.page-about {
  --about-measure: 46rem;
  --about-toc-w: 13rem;
  display: block;
  background: var(--night);
  color: var(--paper);
  overflow-x: clip;
  padding-bottom: clamp(3rem, 8vw, 6rem);
}

.page-about .breadcrumb {
  padding-top: clamp(1rem, 3vw, 1.75rem);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(2rem, 6vw, 4.5rem) 0 clamp(1rem, 3vw, 2rem);
}

.page-about .about-hero__inner {
  max-width: 56rem;
}

.page-about .about-hero__title {
  margin: 1rem 0 1.3rem;
  font-size: clamp(2.35rem, 8vw, 5.4rem);
  font-weight: 800;
  line-height: 0.94;
  letter-spacing: -0.03em;
  text-wrap: balance;
}

.page-about .about-hero__accent {
  display: block;
  color: var(--odds);
}

.page-about .about-hero__lede {
  max-width: 40em;
  color: var(--ash);
}

.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 2.4rem;
  margin: 2rem 0 0;
  padding: 1.25rem 0 0;
  border-top: 1px solid var(--line);
  list-style: none;
}

.page-about .about-hero__facts li {
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--ash);
}

.page-about .about-hero__facts .num {
  display: block;
  margin-bottom: 0.2rem;
  font-size: clamp(1.5rem, 4vw, 2.1rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--paper);
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: clamp(1.5rem, 4vw, 2.75rem) auto 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line);
  border-radius: 2px;
  filter: saturate(0.94) contrast(1.04);
}

.page-about .about-figure figcaption {
  margin-top: 0.7rem;
  font-size: 0.78rem;
  line-height: 1.65;
  letter-spacing: 0.03em;
  color: var(--ash);
}

.page-about .about-figure--inset,
.page-about .about-figure--square {
  margin: 1.8rem 0 0;
}

/* ---------- 分栏 ---------- */
.page-about .about-layout {
  display: grid;
  gap: clamp(1.75rem, 4vw, 3rem);
  margin-top: clamp(2.5rem, 6vw, 4.5rem);
}

.page-about .about-toc {
  border-top: 1px solid var(--line);
  padding-top: 0.85rem;
}

.page-about .about-toc__title {
  margin: 0 0 0.7rem;
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--violet);
}

.page-about .about-toc__list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-toc__link {
  display: block;
  padding: 0.3rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 0.82rem;
  color: var(--ash);
  text-decoration: none;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  color: var(--paper);
  border-color: var(--violet);
}

.page-about .about-body {
  max-width: var(--about-measure);
  min-width: 0;
}

/* ---------- 章节 ---------- */
.page-about .about-section {
  padding-top: clamp(1.75rem, 4vw, 2.75rem);
  border-top: 1px solid var(--line);
}

.page-about .about-section + .about-section {
  margin-top: clamp(2rem, 5vw, 3.5rem);
}

.page-about .about-section__head {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  margin-bottom: 1.2rem;
}

.page-about .about-section__num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  color: var(--odds);
}

.page-about .about-section__title {
  margin: 0;
  font-size: clamp(1.5rem, 3.8vw, 2.35rem);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -0.02em;
}

.page-about .about-body p {
  margin: 0 0 1.15rem;
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--ash);
}

.page-about .about-dropcap::first-letter {
  float: left;
  margin: 0.06em 0.14em 0 0;
  font-size: 3.4rem;
  font-weight: 800;
  line-height: 0.8;
  color: var(--odds);
}

/* ---------- 引用块 ---------- */
.page-about .about-quote {
  margin: clamp(1.6rem, 4vw, 2.4rem) 0 0;
  padding: clamp(1.4rem, 4vw, 2.4rem);
  background: var(--paper);
  border-radius: 2px;
}

.page-about .about-quote p {
  margin: 0;
  color: var(--ink-on-paper);
  font-size: clamp(1.05rem, 2.4vw, 1.3rem);
  line-height: 1.6;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .about-quote__meta {
  display: block;
  margin-top: 1rem;
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  color: var(--violet-deep);
}

/* ---------- 角色分工 ---------- */
.page-about .about-roles {
  display: grid;
  gap: 1px;
  margin: 1.6rem 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-role {
  padding: 1.35rem 1.15rem;
  background: var(--board);
}

.page-about .about-role__name {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  margin: 0 0 0.6rem;
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-role__dot {
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--violet);
}

.page-about .about-role--a .about-role__dot { background: var(--violet); }
.page-about .about-role--b .about-role__dot { background: var(--odds); }
.page-about .about-role--c .about-role__dot { background: var(--turf); }

.page-about .about-role p {
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.78;
}

/* ---------- 流程 ---------- */
.page-about .about-flow {
  margin: 1.4rem 0 1.8rem;
  padding: 0;
  list-style: none;
  counter-reset: about-flow;
}

.page-about .about-flow li {
  position: relative;
  counter-increment: about-flow;
  padding: 0.85rem 0 0.85rem 2.6rem;
  border-top: 1px solid var(--line);
  font-size: 0.98rem;
  line-height: 1.75;
  color: var(--ash);
}

.page-about .about-flow li:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .about-flow li::before {
  content: counter(about-flow, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0.9rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--amber);
}

/* ---------- 纵向时间线 ---------- */
.page-about .about-timeline {
  margin: 1.5rem 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-node {
  position: relative;
  padding-left: 2rem;
  padding-bottom: 0.6rem;
}

.page-about .about-node::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 1.55rem;
  bottom: 0;
  width: 1px;
  background: var(--line);
}

.page-about .about-node::after {
  content: "";
  position: absolute;
  left: 1px;
  top: 1.05rem;
  z-index: 1;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--night);
  border: 1px solid var(--violet);
}

.page-about .about-node:last-child::before {
  display: none;
}

.page-about .about-node:last-child::after {
  border-color: var(--amber);
}

.page-about .about-node__box {
  border-top: 1px solid var(--line);
}

.page-about .about-node__summary {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: baseline;
  gap: 0.7rem;
  padding: 0.75rem 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-node__summary::marker {
  content: "";
}

.page-about .about-node__stage {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.08em;
  color: var(--odds);
}

.page-about .about-node__title {
  font-size: 1.02rem;
  font-weight: 700;
  line-height: 1.5;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-node__toggle {
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 1;
  color: var(--amber);
  transition: transform 0.25s var(--ease);
}

.page-about .about-node__box[open] .about-node__toggle {
  transform: rotate(45deg);
}

.page-about .about-node__text {
  margin: 0;
  padding: 0 0 1.1rem;
  font-size: 0.95rem;
  line-height: 1.82;
  color: var(--ash);
}

/* ---------- 共建 ---------- */
.page-about .about-join {
  display: grid;
  gap: 1px;
  margin: 1.5rem 0 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-join__item {
  padding: 1.2rem 1.1rem;
  background: var(--night);
}

.page-about .about-join__title {
  display: flex;
  align-items: baseline;
  gap: 0.55rem;
  margin: 0 0 0.45rem;
  font-size: 0.98rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-join__title .num {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--turf);
}

.page-about .about-join__item p {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.75;
}

/* ---------- 结尾行动 ---------- */
.page-about .about-next__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-roles {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (min-width: 700px) {
  .page-about .about-join {
    grid-template-columns: 1fr 1fr;
  }
}

@media (min-width: 900px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-toc-w) minmax(0, 1fr);
    align-items: start;
    gap: clamp(2rem, 4vw, 3.5rem);
  }

  .page-about .about-toc {
    position: sticky;
    top: 5.5rem;
    border-top: none;
    padding-top: 0;
  }

  .page-about .about-toc__list {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 0.2rem;
  }

  .page-about .about-toc__link {
    padding: 0.28rem 0 0.28rem 0.7rem;
    border: none;
    border-left: 1px solid var(--line);
    border-radius: 0;
  }

  .page-about .about-toc__link:hover,
  .page-about .about-toc__link:focus-visible {
    border-left-color: var(--odds);
  }

  .page-about .about-figure--inset {
    max-width: 34rem;
  }

  .page-about .about-figure--square {
    max-width: 26rem;
  }
}

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