metric-card__num {
  font-family: var(--font-mono);
  font-size: clamp(1.8rem, 4.4vw, 2.6rem);
  font-weight: 700;
  line-height: 1;
  color: var(--gold-400);
}

.page-about .metric-card__unit {
  font-size: var(--fs-sm);
  color: var(--gold-200);
}

.page-about .metric-card__label {
  margin: .6rem 0 0;
  font-family: var(--font-head);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--paper-50);
}

.page-about .metric-card__note {
  margin: .35rem 0 0;
  font-size: var(--fs-sm);
  line-height: 1.7;
  color: var(--rock-300);
}

.page-about .about-split {
  margin: clamp(1.5rem, 3vw, 2.25rem) 0 0;
}

.page-about .about-split__bar {
  display: flex;
  gap: 4px;
  height: 10px;
  overflow: hidden;
  border-radius: 999px;
}

.page-about .about-split__seg {
  flex: 1 1 0;
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(63, 224, 208, .75), rgba(63, 224, 208, .28));
}

.page-about .about-split__seg:nth-child(2) {
  background: linear-gradient(90deg, rgba(242, 180, 92, .8), rgba(242, 180, 92, .3));
}

.page-about .about-split__seg:nth-child(3) {
  background: linear-gradient(90deg, rgba(168, 243, 236, .7), rgba(168, 243, 236, .25));
}

.page-about .about-split__seg:nth-child(4) {
  background: linear-gradient(90deg, rgba(255, 217, 160, .75), rgba(255, 217, 160, .28));
}

.page-about .about-split__legend {
  display: flex;
  flex-wrap: wrap;
  gap: .4rem .9rem;
  margin: .85rem 0 0;
  padding: 0;
  list-style: none;
  font-size: var(--fs-tag);
  letter-spacing: .05em;
  color: var(--rock-300);
}

.page-about .about-split figcaption {
  margin-top: .6rem;
  font-size: var(--fs-sm);
  line-height: 1.7;
  color: var(--rock-300);
}

/* ---------- 服务覆盖与响应 ---------- */
.page-about .about-reach {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.25rem, 2.5vw, 2rem);
}

.page-about .about-reach__scope {
  padding: clamp(1.1rem, 2.2vw, 1.6rem);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: linear-gradient(160deg, rgba(63, 224, 208, .1), rgba(12, 27, 46, .8) 55%);
}

.page-about .about-reach__big {
  display: flex;
  align-items: baseline;
  gap: .45rem;
  margin: 0;
  font-family: var(--font-head);
  font-size: var(--fs-h3);
  font-weight: 700;
  color: var(--paper-50);
}

.page-about .about-reach__num {
  font-family: var(--font-mono);
  font-size: clamp(2.2rem, 5vw, 3rem);
  font-weight: 700;
  line-height: 1;
  color: var(--cyan-400);
}

.page-about .about-reach__note {
  margin: .9rem 0 0;
  font-size: var(--fs-sm);
  line-height: 1.8;
  color: var(--rock-300);
}

.page-about .about-reach__facts {
  display: grid;
  gap: .55rem;
  margin: 1.2rem 0 0;
  padding: 1rem 0 0;
  border-top: 1px dashed var(--line);
}

.page-about .about-reach__fact {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
}

.page-about .about-reach__fact dt {
  font-size: var(--fs-sm);
  color: var(--rock-300);
}

.page-about .about-reach__fact dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  color: var(--gold-200);
  text-align: right;
}

.page-about .about-reach__steps {
  display: grid;
  gap: .8rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-reach__step {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: .9rem;
  align-items: start;
  padding: .95rem 1.05rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  transition: border-color 200ms var(--ease);
}

.page-about .about-reach__step:hover {
  border-color: var(--line-strong);
}

.page-about .about-reach__stepnum {
  font-family: var(--font-mono);
  font-size: .82rem;
  font-weight: 700;
  line-height: 1.9;
  color: var(--cyan-400);
}

.page-about .about-reach__step h3 {
  margin: 0 0 .3rem;
  font-family: var(--font-head);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--paper-50);
}

.page-about .about-reach__step p {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.78;
  color: var(--rock-300);
}

/* ---------- 持续节奏 ---------- */
.page-about .about-rhythm {
  display: grid;
  gap: clamp(1rem, 2vw, 1.5rem);
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-rhythm__item {
  position: relative;
  padding: 0 0 0 3.2rem;
}

.page-about .about-rhythm__item::before {
  content: "";
  position: absolute;
  left: 1rem;
  top: 1.9rem;
  bottom: -1.5rem;
  width: 1px;
  background: linear-gradient(180deg, rgba(63, 224, 208, .45), transparent);
}

.page-about .about-rhythm__item:last-child::before {
  display: none;
}

.page-about .about-rhythm__num {
  position: absolute;
  left: 0;
  top: 0;
  display: inline-grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  border: 1px solid var(--line-strong);
  background: var(--ink-900);
  font-family: var(--font-mono);
  font-size: .72rem;
  color: var(--cyan-400);
}

.page-about .about-rhythm__item h3 {
  margin: 0 0 .35rem;
  font-family: var(--font-head);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--paper-50);
}

.page-about .about-rhythm__item p {
  margin: 0;
  max-width: 40rem;
  font-size: var(--fs-sm);
  line-height: 1.82;
  color: var(--rock-300);
}

.page-about .about-cta {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: clamp(2rem, 4vw, 3rem);
  padding: clamp(1.2rem, 2.4vw, 1.8rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: linear-gradient(120deg, rgba(18, 38, 61, .9), rgba(8, 17, 31, .7));
}

.page-about .about-cta p {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.8;
  color: var(--rock-300);
}

.page-about .about-cta .row {
  display: flex;
  flex-wrap: wrap;
  gap: .7rem;
}

/* ---------- 平板 ---------- */
@media (min-width: 720px) {
  .page-about .about-open__frame .media-frame {
    aspect-ratio: 16 / 7;
  }

  .page-about .about-library__figure .media-frame {
    aspect-ratio: 21 / 8;
  }

  .page-about .about-versions__rail {
    grid-auto-columns: minmax(300px, 1fr);
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-about .about-versions__head {
    display: grid;
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    gap: clamp(1.5rem, 3vw, 3rem);
    align-items: center;
  }

  .page-about .about-versions__head .media-frame {
    margin: 0;
  }

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

  .page-about .about-reach {
    grid-template-columns: minmax(0, .85fr) minmax(0, 1.15fr);
    align-items: start;
  }

  .page-about .about-cta {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
  }

  .page-about .about-cta p {
    max-width: 34rem;
  }

  .page-about .team-card__more {
    max-height: 0;
    opacity: 0;
    margin-top: 0;
  }

  .page-about .team-card:hover .team-card__more,
  .page-about .team-card:focus-within .team-card__more,
  .page-about .team-card:focus .team-card__more {
    max-height: 26rem;
    opacity: 1;
    margin-top: .3rem;
  }
}

@media (min-width: 1024px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(2rem, 4vw, 4rem);
    align-items: start;
  }

  .page-about .index-rail {
    position: sticky;
    top: 6.5rem;
    flex-direction: column;
    align-items: stretch;
    gap: 1.15rem;
    overflow: visible;
    padding: 0 0 0 2px;
    border: 0;
    border-radius: 0;
    background: none;
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
  }

  .page-about .index-rail::before {
    content: "";
    position: absolute;
    left: 13px;
    top: .55rem;
    bottom: .55rem;
    width: 1px;
    background: linear-gradient(180deg, transparent, rgba(63, 224, 208, .34) 12%, rgba(63, 224, 208, .34) 88%, transparent);
  }

  .page-about .index-rail__item {
    padding: 0;
    border-radius: 0;
    background: none;
    font-size: var(--fs-tag);
    letter-spacing: .05em;
  }

  .page-about .index-rail__item:hover,
  .page-about .index-rail__item[aria-current="true"],
  .page-about .index-rail__item[aria-current="step"] {
    color: var(--cyan-400);
    background: none;
  }

  .page-about .index-rail__item[aria-current="true"] .index-rail__num,
  .page-about .index-rail__item[aria-current="step"] .index-rail__num {
    background: var(--cyan-400);
    color: var(--ink-950);
    border-color: var(--cyan-400);
  }

  .page-about .about-versions__rail {
    grid-auto-flow: row;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    grid-auto-columns: auto;
    overflow: visible;
    padding-bottom: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .version-card,
  .page-about .team-card,
  .page-about .team-card__more,
  .page-about .about-reach__step,
  .page-about .index-rail__item,
  .page-about .index-rail__num {
    transition: none;
  }
}