.page-about {
  --about-rail: 180px;
  --about-pad: clamp(2.25rem, 5vw, 3.75rem);
}

.page-about .crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .35rem;
  padding-top: 1.5rem;
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .05em;
  color: var(--muted);
}

.page-about .crumbs__item {
  color: var(--muted);
  text-decoration: none;
}

.page-about .crumbs a.crumbs__item:hover {
  color: var(--cyan);
}

.page-about .crumbs__item + .crumbs__item::before {
  content: "/";
  margin-right: .4rem;
  color: var(--line);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding: 1.75rem 0 clamp(2rem, 5vw, 3.25rem);
}

.page-about .about-hero::before {
  content: "";
  display: block;
  height: 10px;
  margin-bottom: 1.5rem;
  border-top: 1px solid var(--line);
  background-image: repeating-linear-gradient(to right, var(--line) 0 1px, transparent 1px 28px);
}

.page-about .about-hero .display {
  margin: 0 0 1.25rem;
  max-width: 20ch;
  line-height: 1.08;
}

.page-about .about-hero__lead {
  max-width: 62ch;
  margin: 0;
  font-size: clamp(1rem, 1.6vw, 1.12rem);
  line-height: 1.9;
  color: var(--text);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: 2.25rem 0 0;
  padding: 1.25rem 0 0;
  border-top: 1px solid var(--line);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.1rem .75rem;
}

.page-about .about-hero__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1.35rem;
  line-height: 1.1;
  color: var(--cyan);
}

.page-about .about-hero__key {
  display: block;
  margin-top: .35rem;
  font-size: .78rem;
  letter-spacing: .04em;
  color: var(--muted);
}

/* ---------- 两栏骨架 ---------- */

.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.75rem;
  padding-bottom: var(--pad-y);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 .5rem;
  display: flex;
  gap: .5rem;
  overflow-x: auto;
  scrollbar-width: none;
}

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

.page-about .about-rail__link {
  display: inline-block;
  white-space: nowrap;
  padding: .35rem .8rem;
  border: 1px solid var(--line);
  border-radius: var(--r-pill);
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--muted);
  text-decoration: none;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}

.page-about .about-rail__link:hover {
  color: var(--text);
}

.page-about .about-rail__link[aria-current="true"] {
  color: var(--cyan);
  border-color: var(--cyan);
}

/* ---------- 章节通用 ---------- */

.page-about .about-section {
  padding-top: var(--about-pad);
}

.page-about .about-body > .about-section:first-child {
  padding-top: .5rem;
}

.page-about .about-section__index {
  margin: 0 0 .7rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .2em;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .about-section .section__title {
  margin: 0 0 1rem;
  font-size: clamp(1.4rem, 3.4vw, 1.95rem);
  line-height: 1.3;
  letter-spacing: -.01em;
  color: var(--text);
}

.page-about .about-section .section__lead {
  max-width: 64ch;
  margin: 0 0 .5rem;
  font-size: .97rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .prose {
  max-width: 64ch;
}

.page-about .prose p {
  margin: 0 0 1.1rem;
  line-height: 1.9;
  color: var(--text);
}

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

.page-about .about-quote {
  max-width: 58ch;
  margin: 1.75rem 0;
  padding: .35rem 0 .35rem 1.25rem;
  border-left: 3px solid var(--amber);
  font-size: clamp(1rem, 2.2vw, 1.12rem);
  line-height: 1.85;
  color: var(--amber-soft);
}

/* ---------- 图片 ---------- */

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

.page-about .media img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--panel-2);
}

.page-about .media__cap {
  margin: .7rem 0 0;
  font-family: var(--font-mono);
  font-size: .78rem;
  line-height: 1.65;
  letter-spacing: .02em;
  color: var(--muted);
}

.page-about .about-figure {
  max-width: 440px;
  margin: 2.25rem 0 0;
}

.page-about .process-figure {
  max-width: 100%;
  margin: 0;
}

/* ---------- 时间线 ---------- */

.page-about .timeline {
  list-style: none;
  margin: 1.75rem 0 0;
  padding: 0 0 0 1.6rem;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: .6rem;
  bottom: 1rem;
  width: 1px;
  background: var(--line);
}

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

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -1.6rem;
  top: .68rem;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--cyan);
  transition: transform .24s var(--ease), box-shadow .24s var(--ease);
}

.page-about .timeline__item:has(details[open])::before {
  transform: scale(1.2);
  box-shadow: 0 0 0 5px rgba(0, 229, 200, .14);
}

.page-about .timeline__summary {
  display: flex;
  align-items: baseline;
  gap: .75rem;
  padding: .55rem 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .timeline__year {
  flex: none;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: .76rem;
  letter-spacing: .06em;
  color: var(--cyan);
}

.page-about .timeline__title {
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--text);
}

.page-about .timeline__summary::after {
  content: "＋";
  margin-left: auto;
  flex: none;
  font-family: var(--font-mono);
  color: var(--muted);
}

.page-about .timeline__details[open] .timeline__summary::after {
  content: "－";
  color: var(--amber);
}

.page-about .timeline__details[open] .timeline__title {
  color: var(--cyan-soft);
}

.page-about .timeline__body {
  max-width: 60ch;
  padding: .1rem 0 1rem;
  font-size: .94rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .timeline__body p {
  margin: 0;
}

.page-about .timeline__media {
  list-style: none;
  padding: 1.25rem 0 .5rem;
  max-width: 400px;
}

/* ---------- 团队 ---------- */

.page-about .team-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
  margin-top: 1.75rem;
}

.page-about .team-card {
  padding: 1.35rem 1.25rem 1.5rem;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--panel);
}

.page-about .team-card__role {
  margin: 0 0 .6rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .16em;
  color: var(--violet);
}

.page-about .team-card__count {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.9rem, 5vw, 2.4rem);
  line-height: 1;
  color: var(--text);
}

.page-about .team-card__unit {
  margin-left: .3rem;
  font-size: .85rem;
  color: var(--muted);
}

.page-about .team-card__text {
  margin: .9rem 0 0;
  font-size: .94rem;
  line-height: 1.82;
  color: var(--muted);
}

/* ---------- 流程 ---------- */

.page-about .process-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.75rem;
  margin-top: 1.75rem;
}

.page-about .flow {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: flow;
}

.page-about .flow__item {
  position: relative;
  padding: 0 0 1.4rem 3rem;
}

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

.page-about .flow__item::before {
  counter-increment: flow;
  content: counter(flow, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0;
  width: 2.1rem;
  height: 2.1rem;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--panel-2);
  font-family: var(--font-mono);
  font-size: .78rem;
  color: var(--cyan);
}

.page-about .flow__title {
  margin: 0 0 .3rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
}

.page-about .flow__text {
  margin: 0;
  font-size: .94rem;
  line-height: 1.82;
  color: var(--muted);
}

/* ---------- 覆盖范围 ---------- */

.page-about .scope-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.5rem;
  margin-top: 1.75rem;
}

.page-about .scope-block {
  padding-top: 1rem;
  border-top: 1px solid var(--line);
}

.page-about .scope-block__title {
  margin: 0 0 .85rem;
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .14em;
  color: var(--cyan);
}

.page-about .scope-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .scope-list li {
  position: relative;
  margin-bottom: .75rem;
  padding-left: 1rem;
  font-size: .94rem;
  line-height: 1.82;
  color: var(--muted);
}

.page-about .scope-list li:last-child {
  margin-bottom: 0;
}

.page-about .scope-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .72rem;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--violet);
}

/* ---------- 里程碑 ---------- */

.page-about .milestones {
  list-style: none;
  margin: 1.75rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
}

.page-about .milestone {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: 1.25rem 1.15rem;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--panel-2);
}

.page-about .milestone__num {
  flex: none;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1.35rem;
  line-height: 1.1;
  color: var(--amber);
}

.page-about .milestone__text {
  margin: 0;
  font-size: .93rem;
  line-height: 1.78;
  color: var(--muted);
}

/* ---------- 结尾行动 ---------- */

.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1.25rem;
  margin-top: 2.5rem;
  padding: 1.75rem 1.5rem;
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  background: linear-gradient(135deg, rgba(0, 229, 200, .09), rgba(183, 156, 255, .07) 62%, rgba(10, 20, 40, 0));
}

.page-about .about-cta p {
  flex: 1 1 17rem;
  margin: 0;
  font-size: .97rem;
  line-height: 1.8;
  color: var(--text);
}

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

/* ---------- 桌面版 ---------- */

@media (min-width: 760px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1rem;
  }

  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.25rem;
  }

  .page-about .team-card:nth-child(2) {
    margin-top: 1.75rem;
  }

  .page-about .team-card:nth-child(3) {
    margin-top: 3.5rem;
  }

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

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

  .page-about .milestone:nth-child(2) {
    margin-top: 1rem;
  }
}

@media (min-width: 900px) {
  .page-about .process-layout {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
    gap: 3rem;
    align-items: start;
  }
}

@media (min-width: 960px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 3.5rem;
  }

  .page-about .about-rail {
    position: sticky;
    top: 148px;
    align-self: start;
  }

  .page-about .about-rail__list {
    display: block;
    overflow: visible;
    padding: 0;
    position: relative;
  }

  .page-about .about-rail__list::before {
    content: "";
    position: absolute;
    left: 3px;
    top: 1rem;
    bottom: 1rem;
    width: 1px;
    background: var(--line);
  }

  .page-about .about-rail__link {
    display: block;
    position: relative;
    padding: .55rem 0 .55rem 1.3rem;
    border: 0;
    border-radius: 0;
    font-size: .74rem;
  }

  .page-about .about-rail__link::before {
    content: "";
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--panel-2);
    border: 1px solid var(--line);
    transition: transform .2s var(--ease), background .2s var(--ease), box-shadow .2s var(--ease);
  }

  .page-about .about-rail__link[aria-current="true"] {
    border: 0;
    color: var(--cyan);
  }

  .page-about .about-rail__link[aria-current="true"]::before {
    width: 9px;
    height: 9px;
    background: var(--cyan);
    border-color: var(--cyan);
    box-shadow: 0 0 0 4px rgba(0, 229, 200, .16);
  }

  .page-about .about-section {
    padding-top: clamp(3rem, 6vw, 4.5rem);
  }

  .page-about .prose p {
    font-size: 1.02rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .timeline__item::before,
  .page-about .about-rail__link,
  .page-about .about-rail__link::before {
    transition: none;
  }
}