.page-about {
  --about-clip-sm: polygon(0 0, calc(100% - 5px) 0, 100% 5px, 100% 100%, 0 100%);
  --about-clip-xs: polygon(0 0, calc(100% - 4px) 0, 100% 4px, 100% 100%, 0 100%);
  padding-bottom: var(--chapter);
}

.page-about .breadcrumb {
  padding-block: var(--block);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  display: grid;
  gap: 32px;
  padding-bottom: var(--chapter);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__intro {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: var(--block);
}

.page-about .about-hero__title {
  margin: 0;
  letter-spacing: -0.02em;
  max-width: 18ch;
}

.page-about .about-hero__lead {
  margin: 0;
  max-width: 46ch;
  color: var(--silver);
  font-size: var(--fs-16);
  line-height: 1.75;
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--gap);
  width: 100%;
  margin: 0;
  padding: var(--block) 0 0;
  border-top: 1px solid var(--line);
  list-style: none;
}

.page-about .about-fact {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.page-about .about-fact__num {
  font-family: var(--font-mono);
  font-size: var(--fs-28);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--lime);
  letter-spacing: -0.01em;
}

.page-about .about-fact__label {
  font-size: var(--fs-13);
  color: var(--slate);
}

.page-about .about-hero__figure {
  margin: 0;
}

.page-about .about-hero__figure img,
.page-about .about-chapter__figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

.page-about .about-hero__figure img {
  aspect-ratio: 16 / 10;
}

/* ---------- 章节骨架 ---------- */
.page-about .about-layout {
  display: grid;
  gap: 40px;
  padding-top: var(--chapter);
}

.page-about .about-body {
  display: flex;
  flex-direction: column;
  gap: var(--chapter);
  min-width: 0;
}

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

.page-about .about-chapter__head {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: var(--block);
}

.page-about .about-chapter__no {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
  width: 34px;
  height: 34px;
  background: var(--teal-deep);
  color: var(--lime);
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  clip-path: var(--about-clip-sm);
}

.page-about .about-chapter__head h2 {
  margin: 0;
  letter-spacing: -0.02em;
}

.page-about .about-chapter p {
  margin: 0 0 20px;
  max-width: 68ch;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--cloud);
}

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

.page-about .about-chapter__lead {
  color: var(--silver) !important;
  font-size: var(--fs-20) !important;
  line-height: 1.7 !important;
}

.page-about .about-chapter__figure {
  margin: 0 0 32px;
}

.page-about .about-chapter__figure img {
  aspect-ratio: 16 / 9;
}

.page-about .media-frame__caption {
  font-size: var(--fs-11);
  color: var(--slate);
  letter-spacing: 0.04em;
  margin-top: 10px;
}

/* ---------- 左侧索引 ---------- */
.page-about .about-index {
  display: flex;
  flex-direction: column;
  gap: 32px;
  min-width: 0;
}

.page-about .about-index__group {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.page-about .about-index__list,
.page-about .about-terms {
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-index__node {
  position: relative;
  display: block;
  padding: 9px 0 9px 16px;
  border-left: 1px solid var(--line);
  color: var(--slate);
  font-size: var(--fs-13);
  line-height: 1.5;
  text-decoration: none;
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .about-index__node::before {
  content: "";
  position: absolute;
  left: -4px;
  top: 15px;
  width: 7px;
  height: 7px;
  background: var(--night);
  border: 1px solid var(--line-strong);
  clip-path: var(--about-clip-xs);
  transition: background 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .about-index__node:hover,
.page-about .about-index__node:focus-visible {
  color: var(--lime);
  border-left-color: var(--line-lime);
}

.page-about .about-index__node:hover::before,
.page-about .about-index__node:focus-visible::before {
  background: var(--lime);
  border-color: var(--lime);
}

.page-about .about-index__node[aria-current="true"] {
  color: var(--cloud);
  border-left-color: var(--lime);
}

.page-about .about-index__node[aria-current="true"]::before {
  background: var(--lime);
  border-color: var(--lime);
}

.page-about .about-terms {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .about-terms__link {
  display: inline-block;
  padding: 5px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  color: var(--silver);
  font-size: var(--fs-13);
  text-decoration: none;
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .about-terms__link:hover,
.page-about .about-terms__link:focus-visible {
  color: var(--night);
  background: var(--lime);
  border-color: var(--lime);
}

.page-about .about-index__note {
  margin: 0;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  font-size: var(--fs-13);
  line-height: 1.7;
  color: var(--slate);
}

/* ---------- 口径定义列表 ---------- */
.page-about .about-defs {
  margin: 0 0 32px;
  border-top: 1px solid var(--line);
}

.page-about .about-defs__row {
  display: grid;
  gap: 6px;
  padding: 18px 0 18px 0;
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 120px;
  transition: background 200ms var(--ease);
}

.page-about .about-defs__row:target {
  background: rgba(85, 242, 160, 0.07);
  box-shadow: inset 3px 0 0 var(--lime);
  padding-left: 14px;
}

.page-about .about-defs__term {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

.page-about .about-defs__desc {
  margin: 0;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--cloud);
}

/* ---------- 折叠细则 ---------- */
.page-about .about-fold {
  margin-bottom: 16px;
  border-top: 2px solid transparent;
  background: rgba(6, 49, 47, 0.42);
  clip-path: var(--clip-card);
  transition: border-color 180ms var(--ease);
}

.page-about .about-fold[open] {
  border-top-color: var(--wine);
}

.page-about .about-fold .fold-panel__summary {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 18px;
  cursor: pointer;
  font-size: var(--fs-16);
  color: var(--cloud);
  list-style: none;
}

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

.page-about .about-fold .about-fold__title {
  flex: 1 1 auto;
  min-width: 0;
}

.page-about .about-fold .about-fold__hint {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--fs-11);
  letter-spacing: 0.14em;
  color: var(--slate);
}

.page-about .about-fold[open] .about-fold__hint {
  color: var(--orange);
}

.page-about .about-fold .fold-panel__body {
  padding: 0 18px 20px;
  border-top: 1px solid var(--line);
}

.page-about .about-notes {
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.page-about .about-notes li {
  position: relative;
  padding-left: 18px;
  font-size: var(--fs-13);
  line-height: 1.75;
  color: var(--silver);
}

.page-about .about-notes li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 8px;
  height: 1px;
  background: var(--lime);
}

.page-about .about-notes strong {
  color: var(--cloud);
  font-weight: 600;
}

/* ---------- 演进时间轴 ---------- */
.page-about .about-timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 30px;
  list-style: none;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--lime) 0%, var(--line-strong) 55%, rgba(198, 211, 222, 0) 100%);
}

.page-about .about-timeline__item {
  position: relative;
  padding-bottom: 32px;
}

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

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -30px;
  top: 6px;
  width: 13px;
  height: 13px;
  background: var(--night);
  border: 1px solid var(--lime);
  clip-path: var(--about-clip-sm);
}

.page-about .about-timeline__year {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.12em;
  color: var(--lime);
  margin-bottom: 4px;
}

.page-about .about-timeline__title {
  margin: 0 0 6px;
  font-size: var(--fs-20);
  font-weight: 400;
  line-height: 1.45;
  color: var(--cloud);
}

.page-about .about-timeline__item p {
  margin: 0;
  max-width: 62ch;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--silver);
}

/* ---------- 协作生态 ---------- */
.page-about .about-network {
  display: grid;
  gap: var(--gap);
  margin-bottom: 32px;
}

.page-about .about-network__item {
  padding: 24px 20px;
}

.page-about .about-network__num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-56);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--orange);
  margin-bottom: 10px;
}

.page-about .about-network__title {
  margin: 0 0 10px;
  font-size: var(--fs-20);
  font-weight: 400;
  line-height: 1.4;
  color: var(--cloud);
}

.page-about .about-network__desc {
  margin: 0;
  font-size: var(--fs-13);
  line-height: 1.75;
  color: var(--slate);
}

/* ---------- 误读澄清 ---------- */
.page-about .about-misread {
  margin: 0 0 32px;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0;
  border-top: 1px solid var(--line);
}

.page-about .about-misread__item {
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-misread__title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 8px;
  font-size: var(--fs-20);
  font-weight: 400;
  color: var(--cloud);
}

.page-about .about-misread__title::before {
  content: "";
  flex: none;
  width: 9px;
  height: 9px;
  background: var(--wine);
  border: 1px solid var(--orange);
  clip-path: var(--about-clip-xs);
}

.page-about .about-misread__item p {
  margin: 0;
  max-width: 66ch;
  font-size: var(--fs-16);
  line-height: 1.75;
  color: var(--silver);
}

.page-about .about-misread__tail {
  padding: 20px;
  background: rgba(89, 24, 43, 0.28);
  border-left: 2px solid var(--wine);
  color: var(--cloud) !important;
}

.page-about .link-inline {
  color: var(--silver);
  text-decoration: none;
  border-bottom: 1px solid var(--line-strong);
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .link-inline:hover,
.page-about .link-inline:focus-visible {
  color: var(--lime);
  border-bottom-color: var(--line-lime);
}

/* ---------- 延伸阅读 ---------- */
.page-about .about-more {
  padding-top: 32px;
  border-top: 1px solid var(--line);
}

.page-about .about-more__list {
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.page-about .about-more__link {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px 20px;
  background: rgba(34, 26, 69, 0.5);
  clip-path: var(--clip-card);
  text-decoration: none;
  transition: background 180ms var(--ease);
}

.page-about .about-more__link:hover,
.page-about .about-more__link:focus-visible {
  background: rgba(34, 26, 69, 0.82);
}

.page-about .about-more__label {
  position: relative;
  padding-left: 14px;
  font-size: var(--fs-20);
  color: var(--cloud);
  transition: color 160ms var(--ease);
}

.page-about .about-more__label::before {
  content: "";
  position: absolute;
  left: 0;
  top: 12px;
  width: 0;
  height: 1px;
  background: var(--orange);
  transition: width 160ms var(--ease);
}

.page-about .about-more__link:hover .about-more__label,
.page-about .about-more__link:focus-visible .about-more__label {
  color: var(--lime);
}

.page-about .about-more__link:hover .about-more__label::before,
.page-about .about-more__link:focus-visible .about-more__label::before {
  width: 8px;
}

.page-about .about-more__desc {
  font-size: var(--fs-13);
  line-height: 1.7;
  color: var(--slate);
}

/* ---------- 平板 ---------- */
@media (min-width: 768px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-defs__row {
    grid-template-columns: 170px minmax(0, 1fr);
    gap: var(--gap);
  }

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

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

/* ---------- 桌面分栏 ---------- */
@media (min-width: 1024px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
    gap: 56px;
    align-items: start;
  }

  .page-about .about-layout {
    grid-template-columns: minmax(200px, 23%) minmax(0, 1fr);
    gap: 56px;
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: 104px;
  }

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

  .page-about .about-network__item:nth-child(2) {
    transform: translateY(24px);
  }
}

@media (min-width: 1440px) {
  .page-about .about-layout {
    grid-template-columns: minmax(220px, 20%) minmax(0, 1fr);
    gap: 72px;
  }
}

/* ---------- 降低动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about .about-index__node,
  .page-about .about-index__node::before,
  .page-about .about-terms__link,
  .page-about .about-fold,
  .page-about .about-defs__row,
  .page-about .about-more__link,
  .page-about .about-more__label,
  .page-about .about-more__label::before,
  .page-about .link-inline {
    transition: none;
  }

  .page-about .about-network__item:nth-child(2) {
    transform: none;
  }
}