.page-about {
  --about-paper-soft: #55607a;
  --about-paper-mono: #3a4a66;
  --about-paper-line: var(--paper-300);
  background: var(--ink-950);
  color: var(--white);
  font-family: var(--font-body);
}

.page-about img {
  max-width: 100%;
  height: auto;
}

.page-about .about-topbar {
  padding: clamp(0.9rem, 2.5vw, 1.6rem) 0 0;
}

/* ---------- 首屏分屏 ---------- */
.page-about .about-hero {
  padding: clamp(1.5rem, 4vw, 2.75rem) 0 clamp(2.5rem, 6vw, 4.5rem);
  border-bottom: 1px solid var(--ink-700);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
  align-items: start;
}

.page-about .about-hero h1 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.05rem, 7.2vw, 3.5rem);
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin: 0.85rem 0 1.1rem;
  max-width: 15em;
}

.page-about .about-hero .lead {
  color: var(--text-soft);
  max-width: 32em;
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.75rem;
}

.page-about .about-build {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--ink-700);
  background:
    linear-gradient(155deg, var(--ink-850) 0%, var(--ink-950) 72%);
  padding: clamp(1.25rem, 4vw, 2.1rem);
}

.page-about .about-build::after {
  content: "";
  position: absolute;
  right: -18%;
  bottom: -35%;
  width: 62%;
  height: 118%;
  background: radial-gradient(circle at 68% 32%, var(--cyan-wash), transparent 66%);
  pointer-events: none;
}

.page-about .about-build__label {
  color: var(--gray-400);
  margin: 0;
}

.page-about .about-build__num {
  position: relative;
  margin: 0.35rem 0 0.9rem;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(3.6rem, 15vw, 6.2rem);
  line-height: 0.9;
  letter-spacing: -0.05em;
  color: var(--cyan-400);
}

.page-about .about-build__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin: 0 0 1.35rem;
  padding: 0;
  list-style: none;
}

.page-about .about-build__facts {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0.7rem;
}

.page-about .about-build__facts li {
  display: grid;
  grid-template-columns: 3.75rem 1fr;
  gap: 0.85rem;
  padding-top: 0.7rem;
  border-top: 1px solid var(--ink-700);
  font-size: 0.92rem;
  line-height: 1.65;
  color: var(--text-soft);
}

.page-about .about-build__facts .mono-label {
  color: var(--cyan-150);
}

.page-about .about-jump {
  position: relative;
  display: inline-block;
  margin-top: 1.4rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--cyan-400);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 227, 218, 0.4);
  padding-bottom: 0.2rem;
}

/* ---------- 章节头 ---------- */
.page-about .about-head {
  max-width: 44rem;
}

.page-about .about-head .eyebrow {
  color: var(--gray-400);
  margin: 0 0 0.6rem;
}

.page-about .about-head .section-title {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .about-head .section-note {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.98rem;
  line-height: 1.8;
}

/* ---------- 三条业务线 ---------- */
.page-about .about-section {
  padding: clamp(3rem, 7vw, 5.5rem) 0;
}

.page-about .about-lines {
  margin: clamp(1.75rem, 4vw, 2.5rem) 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--ink-700);
}

.page-about .about-line {
  display: grid;
  gap: 0.55rem;
  padding: clamp(1.25rem, 3.5vw, 2rem) 0;
  border-bottom: 1px solid var(--ink-700);
  transition: background-color 220ms var(--ease);
}

.page-about .about-line:hover {
  background: var(--cyan-wash);
}

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

.page-about .about-line__title {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.24rem;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.page-about .about-line__text {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.96rem;
  line-height: 1.85;
  max-width: 40em;
}

.page-about .about-line__link {
  justify-self: start;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--cyan-150);
  text-decoration: none;
  border-bottom: 1px solid rgba(166, 242, 238, 0.35);
  padding-bottom: 0.15rem;
}

.page-about .about-line__link:hover,
.page-about .about-line__link:focus-visible {
  color: var(--orange-500);
  border-bottom-color: var(--orange-500);
}

/* ---------- 版本演进 ---------- */
.page-about .about-versions {
  padding: clamp(3rem, 7vw, 5.5rem) 0;
  border-top: 1px solid var(--ink-700);
}

.page-about .about-versions__grid {
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
  margin-top: clamp(1.75rem, 4vw, 2.5rem);
  align-items: start;
}

.page-about .about-portrait {
  margin: 0;
  border: 1px solid var(--ink-700);
  background: var(--ink-850);
}

.page-about .about-portrait img {
  display: block;
  width: 100%;
  object-fit: cover;
  aspect-ratio: 3 / 4;
}

.page-about .about-portrait figcaption,
.page-about .about-figure figcaption {
  padding: 0.7rem 1rem;
  border-top: 1px solid var(--ink-700);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  color: var(--gray-400);
  line-height: 1.6;
}

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

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 0.4rem;
  top: 0.5rem;
  bottom: 1.6rem;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan-400) 0%, var(--ink-700) 55%, var(--ink-700) 100%);
}

.page-about .about-node {
  position: relative;
  padding: 0 0 clamp(1.5rem, 4vw, 2.1rem) 2.15rem;
}

.page-about .about-node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.45rem;
  width: 0.85rem;
  height: 0.85rem;
  border-radius: 50%;
  background: var(--ink-950);
  border: 1px solid var(--cyan-400);
  transition: box-shadow 220ms var(--ease), background-color 220ms var(--ease);
}

.page-about .about-node:hover::before,
.page-about .about-node:focus-within::before {
  background: var(--cyan-400);
  box-shadow: 0 0 0 4px var(--cyan-wash);
}

.page-about .about-node--current::before {
  background: var(--orange-500);
  border-color: var(--orange-500);
}

.page-about .about-node__index {
  margin: 0 0 0.35rem;
  color: var(--cyan-150);
}

.page-about .about-node__title {
  margin: 0 0 0.45rem;
  font-family: var(--font-display);
  font-size: 1.12rem;
  font-weight: 700;
}

.page-about .about-node__text {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.94rem;
  line-height: 1.85;
  max-width: 34em;
}

.page-about .about-timeline__note {
  margin: 0;
  padding-top: 1rem;
  border-top: 1px dashed var(--ink-700);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.05em;
  color: var(--gray-400);
}

/* ---------- 浅色纸张区 ---------- */
.page-about .about-paper {
  position: relative;
  margin-top: clamp(2.5rem, 7vw, 5rem);
  padding: clamp(3rem, 8vw, 6rem) 0 clamp(3rem, 7vw, 5rem);
  background: var(--paper-100);
  color: var(--paper-ink);
}

.page-about .about-paper::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: -11px;
  height: 12px;
  background-image:
    linear-gradient(135deg, var(--paper-100) 50%, transparent 50%),
    linear-gradient(225deg, var(--paper-100) 50%, transparent 50%);
  background-size: 18px 12px;
  background-repeat: repeat-x;
  background-position: 0 0;
}

.page-about .about-paper .eyebrow {
  color: var(--about-paper-mono);
}

.page-about .about-paper .section-title {
  color: var(--paper-ink);
}

.page-about .about-paper .section-note {
  color: var(--about-paper-soft);
}

.page-about .about-sheets {
  display: grid;
  gap: 1.15rem;
  margin-top: clamp(1.75rem, 4vw, 2.5rem);
}

.page-about .about-sheet {
  background: var(--white);
  border: 1px solid var(--about-paper-line);
  box-shadow: 6px 6px 0 var(--paper-300);
  padding: clamp(1.2rem, 3vw, 1.75rem);
}

.page-about .about-sheet__index {
  margin: 0 0 0.7rem;
  color: var(--about-paper-mono);
}

.page-about .about-sheet__title {
  margin: 0 0 0.55rem;
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--paper-ink);
}

.page-about .about-sheet__text {
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.85;
  color: var(--about-paper-soft);
}

.page-about .about-partners {
  margin-top: clamp(2.5rem, 6vw, 4rem);
  padding-top: clamp(1.75rem, 4vw, 2.5rem);
  border-top: 1px solid var(--about-paper-line);
}

.page-about .about-partners__grid {
  display: grid;
  gap: 1.5rem;
  margin-top: clamp(1.5rem, 3.5vw, 2rem);
}

.page-about .about-partner {
  border-left: 3px solid var(--cyan-400);
  padding-left: 1rem;
}

.page-about .about-partner__num {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.4rem, 7vw, 3.4rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--paper-ink);
}

.page-about .about-partner__title {
  margin: 0.55rem 0 0.5rem;
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--paper-ink);
}

.page-about .about-partner__text {
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.85;
  color: var(--about-paper-soft);
  max-width: 32em;
}

.page-about .about-inline-link {
  display: inline-block;
  margin-top: 1.75rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--paper-ink);
  text-decoration: none;
  border-bottom: 2px solid var(--orange-500);
  padding-bottom: 0.2rem;
}

/* ---------- 服务覆盖 ---------- */
.page-about .about-coverage {
  padding: clamp(3rem, 7vw, 5.5rem) 0;
  border-top: 1px solid var(--ink-700);
}

.page-about .about-coverage__grid {
  display: grid;
  gap: clamp(1.75rem, 4vw, 2.75rem);
  margin-top: clamp(1.75rem, 4vw, 2.5rem);
  align-items: center;
}

.page-about .about-figure {
  margin: 0;
  border: 1px solid var(--ink-700);
  background: var(--ink-850);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  object-fit: cover;
}

.page-about .about-stats {
  display: grid;
  gap: 1rem;
}

.page-about .about-stat {
  padding-top: 0.8rem;
  border-top: 1px solid var(--ink-700);
}

.page-about .about-stat__num {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2rem, 6vw, 2.6rem);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--cyan-400);
}

.page-about .about-stat__label {
  margin: 0.45rem 0 0.3rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.08em;
  color: var(--white);
}

.page-about .about-stat__text {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.75;
  color: var(--text-soft);
}

/* ---------- 工作方式 ---------- */
.page-about .about-method {
  padding: clamp(3rem, 7vw, 5.5rem) 0;
  border-top: 1px solid var(--ink-700);
}

.page-about .about-method__list {
  margin: clamp(1.5rem, 4vw, 2.5rem) 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1.5rem;
}

.page-about .about-method__item {
  padding-top: 1rem;
  border-top: 1px solid var(--ink-700);
}

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

.page-about .about-method__title {
  margin: 0.5rem 0 0.5rem;
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
}

.page-about .about-method__text {
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.85;
  color: var(--text-soft);
}

/* ---------- 收尾 ---------- */
.page-about .about-cta-wrap {
  padding: 0 0 clamp(3rem, 7vw, 5rem);
}

.page-about .about-cta {
  display: grid;
  gap: 1.5rem;
  padding: clamp(1.6rem, 5vw, 3rem);
  border: 1px solid var(--ink-700);
  background:
    linear-gradient(120deg, var(--ink-850) 0%, var(--ink-950) 100%);
}

.page-about .about-cta__title {
  margin: 0 0 0.6rem;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.5rem, 4.5vw, 2rem);
  letter-spacing: -0.01em;
}

.page-about .about-cta__text {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.96rem;
  line-height: 1.8;
  max-width: 30em;
}

.page-about .about-cta .about-actions {
  margin-top: 0;
}

/* ---------- 断点 ---------- */
@media (min-width: 560px) {
  .page-about .about-stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .about-sheets {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1.4rem;
  }

  .page-about .about-sheets .about-sheet:first-child {
    grid-column: 1 / -1;
    box-shadow: 6px 6px 0 var(--paper-300);
  }

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

  .page-about .about-method__list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 2rem;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: 5fr 7fr;
    gap: clamp(2rem, 4vw, 4rem);
  }

  .page-about .about-line {
    grid-template-columns: 4rem 11rem minmax(0, 1fr) 9rem;
    align-items: start;
    gap: 0.75rem 1.5rem;
    padding-inline: 0.9rem;
  }

  .page-about .about-line__link {
    justify-self: end;
    margin-top: 0.15rem;
  }

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

  .page-about .about-sheets .about-sheet:first-child {
    grid-column: auto;
  }

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

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

  .page-about .about-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
  }
}

@media (min-width: 960px) {
  .page-about .about-versions__grid {
    grid-template-columns: 5fr 7fr;
  }

  .page-about .about-portrait {
    position: sticky;
    top: calc(var(--header-h-scrolled) + 1.5rem);
  }

  .page-about .about-coverage__grid {
    grid-template-columns: 7fr 5fr;
  }

  .page-about .about-stats {
    grid-template-columns: minmax(0, 1fr);
    gap: 1.1rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-line,
  .page-about .about-node::before {
    transition: none;
  }
}
<<<END>>>