.page-about {
  --about-h1: clamp(36px, 6vw, 74px);
  --about-tl-h: 420px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding-top: clamp(18px, 3.5vw, 44px);
}

.page-about .about-hero__title {
  font-family: var(--font-head);
  font-size: var(--about-h1);
  line-height: 1.08;
  letter-spacing: -.02em;
  margin: 16px 0 0;
  max-width: 16em;
}

.page-about .about-hero__lead {
  margin-top: 20px;
  max-width: 44em;
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  margin: 38px 0 0;
  padding: 22px 0 0;
  list-style: none;
  border-top: var(--line) solid var(--ink);
}

.page-about .about-fact {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-about .about-fact__num {
  font-family: var(--font-num);
  font-size: clamp(34px, 4.6vw, 52px);
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--guava);
}

.page-about .about-fact__unit {
  font-size: .48em;
  margin-left: 3px;
}

.page-about .about-fact__label {
  font-size: var(--fs-13);
  color: var(--ink-70);
}

@media (min-width: 700px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 28px;
  }
}

/* ---------- 起点 ---------- */
.page-about .about-origin {
  align-items: start;
  row-gap: 34px;
}

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

.page-about .about-origin__figure figcaption {
  margin-top: 10px;
  font-size: var(--fs-13);
  line-height: 1.7;
  color: var(--ink-70);
}

/* ---------- 时间轴 ---------- */
.page-about .tl {
  position: relative;
  display: grid;
  gap: 22px;
  padding-left: 34px;
  margin-top: 34px;
}

.page-about .tl__axis {
  position: absolute;
  left: 8px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--grid);
}

.page-about .tl-node {
  position: relative;
  display: grid;
  gap: 3px;
  min-height: 44px;
  padding: 0;
  border: 0;
  background: none;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
}

.page-about .tl-node__dot {
  position: absolute;
  left: -34px;
  top: 8px;
  width: 16px;
  height: 16px;
  box-sizing: border-box;
  border: 2px solid var(--cream);
  background: var(--guava);
  transform: rotate(45deg);
  transition: background-color 180ms var(--ease), transform 180ms var(--ease);
}

.page-about .tl-node:nth-child(3) .tl-node__dot { background: var(--mango); }
.page-about .tl-node:nth-child(4) .tl-node__dot { background: var(--lime); }
.page-about .tl-node:nth-child(5) .tl-node__dot { background: var(--blueberry); }
.page-about .tl-node:nth-child(6) .tl-node__dot { background: var(--tangerine); }

.page-about .tl-node__num {
  font-family: var(--font-num);
  font-size: 26px;
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--ink-55);
  transition: color 180ms var(--ease);
}

.page-about .tl-node__label {
  font-family: var(--font-head);
  font-size: var(--fs-28);
  line-height: 1.22;
  letter-spacing: -.01em;
}

.page-about .tl-node__note {
  font-size: var(--fs-13);
  line-height: 1.7;
  color: var(--ink-70);
  max-width: 26ch;
}

.page-about .tl-node:hover .tl-node__num,
.page-about .tl-node.is-active .tl-node__num {
  color: var(--guava);
}

.page-about .tl-node.is-active .tl-node__dot {
  transform: rotate(45deg) scale(1.35);
}

.page-about .tl-node:focus-visible {
  outline: 2px solid var(--mango);
  outline-offset: 4px;
}

@media (min-width: 900px) {
  .page-about .tl {
    display: flex;
    align-items: center;
    gap: 0;
    height: var(--about-tl-h);
    padding-left: 0;
    margin-top: 56px;
  }

  .page-about .tl__axis {
    left: 0;
    right: 0;
    top: 50%;
    bottom: auto;
    width: auto;
    height: 2px;
  }

  .page-about .tl-node {
    flex: 1 1 0;
    height: 50%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 0 14px;
  }

  .page-about .tl-node--up {
    align-self: flex-start;
    justify-content: flex-end;
    padding-bottom: 26px;
  }

  .page-about .tl-node--down {
    align-self: flex-end;
    justify-content: flex-start;
    padding-top: 26px;
  }

  .page-about .tl-node__dot {
    left: 50%;
    margin-left: -8px;
    top: auto;
  }

  .page-about .tl-node--up .tl-node__dot {
    bottom: -9px;
  }

  .page-about .tl-node--down .tl-node__dot {
    top: -9px;
  }
}

/* ---------- 三次分叉 ---------- */
.page-about .about-timeline-map {
  margin: 0 0 42px;
}

.page-about .upgrades {
  display: grid;
  gap: 34px;
}

.page-about .upgrade {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 16px 20px;
  border-top: var(--line) solid var(--ink);
  padding-top: 20px;
}

.page-about .upgrade__index {
  font-family: var(--font-num);
  font-size: 26px;
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--guava);
}

.page-about .upgrade:nth-child(2) .upgrade__index { color: var(--lime); }
.page-about .upgrade:nth-child(3) .upgrade__index { color: var(--blueberry); }

.page-about .upgrade__body h3 {
  font-family: var(--font-head);
  font-size: var(--fs-28);
  line-height: 1.22;
  letter-spacing: -.01em;
  margin: 0 0 10px;
}

.page-about .upgrade__body p {
  font-size: var(--fs-17);
  line-height: 1.9;
  color: var(--ink-70);
  max-width: 62ch;
  margin: 0;
}

.page-about .upgrade__specs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .spec {
  font-family: var(--font-num);
  font-size: var(--fs-13);
  padding: 5px 11px;
  border: 1px solid var(--grid);
  color: var(--ink-70);
  white-space: nowrap;
}

@media (min-width: 900px) {
  .page-about .upgrade {
    grid-template-columns: 84px minmax(0, 1fr);
    gap: 24px;
  }

  .page-about .upgrade:nth-child(1) { margin-right: 24%; }
  .page-about .upgrade:nth-child(2) { margin-left: 18%; margin-right: 4%; }
  .page-about .upgrade:nth-child(3) { margin-left: 7%; margin-right: 14%; }
}

/* ---------- 发布节奏 ---------- */
.page-about .about-cadence {
  row-gap: 34px;
}

.page-about .cadence {
  display: grid;
  gap: 0;
  border-top: var(--line) solid var(--ink);
}

.page-about .cadence__item {
  display: grid;
  gap: 8px;
  padding: 20px 0 20px 18px;
  border-bottom: 1px solid var(--grid);
  border-left: 6px solid var(--guava);
}

.page-about .cadence__item:nth-child(2) {
  border-left-color: var(--mango);
}

.page-about .cadence__item--plain {
  border-left-color: var(--lime);
}

.page-about .cadence__big {
  font-family: var(--font-head);
  font-size: var(--fs-28);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -.01em;
}

.page-about .cadence__desc {
  font-size: var(--fs-17);
  line-height: 1.9;
  color: var(--ink-70);
  max-width: 46ch;
}

/* ---------- 覆盖范围 ---------- */
.page-about .about-coverage {
  align-items: start;
  row-gap: 32px;
}

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

.page-about .about-coverage__figure figcaption {
  margin-top: 10px;
  font-size: var(--fs-13);
  line-height: 1.7;
  color: var(--ink-70);
}

/* ---------- 服务能力 ---------- */
.page-about .about-service {
  color: var(--cream);
}

.page-about .about-service .section-title {
  color: var(--cream);
}

.page-about .about-service .eyebrow {
  color: var(--mango);
}

.page-about .service-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  margin-top: 34px;
}

.page-about .service-card {
  border-top: 2px solid var(--cream-45);
  padding-top: 18px;
}

.page-about .service-card__num {
  display: block;
  font-family: var(--font-num);
  font-size: clamp(26px, 3.4vw, 40px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -.02em;
  color: var(--mango);
}

.page-about .service-card__text {
  margin: 12px 0 0;
  font-size: var(--fs-17);
  line-height: 1.9;
  color: var(--cream-70);
  max-width: 42ch;
}

.page-about .service-contact {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 30px;
  margin-top: 36px;
  padding-top: 24px;
  border-top: 2px solid var(--cream-45);
}

.page-about .service-contact__item {
  font-family: var(--font-num);
  font-size: var(--fs-17);
  color: var(--cream);
}

.page-about .service-contact__label {
  display: inline-block;
  margin-right: 8px;
  padding: 3px 9px;
  font-family: var(--font-body);
  font-size: var(--fs-13);
  color: var(--ink);
  background: var(--cream);
}

@media (min-width: 760px) {
  .page-about .service-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 30px;
  }
}

/* ---------- 生态与认可 ---------- */
.page-about .eco-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  margin-top: 34px;
}

.page-about .eco-card {
  border-top: var(--line) solid var(--guava);
  padding-top: 18px;
}

.page-about .eco-card--lime { border-top-color: var(--lime); }
.page-about .eco-card--blueberry { border-top-color: var(--blueberry); }

.page-about .eco-card h3 {
  font-family: var(--font-head);
  font-size: var(--fs-28);
  line-height: 1.22;
  letter-spacing: -.01em;
  margin: 0 0 12px;
}

.page-about .eco-card p {
  font-size: var(--fs-17);
  line-height: 1.9;
  color: var(--ink-70);
  margin: 0;
  max-width: 40ch;
}

@media (min-width: 760px) {
  .page-about .eco-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 30px;
  }
}

/* ---------- 继续了解 ---------- */
.page-about .next-links {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-top: 30px;
}

.page-about .next-link {
  display: grid;
  gap: 8px;
  min-height: 44px;
  padding: 22px 20px;
  border: var(--line) solid var(--ink);
  background: var(--cream);
  color: var(--ink);
  text-decoration: none;
  transition: transform 180ms var(--ease), background-color 180ms var(--ease), color 180ms var(--ease);
}

.page-about .next-link__name {
  font-family: var(--font-head);
  font-size: var(--fs-28);
  line-height: 1.2;
  letter-spacing: -.01em;
}

.page-about .next-link__desc {
  font-size: var(--fs-13);
  line-height: 1.7;
  color: var(--ink-70);
}

.page-about .next-link:hover,
.page-about .next-link:focus-visible {
  background: var(--guava);
  color: var(--cream);
  transform: translateY(-6px);
}

.page-about .next-link:hover .next-link__desc,
.page-about .next-link:focus-visible .next-link__desc {
  color: var(--cream-70);
}

.page-about .next-link:focus-visible {
  outline: 2px solid var(--mango);
  outline-offset: 2px;
}

@media (min-width: 720px) {
  .page-about .next-links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
  }
}

@media (min-width: 1040px) {
  .page-about .next-links {
    grid-template-columns: 1.15fr .9fr 1.05fr .8fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .tl-node__dot,
  .page-about .tl-node__num,
  .page-about .next-link {
    transition: none;
  }

  .page-about .next-link:hover,
  .page-about .next-link:focus-visible {
    transform: none;
  }
}