.page-about {
  --ab-chapter-gap: clamp(40px, 6vw, 78px);
}

/* ---------- 首屏拼贴 ---------- */
.page-about .ab-hero {
  position: relative;
  padding: clamp(20px, 3vw, 40px) 0 clamp(36px, 6vw, 84px);
  overflow: hidden;
}
.page-about .ab-hero::before {
  content: "";
  position: absolute;
  left: -18%;
  top: -34%;
  width: 78%;
  height: 560px;
  background: radial-gradient(58% 58% at 50% 50%, rgba(200, 255, 62, 0.10), rgba(200, 255, 62, 0) 72%);
  pointer-events: none;
}
.page-about .ab-hero__grid {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(28px, 4vw, 56px);
  align-items: end;
}
.page-about .ab-hero__lead .wm-label {
  display: block;
  margin-bottom: 14px;
}
.page-about .ab-hero__title {
  margin: 0 0 .55em;
  font-family: var(--font-display);
  font-size: clamp(2.1rem, 7vw, 4.4rem);
  line-height: 1.02;
  letter-spacing: -0.02em;
  color: var(--text);
  max-width: 22ch;
}
.page-about .ab-hero__text {
  margin: 0;
  max-width: 62ch;
  font-size: clamp(1rem, 1.6vw, 1.1rem);
  line-height: 1.9;
  color: var(--text);
}
.page-about .ab-hero__actions {
  margin-top: clamp(22px, 3vw, 34px);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}
.page-about .ab-hero__panel {
  background: linear-gradient(158deg, var(--moss-800), var(--pitch-950) 78%);
  border: 1px solid var(--line);
  padding: clamp(20px, 3vw, 30px);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 30px), calc(100% - 30px) 100%, 0 100%);
}
.page-about .ab-stats {
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
}
.page-about .ab-stat {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
}
.page-about .ab-stat:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}
.page-about .ab-stat__n {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.6rem, 3.4vw, 2.3rem);
  line-height: 1;
  color: var(--lime);
}
.page-about .ab-stat__t {
  font-size: .86rem;
  line-height: 1.5;
  color: var(--muted);
}

/* ---------- 索引 + 正文布局 ---------- */
.page-about .ab-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 3.4vw, 48px);
  padding-block: clamp(8px, 2vw, 20px) clamp(56px, 8vw, 110px);
  align-items: start;
}
.page-about .ab-side {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding-block: 10px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}
.page-about .ab-side__label {
  display: none;
}
.page-about .ab-side__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  gap: 8px;
}
.page-about .ab-node {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 2px;
  color: var(--muted);
  font-size: .84rem;
  white-space: nowrap;
  text-decoration: none;
  transition: color .2s var(--ease), background-color .2s var(--ease), border-color .2s var(--ease);
}
.page-about .ab-node::before {
  display: none;
}
.page-about .ab-node__y {
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--blue);
}
.page-about .ab-node:hover,
.page-about .ab-node:focus-visible {
  color: var(--text);
  border-color: var(--line-strong);
  background: rgba(77, 216, 255, .08);
}
.page-about .ab-node:hover .ab-node__y,
.page-about .ab-node:focus-visible .ab-node__y {
  color: var(--lime);
}

/* ---------- 章节 ---------- */
.page-about .ab-flow {
  min-width: 0;
}
.page-about .ab-chapter {
  scroll-margin-top: calc(var(--header-h) + 28px);
}
.page-about .ab-chapter + .ab-chapter {
  margin-top: var(--ab-chapter-gap);
  padding-top: var(--ab-chapter-gap);
  border-top: 1px solid var(--line);
}
.page-about .ab-chapter__no {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .18em;
  color: var(--lime);
}
.page-about .ab-chapter__title {
  margin: 0 0 .62em;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 4vw, 2.7rem);
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--text);
  max-width: 24ch;
}
.page-about .ab-p {
  margin: 0 0 1.4em;
  max-width: 64ch;
  font-size: clamp(1rem, 1.5vw, 1.05rem);
  line-height: 1.9;
  color: var(--text);
}
.page-about .ab-p:last-child {
  margin-bottom: 0;
}
.page-about .ab-p a {
  color: var(--blue);
  text-decoration: none;
  border-bottom: 1px solid rgba(77, 216, 255, .4);
  transition: border-color .2s var(--ease), color .2s var(--ease);
}
.page-about .ab-p a:hover,
.page-about .ab-p a:focus-visible {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

/* ---------- 配图 ---------- */
.page-about .ab-figure {
  margin: clamp(24px, 3.6vw, 38px) 0;
  border: 1px solid var(--line);
  background: var(--pitch-950);
  overflow: hidden;
}
.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(.86) contrast(1.06);
}
.page-about .ab-figure figcaption {
  padding: 11px 16px;
  border-top: 1px solid var(--line);
  background: var(--pitch-950);
  font-size: .78rem;
  letter-spacing: .03em;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- 三个阶段 ---------- */
.page-about .ab-stages {
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
  list-style: none;
}
.page-about .ab-stage {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  padding: clamp(18px, 2.6vw, 26px) 0;
  border-top: 1px solid var(--line);
}
.page-about .ab-stage:last-child {
  border-bottom: 1px solid var(--line);
}
.page-about .ab-stage__head {
  display: flex;
  align-items: baseline;
  gap: 12px;
}
.page-about .ab-stage__yr {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1rem, 2.2vw, 1.35rem);
  color: var(--amber);
}
.page-about .ab-stage__tag {
  font-size: .74rem;
  letter-spacing: .2em;
  color: var(--muted);
}
.page-about .ab-stage__body h3 {
  margin: 0 0 .5em;
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 2vw, 1.28rem);
  line-height: 1.3;
  color: var(--text);
}
.page-about .ab-stage__body p {
  margin: 0;
  max-width: 62ch;
  font-size: .98rem;
  line-height: 1.88;
  color: var(--text);
}

/* ---------- 三级校订流程 ---------- */
.page-about .ab-steps {
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .ab-step {
  background: var(--ink-900);
  padding: clamp(18px, 2.6vw, 26px);
  display: grid;
  gap: 8px;
}
.page-about .ab-step__n {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .2em;
  color: var(--blue);
}
.page-about .ab-step__body h3 {
  margin: 0 0 .5em;
  font-size: 1rem;
  line-height: 1.4;
  color: var(--text);
}
.page-about .ab-step__body p {
  margin: 0;
  font-size: .94rem;
  line-height: 1.85;
  color: var(--text);
}

/* ---------- 浅色档案纸面板 ---------- */
.page-about .ab-paper-panel {
  margin: clamp(22px, 3vw, 34px) 0;
  padding: clamp(22px, 3.6vw, 42px);
  background: var(--paper);
  color: var(--paper-ink);
  background-image:
    repeating-linear-gradient(0deg, rgba(20, 24, 15, .045) 0 1px, rgba(20, 24, 15, 0) 1px 26px);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 34px), calc(100% - 34px) 100%, 0 100%);
}
.page-about .ab-paper-panel__label {
  display: block;
  margin-bottom: 16px;
  color: #3E5A2E;
}
.page-about .ab-src {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1px;
  background: rgba(20, 24, 15, .16);
  border: 1px solid rgba(20, 24, 15, .16);
}
.page-about .ab-src__item {
  background: var(--paper);
  padding: clamp(16px, 2.4vw, 24px);
  display: grid;
  gap: 8px;
}
.page-about .ab-src__n {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .16em;
  color: #5C6E4E;
}
.page-about .ab-src__body h3 {
  margin: 0 0 .45em;
  font-size: 1.02rem;
  line-height: 1.4;
  color: var(--paper-ink);
}
.page-about .ab-src__body p {
  margin: 0;
  max-width: 58ch;
  font-size: .94rem;
  line-height: 1.85;
  color: #2C3427;
}

/* ---------- 三代体系对比带 ---------- */
.page-about .ab-vers {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin-top: clamp(22px, 3vw, 34px);
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .ab-ver {
  position: relative;
  background: var(--pitch-950);
  padding: clamp(20px, 3vw, 30px);
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: background-color .3s var(--ease);
}
.page-about .ab-ver::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
}
.page-about .ab-ver--v1::before {
  background: var(--blue);
}
.page-about .ab-ver--v2::before {
  background: linear-gradient(90deg, var(--blue), var(--lime));
}
.page-about .ab-ver--v3::before {
  background: var(--lime);
}
.page-about .ab-ver:hover,
.page-about .ab-ver:focus-within {
  background: var(--moss-800);
}
.page-about .ab-ver__tag {
  font-family: var(--font-mono);
  font-size: 1.9rem;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--text);
}
.page-about .ab-ver__yr {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .14em;
  color: var(--amber);
}
.page-about .ab-ver h3 {
  margin: 6px 0 0;
  font-family: var(--font-display);
  font-size: clamp(1.02rem, 1.9vw, 1.18rem);
  line-height: 1.32;
  color: var(--text);
}
.page-about .ab-ver p {
  margin: 0;
  font-size: .93rem;
  line-height: 1.85;
  color: var(--text);
}
.page-about .ab-ver details {
  margin-top: auto;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}
.page-about .ab-ver summary {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .1em;
  color: var(--blue);
}
.page-about .ab-ver summary::-webkit-details-marker {
  display: none;
}
.page-about .ab-ver summary::before {
  content: "+";
  color: var(--lime);
  font-size: 1rem;
  line-height: 1;
}
.page-about .ab-ver details[open] summary::before {
  content: "–";
}
.page-about .ab-ver summary:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 3px;
}
.page-about .ab-ver__fields {
  margin: .8em 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 5px;
  font-size: .84rem;
  line-height: 1.7;
  color: var(--muted);
}
.page-about .ab-ver__fields li {
  padding-left: 14px;
  position: relative;
}
.page-about .ab-ver__fields li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .72em;
  width: 6px;
  height: 1px;
  background: var(--line-strong);
}

/* ---------- 使用场景数据带 ---------- */
.page-about .ab-eco {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin-top: clamp(20px, 3vw, 30px);
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .ab-eco__cell {
  background: var(--ink-900);
  padding: clamp(18px, 2.6vw, 26px);
}
.page-about .ab-eco__n {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(2rem, 5vw, 3.2rem);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--lime);
}
.page-about .ab-eco__t {
  margin: 14px 0 0;
  font-size: .92rem;
  line-height: 1.85;
  color: var(--text);
}

/* ---------- 收尾 ---------- */
.page-about .ab-cta {
  margin-top: clamp(44px, 6vw, 76px);
  padding: clamp(24px, 4vw, 46px);
  border: 1px solid var(--line-strong);
  background: linear-gradient(135deg, var(--moss-800), var(--pitch-950) 72%);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 38px), calc(100% - 38px) 100%, 0 100%);
  display: grid;
  gap: clamp(20px, 3vw, 32px);
}
.page-about .ab-cta__copy h2 {
  margin: .3em 0 .5em;
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 3.4vw, 2.2rem);
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--text);
}
.page-about .ab-cta__copy p {
  margin: 0;
  max-width: 56ch;
  font-size: .98rem;
  line-height: 1.9;
  color: var(--text);
}
.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-self: end;
}

/* ---------- 平板与桌面 ---------- */
@media (min-width: 720px) {
  .page-about .ab-stage {
    grid-template-columns: 150px minmax(0, 1fr);
    gap: 26px;
  }
  .page-about .ab-stage__head {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }
  .page-about .ab-src__item {
    grid-template-columns: 96px minmax(0, 1fr);
    gap: 22px;
  }
  .page-about .ab-eco {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .ab-vers {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 960px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(280px, .95fr);
  }
  .page-about .ab-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
  }
}

@media (min-width: 1040px) {
  .page-about .ab-layout {
    grid-template-columns: 228px minmax(0, 1fr);
    gap: clamp(32px, 4vw, 64px);
  }
  .page-about .ab-side {
    position: sticky;
    top: calc(var(--header-h) + 28px);
    border-top: 0;
    border-bottom: 0;
    border-left: 1px solid var(--line-strong);
    padding: 4px 0 20px 22px;
    overflow: visible;
  }
  .page-about .ab-side__label {
    display: block;
    margin: 0 0 16px;
  }
  .page-about .ab-side__list {
    flex-direction: column;
    gap: 2px;
  }
  .page-about .ab-node {
    border: 0;
    border-radius: 0;
    padding: 7px 10px 7px 0;
  }
  .page-about .ab-node::before {
    display: block;
    content: "";
    position: absolute;
    left: -26px;
    top: 1.05em;
    width: 7px;
    height: 7px;
    background: var(--line-strong);
    transform: translateY(-50%);
    transition: background-color .2s var(--ease), box-shadow .2s var(--ease);
  }
  .page-about .ab-node:hover,
  .page-about .ab-node:focus-visible {
    background: transparent;
  }
  .page-about .ab-node:hover::before,
  .page-about .ab-node:focus-visible::before {
    background: var(--lime);
    box-shadow: 0 0 0 3px rgba(200, 255, 62, .16);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-node,
  .page-about .ab-ver,
  .page-about .ab-p a {
    transition: none;
  }
}
</main>