.page-about {
  --ab-side-w: 248px;
  --ab-toc-w: 168px;
  display: block;
}

/* ============ 首屏：左叙事 / 右星图刻度 ============ */

.page-about .ab-hero {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--ice-line);
  background:
    radial-gradient(1100px 520px at 80% 8%, rgba(108, 75, 244, 0.20), transparent 62%),
    radial-gradient(880px 440px at 8% 92%, rgba(52, 224, 255, 0.10), transparent 60%),
    var(--deep-space);
}

.page-about .ab-hero::after {
  content: "";
  position: absolute;
  left: -12%;
  right: -12%;
  top: 64%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--ice-line) 22%, var(--ice-line) 78%, transparent);
  transform: rotate(-8deg);
  transform-origin: center;
  pointer-events: none;
}

.page-about .ab-hero__grid {
  position: relative;
  z-index: 1;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding: clamp(44px, 6vw, 88px) var(--gutter) clamp(52px, 7vw, 100px);
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
  gap: clamp(30px, 4vw, 62px);
  align-items: start;
}

.page-about .ab-hero__text {
  display: flex;
  flex-direction: column;
  gap: 18px;
  min-width: 0;
}

.page-about .ab-hero h1 {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(30px, 3.8vw, 52px);
  line-height: 1.18;
  letter-spacing: -0.01em;
  color: var(--ink-white);
}

.page-about .ab-hero__lede {
  margin: 0;
  max-width: 34em;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.9;
  color: var(--star-mist);
}

.page-about .ab-facts {
  margin: 6px 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ice-line);
  border: 1px solid var(--ice-line);
}

.page-about .ab-facts__item {
  background: var(--deep-space);
  padding: 14px 18px 16px;
}

.page-about .ab-facts dt {
  font-family: var(--font-head);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--star-mist);
}

.page-about .ab-facts dd {
  margin: 8px 0 0;
  font-family: var(--font-display);
  font-size: 40px;
  font-weight: 600;
  line-height: 1;
  color: var(--cygnus);
}

.page-about .ab-facts__unit {
  margin-left: 0.28em;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.04em;
  color: var(--star-mist);
}

.page-about .ab-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 4px;
}

.page-about .ab-hero__visual {
  display: flex;
  flex-direction: column;
  gap: 22px;
  min-width: 0;
}

.page-about .figure__media {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--ice-line);
  border-radius: 2px;
  background: var(--navy-deck);
}

.page-about .figure__media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.78) brightness(0.92);
}

.page-about .ab-hero__figure {
  margin: 0;
}

.page-about .ab-hero__figure .figure__media {
  aspect-ratio: 16 / 9;
}

.page-about .ab-hero__figure .figure__caption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--star-mist);
}

/* 刻度盘 */

.page-about .ab-dial {
  border: 1px solid var(--ice-line);
  border-radius: 2px;
  padding: 20px 20px 18px;
  background: linear-gradient(180deg, rgba(108, 75, 244, 0.16), rgba(52, 224, 255, 0.05) 60%, transparent);
}

.page-about .ab-dial__arc {
  display: block;
  width: min(220px, 72%);
  height: auto;
  margin: 0 auto 20px;
}

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

.page-about .ab-dial__item {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  grid-template-areas:
    "idx name"
    "idx meta";
  column-gap: 10px;
  padding: 10px 0;
  border-top: 1px solid var(--ice-line);
}

.page-about .ab-dial__idx {
  grid-area: idx;
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  line-height: 1.2;
  color: var(--nebula);
}

.page-about .ab-dial__name {
  grid-area: name;
  font-family: var(--font-head);
  font-size: 15px;
  letter-spacing: 0.02em;
  color: var(--ink-white);
}

.page-about .ab-dial__meta {
  grid-area: meta;
  margin-top: 3px;
  font-size: 13px;
  line-height: 1.55;
  color: var(--star-mist);
}

/* ============ 主体：目录 + 窄正文 + 侧注 ============ */

.page-about .ab-body {
  max-width: var(--shell-max);
  margin-inline: auto;
  padding: clamp(44px, 5.5vw, 84px) var(--gutter) clamp(56px, 7vw, 104px);
  display: grid;
  grid-template-columns: var(--ab-toc-w) minmax(0, 1fr);
  gap: 0 40px;
  align-items: start;
}

.page-about .ab-toc {
  position: sticky;
  top: 96px;
  align-self: start;
}

.page-about .ab-toc__title {
  margin: 0 0 12px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--ice-line);
  font-family: var(--font-head);
  font-size: 13px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--star-mist);
}

.page-about .ab-toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
}

.page-about .ab-toc__link {
  display: block;
  padding: 8px 0;
  font-family: var(--font-head);
  font-size: 14px;
  line-height: 1.4;
  color: var(--star-mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .ab-toc__link:hover,
.page-about .ab-toc__link:focus-visible {
  color: var(--ink-white);
}

.page-about .ab-toc__link[aria-current="true"] {
  color: var(--cygnus);
  border-bottom-color: var(--cygnus);
}

.page-about .ab-flow {
  min-width: 0;
  display: flex;
  flex-direction: column;
}

.page-about .ab-sec {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--ab-side-w);
  gap: 0 32px;
  padding: clamp(38px, 4.6vw, 68px) 0;
  border-top: 1px solid var(--ice-line);
  scroll-margin-top: 104px;
}

.page-about .ab-sec:first-child {
  padding-top: 0;
  border-top: 0;
}

.page-about .ab-sec__main {
  min-width: 0;
}

.page-about .ab-sec__num {
  margin: 0 0 14px;
  font-family: var(--font-display);
  font-size: clamp(32px, 3.4vw, 44px);
  font-weight: 600;
  line-height: 0.9;
  letter-spacing: 0.02em;
  color: rgba(108, 75, 244, 0.78);
}

.page-about .ab-sec__title {
  margin: 0 0 20px;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(23px, 2.5vw, 31px);
  line-height: 1.32;
  letter-spacing: -0.01em;
  color: var(--ink-white);
}

.page-about .ab-sec__main .prose {
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.9;
  color: var(--star-mist);
  max-width: 34em;
}

.page-about .ab-sec__main .prose p {
  margin: 0 0 1.1em;
}

.page-about .ab-sec__main .prose p:last-child {
  margin-bottom: 0;
}

.page-about .ab-sec__main .prose strong {
  color: var(--ink-white);
  font-weight: 600;
}

.page-about .ab-jump {
  color: var(--cygnus);
  text-decoration: none;
  border-bottom: 1px solid rgba(52, 224, 255, 0.4);
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .ab-jump:hover,
.page-about .ab-jump:focus-visible {
  color: var(--ink-white);
  border-bottom-color: var(--ink-white);
}

.page-about .ab-sec__side {
  min-width: 0;
  padding-top: 6px;
}

.page-about .ab-note {
  margin: 0;
  padding: 14px 0 0 16px;
  border-left: 1px solid var(--ice-line);
  font-family: var(--font-body);
  font-size: 13px;
  line-height: 1.78;
  color: var(--star-mist);
}

.page-about .ab-note__label {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-head);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cygnus);
}

/* ============ 口径对照 ============ */

.page-about .ab-contrast {
  margin: 26px 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ice-line);
  border: 1px solid var(--ice-line);
}

.page-about .ab-contrast__col {
  padding: 20px 20px 22px;
  background: var(--navy-deck);
}

.page-about .ab-contrast__col--a {
  background: linear-gradient(180deg, rgba(108, 75, 244, 0.18), var(--navy-deck) 68%);
}

.page-about .ab-contrast__col--b {
  background: linear-gradient(180deg, rgba(52, 224, 255, 0.13), var(--navy-deck) 68%);
}

.page-about .ab-contrast__title {
  margin: 0 0 14px;
  font-family: var(--font-head);
  font-size: 14px;
  letter-spacing: 0.12em;
  color: var(--ink-white);
}

.page-about .ab-contrast__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-contrast__list li {
  position: relative;
  padding-left: 14px;
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.72;
  color: var(--star-mist);
}

.page-about .ab-contrast__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.78em;
  width: 6px;
  height: 1px;
  background: var(--cygnus);
}

/* ============ 四个坐标 ============ */

.page-about .ab-coord__figure {
  margin: 26px 0 30px;
}

.page-about .ab-coord__media {
  aspect-ratio: 3 / 2;
}

.page-about .ab-coord__figure .figure__caption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--star-mist);
}

.page-about .ab-coord__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 22px;
}

.page-about .ab-coord__item {
  position: relative;
  padding-left: 18px;
  border-left: 1px solid var(--ice-line);
}

.page-about .ab-coord__item:nth-child(even) {
  margin-left: clamp(0px, 7%, 60px);
}

.page-about .ab-coord__idx {
  margin: 0 0 6px;
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 600;
  line-height: 1;
  color: var(--cygnus);
}

.page-about .ab-coord__name {
  margin: 0 0 7px;
  font-family: var(--font-head);
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--ink-white);
}

.page-about .ab-coord__body {
  margin: 0;
  max-width: 32em;
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.82;
  color: var(--star-mist);
}

/* ============ 版本轨道 ============ */

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

.page-about .ab-track {
  position: relative;
}

.page-about .ab-track__texture {
  position: absolute;
  top: -8%;
  right: 0;
  width: min(320px, 38%);
  margin: 0;
  opacity: 0.26;
  pointer-events: none;
  z-index: 0;
}

.page-about .ab-track__texture img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: contain;
  filter: saturate(0.6);
}

.page-about .ab-track > .ab-sec__num,
.page-about .ab-track > .ab-sec__title,
.page-about .ab-track__lede,
.page-about .ab-track__rail {
  position: relative;
  z-index: 1;
}

.page-about .ab-track__lede {
  margin: 0 0 8px;
  max-width: 34em;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.88;
  color: var(--star-mist);
}

.page-about .ab-track__rail {
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
}

.page-about .ab-track__rail::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 6px;
  height: 1px;
  background: linear-gradient(90deg, var(--nebula), var(--cygnus));
  opacity: 0.6;
}

.page-about .ab-track__node {
  position: relative;
  padding: 34px 22px 0 0;
}

.page-about .ab-track__node::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  border: 1px solid var(--cygnus);
  background: var(--deep-space);
  box-shadow: 0 0 0 5px var(--deep-space);
}

.page-about .ab-track__year {
  display: block;
  font-family: var(--font-display);
  font-size: clamp(34px, 3.6vw, 46px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: 0.01em;
  color: var(--cygnus);
}

.page-about .ab-track__ver {
  margin: 12px 0 12px;
  font-family: var(--font-head);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--ink-white);
}

.page-about .ab-track__items {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 9px;
}

.page-about .ab-track__items li {
  position: relative;
  padding-left: 14px;
  font-family: var(--font-body);
  font-size: 14px;
  line-height: 1.78;
  color: var(--star-mist);
}

.page-about .ab-track__items li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.82em;
  width: 5px;
  height: 1px;
  background: var(--ice-line);
}

/* ============ 勘误流程 ============ */

.page-about .ab-steps {
  list-style: none;
  margin: 26px 0 28px;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--ice-line);
  border: 1px solid var(--ice-line);
}

.page-about .ab-steps li {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 14px;
  align-items: baseline;
  padding: 15px 18px;
  background: var(--navy-deck);
}

.page-about .ab-steps__n {
  font-family: var(--font-display);
  font-size: 24px;
  font-weight: 600;
  line-height: 1;
  color: var(--amber);
}

.page-about .ab-steps__txt {
  margin: 0;
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.78;
  color: var(--star-mist);
}

.page-about .ab-steps__txt strong {
  display: block;
  margin-bottom: 2px;
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 700;
  color: var(--ink-white);
}

/* ============ 尾部交叉入口 ============ */

.page-about .ab-next-band {
  border-top: 1px solid var(--ice-line);
  background: var(--navy-deck);
}

.page-about .ab-next {
  max-width: var(--shell-max);
  margin-inline: auto;
  padding: clamp(40px, 5vw, 68px) var(--gutter) clamp(48px, 6vw, 80px);
}

.page-about .ab-next__title {
  margin: 0 0 20px;
  font-family: var(--font-head);
  font-size: 13px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--star-mist);
}

.page-about .ab-next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ice-line);
  border: 1px solid var(--ice-line);
}

.page-about .ab-next__list li {
  background: var(--navy-deck);
}

.page-about .ab-next__link {
  display: block;
  padding: 18px 20px;
  font-family: var(--font-head);
  font-size: 15px;
  line-height: 1.5;
  color: var(--star-mist);
  text-decoration: none;
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .ab-next__link:hover,
.page-about .ab-next__link:focus-visible {
  color: var(--cygnus);
  background: rgba(52, 224, 255, 0.06);
}

/* ============ 响应式 ============ */

@media (max-width: 1080px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .ab-hero__visual {
    max-width: 640px;
  }

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

  .page-about .ab-toc {
    position: static;
    padding-bottom: 10px;
    margin-bottom: 28px;
    border-bottom: 1px solid var(--ice-line);
  }

  .page-about .ab-toc__list {
    flex-direction: row;
    gap: 0 20px;
    overflow-x: auto;
    scrollbar-width: thin;
    -webkit-overflow-scrolling: touch;
  }

  .page-about .ab-toc__list li {
    flex: 0 0 auto;
  }

  .page-about .ab-toc__link {
    white-space: nowrap;
    border-bottom: 1px solid transparent;
  }
}

@media (max-width: 900px) {
  .page-about .ab-sec {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px 0;
  }

  .page-about .ab-sec__side {
    padding-top: 0;
  }

  .page-about .ab-note {
    padding: 14px 0 0;
    border-left: 0;
    border-top: 1px solid var(--ice-line);
  }

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

  .page-about .ab-track__rail::before {
    top: 0;
    bottom: 0;
    left: 6px;
    right: auto;
    width: 1px;
    height: auto;
    background: linear-gradient(180deg, var(--nebula), var(--cygnus));
  }

  .page-about .ab-track__node {
    padding: 0 0 30px 34px;
  }

  .page-about .ab-track__node::before {
    top: 4px;
    left: 0;
  }

  .page-about .ab-track__node:last-child {
    padding-bottom: 0;
  }

  .page-about .ab-track__texture {
    display: none;
  }
}

@media (max-width: 640px) {
  .page-about .ab-facts {
    grid-template-columns: minmax(0, 1fr);
  }

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

  .page-about .ab-coord__item:nth-child(even) {
    margin-left: 0;
  }

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

  .page-about .ab-steps li {
    grid-template-columns: 34px minmax(0, 1fr);
    gap: 10px;
    padding: 14px 15px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-toc__link,
  .page-about .ab-jump,
  .page-about .ab-next__link {
    transition: none;
  }
}