.page-about {
  --ab-line: rgba(232, 181, 75, .24);
  --ab-line-soft: rgba(232, 181, 75, .1);
  display: block;
  background:
    radial-gradient(120% 70% at 90% -8%, rgba(232, 181, 75, .14), transparent 58%),
    radial-gradient(100% 60% at 0% 4%, rgba(74, 43, 122, .5), transparent 72%),
    var(--c-purple);
  color: var(--c-paper);
  overflow-x: hidden;
}

/* ============ 首屏 ============ */
.page-about .ab-hero {
  position: relative;
  padding: 30px 0 48px;
}

.page-about .ab-hero__grid {
  display: grid;
  gap: 28px;
  margin-top: 22px;
}

.page-about .ab-hero__lead h1 {
  margin: 14px 0 0;
  font-size: clamp(32px, 7.4vw, 66px);
  line-height: 1.08;
  letter-spacing: -.02em;
  font-weight: 800;
  color: var(--c-paper);
}

.page-about .ab-hero__lede {
  margin: 20px 0 0;
  max-width: 40ch;
  font-size: 16px;
  line-height: 1.82;
  color: rgba(245, 241, 232, .8);
}

.page-about .ab-hero__panel {
  position: relative;
  padding: 22px 20px 24px;
  border: 1px solid var(--ab-line);
  background: linear-gradient(165deg, rgba(74, 43, 122, .44), rgba(20, 4, 31, .68));
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 22px), calc(100% - 22px) 100%, 0 100%);
}

.page-about .ab-hero__big {
  display: block;
  font-family: var(--font-sans);
  font-size: clamp(78px, 20vw, 140px);
  font-weight: 800;
  line-height: .84;
  letter-spacing: -.04em;
  color: var(--c-gold);
  text-shadow: 0 0 46px rgba(232, 181, 75, .3);
}

.page-about .ab-hero__big-label {
  display: block;
  margin-top: 12px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .16em;
  color: var(--c-mist);
}

.page-about .ab-hero__panel-note {
  margin: 18px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--ab-line-soft);
  font-size: 14px;
  line-height: 1.75;
  color: rgba(245, 241, 232, .74);
}

.page-about .ab-hero__panel-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 18px;
  padding-bottom: 3px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .1em;
  color: var(--c-gold-bright);
  text-decoration: none;
  border-bottom: 1px solid var(--edge-strong);
  transition: color var(--dur) var(--ease);
}

.page-about .ab-hero__panel-link::after {
  content: "→";
  transition: transform var(--dur) var(--ease);
}

.page-about .ab-hero__panel-link:hover,
.page-about .ab-hero__panel-link:focus-visible {
  color: var(--c-gold);
}

.page-about .ab-hero__panel-link:hover::after {
  transform: translateX(4px);
}

.page-about .ab-rule {
  position: relative;
  height: 28px;
  margin-top: 36px;
  background-image: repeating-linear-gradient(90deg, var(--ab-line-soft) 0 1px, transparent 1px 22px);
}

.page-about .ab-rule::after {
  content: "";
  position: absolute;
  inset: 50% 0 auto 0;
  height: 1px;
  background: var(--ab-line);
}

@media (min-width: 900px) {
  .page-about .ab-hero {
    padding: 40px 0 56px;
  }
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.4fr) minmax(250px, .6fr);
    align-items: end;
    gap: 52px;
    margin-top: 30px;
  }
}

/* ============ 主体骨架 ============ */
.page-about .ab-shell {
  padding: 40px 0 60px;
}

.page-about .ab-shell__grid {
  display: grid;
  gap: 30px;
}

@media (min-width: 1024px) {
  .page-about .ab-shell {
    padding: 56px 0 84px;
  }
  .page-about .ab-shell__grid {
    grid-template-columns: 216px minmax(0, 1fr);
    gap: 60px;
    align-items: start;
  }
}

/* ============ 左侧章节索引 ============ */
.page-about .ab-rail {
  border-left: 1px solid var(--ab-line-soft);
  padding-left: 16px;
}

.page-about .ab-rail__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .26em;
  text-transform: uppercase;
  color: var(--c-gold);
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .ab-rail__list a {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  gap: 10px;
  align-items: baseline;
  padding: 9px 0;
  font-size: 14px;
  color: rgba(245, 241, 232, .72);
  text-decoration: none;
  border-bottom: 1px dashed rgba(232, 181, 75, .16);
  transition: color var(--dur) var(--ease), padding-left var(--dur) var(--ease);
}

.page-about .ab-rail__num {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  color: var(--c-gold);
}

.page-about .ab-rail__list a:hover,
.page-about .ab-rail__list a:focus-visible {
  color: var(--c-gold-bright);
  padding-left: 6px;
}

@media (max-width: 1023px) {
  .page-about .ab-rail {
    border-left: 0;
    padding-left: 0;
    border-top: 1px solid var(--ab-line-soft);
    padding-top: 16px;
  }
  .page-about .ab-rail__list {
    grid-auto-flow: column;
    grid-auto-columns: max-content;
    gap: 8px;
    overflow-x: auto;
    padding-bottom: 8px;
    scrollbar-width: thin;
  }
  .page-about .ab-rail__list a {
    grid-template-columns: auto auto;
    gap: 8px;
    border: 1px solid var(--ab-line-soft);
    border-radius: 2px;
    padding: 8px 12px;
    white-space: nowrap;
  }
}

@media (min-width: 1024px) {
  .page-about .ab-rail {
    position: sticky;
    top: calc(var(--header-h) + 24px);
  }
}

/* ============ 章节 ============ */
.page-about .ab-chapter {
  position: relative;
  padding: 34px 0 46px;
  border-top: 1px solid var(--ab-line-soft);
}

.page-about .ab-chapter:first-of-type {
  border-top: 0;
  padding-top: 0;
}

.page-about .ab-chapter__head {
  display: grid;
  gap: 12px;
}

.page-about .ab-chapter__index {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .22em;
  color: var(--c-gold);
}

.page-about .ab-chapter__index::after {
  content: "";
  width: 64px;
  height: 1px;
  background: var(--ab-line);
}

.page-about .ab-chapter h2 {
  margin: 0;
  font-size: clamp(23px, 3.6vw, 38px);
  line-height: 1.18;
  letter-spacing: -.01em;
  font-weight: 800;
  color: var(--c-paper);
}

.page-about .ab-quote {
  margin: 0;
  max-width: 42ch;
  padding-left: 15px;
  border-left: 2px solid var(--c-gold);
  font-size: 15px;
  line-height: 1.75;
  color: rgba(245, 241, 232, .68);
}

.page-about .ab-chapter > p {
  margin: 18px 0 0;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.82;
  color: rgba(245, 241, 232, .8);
}

/* ============ 配图 ============ */
.page-about .ab-figure {
  position: relative;
  margin: 26px 0 0;
  border: 1px solid var(--ab-line-soft);
  background: linear-gradient(150deg, rgba(74, 43, 122, .5), rgba(20, 4, 31, .72));
  overflow: hidden;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 16 / 7;
  object-fit: cover;
  filter: saturate(.92) contrast(1.04);
}

.page-about .ab-figure::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 44px;
  width: 0;
  height: 0;
  border-style: solid;
  border-width: 0 0 40px 40px;
  border-color: transparent transparent var(--c-gold) transparent;
  opacity: .85;
  pointer-events: none;
}

.page-about .ab-figure figcaption {
  padding: 11px 14px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  color: var(--c-mist);
  background: rgba(20, 4, 31, .74);
  border-top: 1px solid var(--ab-line-soft);
}

/* ============ 数据条 ============ */
.page-about .ab-stats {
  margin-top: 26px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ab-line-soft);
  border: 1px solid var(--ab-line-soft);
}

.page-about .ab-stat {
  padding: 18px 14px 16px;
  background: linear-gradient(170deg, rgba(74, 43, 122, .38), rgba(20, 4, 31, .64));
}

.page-about .ab-stat__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(28px, 4.6vw, 40px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.01em;
  color: var(--c-gold-bright);
}

.page-about .ab-stat__num small {
  margin-left: 3px;
  font-size: .42em;
  letter-spacing: .04em;
  color: var(--c-gold);
}

.page-about .ab-stat__label {
  display: block;
  margin-top: 11px;
  font-size: 12.5px;
  line-height: 1.65;
  color: rgba(245, 241, 232, .68);
}

@media (min-width: 760px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* ============ 双栏分工 ============ */
.page-about .ab-split {
  margin-top: 26px;
  display: grid;
  gap: 1px;
  background: var(--ab-line-soft);
  border: 1px solid var(--ab-line-soft);
}

.page-about .ab-split__cell {
  padding: 20px 18px;
  background: linear-gradient(170deg, rgba(74, 43, 122, .34), rgba(20, 4, 31, .6));
}

.page-about .ab-split__tag {
  display: inline-block;
  margin-bottom: 12px;
  padding: 5px 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .1em;
  color: var(--c-gold-bright);
  border: 1px solid var(--ab-line);
  background: rgba(232, 181, 75, .08);
}

.page-about .ab-split__cell p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(245, 241, 232, .78);
}

@media (min-width: 760px) {
  .page-about .ab-split {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* ============ 流程步骤 ============ */
.page-about .ab-steps {
  margin-top: 26px;
  display: grid;
  gap: 10px;
}

.page-about .ab-step {
  border: 1px solid var(--ab-line-soft);
  background: linear-gradient(160deg, rgba(74, 43, 122, .32), rgba(20, 4, 31, .48));
  transition: border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.page-about .ab-step[open] {
  border-color: var(--ab-line);
  background: linear-gradient(160deg, rgba(74, 43, 122, .5), rgba(20, 4, 31, .62));
}

.page-about .ab-step__sum {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: 14px;
  align-items: center;
  padding: 15px 16px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .ab-step__sum:hover .ab-step__title,
.page-about .ab-step__sum:focus-visible .ab-step__title {
  color: var(--c-gold-bright);
}

.page-about .ab-step__num {
  padding: 4px 7px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 1;
  letter-spacing: .1em;
  color: var(--c-gold);
  border: 1px solid var(--ab-line);
}

.page-about .ab-step__title {
  font-size: 16px;
  font-weight: 700;
  color: var(--c-paper);
  transition: color var(--dur) var(--ease);
}

.page-about .ab-step__chev {
  width: 10px;
  height: 10px;
  border-right: 2px solid var(--c-gold);
  border-bottom: 2px solid var(--c-gold);
  transform: rotate(45deg) translateY(-2px);
  transition: transform var(--dur) var(--ease);
}

.page-about .ab-step[open] .ab-step__chev {
  transform: rotate(225deg) translateY(-2px);
}

.page-about .ab-step .ab-step__body {
  padding: 0 16px 16px;
  border-top: 1px solid var(--ab-line-soft);
}

.page-about .ab-step .ab-step__body p {
  margin: 14px 0 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(245, 241, 232, .78);
}

/* ============ 纸张档案 ============ */
.page-about .ab-sheet-stack {
  position: relative;
  margin-top: 30px;
}

.page-about .ab-sheet-stack::after {
  content: "";
  position: absolute;
  inset: 0;
  transform: translate(9px, 9px);
  background: rgba(217, 211, 199, .26);
  border: 1px solid rgba(217, 211, 199, .32);
  z-index: 0;
  pointer-events: none;
}

.page-about .ab-sheet {
  position: relative;
  z-index: 1;
  padding: 20px 18px 22px;
  background: var(--c-paper);
  color: var(--c-purple);
  border-top: 3px solid var(--c-gold);
  box-shadow: 0 20px 44px rgba(20, 4, 31, .5);
}

.page-about .ab-sheet__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .22em;
  color: rgba(43, 11, 69, .66);
}

.page-about .ab-fields {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid rgba(43, 11, 69, .18);
}

.page-about .ab-field {
  display: grid;
  gap: 5px;
  padding: 13px 2px;
  border-bottom: 1px dashed rgba(43, 11, 69, .24);
  transition: background var(--dur) var(--ease);
}

.page-about .ab-field:hover {
  background: rgba(232, 181, 75, .18);
}

.page-about .ab-field__key {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: rgba(43, 11, 69, .74);
}

.page-about .ab-field__val {
  display: block;
  font-size: 15px;
  line-height: 1.72;
  color: var(--c-purple);
}

.page-about .ab-field__hint {
  display: block;
  margin-top: 4px;
  font-size: 12.5px;
  line-height: 1.66;
  color: rgba(43, 11, 69, .6);
  opacity: .75;
  transition: opacity var(--dur) var(--ease);
}

.page-about .ab-field:hover .ab-field__hint {
  opacity: 1;
}

@media (min-width: 640px) {
  .page-about .ab-field {
    grid-template-columns: minmax(0, 148px) minmax(0, 1fr);
    gap: 18px;
    align-items: baseline;
  }
}

/* ============ 年龄段标签 ============ */
.page-about .ab-ages {
  margin-top: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .ab-age {
  padding: 7px 13px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .08em;
  color: var(--c-green);
  border: 1px solid rgba(57, 224, 140, .34);
  background: rgba(57, 224, 140, .07);
}

/* ============ 合作卡片 ============ */
.page-about .ab-partners {
  margin-top: 26px;
  display: grid;
  gap: 12px;
}

.page-about .ab-partner {
  padding: 18px 16px 20px;
  border: 1px solid var(--ab-line-soft);
  border-top: 2px solid var(--c-gold);
  background: linear-gradient(180deg, rgba(74, 43, 122, .32), rgba(20, 4, 31, .58));
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .ab-partner:hover {
  transform: translateY(-4px);
  border-color: var(--ab-line);
}

.page-about .ab-partner__tag {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--c-gold-bright);
}

.page-about .ab-partner p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: rgba(245, 241, 232, .76);
}

@media (min-width: 720px) {
  .page-about .ab-partners {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* ============ 行动区 ============ */
.page-about .ab-cta {
  position: relative;
  margin-top: 38px;
  padding: 24px 20px;
  display: grid;
  gap: 18px;
  border: 1px solid var(--ab-line);
  background:
    linear-gradient(120deg, rgba(74, 43, 122, .6), rgba(20, 4, 31, .74)),
    var(--c-purple);
}

.page-about .ab-cta::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: linear-gradient(180deg, var(--c-gold), rgba(232, 181, 75, 0));
}

.page-about .ab-cta__title {
  margin: 0;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.6;
  color: var(--c-paper);
}

.page-about .ab-cta__note {
  margin: 10px 0 0;
  max-width: 58ch;
  font-size: 14px;
  line-height: 1.78;
  color: rgba(245, 241, 232, .74);
}

.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

@media (min-width: 860px) {
  .page-about .ab-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 32px;
    padding: 30px 32px;
  }
  .page-about .ab-cta__actions {
    flex-wrap: nowrap;
  }
}

/* ============ 收尾指引 ============ */
.page-about .ab-tail {
  margin: 24px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(245, 241, 232, .66);
}

.page-about .ab-tail a {
  color: var(--c-gold-bright);
  text-decoration: none;
  border-bottom: 1px solid var(--edge-strong);
  transition: color var(--dur) var(--ease);
}

.page-about .ab-tail a:hover,
.page-about .ab-tail a:focus-visible {
  color: var(--c-paper);
}

/* ============ 动效降级 ============ */
@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: .01ms !important;
    animation-duration: .01ms !important;
  }
  .page-about .ab-partner:hover {
    transform: none;
  }
}