.page-about {
  --about-text: #C3D3E1;
  --about-dim: #8CA3B8;
}

.page-about a:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

/* ---------- 页头 ---------- */
.page-about .page-head {
  padding: 30px 0 26px;
  border-bottom: 1px solid var(--line);
}

.page-about .page-head .breadcrumb {
  margin: 0 0 22px;
}

.page-about .page-head .kicker {
  margin: 0 0 12px;
}

.page-about .page-head h1 {
  margin: 0;
  max-width: 22ch;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(28px, 6.4vw, 44px);
  line-height: 1.16;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .page-head__lead {
  margin: 18px 0 0;
  max-width: 54ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--about-text);
}

.page-about .about-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 26px;
  margin: 26px 0 0;
  padding: 16px 0 0;
  border-top: 1px solid var(--line);
  list-style: none;
}

.page-about .about-facts li {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.02em;
  color: var(--about-dim);
}

.page-about .about-facts b {
  color: var(--paper);
  font-weight: 700;
}

/* ---------- 首屏横幅 ---------- */
.page-about .about-banner {
  margin: 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-banner img {
  display: block;
  width: 100%;
  height: auto;
  background: var(--panel);
}

/* ---------- 主体栅格 ---------- */
.page-about .about-shell {
  padding-top: 10px;
}

.page-about .about-timeline {
  position: sticky;
  top: var(--head-h);
  z-index: 6;
  margin: 0 -20px;
  padding: 10px 20px;
  background: var(--ink);
  border-bottom: 1px solid var(--line);
}

.page-about .about-timeline__label {
  display: none;
}

.page-about .about-timeline__list {
  display: flex;
  gap: 18px;
  margin: 0;
  padding: 0 0 2px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

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

.page-about .about-timeline__list > li {
  flex: 0 0 auto;
}

.page-about .sec-index__link {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 4px 0;
  font-size: 13px;
  line-height: 1.4;
  white-space: nowrap;
  text-decoration: none;
  color: var(--about-dim);
  border-bottom: 2px solid transparent;
  transition: color 160ms ease, border-color 160ms ease;
}

.page-about .sec-index__link[data-active] {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

.page-about .about-timeline__era {
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--line);
}

.page-about .about-flow {
  padding-top: 6px;
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  padding: 38px 0 42px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-chapter:last-child {
  border-bottom: 0;
  padding-bottom: 8px;
}

.page-about .about-chapter__no {
  display: inline-block;
  margin: 0 0 10px;
  padding-bottom: 5px;
  font-family: var(--font-mono);
  font-size: 22px;
  line-height: 1;
  letter-spacing: 0.04em;
  color: var(--cyan);
  border-bottom: 2px solid var(--cyan-soft);
}

.page-about .about-chapter__title h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(21px, 3.4vw, 28px);
  line-height: 1.25;
  letter-spacing: -0.005em;
  color: var(--paper);
}

.page-about .about-chapter__lead {
  margin: 14px 0 0;
  max-width: 52ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-dim);
}

.page-about .about-chapter__body {
  margin-top: 26px;
}

.page-about .about-chapter__body > p {
  margin: 0 0 16px;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--about-text);
}

.page-about .about-chapter__more {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 26px 0 0;
}

/* ---------- 01 阶段线索 ---------- */
.page-about .about-trace {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
}

.page-about .about-trace__item {
  position: relative;
  display: grid;
  gap: 6px;
  padding: 14px 0 14px 18px;
  border-left: 1px solid var(--line);
}

.page-about .about-trace__item::before {
  content: "";
  position: absolute;
  left: -3px;
  top: 22px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--cyan);
}

.page-about .about-trace__when {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan-soft);
}

.page-about .about-trace__item p {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---------- 02 栏目分类 ---------- */
.page-about .about-taxonomy {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-taxonomy__item {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 4px 14px;
  padding: 20px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-taxonomy__item:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .about-taxonomy__no {
  font-size: 14px;
  line-height: 1.6;
  color: var(--cyan);
}

.page-about .about-taxonomy__text h3 {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .about-taxonomy__text p {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---------- 图框 ---------- */
.page-about .about-figure {
  margin: 28px 0 0;
  border: 1px solid var(--line);
  border-radius: 2px;
  background: var(--panel);
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

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

.page-about .about-figure figcaption {
  padding: 10px 16px;
  border-top: 1px solid var(--line);
  font-size: 12px;
  letter-spacing: 0.02em;
  color: var(--about-dim);
}

/* ---------- 03 团队 ---------- */
.page-about .about-teams {
  display: grid;
  gap: 16px;
}

.page-about .about-team {
  border-top: 2px solid var(--cyan);
  padding-top: 18px;
}

.page-about .about-team__role {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan-soft);
}

.page-about .about-team h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .about-team p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--about-text);
}

.page-about .about-pipeline {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
}

.page-about .about-pipeline li {
  position: relative;
  padding: 0 0 20px 24px;
  border-left: 1px solid var(--line);
}

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

.page-about .about-pipeline li::before {
  content: "";
  position: absolute;
  left: -4px;
  top: 6px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--cyan);
}

.page-about .about-pipeline__step {
  display: block;
  margin-bottom: 6px;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--cyan-soft);
}

.page-about .about-pipeline li p {
  margin: 0;
  max-width: 58ch;
  font-size: 14px;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---------- 04 更新节奏 ---------- */
.page-about .about-cadence {
  margin: 0;
  padding: 0;
}

.page-about .about-cadence > div {
  display: grid;
  gap: 6px;
  padding: 15px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-cadence > div:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .about-cadence dt {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan-soft);
}

.page-about .about-cadence dd {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---------- 05 服务 ---------- */
.page-about .about-service {
  display: grid;
  gap: 22px;
}

.page-about .about-service__item {
  padding-left: 16px;
  border-left: 2px solid var(--line);
}

.page-about .about-service__item h3 {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 16px;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .about-service__item p {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---------- 06 推进方向 ---------- */
.page-about .about-next {
  counter-reset: about-nx;
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-next li {
  counter-increment: about-nx;
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  gap: 14px;
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-next li:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .about-next li::before {
  content: counter(about-nx, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.9;
  color: var(--cyan);
}

.page-about .about-next__text h3 {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .about-next__text p {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-text);
}

/* ---------- 桌面端 ---------- */
@media (min-width: 960px) {
  .page-about .about-shell {
    display: grid;
    grid-template-columns: 232px minmax(0, 1fr);
    gap: 0 56px;
    align-items: start;
    padding-top: 24px;
  }

  .page-about .about-timeline {
    position: sticky;
    top: calc(var(--head-h) + 34px);
    z-index: 2;
    margin: 0;
    padding: 6px 0 6px 22px;
    background: transparent;
    border-bottom: 0;
    border-left: 1px solid var(--line);
  }

  .page-about .about-timeline__label {
    display: block;
    margin: 0 0 14px;
    font-size: 11px;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--line);
  }

  .page-about .about-timeline__list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about .about-timeline__list > li {
    margin: 0 0 2px;
  }

  .page-about .sec-index__link {
    display: flex;
    flex-direction: column;
    gap: 3px;
    padding: 8px 0;
    font-size: 14px;
    white-space: normal;
    border-bottom: 0;
  }

  .page-about .about-timeline__era {
    font-size: 11px;
    color: var(--slate);
    opacity: 0.75;
  }

  .page-about .sec-index__link[data-active] .about-timeline__era {
    color: var(--cyan-soft);
    opacity: 1;
  }

  .page-about .about-chapter {
    padding: 46px 0 52px;
  }

  .page-about .about-chapter__head {
    display: grid;
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: 0 40px;
    align-items: end;
  }

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

  .page-about .about-chapter__body {
    margin-top: 32px;
  }

  .page-about .about-teams {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 20px;
  }

  .page-about .about-cadence > div {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 24px;
    align-items: baseline;
  }

  .page-about .about-service {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 26px 36px;
  }

  .page-about .about-pipeline {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 0 24px;
    margin-top: 34px;
  }

  .page-about .about-pipeline li {
    padding: 22px 0 0;
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .page-about .about-pipeline li::before {
    left: 0;
    top: -4px;
  }

  .page-about .about-taxonomy__item {
    grid-template-columns: 56px minmax(0, 1fr);
    padding: 24px 0;
  }
}

@media (min-width: 1200px) {
  .page-about .about-chapter__body {
    padding-left: 0;
  }

  .page-about .about-figure {
    max-width: 940px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .sec-index__link {
    transition: none;
  }
}