.page-about {
  --ab-rule: var(--yk-line-200);
  --ab-muted: #56646F;
  --ab-space: clamp(36px, 5vw, 68px);
  background: var(--yk-paper-050);
  color: var(--yk-ink-900);
  font-family: var(--yk-sans);
  font-size: 16px;
  line-height: 1.8;
  overflow-x: hidden;
}

.page-about .ab-wrap {
  width: 100%;
  max-width: var(--yk-wrap);
  margin-inline: auto;
  padding-inline: var(--yk-gutter);
}

.page-about .ab-crumbwrap {
  padding-top: clamp(14px, 2.5vw, 24px);
}

.page-about .yk-crumb {
  font-size: 13px;
  color: var(--ab-muted);
}

.page-about .yk-crumb a {
  color: var(--yk-blue-700);
  text-decoration: none;
}

.page-about .yk-crumb a:hover {
  text-decoration: underline;
}

.page-about .yk-btn {
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  padding-block: clamp(16px, 3vw, 32px) clamp(28px, 4.5vw, 52px);
}

.page-about .ab-hero__grid {
  display: grid;
  gap: clamp(24px, 4vw, 48px);
  align-items: start;
}

.page-about .ab-kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 14px;
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--yk-coral-700);
  font-weight: 700;
}

.page-about .ab-kicker::before {
  content: "";
  width: 26px;
  height: 2px;
  background: var(--yk-coral-500);
  flex: none;
}

.page-about .ab-hero h1 {
  margin: 0 0 18px;
  font-family: var(--yk-serif);
  font-weight: 700;
  font-size: clamp(2rem, 6vw, 3.25rem);
  line-height: 1.15;
  letter-spacing: .01em;
  color: var(--yk-blue-900);
}

.page-about .ab-lede {
  margin: 0;
  font-size: clamp(1rem, 1.8vw, 1.075rem);
  line-height: 1.85;
  color: var(--ab-muted);
  max-width: 46em;
}

.page-about .ab-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(20px, 3vw, 30px);
}

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

.page-about .ab-fig__img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  border-radius: var(--yk-radius);
  border: 1px solid var(--ab-rule);
  background: var(--yk-sky-100);
  box-shadow: var(--yk-shadow);
}

.page-about .ab-fig figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--ab-muted);
}

.page-about .ab-stats {
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ab-rule);
  border: 1px solid var(--ab-rule);
  border-radius: var(--yk-radius);
  overflow: hidden;
}

.page-about .ab-stats__item {
  background: var(--yk-paper-050);
  padding: 14px clamp(12px, 2vw, 20px);
}

.page-about .ab-stats__item dt {
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--ab-muted);
}

.page-about .ab-stats__item dd {
  margin: 4px 0 0;
  font-size: 14px;
  color: var(--yk-ink-900);
}

.page-about .ab-statnum {
  font-family: var(--yk-mono);
  font-size: clamp(1.25rem, 2.8vw, 1.6rem);
  font-weight: 700;
  color: var(--yk-blue-900);
  margin-right: 4px;
  line-height: 1.1;
}

/* ---------- 章节导航 ---------- */
.page-about .ab-toc {
  background: var(--yk-sand-100);
  border-block: 1px solid var(--ab-rule);
}

.page-about .ab-toc__list {
  list-style: none;
  margin: 0;
  padding: 12px 0;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .ab-toc__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border-radius: 999px;
  background: var(--yk-paper-050);
  border: 1px solid var(--ab-rule);
  color: var(--yk-blue-900);
  text-decoration: none;
  font-size: 13.5px;
  white-space: nowrap;
  transition: background 180ms var(--yk-ease), border-color 180ms var(--yk-ease), color 180ms var(--yk-ease);
}

.page-about .ab-toc__link:hover {
  background: var(--yk-blue-900);
  border-color: var(--yk-blue-900);
  color: var(--yk-paper-050);
}

.page-about .ab-toc__num {
  font-family: var(--yk-mono);
  font-size: 11px;
  letter-spacing: .05em;
  color: var(--yk-coral-700);
  transition: color 180ms var(--yk-ease);
}

.page-about .ab-toc__link:hover .ab-toc__num {
  color: var(--yk-mint-300);
}

/* ---------- 章节骨架 ---------- */
.page-about .ab-chapter {
  padding-block: var(--ab-space);
  scroll-margin-top: 96px;
}

.page-about .ab-chapter--sand {
  background: var(--yk-sand-100);
  border-block: 1px solid var(--ab-rule);
}

.page-about .ab-chapter--sky {
  background: var(--yk-sky-100);
  border-block: 1px solid var(--ab-rule);
}

.page-about .ab-chapter__grid {
  display: grid;
  gap: clamp(12px, 2.4vw, 22px);
}

.page-about .ab-chapter__grid--tight {
  margin-top: clamp(18px, 3vw, 28px);
}

.page-about .ab-chapter__side {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .ab-chapter__num {
  font-family: var(--yk-mono);
  font-size: 12px;
  letter-spacing: .22em;
  font-weight: 700;
  color: var(--yk-coral-700);
}

.page-about .ab-chapter__title {
  margin: 0;
  font-family: var(--yk-serif);
  font-weight: 700;
  font-size: clamp(1.35rem, 3.4vw, 1.85rem);
  line-height: 1.3;
  color: var(--yk-blue-900);
}

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

.page-about .ab-chapter__body p {
  margin: 0 0 1.05em;
  font-size: 15.5px;
}

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

.page-about .ab-chapter__body a {
  color: var(--yk-blue-700);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

.page-about .ab-chapter__body a:hover {
  color: var(--yk-coral-700);
}

.page-about .ab-quote {
  margin: 0 0 1.25em;
  padding: 14px 18px;
  border-left: 3px solid var(--yk-coral-500);
  background: var(--yk-paper-050);
  font-family: var(--yk-serif);
  font-size: clamp(1.02rem, 2.2vw, 1.22rem);
  line-height: 1.65;
  color: var(--yk-blue-900);
  border-radius: 0 var(--yk-radius) var(--yk-radius) 0;
}

/* ---------- 适配人群 ---------- */
.page-about .ab-audience {
  list-style: none;
  margin: clamp(22px, 3.5vw, 32px) 0 clamp(24px, 3.5vw, 34px);
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}

.page-about .ab-persona {
  background: var(--yk-paper-050);
  border: 1px solid var(--ab-rule);
  border-radius: var(--yk-radius);
  padding: clamp(16px, 2.4vw, 22px);
  box-shadow: var(--yk-shadow);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .ab-persona__tag {
  align-self: flex-start;
  font-size: 11.5px;
  letter-spacing: .1em;
  padding: 3px 10px;
  border-radius: 999px;
  background: var(--yk-mint-300);
  color: var(--yk-blue-900);
  font-weight: 700;
}

.page-about .ab-persona:nth-child(2) .ab-persona__tag {
  background: var(--yk-coral-500);
  color: #FFFFFF;
}

.page-about .ab-persona:nth-child(3) .ab-persona__tag {
  background: var(--yk-sky-100);
  color: var(--yk-blue-700);
  border: 1px solid var(--yk-line-200);
}

.page-about .ab-persona:nth-child(4) .ab-persona__tag {
  background: var(--yk-sand-100);
  color: var(--yk-coral-700);
  border: 1px solid var(--yk-line-200);
}

.page-about .ab-persona h3 {
  margin: 0;
  font-family: var(--yk-sans);
  font-weight: 700;
  font-size: 1.02rem;
  line-height: 1.5;
  color: var(--yk-blue-900);
}

.page-about .ab-persona p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--ab-muted);
}

.page-about .ab-persona__link {
  margin-top: auto;
  align-self: flex-start;
  font-size: 13.5px;
  font-weight: 700;
  color: var(--yk-blue-700);
  text-decoration: none;
  border-bottom: 1px solid currentColor;
  padding-bottom: 1px;
}

.page-about .ab-persona__link:hover {
  color: var(--yk-coral-700);
}

.page-about .ab-fig--wide {
  margin-inline: auto;
  max-width: 640px;
}

/* ---------- 四块之外 ---------- */
.page-about .ab-scope {
  list-style: none;
  margin: clamp(22px, 3.5vw, 32px) 0 0;
  padding: 0;
  border-top: 1px solid var(--ab-rule);
}

.page-about .ab-scope__item {
  display: grid;
  gap: 4px;
  padding: 16px 0;
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .ab-scope__label {
  font-weight: 700;
  font-size: 15px;
  letter-spacing: .02em;
  color: var(--yk-blue-900);
}

.page-about .ab-scope__item p {
  margin: 0;
  font-size: 14.5px;
  color: var(--ab-muted);
}

.page-about .ab-scope__link {
  justify-self: start;
  font-size: 13.5px;
  font-weight: 700;
  color: var(--yk-blue-700);
  text-decoration: none;
  border-bottom: 1px solid var(--yk-line-200);
}

.page-about .ab-scope__link:hover {
  color: var(--yk-coral-700);
  border-bottom-color: var(--yk-coral-500);
}

/* ---------- 维护记录 ---------- */
.page-about .ab-ledger {
  margin: clamp(22px, 3.5vw, 32px) 0 0;
  border-top: 1px solid rgba(11, 42, 74, .16);
}

.page-about .ab-ledger__row {
  display: grid;
  gap: 4px;
  padding: 14px 0;
  border-bottom: 1px solid rgba(11, 42, 74, .16);
}

.page-about .ab-ledger__key {
  font-family: var(--yk-mono);
  font-size: 11.5px;
  letter-spacing: .14em;
  color: var(--yk-blue-700);
  text-transform: uppercase;
}

.page-about .ab-ledger__val {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--yk-ink-900);
}

/* ---------- 时间轴 ---------- */
.page-about .ab-fig--banner {
  margin: clamp(22px, 3.5vw, 32px) 0 clamp(24px, 3.5vw, 34px);
}

.page-about .ab-timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 26px;
  border-left: 2px solid var(--yk-line-200);
}

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

.page-about .ab-timeline__item::before {
  content: "";
  position: absolute;
  left: -36px;
  top: 16px;
  width: 12px;
  height: 12px;
  box-sizing: content-box;
  border-radius: 50%;
  background: var(--yk-paper-050);
  border: 3px solid var(--yk-coral-500);
}

.page-about .ab-timeline__details {
  border: 1px solid var(--ab-rule);
  border-radius: var(--yk-radius);
  background: var(--yk-paper-050);
  margin-bottom: 10px;
  overflow: hidden;
  transition: border-color 180ms var(--yk-ease);
}

.page-about .ab-timeline__details:hover {
  border-color: var(--yk-blue-700);
}

.page-about .ab-timeline__summary {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 12px 16px;
  cursor: pointer;
  list-style: none;
  color: var(--yk-blue-900);
  transition: background 180ms var(--yk-ease);
}

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

.page-about .ab-timeline__summary::marker {
  content: "";
}

.page-about .ab-timeline__summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--yk-mono);
  font-size: 16px;
  line-height: 1;
  color: var(--yk-coral-700);
}

.page-about .ab-timeline__details[open] .ab-timeline__summary {
  background: var(--yk-sand-100);
}

.page-about .ab-timeline__details[open] .ab-timeline__summary::after {
  content: "−";
}

.page-about .ab-timeline__year {
  font-family: var(--yk-mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: .03em;
  color: var(--yk-coral-700);
  flex: none;
}

.page-about .ab-timeline__head {
  font-size: 14.5px;
  font-weight: 700;
}

.page-about .ab-timeline__body {
  padding: 0 16px 14px;
}

.page-about .ab-timeline__body p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--ab-muted);
}

/* ---------- 团队 ---------- */
.page-about .ab-team {
  list-style: none;
  margin: clamp(22px, 3.5vw, 32px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}

.page-about .ab-team__card {
  position: relative;
  overflow: hidden;
  background: var(--yk-paper-050);
  border: 1px solid var(--ab-rule);
  border-radius: var(--yk-radius);
  padding: 20px 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  box-shadow: var(--yk-shadow);
}

.page-about .ab-team__card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: var(--yk-blue-700);
}

.page-about .ab-team__card:nth-child(2)::before {
  background: var(--yk-coral-500);
}

.page-about .ab-team__card:nth-child(3)::before {
  background: var(--yk-mint-300);
}

.page-about .ab-team__card:nth-child(4)::before {
  background: var(--yk-focus-500);
}

.page-about .ab-team__num {
  font-family: var(--yk-mono);
  font-size: 1.65rem;
  font-weight: 700;
  line-height: 1;
  color: var(--yk-blue-900);
}

.page-about .ab-team__num small {
  font-family: var(--yk-sans);
  font-size: 12px;
  font-weight: 400;
  color: var(--ab-muted);
  margin-left: 3px;
}

.page-about .ab-team__role {
  font-size: 13.5px;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--yk-blue-700);
}

.page-about .ab-team__card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--ab-muted);
}

.page-about .ab-team__note {
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 14px 18px;
  border-left: 3px solid var(--yk-mint-300);
  background: var(--yk-paper-050);
  border-radius: 0 var(--yk-radius) var(--yk-radius) 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--yk-ink-900);
}

/* ---------- 联系带 ---------- */
.page-about .ab-cta {
  background: var(--yk-blue-900);
  color: var(--yk-paper-050);
  padding-block: clamp(34px, 5vw, 58px);
}

.page-about .ab-cta__inner {
  display: grid;
  gap: 22px;
}

.page-about .ab-cta h2 {
  margin: 0 0 10px;
  font-family: var(--yk-serif);
  font-weight: 700;
  font-size: clamp(1.35rem, 3.2vw, 1.95rem);
  line-height: 1.35;
  color: var(--yk-paper-050);
}

.page-about .ab-cta p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(251, 249, 245, .84);
  max-width: 56ch;
}

.page-about .ab-cta__contact {
  margin-top: 14px;
  font-family: var(--yk-mono);
  font-size: 13.5px;
  letter-spacing: .02em;
  color: var(--yk-mint-300);
}

.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .ab-cta .yk-btn--ghost {
  color: var(--yk-paper-050);
  border-width: 1px;
}

.page-about .ab-cta .yk-btn--ghost:hover {
  color: var(--yk-blue-900);
}

/* ---------- 断点 ---------- */
@media (min-width: 620px) {
  .page-about .ab-audience,
  .page-about .ab-team {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ab-ledger__row {
    grid-template-columns: 124px minmax(0, 1fr);
    column-gap: 20px;
    align-items: baseline;
  }
}

@media (min-width: 720px) {
  .page-about .ab-scope__item {
    grid-template-columns: 132px minmax(0, 1fr) auto;
    column-gap: 20px;
    align-items: baseline;
  }

  .page-about .ab-scope__link {
    justify-self: end;
    white-space: nowrap;
  }
}

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

@media (min-width: 900px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.06fr) minmax(0, .94fr);
    column-gap: clamp(32px, 5vw, 60px);
  }

  .page-about .ab-toc__list {
    flex-wrap: wrap;
    overflow: visible;
  }

  .page-about .ab-chapter__grid {
    grid-template-columns: 236px minmax(0, 1fr);
    column-gap: clamp(28px, 4.5vw, 60px);
  }

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

  .page-about .ab-chapter__grid--tight .ab-chapter__side {
    position: static;
  }

  .page-about .ab-fig--wide {
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
  }
}

@media (min-width: 1000px) {
  .page-about .ab-team {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .ab-cta__inner {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
    column-gap: 44px;
  }

  .page-about .ab-cta__actions {
    padding-bottom: 4px;
  }
}

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