.page-about {
  --about-h2-rule: clamp(1.5rem, 4vw, 2.5rem);
  display: block;
  background: var(--paper);
  color: var(--ink);
  overflow-x: clip;
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumb {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: clamp(1.1rem, 3vw, 1.9rem) var(--gutter) 0;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: clamp(2rem, 6vw, 3.6rem) var(--gutter) clamp(2.4rem, 6vw, 4rem);
  display: grid;
  gap: clamp(1rem, 2.4vw, 1.6rem);
}

.page-about .about-hero__title {
  margin: 0;
  max-width: 16ch;
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 40em;
  font-size: clamp(1rem, 1.15vw + 0.7rem, 1.12rem);
  line-height: 1.8;
  color: var(--ink);
}

.page-about .about-hero__lede + .about-hero__lede {
  color: var(--stone);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: clamp(0.6rem, 2vw, 1.2rem) 0 0;
  padding: clamp(1rem, 2.5vw, 1.6rem) 0 0;
  border-top: 1px solid var(--line);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(0.9rem, 3vw, 1.6rem);
}

.page-about .about-hero__facts li {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.page-about .about-hero__facts .num {
  font-size: clamp(1.6rem, 3.4vw, 2.4rem);
  font-weight: 600;
  line-height: 1;
  color: var(--green-pitch);
}

.page-about .about-hero__factlabel {
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--stone);
}

/* ---------- 主场地图时间轴 ---------- */
.page-about .about-axis {
  background: var(--green-night);
  color: var(--on-dark-1);
  padding: clamp(2.8rem, 8vw, 5.5rem) 0 clamp(3rem, 8vw, 5.5rem);
}

.page-about .about-axis__inner {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.page-about .about-axis__label {
  color: var(--amber);
}

.page-about .about-axis__title {
  margin: 0.7rem 0 0;
  color: var(--on-dark-1);
  max-width: 20ch;
}

.page-about .about-axis__lede {
  margin: clamp(0.9rem, 2.5vw, 1.4rem) 0 0;
  max-width: 44em;
  font-size: 1rem;
  line-height: 1.8;
  color: var(--on-dark-2);
}

.page-about .about-axis__media {
  margin: clamp(1.6rem, 4vw, 2.6rem) 0 0;
  background: var(--shade);
  clip-path: var(--cut);
  overflow: hidden;
}

.page-about .about-axis__media img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  aspect-ratio: 7 / 4;
}

/* 分段切换 */
.page-about .about-axis .tabs {
  margin-top: clamp(1.6rem, 4vw, 2.4rem);
}

.page-about .about-axis .tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem;
  margin: 0;
  padding: 0;
  border-bottom: 1px solid var(--line-dark);
}

.page-about .about-axis .tab {
  appearance: none;
  background: transparent;
  border: 0;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  padding: 0.7rem 1rem;
  color: var(--on-dark-2);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
  transition: color 260ms var(--ease), border-color 260ms var(--ease);
}

.page-about .about-axis .tab:hover {
  color: var(--on-dark-1);
}

.page-about .about-axis .tab[aria-selected="true"] {
  color: var(--amber);
  border-bottom-color: var(--amber);
}

.page-about .about-axis .tab:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
}

.page-about .about-axis .tabpanel {
  padding-top: clamp(1.2rem, 3vw, 1.8rem);
}

.page-about .about-axis .tabpanel[hidden] {
  display: none;
}

.page-about .about-axis .tabpanel:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 6px;
}

.page-about .about-axis__phase {
  margin: 0 0 clamp(1rem, 2.5vw, 1.5rem);
  max-width: 44em;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--on-dark-1);
}

.page-about .about-axis__fields {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.75rem;
}

.page-about .about-axis__fields li {
  display: grid;
  gap: 0.3rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--line-dark);
}

.page-about .about-axis__k {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--amber);
}

.page-about .about-axis__v {
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--on-dark-1);
}

.page-about .about-axis__more {
  margin: clamp(1.6rem, 4vw, 2.4rem) 0 0;
  font-size: 0.875rem;
  line-height: 1.75;
  color: var(--on-dark-2);
}

.page-about .about-axis__more a {
  color: var(--amber);
  text-decoration: none;
  border-bottom: 1px solid rgba(242, 178, 51, 0.45);
  transition: border-color 240ms var(--ease);
}

.page-about .about-axis__more a:hover,
.page-about .about-axis__more a:focus-visible {
  border-bottom-color: var(--amber);
}

/* ---------- 长文主体 ---------- */
.page-about .about-body {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: clamp(3rem, 8vw, 5.5rem) var(--gutter) clamp(3.5rem, 9vw, 6.5rem);
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
}

.page-about .about-index {
  align-self: start;
}

.page-about .about-index ol {
  list-style: none;
  margin: 0.9rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.15rem;
}

.page-about .about-index a {
  display: flex;
  align-items: baseline;
  gap: 0.65rem;
  padding: 0.35rem 0 0.35rem 0.7rem;
  border-left: 2px solid transparent;
  color: var(--stone);
  font-size: 0.8125rem;
  line-height: 1.55;
  text-decoration: none;
  transition: color 240ms var(--ease), border-color 240ms var(--ease);
}

.page-about .about-index a .num {
  font-size: 0.6875rem;
  letter-spacing: 0.1em;
  color: var(--stone);
  transition: color 240ms var(--ease);
}

.page-about .about-index a:hover,
.page-about .about-index a:focus-visible {
  color: var(--ink);
  border-left-color: var(--amber);
}

.page-about .about-index a:hover .num,
.page-about .about-index a:focus-visible .num {
  color: var(--amber);
}

.page-about .about-chapters {
  display: grid;
  gap: clamp(2.6rem, 6vw, 4.5rem);
  min-width: 0;
}

.page-about .chapter {
  padding-top: clamp(1.2rem, 3vw, 1.9rem);
  border-top: 1px solid var(--line);
  min-width: 0;
}

.page-about .chapter__num {
  color: var(--stone);
}

.page-about .chapter .section-title {
  margin: 0.55rem 0 clamp(1rem, 2.4vw, 1.5rem);
  max-width: 22ch;
}

.page-about .chapter .prose p {
  margin: 0 0 1.05em;
}

.page-about .chapter .prose p:last-child {
  margin-bottom: 0;
}

.page-about .chapter__media {
  margin: clamp(1.6rem, 4vw, 2.4rem) 0 0;
  max-width: 900px;
  background: var(--mist);
  clip-path: var(--cut);
  overflow: hidden;
}

.page-about .chapter__media img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  aspect-ratio: 3 / 2;
}

.page-about .chapter__media .media__cap,
.page-about .about-break .media__cap {
  margin: 0;
  padding: 0.75rem 1rem 0.9rem;
  font-size: 0.75rem;
  line-height: 1.6;
  color: var(--stone);
  background: var(--mist);
}

/* 全宽打断图 */
.page-about .about-break {
  margin: 0;
  background: var(--green-night);
  clip-path: var(--cut);
  overflow: hidden;
}

.page-about .about-break img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  aspect-ratio: 16 / 7;
}

.page-about .about-break .media__cap {
  background: var(--shade);
  color: var(--on-dark-2);
  padding: 0.8rem 1.1rem 0.95rem;
}

/* 合作区块 */
.page-about .chapter--invite {
  background: var(--mist);
  border-top: 0;
  padding: clamp(1.6rem, 4vw, 2.6rem) clamp(1.2rem, 4vw, 2.4rem) clamp(1.8rem, 4.5vw, 2.8rem);
  clip-path: var(--cut);
}

.page-about .chapter--invite .chapter__num {
  color: var(--green-pitch);
}

.page-about .chapter__actions {
  margin-top: clamp(1.3rem, 3vw, 1.9rem);
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

/* ---------- 响应式 ---------- */
@media (min-width: 560px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-axis__fields li {
    grid-template-columns: 7.5rem minmax(0, 1fr);
    align-items: baseline;
    gap: 1rem;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
    grid-template-areas:
      "label label"
      "title lede"
      "title lede2"
      "facts facts";
    align-items: start;
    column-gap: clamp(2rem, 5vw, 4.5rem);
  }

  .page-about .about-hero > .index-label {
    grid-area: label;
  }

  .page-about .about-hero__title {
    grid-area: title;
  }

  .page-about .about-hero__lede:nth-of-type(1) {
    grid-area: lede;
  }

  .page-about .about-hero__lede:nth-of-type(2) {
    grid-area: lede2;
  }

  .page-about .about-hero__facts {
    grid-area: facts;
    margin-top: clamp(1.4rem, 3vw, 2.2rem);
  }
}

@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: minmax(150px, 195px) minmax(0, 1fr);
    column-gap: clamp(2rem, 5.5vw, 4.5rem);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--hdr-h) + 2.2rem);
  }
}

@media (min-width: 1180px) {
  .page-about .about-chapters {
    gap: clamp(3.4rem, 5vw, 5rem);
  }

  .page-about .chapter .prose {
    max-width: 40em;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index a,
  .page-about .about-axis .tab,
  .page-about .about-axis__more a {
    transition: none;
  }
}
</main>