.page-about {
  position: relative;
  isolation: isolate;
  overflow-x: clip;
  color: var(--paper);
}

.page-about::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(42, 52, 49, 0.2) 1px, transparent 1px),
    linear-gradient(90deg, rgba(42, 52, 49, 0.2) 1px, transparent 1px);
  background-size: 80px 80px;
  background-position: center top;
  -webkit-mask-image: linear-gradient(180deg, #000 0%, #000 72%, transparent 100%);
  mask-image: linear-gradient(180deg, #000 0%, #000 72%, transparent 100%);
}

.page-about .ab-crumb {
  margin-bottom: 1.75rem;
}

/* ---------- 首屏 ---------- */

.page-about .ab-hero {
  position: relative;
  padding: clamp(1.75rem, 5vw, 3rem) 0 clamp(2.5rem, 7vw, 4.5rem);
}

.page-about .ab-hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.75rem, 5vw, 3rem);
}

.page-about .ab-hero h1 {
  margin: 0.5rem 0 1rem;
  font-family: var(--font-display);
  font-size: clamp(2rem, 6.4vw, 3.5rem);
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: -0.02em;
  color: var(--white);
  max-width: 17em;
}

.page-about .ab-lede {
  margin: 0;
  max-width: 44em;
  font-size: clamp(1rem, 1.6vw, 1.125rem);
  line-height: 1.85;
  color: rgba(242, 239, 230, 0.82);
}

.page-about .ab-index {
  list-style: none;
  margin: 1.75rem 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0.75rem;
}

.page-about .ab-index a {
  display: inline-block;
  padding: 0.4rem 0.9rem;
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  color: rgba(242, 239, 230, 0.75);
  border: 1px solid var(--line);
  background: rgba(61, 90, 76, 0.22);
  text-decoration: none;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease), background 0.25s var(--ease);
}

.page-about .ab-index a:hover,
.page-about .ab-index a:focus-visible {
  color: var(--ink-900);
  background: var(--mint);
  border-color: var(--mint);
}

.page-about .ab-hero-panel {
  padding: clamp(1.25rem, 3.5vw, 1.85rem);
  background: linear-gradient(155deg, rgba(61, 90, 76, 0.55) 0%, rgba(7, 21, 18, 0.94) 100%);
  border-left: 2px solid var(--mint);
  clip-path: polygon(var(--cut) 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%, 0 var(--cut));
}

.page-about .ab-panel-label {
  margin: 0 0 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--mint);
}

.page-about .ab-figures {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 1rem;
}

.page-about .ab-figure {
  padding: 0.95rem 0 0.85rem;
  border-top: 1px solid rgba(42, 52, 49, 0.95);
}

.page-about .ab-figure-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.45rem, 4vw, 1.95rem);
  font-weight: 700;
  line-height: 1;
  color: var(--mint);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

.page-about .ab-figure-label {
  display: block;
  margin-top: 0.4rem;
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
  color: var(--muted);
}

/* ---------- 通用章节 ---------- */

.page-about .ab-section {
  position: relative;
  padding: clamp(2.75rem, 7vw, 5.25rem) 0;
}

.page-about .ab-head {
  max-width: 56rem;
}

.page-about .ab-section-lede {
  margin: 0.9rem 0 0;
  max-width: 50em;
  font-size: 1rem;
  line-height: 1.85;
  color: rgba(242, 239, 230, 0.75);
}

/* ---------- 运营历程 ---------- */

.page-about .ab-timeline-figure {
  margin: clamp(1.75rem, 4.5vw, 2.75rem) 0;
}

.page-about .ab-timeline-figure img,
.page-about .ab-lines-figure img,
.page-about .ab-team-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .ab-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: clamp(1.5rem, 3.5vw, 2.25rem);
}

.page-about .ab-filter {
  appearance: none;
  -webkit-appearance: none;
  padding: 0.5rem 1rem;
  border: 1px solid var(--line);
  background: rgba(61, 90, 76, 0.26);
  color: rgba(242, 239, 230, 0.78);
  font-family: inherit;
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  cursor: pointer;
  clip-path: polygon(10px 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%, 0 10px);
  transition: color 0.25s var(--ease), background 0.25s var(--ease), border-color 0.25s var(--ease);
}

.page-about .ab-filter:hover {
  color: var(--white);
  border-color: var(--moss);
}

.page-about .ab-filter:focus-visible {
  outline: 2px solid var(--aqua);
  outline-offset: 2px;
}

.page-about .ab-filter.is-active {
  background: var(--mint);
  border-color: var(--mint);
  color: var(--ink-900);
  font-weight: 700;
}

.page-about .ab-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
  display: grid;
  row-gap: clamp(1.25rem, 3vw, 1.75rem);
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 13px;
  top: 1.75rem;
  bottom: 1.75rem;
  width: 1px;
  background: linear-gradient(180deg, var(--mint) 0%, var(--moss) 62%, rgba(61, 90, 76, 0) 100%);
}

.page-about .ab-node {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  column-gap: clamp(1rem, 3vw, 1.75rem);
  position: relative;
}

.page-about .ab-node-dot {
  grid-column: 1;
  grid-row: 1;
  justify-self: center;
  align-self: start;
  margin-top: 1.65rem;
  width: 12px;
  height: 12px;
  background: var(--ink-900);
  border: 2px solid var(--mint);
  transform: rotate(45deg);
  position: relative;
  z-index: 1;
}

.page-about .ab-node-card {
  grid-column: 2;
  grid-row: 1;
  padding: clamp(1.1rem, 2.8vw, 1.6rem) clamp(1.05rem, 2.6vw, 1.6rem);
  background: linear-gradient(150deg, rgba(42, 52, 49, 0.55) 0%, rgba(11, 31, 26, 0.88) 100%);
  border: 1px solid rgba(42, 52, 49, 0.95);
  border-left: 2px solid var(--moss);
  clip-path: polygon(0 0, calc(100% - 18px) 0, 100% 18px, 100% 100%, 0 100%);
  transition: transform 0.3s var(--ease), border-left-color 0.3s var(--ease);
}

.page-about .ab-node-card:hover {
  transform: translateX(4px);
  border-left-color: var(--mint);
}

.page-about .ab-node-year {
  margin: 0 0 0.4rem;
  font-family: var(--font-mono);
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--mint);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-node-card h3 {
  margin: 0.6rem 0 0.5rem;
  font-family: var(--font-display);
  font-size: clamp(1.0625rem, 2.4vw, 1.25rem);
  font-weight: 800;
  line-height: 1.35;
  color: var(--white);
}

.page-about .ab-node-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: rgba(242, 239, 230, 0.78);
}

/* ---------- 三条内容线 ---------- */

.page-about .ab-lines-figure {
  margin: clamp(1.75rem, 4.5vw, 2.75rem) 0;
}

.page-about .ab-line-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1rem, 2.6vw, 1.5rem);
}

.page-about .ab-line-card {
  --ab-accent: var(--mint);
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0;
  padding: clamp(1.3rem, 3vw, 1.85rem);
  background: linear-gradient(165deg, rgba(42, 52, 49, 0.5) 0%, rgba(7, 21, 18, 0.9) 100%);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 22px), calc(100% - 22px) 100%, 0 100%);
  box-shadow: inset 0 0 0 1px rgba(42, 52, 49, 0.95);
  transition: transform 0.3s var(--ease);
}

.page-about .ab-line-card::before {
  content: "";
  position: absolute;
  inset: 0 auto auto 0;
  width: 100%;
  height: 3px;
  background: var(--ab-accent);
}

.page-about .ab-line-card:hover {
  transform: translateY(-4px);
}

.page-about .ab-line-card--ios {
  --ab-accent: var(--amber);
}

.page-about .ab-line-card--android {
  --ab-accent: var(--clay);
}

.page-about .ab-line-card--pad {
  --ab-accent: var(--aqua);
}

.page-about .ab-line-chip {
  align-self: flex-start;
  display: inline-block;
  padding: 0.22rem 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  color: var(--ab-accent, var(--mint));
  border: 1px solid currentColor;
  background: rgba(7, 21, 18, 0.55);
}

.page-about .ab-line-card h3 {
  margin: 0.9rem 0 0.6rem;
  font-family: var(--font-display);
  font-size: clamp(1.125rem, 2.6vw, 1.375rem);
  font-weight: 800;
  line-height: 1.35;
  color: var(--white);
}

.page-about .ab-line-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: rgba(242, 239, 230, 0.78);
}

.page-about .ab-line-list {
  list-style: none;
  margin: 1.1rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.55rem;
}

.page-about .ab-line-list li {
  position: relative;
  padding-left: 1.1rem;
  font-size: 0.875rem;
  line-height: 1.7;
  color: rgba(168, 181, 174, 0.95);
}

.page-about .ab-line-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 6px;
  height: 6px;
  background: var(--ab-accent, var(--mint));
  transform: rotate(45deg);
}

/* ---------- 团队与数据合作 ---------- */

.page-about .ab-team-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.5rem, 4vw, 2.75rem);
  align-items: center;
}

.page-about .ab-team-text {
  margin: 1rem 0 0;
  max-width: 40em;
  font-size: 0.9375rem;
  line-height: 1.85;
  color: rgba(242, 239, 230, 0.78);
}

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

.page-about .ab-team-stats {
  list-style: none;
  margin: clamp(1.75rem, 4.5vw, 2.75rem) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: rgba(42, 52, 49, 0.9);
  border: 1px solid rgba(42, 52, 49, 0.9);
}

.page-about .ab-team-stat {
  padding: 1.15rem 1rem;
  background: rgba(11, 31, 26, 0.95);
}

.page-about .ab-team-stat strong {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.4rem, 3.6vw, 1.75rem);
  font-weight: 700;
  line-height: 1;
  color: var(--mint);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-team-stat span {
  display: block;
  margin-top: 0.55rem;
  font-size: 0.8125rem;
  letter-spacing: 0.03em;
  color: var(--muted);
}

/* ---------- 服务与支持 ---------- */

.page-about .ab-service-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1rem, 2.6vw, 1.5rem);
  margin-top: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .ab-service-card {
  position: relative;
  padding: clamp(1.3rem, 3vw, 1.85rem);
  background: linear-gradient(160deg, rgba(42, 52, 49, 0.4) 0%, rgba(7, 21, 18, 0.85) 100%);
  border: 1px solid var(--line);
  border-left: 2px solid var(--moss);
  transition: border-left-color 0.3s var(--ease), transform 0.3s var(--ease);
}

.page-about .ab-service-card:hover {
  border-left-color: var(--mint);
  transform: translateY(-3px);
}

.page-about .ab-service-num {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.22em;
  color: var(--mint);
}

.page-about .ab-service-card h3 {
  margin: 0.7rem 0 0.55rem;
  font-family: var(--font-display);
  font-size: clamp(1.0625rem, 2.4vw, 1.25rem);
  font-weight: 800;
  line-height: 1.35;
  color: var(--white);
}

.page-about .ab-service-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: rgba(242, 239, 230, 0.78);
}

/* ---------- 结尾指引 ---------- */

.page-about .ab-cta {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin-top: clamp(2rem, 5vw, 3.25rem);
  padding: clamp(1.5rem, 4vw, 2.35rem);
  background: linear-gradient(125deg, rgba(61, 90, 76, 0.55) 0%, rgba(7, 21, 18, 0.94) 100%);
  clip-path: polygon(var(--cut) 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%, 0 var(--cut));
}

.page-about .ab-cta-copy h2 {
  margin: 0 0 0.55rem;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 3vw, 1.625rem);
  font-weight: 800;
  line-height: 1.3;
  color: var(--white);
}

.page-about .ab-cta-copy p {
  margin: 0;
  max-width: 38em;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: rgba(242, 239, 230, 0.78);
}

.page-about .ab-cta-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .ab-service-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ab-team-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

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

  .page-about .ab-cta {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }

  .page-about .ab-cta-links {
    flex: 0 0 auto;
    justify-content: flex-end;
  }
}

@media (min-width: 900px) {
  .page-about .ab-hero-grid {
    grid-template-columns: minmax(0, 1.3fr) minmax(0, 1fr);
    align-items: end;
  }

  .page-about .ab-team-grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
  }

  .page-about .ab-node:nth-child(even) .ab-node-card {
    margin-left: clamp(1.5rem, 5vw, 3.5rem);
  }
}

@media (min-width: 1100px) {
  .page-about .ab-figures {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-index a,
  .page-about .ab-filter,
  .page-about .ab-node-card,
  .page-about .ab-line-card,
  .page-about .ab-service-card {
    transition: none;
  }

  .page-about .ab-node-card:hover,
  .page-about .ab-line-card:hover,
  .page-about .ab-service-card:hover {
    transform: none;
  }
}