.page-about {
  --ab-gap: clamp(56px, 8vw, 120px);
  --ab-split-gap: clamp(24px, 3.6vw, 52px);
  background: var(--fh-carbon);
  color: var(--fh-bone);
  overflow-x: clip;
}

.page-about img {
  max-width: 100%;
}

/* ---------- 首屏 ---------- */

.page-about .ab-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: clamp(34px, 6vw, 82px) 0 clamp(46px, 7vw, 96px);
}

.page-about .ab-hero::before {
  content: "";
  position: absolute;
  z-index: -1;
  left: 30%;
  right: -14%;
  top: 32%;
  height: clamp(150px, 22vw, 290px);
  background: linear-gradient(96deg, rgba(255, 90, 31, .22), rgba(194, 21, 27, .09) 52%, rgba(47, 224, 214, 0) 100%);
  transform: skewY(-6deg);
  pointer-events: none;
}

.page-about .ab-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--fh-ember) 0 16%, var(--fh-iron) 16% 100%);
}

.page-about .ab-hero .fh-breadcrumb {
  margin-bottom: clamp(22px, 3vw, 40px);
}

.page-about .ab-hero__eyebrow {
  margin: 0;
  color: var(--fh-amber);
}

.page-about .ab-hero__title {
  margin: 16px 0 0;
  font-family: var(--fh-font-sans);
  font-size: clamp(2rem, 6.2vw, 4.9rem);
  font-weight: 900;
  line-height: 1.03;
  letter-spacing: -.02em;
  color: var(--fh-bone);
  max-width: 16em;
}

.page-about .ab-hero__lede {
  margin: clamp(20px, 3vw, 34px) 0 0;
  max-width: 40em;
  font-size: clamp(1rem, 1.35vw, 1.12rem);
  line-height: 1.85;
  color: rgba(244, 241, 236, .84);
}

.page-about .ab-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(28px, 4vw, 52px) 0 0;
  padding: 0;
  max-width: 760px;
  background: var(--fh-iron);
  border: 1px solid var(--fh-iron);
}

.page-about .ab-hero__fact {
  background: rgba(20, 23, 27, .86);
  padding: 16px 18px 18px;
}

.page-about .ab-hero__fact dt {
  margin: 0;
  font-size: 11px;
  letter-spacing: .24em;
  color: var(--fh-mist);
}

.page-about .ab-hero__fact dd {
  margin: 10px 0 0;
  display: flex;
  align-items: baseline;
  gap: 4px;
  font-family: var(--fh-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.4rem, 3vw, 2rem);
  font-weight: 700;
  line-height: 1;
  color: var(--fh-flame);
}

.page-about .ab-hero__fact dd em {
  font-family: var(--fh-font-sans);
  font-style: normal;
  font-size: .76rem;
  font-weight: 400;
  letter-spacing: .06em;
  color: var(--fh-mist);
}

@media (min-width: 640px) {
  .page-about .ab-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 901px) {
  .page-about .ab-hero__title {
    transform: skewX(-5deg);
    transform-origin: left center;
    margin-left: 5px;
  }
  .page-about .ab-hero__lede {
    margin-left: 5px;
  }
}

/* ---------- 长卷骨架 ---------- */

.page-about .ab-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  padding-bottom: clamp(40px, 6vw, 90px);
}

@media (min-width: 1040px) {
  .page-about .ab-shell {
    grid-template-columns: 74px minmax(0, 1fr);
    column-gap: clamp(24px, 3.4vw, 50px);
  }
}

.page-about .fh-rail {
  display: none;
}

.page-about .fh-rail__item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 7px 0;
  font-family: var(--fh-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--fh-mist);
  text-decoration: none;
  transition: color .25s var(--fh-ease);
}

.page-about .fh-rail__dot {
  display: block;
  width: 14px;
  height: 1px;
  background: var(--fh-iron);
  transition: width .25s var(--fh-ease), background .25s var(--fh-ease);
}

.page-about .fh-rail__item:hover,
.page-about .fh-rail__item.is-active {
  color: var(--fh-amber);
}

.page-about .fh-rail__item.is-active .fh-rail__dot {
  width: 26px;
  background: var(--fh-flame);
}

@media (min-width: 1040px) {
  .page-about .fh-rail {
    position: sticky;
    inset: auto;
    top: 104px;
    align-self: start;
    display: flex;
    flex-direction: column;
    gap: 2px;
    padding: 8px 0 8px 16px;
    border-left: 1px solid var(--fh-iron);
  }
}

/* ---------- 章节 ---------- */

.page-about .ab-chapter {
  padding: var(--ab-gap) 0;
  border-top: 1px solid var(--fh-iron);
  scroll-margin-top: 110px;
}

.page-about .ab-flow > .ab-chapter:first-child {
  border-top: 0;
}

.page-about .ab-chapter__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: clamp(14px, 2.6vw, 30px);
  align-items: start;
  margin-bottom: clamp(24px, 3.4vw, 44px);
}

.page-about .ab-chapter__no {
  min-width: 2.1em;
  padding-top: 12px;
  border-top: 3px solid var(--fh-ember);
  font-family: var(--fh-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.05rem, 2.1vw, 1.6rem);
  font-weight: 700;
  line-height: 1;
  color: var(--fh-ember);
}

.page-about .ab-chapter__heading .fh-eyebrow {
  margin: 0 0 10px;
  color: var(--fh-cyan);
}

.page-about .ab-chapter__title {
  margin: 0;
  max-width: 22em;
  font-size: clamp(1.4rem, 3.1vw, 2.3rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -.015em;
  color: var(--fh-bone);
}

@media (max-width: 620px) {
  .page-about .ab-chapter__head {
    grid-template-columns: minmax(0, 1fr);
    gap: 10px;
  }
  .page-about .ab-chapter__no {
    min-width: 0;
    padding: 0 0 0 10px;
    border-top: 0;
    border-left: 3px solid var(--fh-ember);
  }
}

.page-about .ab-lead {
  margin: 0;
  max-width: 42em;
  font-size: clamp(.98rem, 1.2vw, 1.06rem);
  line-height: 1.85;
  color: rgba(244, 241, 236, .84);
}

/* ---------- 媒体 ---------- */

.page-about .fh-media {
  margin: clamp(24px, 3.4vw, 44px) 0 0;
  border: 1px solid var(--fh-iron);
  background: var(--fh-ink);
  overflow: hidden;
}

.page-about .fh-media__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(.92) contrast(1.06);
}

.page-about .fh-media__caption {
  padding: 12px 16px 14px;
  border-top: 1px solid var(--fh-iron);
  background: rgba(20, 23, 27, .72);
  font-size: .78rem;
  letter-spacing: .04em;
  color: var(--fh-mist);
}

.page-about .ab-chapter__figure--tall {
  margin-top: 0;
}

/* ---------- 分栏 ---------- */

.page-about .ab-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--ab-split-gap);
  margin-top: clamp(24px, 3.4vw, 44px);
}

@media (min-width: 900px) {
  .page-about .ab-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  }
}

.page-about .ab-split__main p {
  margin: 0 0 1.3em;
  max-width: 38em;
  font-size: clamp(.97rem, 1.15vw, 1.06rem);
  line-height: 1.85;
  color: rgba(244, 241, 236, .84);
}

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

.page-about .ab-split__side {
  padding-top: 18px;
  border-top: 1px solid var(--fh-iron);
}

.page-about .ab-side__title {
  margin: 0 0 16px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: .26em;
  color: var(--fh-mist);
}

.page-about .ab-side__note {
  margin: 0;
  max-width: 30em;
  font-size: .9rem;
  line-height: 1.8;
  color: var(--fh-mist);
}

.page-about .ab-side__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-side__list li {
  display: flex;
  gap: 12px;
  padding: 11px 0;
  border-bottom: 1px solid rgba(42, 47, 54, .8);
  font-size: .92rem;
  line-height: 1.6;
  color: rgba(244, 241, 236, .88);
}

.page-about .ab-side__list li:last-child {
  border-bottom: 0;
}

.page-about .ab-side__list li span {
  flex: 0 0 22px;
  padding-top: 3px;
  font-family: var(--fh-font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--fh-cyan);
}

.page-about .ab-ways {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0;
  padding: 0;
}

.page-about .ab-ways li {
  padding: 8px 14px;
  border: 1px solid var(--fh-iron);
  background: rgba(20, 23, 27, .62);
  font-size: .84rem;
  color: var(--fh-bone);
}

.page-about .ab-quote {
  margin: 22px 0 0;
  padding: 14px 0 14px 16px;
  border-left: 2px solid var(--fh-amber);
  font-size: .92rem;
  line-height: 1.7;
  color: var(--fh-amber);
}

/* ---------- 四道处理 ---------- */

.page-about .ab-chain {
  list-style: none;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: clamp(26px, 3.6vw, 46px) 0 0;
  padding: 0;
  background: var(--fh-iron);
  border: 1px solid var(--fh-iron);
}

@media (min-width: 780px) {
  .page-about .ab-chain {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .ab-chain__item {
  position: relative;
  background: var(--fh-ink);
  padding: 28px 20px 30px;
}

.page-about .ab-chain__item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 34px;
  height: 2px;
  background: var(--fh-cyan);
}

.page-about .ab-chain__step {
  font-family: var(--fh-font-mono);
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--fh-mist);
}

.page-about .ab-chain__title {
  margin: 14px 0 8px;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--fh-bone);
}

.page-about .ab-chain__item p {
  margin: 0;
  font-size: .88rem;
  line-height: 1.72;
  color: var(--fh-mist);
}

/* ---------- 指标条 ---------- */

.page-about .ab-metrics {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(22px, 3vw, 36px);
  background: var(--fh-iron);
  border: 1px solid var(--fh-iron);
}

@media (min-width: 720px) {
  .page-about .ab-metrics {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .ab-metrics__cell {
  background: rgba(10, 11, 13, .92);
  padding: 20px 18px 22px;
}

.page-about .ab-metrics__num {
  font-family: var(--fh-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.5rem, 3vw, 2.2rem);
  font-weight: 700;
  line-height: 1;
  color: var(--fh-flame);
}

.page-about .ab-metrics__unit {
  margin-left: 6px;
  font-size: .76rem;
  letter-spacing: .1em;
  color: var(--fh-mist);
}

.page-about .ab-metrics__label {
  margin: 12px 0 0;
  font-size: .82rem;
  line-height: 1.62;
  color: var(--fh-mist);
}

/* ---------- 栏目分类 ---------- */

.page-about .ab-cats {
  list-style: none;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: clamp(24px, 3.4vw, 42px) 0 0;
  padding: 0;
  background: var(--fh-iron);
  border: 1px solid var(--fh-iron);
}

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

.page-about .ab-cats__item {
  position: relative;
  background: var(--fh-ink);
  padding: 22px 22px 24px 58px;
}

.page-about .ab-cats__idx {
  position: absolute;
  left: 22px;
  top: 24px;
  font-family: var(--fh-font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--fh-cyan);
}

.page-about .ab-cats__name {
  margin: 0;
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--fh-bone);
}

.page-about .ab-cats__desc {
  margin: 8px 0 0;
  font-size: .86rem;
  line-height: 1.72;
  color: var(--fh-mist);
}

.page-about .ab-feature {
  display: grid;
  justify-items: start;
  gap: 14px;
  margin-top: clamp(24px, 3.4vw, 42px);
  padding: clamp(22px, 3vw, 36px);
  border: 1px solid var(--fh-iron);
  border-left: 3px solid var(--fh-flame);
  background: linear-gradient(118deg, rgba(255, 90, 31, .13), rgba(20, 23, 27, .92) 48%, rgba(14, 107, 112, .18));
}

.page-about .ab-feature .fh-eyebrow {
  margin: 0;
  color: var(--fh-amber);
}

.page-about .ab-feature__title {
  margin: 0;
  font-size: clamp(1.12rem, 2vw, 1.5rem);
  font-weight: 800;
  color: var(--fh-bone);
}

.page-about .ab-feature p {
  margin: 0;
  max-width: 44em;
  font-size: .95rem;
  line-height: 1.82;
  color: rgba(244, 241, 236, .84);
}

/* ---------- 时间线 ---------- */

.page-about .ab-time-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 58px);
  align-items: start;
  margin-top: clamp(24px, 3.4vw, 42px);
}

@media (min-width: 900px) {
  .page-about .ab-time-wrap {
    grid-template-columns: minmax(0, 4fr) minmax(0, 7fr);
  }
}

.page-about .ab-time {
  list-style: none;
  margin: 0;
  padding: 0 0 0 28px;
  border-left: 1px solid var(--fh-iron);
}

.page-about .ab-time__item {
  position: relative;
  padding-bottom: clamp(24px, 3vw, 40px);
}

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

.page-about .ab-time__item::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 7px;
  width: 9px;
  height: 9px;
  background: var(--fh-carbon);
  border: 1px solid var(--fh-iron);
  transform: rotate(45deg);
  transition: background .3s var(--fh-ease), border-color .3s var(--fh-ease);
}

.page-about .ab-time__item.is-inview::before {
  background: var(--fh-flame);
  border-color: var(--fh-flame);
}

.page-about .ab-time__stage {
  display: inline-block;
  font-family: var(--fh-font-mono);
  font-size: 11px;
  letter-spacing: .2em;
  color: var(--fh-amber);
}

.page-about .ab-time__title {
  margin: 10px 0 8px;
  font-size: clamp(1.02rem, 1.8vw, 1.22rem);
  font-weight: 700;
  color: var(--fh-bone);
}

.page-about .ab-time__item p {
  margin: 0;
  max-width: 42em;
  font-size: .92rem;
  line-height: 1.78;
  color: var(--fh-mist);
}

/* ---------- 团队 ---------- */

.page-about .ab-teams {
  list-style: none;
  margin: clamp(24px, 3.4vw, 42px) 0 0;
  padding: 0;
  border-top: 1px solid var(--fh-iron);
}

.page-about .ab-teams__item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  padding: clamp(22px, 3vw, 34px) 0;
  border-bottom: 1px solid var(--fh-iron);
}

@media (min-width: 780px) {
  .page-about .ab-teams__item {
    grid-template-columns: 168px minmax(0, 1fr);
    gap: clamp(20px, 3vw, 48px);
    align-items: start;
  }
}

.page-about .ab-teams__num {
  display: block;
  font-family: var(--fh-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(2.3rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: .92;
  color: var(--fh-bone);
}

.page-about .ab-teams__num small {
  display: block;
  margin-top: 10px;
  font-family: var(--fh-font-sans);
  font-size: .72rem;
  font-weight: 400;
  letter-spacing: .18em;
  color: var(--fh-mist);
}

.page-about .ab-teams__name {
  margin: 0 0 8px;
  font-size: 1.06rem;
  font-weight: 700;
  color: var(--fh-amber);
}

.page-about .ab-teams__item p {
  margin: 0;
  max-width: 44em;
  font-size: .93rem;
  line-height: 1.78;
  color: rgba(244, 241, 236, .82);
}

/* ---------- 合作 ---------- */

.page-about .ab-partners {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: clamp(22px, 3vw, 38px);
  background: var(--fh-iron);
  border: 1px solid var(--fh-iron);
}

@media (min-width: 760px) {
  .page-about .ab-partners {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .ab-partners__cell {
  background: var(--fh-ink);
  padding: 24px 20px 26px;
}

.page-about .ab-partners__num {
  font-family: var(--fh-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.8rem, 3.6vw, 2.6rem);
  font-weight: 700;
  line-height: 1;
  color: var(--fh-cyan);
}

.page-about .ab-partners__label {
  margin: 12px 0 0;
  font-size: .86rem;
  line-height: 1.7;
  color: var(--fh-mist);
}

/* ---------- 收口 ---------- */

.page-about .ab-close {
  position: relative;
  padding: clamp(46px, 6.5vw, 96px) 0 clamp(52px, 7vw, 106px);
  border-top: 1px solid var(--fh-ember);
  background: linear-gradient(180deg, rgba(194, 21, 27, .24), rgba(10, 11, 13, .96) 74%);
}

.page-about .ab-close .fh-eyebrow {
  margin: 0;
  color: var(--fh-amber);
}

.page-about .ab-close__title {
  margin: 12px 0 0;
  font-size: clamp(1.5rem, 3.4vw, 2.4rem);
  font-weight: 900;
  letter-spacing: -.015em;
  line-height: 1.16;
  color: var(--fh-bone);
}

.page-about .ab-close__lede {
  margin: 16px 0 0;
  max-width: 40em;
  font-size: .98rem;
  line-height: 1.82;
  color: rgba(244, 241, 236, .8);
}

.page-about .ab-close__actions {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: clamp(24px, 3.4vw, 42px);
  background: var(--fh-iron);
  border: 1px solid var(--fh-iron);
}

@media (min-width: 820px) {
  .page-about .ab-close__actions {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .ab-close__card {
  display: block;
  padding: 24px 22px 26px;
  background: rgba(10, 11, 13, .92);
  text-decoration: none;
  transition: background .28s var(--fh-ease), box-shadow .28s var(--fh-ease);
}

.page-about .ab-close__card:hover {
  background: rgba(42, 47, 54, .66);
  box-shadow: inset 0 0 0 1px var(--fh-cyan);
}

.page-about .ab-close__card h3 {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--fh-bone);
}

.page-about .ab-close__card p {
  margin: 10px 0 0;
  font-size: .88rem;
  line-height: 1.7;
  color: var(--fh-mist);
}

.page-about .ab-close__card span {
  display: inline-block;
  margin-top: 16px;
  font-family: var(--fh-font-mono);
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--fh-flame);
}

.page-about .ab-close__foot {
  margin: clamp(26px, 3.4vw, 44px) 0 0;
  font-size: .9rem;
  line-height: 1.8;
  color: var(--fh-mist);
}

.page-about .ab-close__foot a {
  color: var(--fh-amber);
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 179, 71, .5);
}

.page-about .ab-close__foot a:hover {
  border-bottom-color: var(--fh-amber);
}

/* ---------- 动效退化 ---------- */

@media (prefers-reduced-motion: reduce) {
  .page-about .fh-rail__item,
  .page-about .fh-rail__dot,
  .page-about .ab-time__item::before,
  .page-about .ab-close__card {
    transition: none;
  }
  .page-about .ab-hero::before {
    transform: none;
  }
  .page-about .ab-hero__title {
    transform: none;
  }
}