.page-about {
  --about-chapter-gap: clamp(3rem, 7vw, 5.5rem);
  --about-aside-w: 14rem;
  padding-bottom: clamp(3rem, 8vw, 6rem);
  overflow-wrap: break-word;
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  padding-top: clamp(1.25rem, 3vw, 1.75rem);
}

.page-about .about-crumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .35rem;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--ls-font-mono);
  font-size: .72rem;
  letter-spacing: .08em;
  color: var(--ls-slate);
}

.page-about .about-crumb__item {
  display: inline-flex;
  align-items: center;
}

.page-about .about-crumb__item + .about-crumb__item::before {
  content: "/";
  margin-right: .35rem;
  color: var(--ls-line-strong);
}

.page-about .about-crumb__link {
  color: var(--ls-slate);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--ls-dur) var(--ls-ease), border-color var(--ls-dur) var(--ls-ease);
}

.page-about .about-crumb__link:hover,
.page-about .about-crumb__link:focus-visible {
  color: var(--ls-cyan);
  border-bottom-color: var(--ls-cyan);
}

.page-about .about-crumb__item[aria-current="page"] {
  color: var(--ls-cream);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(2.25rem, 6vw, 4.25rem) clamp(1.75rem, 4vw, 2.75rem);
  border-bottom: 1px solid var(--ls-line);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -34%;
  right: -14%;
  width: min(34rem, 78%);
  aspect-ratio: 1 / 1;
  background:
    radial-gradient(circle at 56% 44%, rgba(53, 230, 218, .20), rgba(53, 230, 218, 0) 62%),
    radial-gradient(circle at 78% 74%, rgba(255, 210, 74, .13), rgba(255, 210, 74, 0) 60%);
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  right: -4rem;
  bottom: 1.5rem;
  width: min(26rem, 70%);
  height: 1px;
  background: linear-gradient(90deg, rgba(53, 230, 218, 0), var(--ls-cyan));
  transform: rotate(-22deg);
  transform-origin: right center;
  opacity: .5;
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero__eyebrow,
.page-about .about-hero__title,
.page-about .about-hero__lead,
.page-about .about-hero__facts {
  position: relative;
  z-index: 1;
}

.page-about .about-hero__eyebrow {
  margin: 0 0 .9rem;
}

.page-about .about-hero__title {
  margin: 0 0 1.1rem;
  max-width: 17ch;
  font-size: clamp(2rem, 5.6vw, 3.75rem);
  line-height: 1.06;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: var(--ls-cream);
}

.page-about .about-hero__lead {
  margin: 0 0 1.6rem;
  max-width: 58ch;
  font-size: clamp(1rem, 1.4vw, 1.0625rem);
  line-height: 1.85;
  color: var(--ls-slate);
}

.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-hero__fact {
  padding: .45rem .95rem;
  border-radius: var(--ls-pill);
  border: 1px solid var(--ls-line-strong);
  background: rgba(11, 20, 36, .74);
  font-family: var(--ls-font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--ls-slate);
}

/* ---------- 章节索引 ---------- */
.page-about .about-toc {
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  padding: clamp(1.15rem, 3vw, 1.75rem);
  border: 1px solid var(--ls-line);
  border-radius: var(--ls-r-lg);
  background: linear-gradient(158deg, rgba(11, 20, 36, .92), rgba(5, 7, 14, .5));
}

.page-about .about-toc__list {
  display: grid;
  gap: .2rem;
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-toc__item {
  min-width: 0;
}

.page-about .about-toc__link {
  display: flex;
  align-items: baseline;
  gap: .85rem;
  padding: .7rem .85rem;
  border-radius: var(--ls-r-sm);
  color: var(--ls-cream);
  text-decoration: none;
  font-size: .95rem;
  line-height: 1.5;
  transition: background var(--ls-dur) var(--ls-ease), color var(--ls-dur) var(--ls-ease);
}

.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  background: rgba(53, 230, 218, .09);
  color: var(--ls-cyan);
}

.page-about .about-toc__idx {
  flex: 0 0 auto;
  font-size: .78rem;
  letter-spacing: .06em;
  color: var(--ls-cyan);
}

/* ---------- 章节通用 ---------- */
.page-about .about-chapter {
  padding-top: var(--about-chapter-gap);
  position: relative;
}

.page-about .about-chapter::before {
  content: "";
  position: absolute;
  top: calc(var(--about-chapter-gap) - 1.1rem);
  left: 0;
  width: 3.5rem;
  height: 2px;
  background: linear-gradient(90deg, var(--ls-moss), rgba(79, 107, 88, 0));
}

.page-about .about-chapter__idx {
  display: inline-block;
  font-size: .76rem;
  letter-spacing: .16em;
  color: var(--ls-cyan);
}

.page-about .about-chapter__title {
  margin: .55rem 0 .7rem;
  max-width: 24ch;
  font-size: clamp(1.45rem, 3.1vw, 2.15rem);
  line-height: 1.2;
  letter-spacing: -0.01em;
  font-weight: 750;
  color: var(--ls-cream);
}

.page-about .about-chapter__lede {
  margin: 0;
  max-width: 58ch;
  font-size: 1rem;
  line-height: 1.8;
  color: var(--ls-slate);
}

.page-about .about-chapter__grid {
  display: grid;
  gap: 1.6rem;
  margin-top: 1.5rem;
}

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

.page-about .about-chapter__body > * + * {
  margin-top: 1.15rem;
}

.page-about .about-prose {
  margin: 0;
  max-width: 62ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--ls-cream);
}

.page-about .about-prose + .about-prose {
  color: var(--ls-slate);
}

/* ---------- 三条主线 ---------- */
.page-about .about-route {
  display: grid;
  gap: .85rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-route__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: .5rem 1.1rem;
  padding: 1.15rem 1.25rem;
  border: 1px solid var(--ls-line);
  border-radius: var(--ls-r-md);
  background: rgba(11, 20, 36, .66);
  transition: transform var(--ls-dur) var(--ls-ease), border-color var(--ls-dur) var(--ls-ease);
}

.page-about .about-route__item:hover,
.page-about .about-route__item:focus-within {
  transform: translateY(-2px);
  border-color: rgba(53, 230, 218, .5);
}

.page-about .about-route__num {
  font-size: .78rem;
  letter-spacing: .08em;
  color: var(--ls-volt);
  padding-top: .2rem;
}

.page-about .about-route__body {
  min-width: 0;
}

.page-about .about-route__name {
  margin: 0 0 .4rem;
  font-size: 1.08rem;
  letter-spacing: -0.01em;
  color: var(--ls-cream);
}

.page-about .about-route__desc {
  margin: 0;
  max-width: 60ch;
  font-size: .95rem;
  line-height: 1.8;
  color: var(--ls-slate);
}

.page-about .about-inline-link {
  margin: 0;
}

.page-about .about-textlink {
  display: inline-block;
  font-size: .92rem;
  color: var(--ls-cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 230, 218, .45);
  padding-bottom: 2px;
  transition: border-color var(--ls-dur) var(--ls-ease), color var(--ls-dur) var(--ls-ease);
}

.page-about .about-textlink:hover,
.page-about .about-textlink:focus-visible {
  border-bottom-color: var(--ls-cyan);
  color: var(--ls-cream);
}

/* ---------- 旁注 ---------- */
.page-about .about-aside {
  padding: 1.1rem 1.2rem;
  border: 1px solid var(--ls-line);
  border-left-width: 2px;
  border-radius: var(--ls-r-md);
  background: rgba(11, 20, 36, .78);
}

.page-about .about-aside--moss {
  border-left-color: var(--ls-moss);
}

.page-about .about-aside--clay {
  border-left-color: var(--ls-clay);
}

.page-about .about-aside--volt {
  border-left-color: var(--ls-volt);
}

.page-about .about-aside__label {
  margin: 0 0 .6rem;
  font-family: var(--ls-font-mono);
  font-size: .68rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ls-cyan);
}

.page-about .about-aside__text {
  margin: 0;
  font-size: .88rem;
  line-height: 1.75;
  color: var(--ls-slate);
}

.page-about .about-aside__text + .about-aside__text,
.page-about .about-aside__list + .about-aside__text {
  margin-top: .75rem;
  padding-top: .75rem;
  border-top: 1px solid var(--ls-line);
}

.page-about .about-aside__list {
  display: grid;
  gap: .55rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-aside__row {
  display: flex;
  align-items: baseline;
  gap: .6rem;
  font-size: .88rem;
  line-height: 1.5;
  color: var(--ls-slate);
}

.page-about .about-aside__num {
  flex: 0 0 auto;
  min-width: 2.4rem;
  font-size: .95rem;
  color: var(--ls-volt);
}

/* ---------- 配图 ---------- */
.page-about .about-figure {
  margin: clamp(1.5rem, 4vw, 2.25rem) 0 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
}

/* ---------- 规模数字 ---------- */
.page-about .about-metrics {
  display: grid;
  gap: .7rem;
  margin: clamp(1.5rem, 4vw, 2rem) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-metric {
  padding: 1.05rem 1.15rem;
  border: 1px solid var(--ls-line);
  border-radius: var(--ls-r-md);
  background: linear-gradient(152deg, rgba(11, 20, 36, .95), rgba(5, 7, 14, .6));
}

.page-about .about-metric__num {
  display: block;
  font-size: clamp(1.5rem, 3.6vw, 2rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ls-volt);
}

.page-about .about-metric__name {
  display: block;
  margin-top: .4rem;
  font-size: .8rem;
  letter-spacing: .06em;
  color: var(--ls-slate);
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  margin-top: clamp(3rem, 8vw, 5.5rem);
  padding-top: clamp(2rem, 5vw, 3rem);
  border-top: 1px solid var(--ls-line);
}

.page-about .about-next__title {
  margin: 0;
  font-size: clamp(1.35rem, 2.8vw, 1.85rem);
  line-height: 1.25;
  letter-spacing: -0.01em;
  color: var(--ls-cream);
}

.page-about .about-next__grid {
  display: grid;
  gap: .85rem;
  margin-top: 1.5rem;
}

.page-about .about-next__card {
  display: block;
  padding: 1.25rem 1.3rem;
  border: 1px solid var(--ls-line);
  border-radius: var(--ls-r-md);
  background: rgba(11, 20, 36, .7);
  text-decoration: none;
  color: inherit;
  transition: transform var(--ls-dur) var(--ls-ease), border-color var(--ls-dur) var(--ls-ease);
}

.page-about .about-next__card:hover,
.page-about .about-next__card:focus-visible {
  transform: translateY(-3px);
  border-color: rgba(53, 230, 218, .55);
}

.page-about .about-next__name {
  display: block;
  margin-bottom: .4rem;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  color: var(--ls-cream);
}

.page-about .about-next__desc {
  display: block;
  font-size: .88rem;
  line-height: 1.7;
  color: var(--ls-slate);
}

.page-about .about-next__card::after {
  content: "→";
  display: block;
  margin-top: .85rem;
  font-family: var(--ls-font-mono);
  font-size: .95rem;
  color: var(--ls-cyan);
  transition: transform var(--ls-dur) var(--ls-ease);
}

.page-about .about-next__card:hover::after,
.page-about .about-next__card:focus-visible::after {
  transform: translateX(4px);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-toc__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-metrics {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-next__grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1024px) {
  .page-about .about-metrics {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-hero__title {
    max-width: 20ch;
  }
}

@media (min-width: 1120px) {
  .page-about .about-chapter__grid {
    grid-template-columns: minmax(0, 1fr) var(--about-aside-w);
    gap: clamp(2rem, 4vw, 3rem);
    align-items: start;
  }

  .page-about .about-aside {
    position: sticky;
    top: 2rem;
  }
}

@media (min-width: 1240px) {
  .page-about .about-hero__lead {
    max-width: 64ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-route__item,
  .page-about .about-next__card,
  .page-about .about-next__card::after,
  .page-about .about-toc__link {
    transition: none;
  }

  .page-about .about-route__item:hover,
  .page-about .about-next__card:hover {
    transform: none;
  }

  .page-about .about-next__card:hover::after {
    transform: none;
  }
}