.page-about {
  --about-rail: 176px;
  background: var(--ink-950);
  color: var(--paper);
}

/* ---------- 首屏 ---------- */
.page-about__hero {
  position: relative;
  padding: 34px 0 46px;
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.page-about__hero::before {
  content: "";
  position: absolute;
  inset: -40% -12% auto -12%;
  height: 340px;
  pointer-events: none;
  background:
    radial-gradient(58% 100% at 26% 0%, rgba(53, 240, 200, .14), transparent 70%),
    radial-gradient(42% 92% at 88% 12%, rgba(255, 92, 57, .11), transparent 72%);
}

.page-about__hero > .shell {
  position: relative;
  z-index: 1;
}

.page-about__title {
  margin: 16px 0 0;
  max-width: 15em;
  font-family: var(--font-display);
  font-size: clamp(31px, 7.4vw, 58px);
  font-weight: 600;
  line-height: 1.06;
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__lede {
  margin: 16px 0 0;
  max-width: 620px;
  font-size: 16.5px;
  line-height: 1.75;
  color: var(--mute);
}

.page-about__figures {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin-top: 30px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about__figure {
  display: grid;
  gap: 4px;
  padding: 16px 18px;
  background: var(--ink-800);
}

.page-about__figure-value {
  font-family: var(--font-mono);
  font-size: 28px;
  line-height: 1;
  font-variant-numeric: tabular-nums;
  color: var(--mint-400);
  letter-spacing: -.01em;
}

.page-about__figure-label {
  font-size: 12.5px;
  letter-spacing: .04em;
  color: var(--mute);
}

/* ---------- 正文骨架 ---------- */
.page-about__body {
  padding-top: 44px;
  padding-bottom: 8px;
}

.page-about__flow {
  display: grid;
  gap: 52px;
}

.page-about__rail {
  display: none;
}

/* ---------- 章节通用 ---------- */
.page-about__chapter {
  scroll-margin-top: calc(var(--bar-h) + 20px);
}

.page-about__head {
  display: grid;
  gap: 7px;
  margin-bottom: 22px;
}

.page-about__num {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--ember-300);
  transition: color var(--dur) var(--ease);
}

.page-about__num::before {
  content: "";
  width: 2px;
  height: 13px;
  background: linear-gradient(180deg, var(--ember-500), rgba(255, 92, 57, 0));
}

.page-about__chapter.is-in .page-about__num {
  color: var(--ember-500);
}

.page-about__chapter h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(23px, 3.6vw, 34px);
  font-weight: 600;
  line-height: 1.18;
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__chapter h3 {
  margin: 0 0 7px;
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 500;
  line-height: 1.3;
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__chapter .prose {
  max-width: 68ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--paper);
}

.page-about__chapter .prose p + p {
  margin-top: 14px;
}

/* ---------- 图片容器 ---------- */
.page-about__figure {
  margin: 0 0 26px;
}

.page-about__media {
  overflow: hidden;
  background: var(--ink-700);
  border: 1px solid var(--line);
}

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

/* ---------- 引文块 ---------- */
.page-about__quote {
  margin-top: 24px;
  padding: 18px 20px;
  border-left: 2px solid var(--mint-400);
  font-size: 15px;
  line-height: 1.72;
  color: var(--mint-200);
}

/* ---------- 时间轴 ---------- */
.page-about__timeline {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about__tl-item {
  position: relative;
  margin-left: 5px;
  padding: 0 0 26px 28px;
  border-left: 1px solid var(--line);
}

.page-about__tl-item:last-child {
  padding-bottom: 0;
  border-left-color: transparent;
}

.page-about__tl-item::before {
  content: "";
  position: absolute;
  left: -5.5px;
  top: 5px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  border: 2px solid var(--teal-700);
  background: var(--ink-950);
}

.page-about__tl-item--now::before {
  border-color: var(--ember-500);
  background: var(--ember-500);
  box-shadow: 0 0 0 4px rgba(255, 92, 57, .15);
}

.page-about__tl-ver {
  display: inline-block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--mint-400);
}

.page-about__tl-item--now .page-about__tl-ver {
  color: var(--ember-300);
}

.page-about__tl-item p {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.72;
  color: var(--mute);
}

/* ---------- 团队分工 ---------- */
.page-about__crew {
  display: grid;
  gap: 1px;
  margin-top: 26px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about__crew-item {
  padding: 20px 18px;
  background: var(--ink-800);
}

.page-about__crew-count {
  display: block;
  font-family: var(--font-mono);
  font-size: 34px;
  line-height: 1;
  font-variant-numeric: tabular-nums;
  color: var(--mint-400);
}

.page-about__crew-role {
  display: block;
  margin-top: 9px;
  font-family: var(--font-display);
  font-size: 18px;
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__crew-desc {
  margin: 8px 0 0;
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--mute);
}

.page-about__note {
  margin: 18px 0 0;
  padding-left: 12px;
  max-width: 64ch;
  border-left: 2px solid var(--teal-700);
  font-size: 13px;
  line-height: 1.72;
  color: var(--mute);
}

/* ---------- 合作网络带 ---------- */
.page-about__net {
  display: grid;
  gap: 1px;
  margin-top: 26px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about__net-group {
  padding: 20px 18px;
  background: var(--ink-800);
}

.page-about__net-count {
  display: block;
  font-family: var(--font-mono);
  font-size: 32px;
  line-height: 1;
  font-variant-numeric: tabular-nums;
  color: var(--ember-300);
}

.page-about__net-label {
  display: block;
  margin-top: 9px;
  font-family: var(--font-display);
  font-size: 17px;
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__net-dots {
  display: grid;
  grid-template-columns: repeat(auto-fill, 13px);
  gap: 7px;
  margin-top: 16px;
}

.page-about__net-node {
  width: 13px;
  height: 13px;
  border-radius: 2px;
  background: rgba(14, 125, 106, .55);
  transition: transform var(--dur) var(--ease), background var(--dur) var(--ease);
}

.page-about__net-node:hover {
  transform: scale(1.5);
  background: var(--mint-400);
}

.page-about__net-group--community .page-about__net-node {
  background: rgba(255, 160, 122, .38);
}

.page-about__net-group--community .page-about__net-node:hover {
  background: var(--ember-500);
}

/* ---------- 使用场景 ---------- */
.page-about__scenes {
  list-style: none;
  display: grid;
  gap: 1px;
  margin: 24px 0 0;
  padding: 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about__scene {
  padding: 18px 16px;
  background: var(--ink-800);
}

.page-about__scene-when {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--mint-400);
}

.page-about__scene p {
  margin: 9px 0 0;
  font-size: 14px;
  line-height: 1.68;
  color: var(--mute);
}

/* ---------- 坚持条目 ---------- */
.page-about__creed {
  list-style: none;
  display: grid;
  gap: 18px;
  margin: 22px 0 0;
  padding: 0;
}

.page-about__creed-item {
  display: grid;
  gap: 5px;
  padding-left: 15px;
  border-left: 2px solid var(--line-strong);
}

.page-about__creed-key {
  font-family: var(--font-display);
  font-size: 18px;
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__creed-item p {
  margin: 0;
  max-width: 66ch;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--mute);
}

/* ---------- 收束引导 ---------- */
.page-about__end {
  padding-bottom: 12px;
}

.page-about__cta {
  display: grid;
  gap: 12px;
  padding: 26px 22px;
  border: 1px solid var(--line-strong);
}

.page-about__cta-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(21px, 3.2vw, 28px);
  letter-spacing: .02em;
  color: var(--paper);
}

.page-about__cta-text {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.72;
  color: var(--mint-200);
}

.page-about__cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 4px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 520px) {
  .page-about__figures {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about__figure {
    padding: 18px 20px;
  }

  .page-about__figure-value {
    font-size: clamp(24px, 4.6vw, 34px);
  }
}

@media (min-width: 720px) {
  .page-about__hero {
    padding: 44px 0 56px;
  }

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

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

  .page-about__creed {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px 28px;
  }

  .page-about__cta {
    padding: 34px 32px;
  }
}

@media (min-width: 960px) {
  .page-about__body {
    display: grid;
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: 44px;
    align-items: start;
    padding-top: 62px;
    padding-bottom: 16px;
  }

  .page-about__rail {
    display: block;
    align-self: start;
    position: sticky;
    top: calc(var(--bar-h) + 28px);
  }

  .page-about__rail-list {
    list-style: none;
    position: relative;
    margin: 0;
    padding: 0;
  }

  .page-about__rail-list::before {
    content: "";
    position: absolute;
    left: 6.5px;
    top: 14px;
    bottom: 14px;
    width: 1px;
    background: linear-gradient(180deg, rgba(53, 240, 200, .5), rgba(14, 125, 106, .34) 60%, transparent);
  }

  .page-about__rail-link {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 9px 0;
    font-size: 13px;
    line-height: 1.3;
    color: var(--mute);
    text-decoration: none;
    transition: color var(--dur) var(--ease);
  }

  .page-about__rail-link:hover,
  .page-about__rail-link:focus-visible {
    color: var(--mint-200);
  }

  .page-about__rail-dot {
    position: relative;
    z-index: 1;
    flex: 0 0 auto;
    display: grid;
    place-items: center;
    width: 14px;
    height: 14px;
    background: var(--ink-950);
  }

  .page-about__rail-dot::after {
    content: "";
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--teal-700);
    transition: background var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
  }

  .page-about__rail-link:hover .page-about__rail-dot::after,
  .page-about__rail-link:focus-visible .page-about__rail-dot::after {
    background: var(--mint-400);
    box-shadow: 0 0 0 4px rgba(53, 240, 200, .16);
  }

  .page-about__flow {
    gap: 74px;
  }

  .page-about__chapter {
    scroll-margin-top: calc(var(--bar-h) + 40px);
  }

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

  .page-about__tl-item {
    padding-bottom: 32px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about__net-node,
  .page-about__num,
  .page-about__rail-dot::after {
    transition: none;
  }

  .page-about__net-node:hover {
    transform: none;
  }
}