.page-about {
  background: var(--ink-950);
  color: var(--text);
}

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

/* ---------- 面包屑 ---------- */
.page-about .about-crumbs {
  padding-block: 1rem 0;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(1.25rem, 3.5vw, 2.5rem) clamp(2rem, 5vw, 4rem);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, var(--line-soft) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line-soft) 1px, transparent 1px);
  background-size: 96px 96px;
  opacity: .55;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(120% 85% at 10% 0%, rgba(57, 230, 208, .13), transparent 62%),
    radial-gradient(95% 75% at 94% 100%, rgba(255, 180, 95, .10), transparent 64%);
}

.page-about .about-hero__grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(1.5rem, 4vw, 3rem);
  align-items: end;
}

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

.page-about .about-hero h1 {
  margin: .7rem 0 1.25rem;
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(2rem, 6.2vw, 4.4rem);
  line-height: 1.05;
  letter-spacing: -.03em;
  color: var(--frost);
  max-width: 20ch;
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 56ch;
  padding-left: 1rem;
  border-left: 3px solid var(--signal-cyan);
  font-size: clamp(1rem, 1.5vw, 1.125rem);
  line-height: 1.85;
  color: var(--mist);
}

.page-about .about-hero__tags {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin-top: 1.5rem;
}

.page-about .about-hero__fig {
  margin: 0;
  min-width: 0;
}

/* ---------- 主体：索引 + 章节 ---------- */
.page-about .about-body {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.5rem);
  padding-block: clamp(2rem, 5vw, 4rem);
}

.page-about .about-index {
  min-width: 0;
  background: var(--ink-900);
  border: 1px solid var(--line);
  padding: 1.15rem 1rem 1.25rem;
  box-shadow: var(--shadow-hard);
}

.page-about .about-index__title {
  margin: 0 0 .9rem;
  padding-bottom: .6rem;
  border-bottom: 1px solid var(--line-soft);
  font-size: var(--step-12);
  letter-spacing: .14em;
  color: var(--signal-cyan);
}

.page-about .about-index .toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .15rem;
}

.page-about .about-index .toc__link {
  display: block;
  padding: .55rem .5rem .55rem .8rem;
  border-left: 2px solid var(--line-soft);
  font-size: var(--step-14);
  line-height: 1.5;
  color: var(--text-dim);
  text-decoration: none;
  transition:
    color var(--dur) var(--ease),
    border-color var(--dur) var(--ease),
    background-color var(--dur) var(--ease),
    padding-left var(--dur) var(--ease);
}

.page-about .about-index .toc__link:hover,
.page-about .about-index .toc__link:focus-visible {
  color: var(--signal-cyan);
  border-left-color: var(--signal-cyan);
  background-color: rgba(57, 230, 208, .07);
  padding-left: 1rem;
  outline: none;
}

.page-about .about-index .toc__link.is-active,
.page-about .about-index .toc__link[aria-current] {
  color: var(--signal-cyan);
  border-left-color: var(--signal-cyan);
  background-color: rgba(57, 230, 208, .09);
}

.page-about .about-index__stamp {
  margin-top: 1.25rem;
  padding: .85rem .9rem;
  border: 1px dashed var(--line);
  background: var(--ink-800);
}

.page-about .about-index__stamp p {
  margin: 0;
}

.page-about .about-index__stamp .mono {
  font-size: var(--step-12);
  letter-spacing: .12em;
  color: var(--text-dim);
}

.page-about .about-index__stamp-value {
  margin-top: .35rem !important;
  font-family: var(--font-display);
  font-size: 1.9rem;
  letter-spacing: -.02em;
  color: var(--amber);
}

.page-about .about-index__stamp-note {
  margin-top: .2rem !important;
  font-size: var(--step-12);
  line-height: 1.6;
  color: var(--text-dim);
}

/* ---------- 章节 ---------- */
.page-about .about-chapters {
  min-width: 0;
}

.page-about .about-chapter {
  border-top: 1px solid var(--line);
  padding-block: clamp(1.75rem, 4vw, 3rem);
  scroll-margin-top: calc(var(--header-h) + 2rem);
}

.page-about .about-chapter:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-chapter__head {
  margin-bottom: 1.1rem;
}

.page-about .about-chapter__title {
  margin: .6rem 0 0;
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(1.55rem, 3.6vw, 2.6rem);
  line-height: 1.15;
  letter-spacing: -.02em;
  color: var(--frost);
}

.page-about .about-chapter__lede {
  margin: 0 0 1rem;
  max-width: 62ch;
  font-size: var(--step-18);
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-chapter p {
  max-width: 66ch;
  line-height: 1.85;
  color: var(--text);
}

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

/* ---------- 数据面板 ---------- */
.page-about .about-figures {
  margin: 1.75rem 0 0;
  display: grid;
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line);
  border-top: 3px solid var(--signal-cyan);
}

.page-about .about-figures__row {
  background: var(--ink-900);
  padding: 1rem 1.1rem;
}

.page-about .about-figures dt {
  font-family: var(--font-mono);
  font-size: var(--step-12);
  letter-spacing: .08em;
  color: var(--text-dim);
}

.page-about .about-figures dd {
  margin: .45rem 0 0;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--signal-cyan);
}

/* ---------- 人群 ---------- */
.page-about .about-split {
  display: grid;
  gap: 1.5rem;
}

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

.page-about .about-split__fig {
  margin: 0;
  min-width: 0;
}

.page-about .about-people {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  display: grid;
  gap: .75rem;
}

.page-about .about-people__item {
  background: var(--ink-900);
  border-left: 3px solid var(--amber);
  padding: .9rem 1rem 1rem;
  transition:
    border-left-color var(--dur) var(--ease),
    background-color var(--dur) var(--ease),
    box-shadow var(--dur) var(--ease);
}

.page-about .about-people__item:hover,
.page-about .about-people__item:focus-within {
  border-left-color: var(--signal-cyan);
  background: var(--ink-800);
  box-shadow: 4px 4px 0 0 rgba(36, 75, 92, .8);
}

.page-about .about-people__item h3 {
  margin: 0 0 .35rem;
  font-family: var(--font-body);
  font-size: var(--step-16);
  font-weight: 700;
  letter-spacing: .01em;
  color: var(--frost);
}

.page-about .about-people__item p {
  margin: 0;
  font-size: var(--step-14);
  line-height: 1.8;
  color: var(--text);
}

/* ---------- 时间线 ---------- */
.page-about .about-timeline {
  list-style: none;
  margin: 1.75rem 0 0;
  padding: .25rem 0 .25rem 1.5rem;
  border-left: 2px solid var(--line);
  display: grid;
  gap: 0;
}

.page-about .about-timeline__item {
  position: relative;
  display: grid;
  gap: .12rem;
  padding: .8rem 0 .8rem .5rem;
  border-bottom: 1px dashed var(--line-soft);
  transition: background-color var(--dur) var(--ease);
}

.page-about .about-timeline__item:last-child {
  border-bottom: 0;
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -1.94rem;
  top: 1.35rem;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--signal-cyan);
  box-shadow: 0 0 0 4px var(--ink-950);
  transition: background-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

.page-about .about-timeline__item:hover::before,
.page-about .about-timeline__item:focus-within::before {
  background: var(--amber);
  box-shadow: 0 0 0 4px var(--ink-950), 0 0 0 6px rgba(255, 180, 95, .28);
}

.page-about .about-timeline__no {
  font-size: var(--step-12);
  letter-spacing: .14em;
  color: var(--amber);
}

.page-about .about-timeline__yr {
  font-family: var(--font-display);
  font-size: 1.25rem;
  letter-spacing: -.01em;
  color: var(--frost);
}

.page-about .about-timeline__note {
  font-size: var(--step-14);
  line-height: 1.6;
  color: var(--text-dim);
  transition: color var(--dur) var(--ease);
}

.page-about .about-timeline__item:hover .about-timeline__note {
  color: var(--mist);
}

.page-about .about-timeline__item--now .about-timeline__yr {
  color: var(--signal-cyan);
}

.page-about .about-timeline__item--now::before {
  background: var(--amber);
}

.page-about .about-wide-fig {
  margin: 1.75rem 0 0;
}

.page-about .about-note {
  margin-top: 1.5rem;
  border-left: 3px solid var(--sage);
  background: var(--ink-900);
}

.page-about .about-note__title {
  margin: 0 0 .5rem;
  font-size: var(--step-12);
  letter-spacing: .14em;
  color: var(--sage);
}

.page-about .about-note p {
  margin: 0;
  font-size: var(--step-14);
  line-height: 1.8;
}

/* ---------- 对照步骤 ---------- */
.page-about .about-steps {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  display: grid;
  gap: .9rem;
}

.page-about .about-steps__item {
  position: relative;
  background: var(--ink-900);
  border: 1px solid var(--line);
  padding: 1.1rem 1.1rem 1.2rem;
  transition:
    border-color var(--dur) var(--ease),
    box-shadow var(--dur) var(--ease),
    background-color var(--dur) var(--ease);
}

.page-about .about-steps__item:hover,
.page-about .about-steps__item:focus {
  border-color: var(--signal-cyan);
  background: var(--ink-800);
  box-shadow: 5px 5px 0 0 rgba(7, 17, 28, .95), 5px 5px 0 1px var(--signal-cyan);
  outline: none;
}

.page-about .about-steps__no {
  display: inline-block;
  font-size: var(--step-12);
  letter-spacing: .16em;
  color: var(--signal-cyan);
}

.page-about .about-steps__item h3 {
  margin: .55rem 0 .4rem;
  font-family: var(--font-body);
  font-size: var(--step-18);
  font-weight: 700;
  color: var(--frost);
}

.page-about .about-steps__item p {
  margin: 0;
  font-size: var(--step-14);
  line-height: 1.8;
  color: var(--text);
}

/* ---------- 入口编号 ---------- */
.page-about .about-codes {
  margin-top: 1.5rem;
  border-top: 1px solid var(--line-soft);
  padding-top: 1.1rem;
}

.page-about .about-codes__label {
  margin: 0 0 .75rem;
  font-size: var(--step-12);
  letter-spacing: .14em;
  color: var(--text-dim);
}

.page-about .about-codes__row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: .5rem .9rem;
  padding: .55rem 0;
  border-bottom: 1px dashed var(--line-soft);
}

.page-about .about-codes__row:last-child {
  border-bottom: 0;
}

.page-about .about-codes__chip {
  display: inline-block;
  padding: .3rem .6rem;
  border: 1px solid var(--signal-cyan);
  color: var(--signal-cyan);
  font-size: var(--step-14);
  letter-spacing: .05em;
  background: rgba(57, 230, 208, .08);
}

.page-about .about-codes__chip--amber {
  border-color: var(--amber);
  color: var(--amber);
  background: rgba(255, 180, 95, .09);
}

.page-about .about-codes__desc {
  font-size: var(--step-14);
  color: var(--text-dim);
}

/* ---------- 生态 ---------- */
.page-about .about-eco {
  margin-top: 1.5rem;
  background: var(--ink-900);
  border: 1px solid var(--line);
  border-top: 3px solid var(--sage);
  padding: 1.1rem 1.1rem 1.2rem;
}

.page-about .about-eco__title {
  margin: 0 0 .8rem;
  font-size: var(--step-12);
  letter-spacing: .14em;
  color: var(--sage);
}

.page-about .about-eco__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .7rem;
}

.page-about .about-eco__list li {
  position: relative;
  padding-left: 1.1rem;
  font-size: var(--step-14);
  line-height: 1.8;
  color: var(--text);
  max-width: 60ch;
}

.page-about .about-eco__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .72em;
  width: 7px;
  height: 7px;
  background: var(--sage);
}

.page-about .about-eco__list strong {
  color: var(--frost);
  font-weight: 700;
}

/* ---------- 收尾 ---------- */
.page-about .about-cta {
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  padding: clamp(1.25rem, 3vw, 2rem);
  background: var(--ink-800);
  border: 1px solid var(--line);
  border-left: 4px solid var(--signal-cyan);
}

.page-about .about-cta__title {
  margin: .5rem 0 .75rem;
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(1.5rem, 3.4vw, 2.2rem);
  line-height: 1.15;
  letter-spacing: -.02em;
  color: var(--frost);
}

.page-about .about-cta p {
  margin: 0;
  max-width: 60ch;
  font-size: var(--step-16);
  line-height: 1.8;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  margin-top: 1.15rem;
}

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

  .page-about .about-split {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
    align-items: start;
  }

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

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

  .page-about .about-steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1024px) {
  .page-about .about-body {
    grid-template-columns: 232px minmax(0, 1fr);
    gap: clamp(2rem, 4vw, 3.5rem);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--header-h) + 1.5rem);
  }

  .page-about .about-figures {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  /* 横向刻度时间线 */
  .page-about .about-timeline {
    grid-template-columns: repeat(9, minmax(0, 1fr));
    border-left: 0;
    border-top: 2px solid var(--line);
    padding: 0 0 .5rem;
    gap: .35rem;
    margin-top: 2.25rem;
  }

  .page-about .about-timeline__item {
    padding: 1.5rem .35rem .5rem;
    border-bottom: 0;
    align-content: start;
  }

  .page-about .about-timeline__item::before {
    left: 0;
    top: -1px;
    transform: translate(-50%, -50%);
  }

  .page-about .about-timeline__yr {
    font-size: 1.05rem;
  }

  .page-about .about-timeline__note {
    font-size: var(--step-12);
    line-height: 1.55;
  }
}

@media (min-width: 1280px) {
  .page-about .about-hero h1 {
    font-size: clamp(3rem, 4.2vw, 4.8rem);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: .01ms !important;
    animation-duration: .01ms !important;
  }
}