.page-about {
  --about-gap: clamp(2.75rem, 6.5vw, 5.5rem);
  --about-rail: 88px;
  display: block;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-top: calc(var(--shell-offset) + 1.5rem);
  padding-bottom: clamp(2.25rem, 5vw, 4rem);
  background: linear-gradient(180deg, rgba(11, 44, 61, 0.55) 0%, rgba(6, 26, 43, 0) 100%);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(138, 106, 60, 0.12) 1px, transparent 1px),
    linear-gradient(90deg, rgba(138, 106, 60, 0.12) 1px, transparent 1px);
  background-size: 96px 96px;
  -webkit-mask-image: linear-gradient(180deg, #000 0%, transparent 90%);
  mask-image: linear-gradient(180deg, #000 0%, transparent 90%);
}

.page-about .about-hero-inner {
  position: relative;
  z-index: 1;
}

.page-about .crumb-sep {
  display: inline-block;
  margin: 0 0.45em;
  color: var(--c-copper);
}

.page-about .about-h1 {
  font-family: var(--f-head);
  font-size: var(--fs-64);
  line-height: 1.06;
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--c-paper);
  margin: 1rem 0 0;
  max-width: 20ch;
}

.page-about .about-lede {
  margin-top: 1.35rem;
  color: var(--c-mist);
}

.page-about .about-strip {
  margin-top: 2.25rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.75rem;
}

.page-about .about-strip span {
  display: inline-flex;
  align-items: baseline;
  gap: 0.4rem;
}

.page-about .about-strip b {
  color: var(--c-cyan);
  font-weight: 600;
}

/* ---------- 通用两栏 ---------- */
.page-about .about-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.75rem, 4vw, 3rem);
}

.page-about .about-split h2,
.page-about .about-lines-head h2,
.page-about .about-authors-head h2,
.page-about .about-versions h2,
.page-about .about-next h2 {
  font-family: var(--f-head);
  font-size: var(--fs-40);
  line-height: 1.16;
  letter-spacing: -0.02em;
  color: var(--c-paper);
  margin: 0.65rem 0 1.1rem;
  max-width: 24ch;
}

/* ---------- 我们做什么 ---------- */
.page-about .about-what {
  padding: var(--about-gap) 0 0;
}

.page-about .scene-list {
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .scene-item {
  display: grid;
  grid-template-columns: 2.4rem minmax(0, 1fr);
  gap: 0.5rem 0.9rem;
  padding: 1.35rem 0;
  border-bottom: 1px solid var(--line-soft);
  transition: border-color var(--dur) var(--ease);
}

.page-about .scene-item:hover {
  border-bottom-color: var(--line-cyan);
}

.page-about .scene-no {
  color: var(--c-cyan);
  font-size: var(--fs-13);
  letter-spacing: 0.06em;
  padding-top: 0.28rem;
}

.page-about .scene-title {
  font-family: var(--f-head);
  font-size: var(--fs-20);
  letter-spacing: -0.01em;
  color: var(--c-paper);
  margin: 0 0 0.4rem;
}

.page-about .scene-item p {
  margin: 0;
  color: var(--c-mist);
  font-size: var(--fs-15);
  line-height: 1.75;
}

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

.page-about .about-figure .plate-media img {
  border: 1px solid var(--line);
}

/* ---------- 四条主线 ---------- */
.page-about .about-lines {
  margin-top: var(--about-gap);
  padding: var(--about-gap) 0;
  background: linear-gradient(180deg, rgba(11, 44, 61, 0.86) 0%, rgba(6, 26, 43, 0.2) 100%);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-lines-head {
  max-width: 62ch;
}

.page-about .lines-grid {
  margin-top: 2.25rem;
}

.page-about .line-card {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  background: rgba(18, 48, 68, 0.55);
}

.page-about .line-card .card-index {
  color: var(--c-amber);
}

.page-about .line-card .card-title {
  margin: 0;
  font-size: var(--fs-20);
  letter-spacing: -0.01em;
}

.page-about .line-card .card-desc {
  margin: 0;
  font-size: var(--fs-15);
  line-height: 1.75;
}

/* ---------- 数据流程 ---------- */
.page-about .about-flow {
  padding: var(--about-gap) 0 0;
}

.page-about .about-flow-main p + p {
  margin-top: 1.15rem;
}

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

.page-about .flow-step {
  display: grid;
  grid-template-columns: 2.6rem minmax(0, 1fr);
  gap: 0.35rem 0.9rem;
  padding: 1.05rem 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .flow-step:first-child {
  border-top: 1px solid var(--line-soft);
}

.page-about .step-no {
  font-size: var(--fs-13);
  color: var(--c-mint);
  letter-spacing: 0.06em;
  padding-top: 0.25rem;
}

.page-about .flow-step h3 {
  margin: 0 0 0.3rem;
  font-family: var(--f-head);
  font-size: var(--fs-17);
  color: var(--c-paper);
  letter-spacing: -0.01em;
}

.page-about .flow-step p {
  margin: 0;
  font-size: var(--fs-15);
  line-height: 1.7;
  color: var(--c-mist);
}

/* ---------- 专家作者 ---------- */
.page-about .about-authors {
  margin-top: var(--about-gap);
  padding: var(--about-gap) 0;
  background: linear-gradient(145deg, rgba(59, 46, 110, 0.72) 0%, rgba(11, 44, 61, 0.9) 72%);
  border-top: 1px solid var(--line);
}

.page-about .about-authors-head {
  max-width: 58ch;
}

.page-about .author-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.5rem, 3.5vw, 2.75rem);
  margin-top: 2rem;
}

.page-about .author-figure {
  border-left: 1px solid var(--line-cyan);
  padding-left: 1.25rem;
}

.page-about .author-big {
  margin: 0;
  font-size: var(--fs-64);
  line-height: 1;
  color: var(--c-amber);
  letter-spacing: 0.02em;
}

.page-about .author-figure .serif-note {
  display: block;
  margin-top: 0.6rem;
  max-width: 22ch;
  color: var(--c-mist);
}

.page-about .author-main p + p {
  margin-top: 1.1rem;
}

.page-about .author-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

.page-about .author-link {
  margin-top: 1.5rem;
}

/* ---------- 版本演进 ---------- */
.page-about .about-versions {
  padding: var(--about-gap) 0 0;
}

.page-about .about-ver-plate {
  margin: 1.75rem 0 0;
}

.page-about .about-ver-plate .plate-media img {
  border: 1px solid var(--line);
  opacity: 0.92;
}

.page-about .ver-list {
  list-style: none;
  margin: 2.5rem 0 0;
  padding: 0;
}

.page-about .ver-item {
  position: relative;
  display: grid;
  grid-template-columns: 3.25rem minmax(0, 1fr);
  gap: 0.4rem 1rem;
  padding-bottom: 2.25rem;
}

.page-about .ver-item::before {
  content: "";
  position: absolute;
  left: 1.58rem;
  top: 2.5rem;
  bottom: 0.2rem;
  width: 1px;
  background: linear-gradient(180deg, var(--line-cyan) 0%, var(--line) 100%);
}

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

.page-about .ver-item:last-child::before {
  display: none;
}

.page-about .ver-node {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 3.25rem;
  height: 3.25rem;
  font-size: var(--fs-13);
  letter-spacing: 0.04em;
  color: var(--c-cyan);
  border: 1px solid var(--line-cyan);
  background: var(--c-ink);
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .ver-item:hover .ver-node {
  border-color: var(--c-cyan);
  color: var(--c-paper);
}

.page-about .ver-title {
  margin: 0.75rem 0 0.45rem;
  font-family: var(--f-head);
  font-size: var(--fs-20);
  letter-spacing: -0.01em;
  color: var(--c-paper);
}

.page-about .ver-body p {
  margin: 0;
  font-size: var(--fs-15);
  line-height: 1.78;
  color: var(--c-mist);
  max-width: 62ch;
}

/* ---------- 合作生态 ---------- */
.page-about .about-partners {
  margin-top: var(--about-gap);
  padding-top: var(--about-gap);
  padding-bottom: var(--about-gap);
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(11, 44, 61, 0.5) 0%, rgba(6, 26, 43, 0) 100%);
}

.page-about .about-pt-plate {
  margin: 0 0 clamp(1.75rem, 4vw, 3rem);
}

.page-about .about-pt-plate .plate-media img {
  -webkit-mask-image: linear-gradient(90deg, #000 0%, #000 62%, transparent 100%);
  mask-image: linear-gradient(90deg, #000 0%, #000 62%, transparent 100%);
}

.page-about .about-pt-split p + p {
  margin-top: 1.1rem;
}

.page-about .about-pt-link {
  margin-top: 1.6rem;
}

.page-about .partner-tags {
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  gap: 0.6rem;
}

.page-about .pt-tag {
  display: inline-block;
  padding: 0.45rem 0.85rem;
  font-size: var(--fs-13);
  letter-spacing: 0.08em;
  color: var(--c-paper);
  border: 1px solid var(--line);
  background: rgba(18, 48, 68, 0.5);
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .pt-tag:hover {
  border-color: var(--c-cyan);
  color: var(--c-cyan);
}

/* ---------- 结尾入口 ---------- */
.page-about .about-next {
  padding: var(--about-gap) 0 calc(var(--about-gap) * 0.9);
}

.page-about .next-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 1.75rem;
}

.page-about .next-card {
  display: grid;
  grid-template-columns: 2rem minmax(0, 1fr);
  gap: 0.3rem 0.9rem;
  padding: 1.15rem 1.15rem 1.25rem;
  border: 1px solid var(--line);
  background: rgba(18, 48, 68, 0.4);
  text-decoration: none;
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .next-card .card-index {
  grid-row: 1 / span 2;
  color: var(--c-copper);
  font-size: var(--fs-13);
  padding-top: 0.2rem;
}

.page-about .next-title {
  font-family: var(--f-head);
  font-size: var(--fs-20);
  color: var(--c-paper);
  letter-spacing: -0.01em;
}

.page-about .next-desc {
  font-size: var(--fs-13);
  color: var(--c-mist);
  line-height: 1.6;
}

.page-about .next-card:hover {
  border-color: var(--c-cyan);
  background: rgba(0, 229, 255, 0.05);
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .next-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1024px) {
  .page-about .about-split {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    gap: clamp(2rem, 5vw, 4.5rem);
    align-items: start;
  }

  .page-about .about-split-rev {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
  }

  .page-about .about-pt-split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 360px);
  }

  .page-about .about-figure {
    margin-top: 2.4rem;
  }

  .page-about .author-grid {
    grid-template-columns: minmax(0, 260px) minmax(0, 1fr);
    gap: clamp(2rem, 5vw, 4rem);
  }

  .page-about .ver-item {
    grid-template-columns: 4.25rem minmax(0, 1fr);
    gap: 0.4rem 1.75rem;
    padding-bottom: 2.75rem;
  }

  .page-about .ver-node {
    width: 4.25rem;
    height: 4.25rem;
    font-size: var(--fs-15);
  }

  .page-about .ver-item::before {
    left: 2.1rem;
    top: 3.4rem;
  }

  .page-about .ver-title {
    margin-top: 1.2rem;
  }
}

@media (max-width: 639px) {
  .page-about .about-h1 {
    font-size: clamp(2rem, 9vw, 2.75rem);
  }

  .page-about .about-strip {
    gap: 0.4rem 1.1rem;
  }
}