.page-about {
  --ab-glow: rgba(43, 232, 200, 0.12);
  --ab-glow-soft: rgba(43, 232, 200, 0.4);
  display: block;
}

/* ── 首屏引言 ───────────────────────────── */
.page-about .ab-hero {
  padding: clamp(1.75rem, 4vw, 3rem) 0 clamp(1.5rem, 3.5vw, 2.5rem);
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(115% 85% at 6% -20%, var(--ab-glow), transparent 62%),
    linear-gradient(180deg, var(--felt-2) 0%, var(--felt) 100%);
}

.page-about .ab-hero__inner {
  max-width: 54rem;
  margin-top: clamp(1.25rem, 3vw, 2rem);
}

.page-about .ab-hero h1 {
  margin: 0.6rem 0 1rem;
  font-size: clamp(1.95rem, 5vw, 3.5rem);
  line-height: 1.14;
  letter-spacing: 0.02em;
  font-weight: 800;
  color: var(--paper);
}

.page-about .ab-hero__lede {
  max-width: 38em;
  font-size: clamp(1rem, 1.6vw, 1.115rem);
  line-height: 1.8;
  color: var(--paper);
}

.page-about .ab-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem 1.9rem;
  margin: 1.6rem 0 0;
  padding: 0;
  list-style: none;
}

.page-about .ab-hero__facts li {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
  font-size: 0.86rem;
  letter-spacing: 0.01em;
  color: var(--muted);
}

.page-about .ab-hero__facts li::before {
  content: "";
  flex: none;
  width: 6px;
  height: 6px;
  background: var(--cyan);
  transform: rotate(45deg) translateY(-1px);
}

.page-about .ab-hero__facts .mono {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--cyan-soft);
}

/* ── 时间线 ─────────────────────────────── */
.page-about .ab-tl-section {
  padding-top: clamp(2rem, 5vw, 3.5rem);
}

.page-about .ab-tl {
  position: relative;
  margin-top: clamp(1.5rem, 3vw, 2.25rem);
}

.page-about .ab-tl::before {
  content: "";
  position: absolute;
  top: 0.5rem;
  bottom: 0.75rem;
  left: 7px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan) 0%, var(--ab-glow-soft) 45%, transparent 100%);
}

.page-about .ab-node {
  position: relative;
  padding-left: 2.15rem;
}

.page-about .ab-node + .ab-node {
  margin-top: 1.15rem;
}

.page-about .ab-node::before {
  content: "";
  position: absolute;
  left: 1px;
  top: 1.4rem;
  width: 11px;
  height: 11px;
  background: var(--felt);
  border: 1px solid var(--cyan);
  transform: rotate(45deg);
}

.page-about .ab-node__year {
  display: inline-block;
  margin: 0 0 0.45rem;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.1em;
  color: var(--amber);
}

.page-about .ab-node__card {
  padding: 0.95rem 1.1rem 1.1rem;
}

.page-about .ab-node__card summary {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  cursor: pointer;
  list-style: none;
  color: var(--paper);
}

.page-about .ab-node__card summary::-webkit-details-marker {
  display: none;
}

.page-about .ab-node__card summary h3 {
  margin: 0;
  font-size: clamp(1rem, 2.2vw, 1.15rem);
  letter-spacing: 0.015em;
  line-height: 1.5;
}

.page-about .ab-node__card summary::after {
  content: "+";
  margin-left: auto;
  flex: none;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--amber);
  transition: transform 0.16s var(--ease);
}

.page-about .ab-node__card[open] summary::after {
  content: "–";
  color: var(--cyan);
}

.page-about .ab-node__card[open] summary h3 {
  color: var(--cyan-soft);
}

.page-about .ab-node__body {
  padding-top: 0.7rem;
}

.page-about .ab-node__body p {
  font-size: 0.94rem;
  line-height: 1.78;
  color: var(--muted);
}

.page-about .ab-tl-fig {
  margin-top: 1rem;
}

/* ── 设计原则 ───────────────────────────── */
.page-about .ab-design {
  padding-block: clamp(2.25rem, 5.5vw, 4rem);
}

.page-about .ab-design__grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.75rem);
  margin-top: clamp(1.5rem, 3vw, 2.25rem);
  align-items: start;
}

.page-about .ab-design__note {
  font-size: 0.94rem;
  line-height: 1.8;
  color: var(--muted);
  padding-left: 1rem;
  border-left: 2px solid var(--cyan);
  margin-bottom: 1.25rem;
}

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

.page-about .ab-pr {
  padding: 1.05rem 1.15rem 1.2rem;
  transition: border-color 0.18s var(--ease), background-color 0.18s var(--ease);
}

.page-about .ab-pr:hover,
.page-about .ab-pr:focus-within {
  border-color: var(--ab-glow-soft);
  background: var(--felt-2);
}

.page-about .ab-pr__idx {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  color: var(--cyan);
}

.page-about .ab-pr h3 {
  margin: 0.35rem 0 0.5rem;
  font-size: clamp(1.02rem, 2vw, 1.22rem);
  letter-spacing: 0.015em;
  color: var(--paper);
}

.page-about .ab-pr > p {
  font-size: 0.92rem;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .ab-pr__diff {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  margin-top: 0.5rem;
  font-size: 0.86rem;
  line-height: 1.6;
  color: var(--paper);
}

.page-about .ab-pr__diff .tag {
  flex: none;
}

/* ── 团队与服务覆盖横带 ─────────────────── */
.page-about .ab-slab {
  padding-block: clamp(2rem, 5vw, 3.5rem);
  border-block: 1px solid var(--line);
  background:
    repeating-linear-gradient(135deg, rgba(43, 232, 200, 0.045) 0 10px, transparent 10px 22px),
    var(--felt-2);
}

.page-about .ab-bar {
  display: flex;
  gap: 3px;
  margin: 1.5rem 0 0;
  padding: 0;
  list-style: none;
  min-height: 66px;
}

.page-about .ab-bar__seg {
  flex: var(--w) 1 0%;
  min-width: 0;
  display: flex;
  align-items: flex-end;
  padding: 0.5rem 0.55rem;
  background: var(--seg-c, var(--cyan));
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 1;
  color: var(--ink);
  transition: filter 0.18s var(--ease), transform 0.18s var(--ease);
}

.page-about .ab-bar__seg--a { --seg-c: #2BE8C8; }
.page-about .ab-bar__seg--b { --seg-c: #7CF3DE; }
.page-about .ab-bar__seg--c { --seg-c: #1FBFA4; }
.page-about .ab-bar__seg--d { --seg-c: #168F7C; }

.page-about .ab-bar__seg:hover,
.page-about .ab-bar__seg:focus-within {
  filter: brightness(1.14);
  transform: translateY(-3px);
}

.page-about .ab-legend {
  display: grid;
  gap: 0.85rem;
  margin: 1.35rem 0 0;
  padding: 0;
  list-style: none;
}

.page-about .ab-legend li {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
}

.page-about .ab-legend li:nth-child(1) { --sw: #2BE8C8; }
.page-about .ab-legend li:nth-child(2) { --sw: #7CF3DE; }
.page-about .ab-legend li:nth-child(3) { --sw: #1FBFA4; }
.page-about .ab-legend li:nth-child(4) { --sw: #168F7C; }

.page-about .ab-legend__sw {
  flex: none;
  width: 9px;
  height: 9px;
  margin-top: 0.5rem;
  background: var(--sw);
  transform: rotate(45deg);
}

.page-about .ab-legend strong {
  display: block;
  font-size: 0.93rem;
  letter-spacing: 0.01em;
  color: var(--paper);
  margin-bottom: 0.15rem;
}

.page-about .ab-legend p {
  margin: 0;
  font-size: 0.87rem;
  line-height: 1.65;
  color: var(--muted);
}

.page-about .ab-team-fig {
  margin-top: clamp(1.5rem, 3vw, 2.25rem);
}

.page-about .ab-cover {
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  padding-top: clamp(1.5rem, 3vw, 2rem);
  border-top: 1px dashed var(--line);
}

.page-about .ab-cover__grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.75rem);
  align-items: start;
}

.page-about .ab-nodes {
  display: grid;
  grid-template-columns: repeat(13, 1fr);
  gap: 4px;
}

.page-about .ab-nodes span {
  aspect-ratio: 1 / 1;
  background: var(--panel);
  border: 1px solid var(--line);
}

.page-about .ab-nodes span.is-origin {
  background: var(--amber);
  border-color: var(--amber);
  box-shadow: 0 0 0 3px rgba(242, 179, 61, 0.18);
}

.page-about .ab-cover__cap {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.85rem;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.page-about .ab-cover__dot {
  flex: none;
  width: 8px;
  height: 8px;
  background: var(--amber);
  transform: rotate(45deg);
}

.page-about .ab-cover__text h3 {
  margin-bottom: 0.6rem;
  font-size: clamp(1.05rem, 2.4vw, 1.3rem);
  color: var(--paper);
}

.page-about .ab-cover__text p {
  font-size: 0.93rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .ab-cover__text .btn {
  margin-top: 0.5rem;
}

/* ── 版本迭代 ───────────────────────────── */
.page-about .ab-iter {
  padding-block: clamp(2.25rem, 5.5vw, 4rem);
}

.page-about .ab-iter__grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.5rem);
  margin-top: clamp(1.5rem, 3vw, 2.25rem);
  align-items: start;
}

.page-about .ab-iter__ver {
  padding: 1.1rem 1.15rem 1.25rem;
  background: var(--panel);
  border-left: 3px solid var(--amber);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

.page-about .ab-iter__verlabel {
  margin: 0;
  font-size: 0.74rem;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.page-about .ab-iter__vernum {
  margin: 0.3rem 0 0.45rem;
  font-family: var(--font-mono);
  font-size: clamp(2rem, 5vw, 2.75rem);
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--amber);
}

.page-about .ab-iter__vermeta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0;
  font-size: 0.79rem;
  line-height: 1.6;
  color: var(--muted);
}

.page-about .ab-iter__lead {
  font-size: 0.96rem;
  line-height: 1.85;
  color: var(--paper);
  max-width: 36em;
}

.page-about .ab-iter__body h3 {
  margin: 1.5rem 0 0.75rem;
  font-size: clamp(1rem, 2.2vw, 1.15rem);
  letter-spacing: 0.015em;
  color: var(--paper);
}

.page-about .ab-checks {
  display: grid;
  gap: 0.75rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .ab-checks li {
  display: flex;
  gap: 0.85rem;
  padding: 0.85rem 1rem;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 2px solid var(--cyan);
}

.page-about .ab-checks .mono {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.1em;
  color: var(--cyan);
  padding-top: 0.15rem;
}

.page-about .ab-checks strong {
  display: block;
  font-size: 0.92rem;
  color: var(--paper);
  margin-bottom: 0.2rem;
}

.page-about .ab-checks p {
  margin: 0;
  font-size: 0.87rem;
  line-height: 1.65;
  color: var(--muted);
}

.page-about .ab-iter__tail {
  margin-top: 1rem;
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--muted);
}

/* ── 指引与内容 ─────────────────────────── */
.page-about .ab-guide {
  padding-block: clamp(2.25rem, 5.5vw, 4rem) clamp(2.5rem, 6vw, 4.5rem);
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, var(--felt) 0%, var(--felt-2) 100%);
}

.page-about .ab-guide__grid {
  display: grid;
  gap: 1rem;
  margin-top: clamp(1.5rem, 3vw, 2.25rem);
  grid-template-columns: 1fr;
}

.page-about .ab-guide__card {
  padding: 1.1rem 1.15rem 1.3rem;
}

.page-about .ab-guide__num {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(1.6rem, 4vw, 2.1rem);
  line-height: 1;
  color: var(--cyan);
}

.page-about .ab-guide__card h3 {
  margin: 0.4rem 0 0.5rem;
  font-size: 1rem;
  letter-spacing: 0.02em;
  color: var(--paper);
}

.page-about .ab-guide__card > p {
  font-size: 0.88rem;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .ab-guide__card--path {
  border-color: var(--ab-glow-soft);
}

.page-about .ab-path {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 0.9rem;
  margin: 0.65rem 0 0;
  padding: 0;
  list-style: none;
}

.page-about .ab-path li {
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
  font-size: 0.86rem;
  color: var(--paper);
}

.page-about .ab-path .mono {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--amber);
}

.page-about .ab-cta {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  padding: clamp(1.1rem, 3vw, 1.6rem);
  background: var(--panel);
  border: 1px solid var(--line);
  border-top: 2px solid var(--cyan);
}

.page-about .ab-cta__text {
  margin: 0;
  font-size: 0.95rem;
  line-height: 1.75;
  color: var(--paper);
}

.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

/* ── 断点 ───────────────────────────────── */
@media (min-width: 640px) {
  .page-about .ab-guide__grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .ab-cover__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
  }
}

@media (min-width: 760px) {
  .page-about .ab-legend {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem 1.75rem;
  }
  .page-about .ab-cta {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
  .page-about .ab-cta__text {
    max-width: 32em;
  }
}

@media (min-width: 900px) {
  .page-about .ab-tl::before {
    left: 121px;
  }
  .page-about .ab-node {
    padding-left: 160px;
  }
  .page-about .ab-node::before {
    left: 116px;
    top: 1.55rem;
  }
  .page-about .ab-node__year {
    position: absolute;
    left: 0;
    top: 1.2rem;
    width: 100px;
    margin: 0;
    text-align: right;
    font-size: 0.86rem;
  }
  .page-about .ab-node:nth-child(even) .ab-node__card {
    margin-left: 2rem;
  }
  .page-about .ab-design__grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
  }
  .page-about .ab-iter__grid {
    grid-template-columns: minmax(0, 3fr) minmax(0, 9fr);
  }
  .page-about .ab-guide__grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .ab-bar {
    min-height: 78px;
  }
}

@media (min-width: 1080px) {
  .page-about .ab-bar__seg {
    padding: 0.65rem 0.75rem;
    font-size: 1.05rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-bar__seg,
  .page-about .ab-pr,
  .page-about .ab-node__card summary::after {
    transition: none;
  }
  .page-about .ab-bar__seg:hover,
  .page-about .ab-bar__seg:focus-within {
    transform: none;
  }
}
<<<END>>>

.page-about {
  --w: var(--sw);
}