.page-about {
  --ax-paper-line: rgba(20, 32, 43, 0.16);
  --ax-paper-teal: #0B5D57;
  display: block;
  overflow-wrap: break-word;
  padding-bottom: clamp(3rem, 7vw, 5rem);
  background-image: linear-gradient(to right, rgba(36, 69, 92, 0.22) 1px, transparent 1px);
  background-size: 96px 100%;
  background-repeat: repeat;
}

.page-about figure {
  margin: 0;
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  padding-top: clamp(1rem, 3vw, 1.75rem);
}

.page-about .breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--c-text-mute);
}

.page-about .breadcrumb__link {
  color: var(--c-text-dim);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

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

.page-about .breadcrumb__sep {
  color: var(--c-line);
}

.page-about .breadcrumb__item [aria-current="page"] {
  color: var(--c-text);
}

/* ---------- 页头 ---------- */
.page-about .about-head {
  position: relative;
  padding: clamp(1.5rem, 4vw, 2.75rem) 0 clamp(1.75rem, 4vw, 3rem);
  border-bottom: 1px solid var(--c-line);
}

.page-about .about-head::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -1px;
  width: min(46%, 420px);
  height: 1px;
  background: linear-gradient(to right, transparent, var(--c-cyan));
  opacity: 0.75;
}

.page-about .about-head__eyebrow {
  margin: 0 0 1rem;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--c-orange);
}

.page-about .about-head h1 {
  margin: 0 0 1.1rem;
  max-width: 24ch;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.85rem, 5.2vw, 3.3rem);
  line-height: 1.1;
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.page-about .about-head .lede {
  margin: 0 0 1.75rem;
  max-width: 62ch;
  font-size: clamp(1rem, 1.6vw, 1.1rem);
  line-height: 1.8;
  color: var(--c-text-dim);
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .about-facts > li {
  background: var(--c-deep);
  padding: 0.85rem 1rem;
}

.page-about .about-facts__v {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.1rem, 2.2vw, 1.45rem);
  line-height: 1.2;
  color: var(--c-cyan);
}

.page-about .about-facts__k {
  display: block;
  margin-top: 0.3rem;
  font-size: 0.76rem;
  letter-spacing: 0.05em;
  color: var(--c-text-mute);
}

/* ---------- 主体骨架 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 3rem);
  padding-top: clamp(1.75rem, 4vw, 3rem);
}

.page-about .about-rail__title {
  margin: 0 0 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--c-text-mute);
}

.page-about .about-rail__list {
  position: relative;
  display: flex;
  gap: 1.1rem;
  margin: 0;
  padding: 0 0 0.7rem;
  list-style: none;
  overflow-x: auto;
  border-bottom: 1px solid var(--c-line);
  -webkit-overflow-scrolling: touch;
}

.page-about .about-rail__item {
  flex: 0 0 auto;
}

.page-about .about-rail__link {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
  padding: 0.25rem 0;
  font-size: 0.8rem;
  white-space: nowrap;
  color: var(--c-text-dim);
  text-decoration: none;
  transition: color var(--t-fast) var(--ease);
}

.page-about .about-rail__num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--c-cyan);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--c-cyan);
}

/* ---------- 章节 ---------- */
.page-about .about-chapters {
  display: grid;
  gap: clamp(2.25rem, 5vw, 3.5rem);
  min-width: 0;
}

.page-about .about-chapter {
  min-width: 0;
  padding-top: clamp(1.5rem, 3vw, 2rem);
  border-top: 1px solid var(--c-line);
  scroll-margin-top: calc(var(--rail-h) + var(--bar-h) + 1rem);
}

.page-about .about-chapter .section__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.35rem 0.9rem;
  align-items: baseline;
  margin-bottom: 1.25rem;
}

.page-about .about-chapter .section__num {
  font-family: var(--font-mono);
  font-size: clamp(1.05rem, 2vw, 1.35rem);
  letter-spacing: 0.04em;
  color: var(--c-cyan);
}

.page-about .about-chapter .section__title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 2.8vw, 1.85rem);
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.page-about .about-chapter .section__desc {
  margin: 0.4rem 0 0;
  font-size: 0.92rem;
  line-height: 1.7;
  color: var(--c-text-mute);
}

.page-about .about-chapter__body {
  display: grid;
  gap: 1.35rem;
  min-width: 0;
}

.page-about .about-chapter__body p {
  margin: 0;
  line-height: 1.8;
  color: var(--c-text-dim);
}

.page-about .about-chapter__body p a,
.page-about .about-list a,
.page-about .about-table a {
  color: var(--c-cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(63, 227, 210, 0.4);
  transition: border-color var(--t-fast) var(--ease);
}

.page-about .about-chapter__body p a:hover,
.page-about .about-chapter__body p a:focus-visible,
.page-about .about-list a:hover,
.page-about .about-list a:focus-visible,
.page-about .about-table a:hover,
.page-about .about-table a:focus-visible {
  border-bottom-color: var(--c-cyan);
}

.page-about .about-sub {
  margin: 0.25rem 0 0;
  font-family: var(--font-display);
  font-size: clamp(1.02rem, 2vw, 1.2rem);
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.page-about .about-note {
  font-size: 0.94rem;
}

/* ---------- 01 分栏 ---------- */
.page-about .about-split {
  display: grid;
  gap: 1.5rem;
  min-width: 0;
}

.page-about .prose p {
  margin: 0 0 1rem;
  line-height: 1.8;
  color: var(--c-text-dim);
}

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

.page-about .about-list {
  margin: 0 0 1rem;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--c-line);
}

.page-about .about-list li {
  position: relative;
  padding: 0.7rem 0 0.7rem 1.4rem;
  border-bottom: 1px solid var(--c-line);
  font-size: 0.92rem;
  line-height: 1.75;
  color: var(--c-text-dim);
}

.page-about .about-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  font-family: var(--font-mono);
  color: var(--c-cyan);
}

.page-about .about-list--out li::before {
  color: var(--c-orange);
}

/* ---------- 媒体 ---------- */
.page-about .media {
  display: block;
  position: relative;
  border: 1px solid var(--c-line);
}

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

.page-about .about-figure--tall img {
  aspect-ratio: 4 / 3;
}

.page-about .about-figure--mid img {
  aspect-ratio: 3 / 2;
}

.page-about .about-wide img {
  aspect-ratio: 2 / 1;
}

.page-about .about-caption {
  margin-top: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  line-height: 1.6;
  letter-spacing: 0.04em;
  color: var(--c-text-mute);
}

/* ---------- 02 场景 ---------- */
.page-about .usecase {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--c-line);
}

.page-about .usecase__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.85rem;
  padding: 1.1rem 0.5rem 1.1rem 0;
  border-bottom: 1px solid var(--c-line);
  transition: background var(--t-fast) var(--ease);
}

.page-about .usecase__item:hover {
  background: rgba(18, 58, 82, 0.45);
}

.page-about .usecase__num {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  line-height: 1.3;
  color: var(--c-cyan);
}

.page-about .usecase__title {
  margin: 0 0 0.4rem;
  font-family: var(--font-display);
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.page-about .usecase__body p {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.75;
  color: var(--c-text-dim);
}

/* ---------- 03 专题标签 ---------- */
.page-about .topic-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .topic {
  background: var(--c-deep);
}

.page-about .topic__link {
  display: block;
  height: 100%;
  padding: 1rem 1.05rem 1.1rem;
  text-decoration: none;
  color: var(--c-text);
  transition: background var(--t-fast) var(--ease);
}

.page-about .topic__link:hover,
.page-about .topic__link:focus-visible {
  background: var(--c-mid);
  outline: none;
}

.page-about .topic__link:focus-visible {
  box-shadow: inset 0 0 0 2px var(--c-cyan);
}

.page-about .topic__name {
  display: block;
  font-family: var(--font-display);
  font-size: 1.02rem;
  letter-spacing: -0.01em;
}

.page-about .topic__field {
  display: block;
  margin-top: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  color: var(--c-cyan);
}

.page-about .topic__note {
  display: block;
  margin-top: 0.6rem;
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--c-text-mute);
}

/* ---------- 表格 ---------- */
.page-about .table-scroll {
  overflow-x: auto;
  border: 1px solid var(--c-line);
  -webkit-overflow-scrolling: touch;
}

.page-about .about-table {
  width: 100%;
  min-width: 620px;
  border-collapse: collapse;
  font-size: 0.86rem;
}

.page-about .about-table caption {
  padding: 0.7rem 0.85rem;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--c-text-mute);
  border-bottom: 1px solid var(--c-line);
}

.page-about .about-table th,
.page-about .about-table td {
  padding: 0.7rem 0.85rem;
  text-align: left;
  vertical-align: top;
  line-height: 1.65;
  border-bottom: 1px solid var(--c-line);
}

.page-about .about-table thead th {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--c-text);
  background: var(--c-night);
}

.page-about .about-table tbody th {
  font-weight: 500;
  color: var(--c-text);
}

.page-about .about-table td {
  color: var(--c-text-dim);
}

.page-about .about-table tbody tr:hover td,
.page-about .about-table tbody tr:hover th {
  background: var(--c-mid);
}

/* ---------- 04 状态与批次 ---------- */
.page-about .status-legend {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: 0;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .status-legend > div {
  background: var(--c-deep);
  padding: 0.9rem 1rem;
}

.page-about .status-legend dt {
  margin: 0 0 0.5rem;
}

.page-about .status-legend dd {
  margin: 0;
  font-size: 0.84rem;
  line-height: 1.7;
  color: var(--c-text-dim);
}

.page-about .stepper {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .stepper__item {
  position: relative;
  background: var(--c-deep);
  padding: 1.3rem 1rem 1.25rem;
  border-top: 2px solid var(--c-line);
  transition: background var(--t-fast) var(--ease);
}

.page-about .stepper__item:hover {
  background: var(--c-mid);
}

.page-about .stepper__item--current {
  border-top-color: var(--c-orange);
}

.page-about .stepper__dot {
  position: absolute;
  top: -6px;
  left: 1rem;
  width: 9px;
  height: 9px;
  background: var(--c-cyan);
  transform: rotate(45deg);
  transition: background var(--t-fast) var(--ease);
}

.page-about .stepper__item--current .stepper__dot {
  background: var(--c-orange);
}

.page-about .stepper__title {
  margin: 0 0 0.45rem;
  font-family: var(--font-display);
  font-size: 0.98rem;
  letter-spacing: -0.01em;
  color: var(--c-text);
}

.page-about .stepper__note {
  margin: 0;
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--c-text-mute);
}

/* ---------- 05 纸色区块 ---------- */
.page-about .paper-block {
  background: var(--c-paper);
  color: var(--c-paper-ink);
  padding: clamp(1.2rem, 3vw, 2rem);
  box-shadow: 9px 9px 0 rgba(5, 21, 32, 0.55), 9px 9px 0 1px var(--c-line);
}

.page-about .paper-lead {
  margin: 0 0 1.35rem;
  font-size: 1.02rem;
  line-height: 1.8;
  color: var(--c-paper-dim);
}

.page-about .team-stats {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: 0 0 1.5rem;
  padding: 0;
  list-style: none;
  background: var(--ax-paper-line);
  border: 1px solid var(--ax-paper-line);
}

.page-about .team-stats > li {
  background: var(--c-paper);
  padding: 0.9rem 1rem;
}

.page-about .team-stats__v {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 4vw, 2rem);
  line-height: 1.1;
  color: var(--ax-paper-teal);
}

.page-about .team-stats__k {
  display: block;
  margin-top: 0.35rem;
  font-size: 0.78rem;
  color: var(--c-paper-dim);
}

.page-about .team-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.1rem;
  margin: 0 0 1.35rem;
}

.page-about .team-split dt {
  margin: 0 0 0.45rem;
  padding-bottom: 0.35rem;
  font-family: var(--font-display);
  font-size: 0.95rem;
  letter-spacing: -0.01em;
  color: var(--c-paper-ink);
  border-bottom: 1px solid var(--ax-paper-line);
}

.page-about .team-split dd {
  margin: 0;
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--c-paper-dim);
}

.page-about .paper-note {
  margin: 0;
  padding-top: 1rem;
  border-top: 1px dashed var(--ax-paper-line);
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--c-paper-dim);
}

/* ---------- 章节收束 ---------- */
.page-about .about-close {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem;
  margin: 1.5rem 0 0;
  padding-top: 0.85rem;
  border-top: 1px dashed var(--c-line);
  font-size: 0.8rem;
  line-height: 1.6;
  color: var(--c-text-mute);
}

/* ---------- 悬停揭示（仅精确指针设备） ---------- */
@media (hover: hover) and (pointer: fine) {
  .page-about .topic__note {
    max-height: 0;
    margin-top: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height var(--t-base) var(--ease), opacity var(--t-base) var(--ease), margin-top var(--t-base) var(--ease);
  }

  .page-about .topic:hover .topic__note,
  .page-about .topic:focus-within .topic__note {
    max-height: 9rem;
    margin-top: 0.6rem;
    opacity: 1;
  }
}

/* ---------- 断点 ---------- */
@media (min-width: 640px) {
  .page-about .about-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

@media (min-width: 700px) {
  .page-about .topic-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

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

@media (min-width: 820px) {
  .page-about .about-split {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
    align-items: start;
    gap: 2rem;
  }

  .page-about .about-figure--tall {
    margin-top: 0.35rem;
  }
}

@media (min-width: 960px) {
  .page-about .about-body {
    grid-template-columns: 116px minmax(0, 1fr);
    gap: clamp(2rem, 4vw, 3.25rem);
  }

  .page-about .about-rail {
    align-self: start;
    position: sticky;
    top: calc(var(--rail-h) + var(--bar-h) + 1.25rem);
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 0;
    padding: 0.3rem 0 0.3rem 1.15rem;
    overflow: visible;
    border-bottom: 0;
  }

  .page-about .about-rail__list::before {
    content: "";
    position: absolute;
    left: 4px;
    top: 0.45rem;
    bottom: 0.45rem;
    width: 1px;
    background: var(--c-line);
  }

  .page-about .about-rail__link {
    padding: 0.5rem 0;
  }

  .page-about .about-rail__link::before {
    content: "";
    position: absolute;
    left: -0.65rem;
    top: 0.85rem;
    width: 7px;
    height: 7px;
    background: var(--c-deep);
    border: 1px solid var(--c-line);
    transform: rotate(45deg);
    transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
  }

  .page-about .about-rail__link:hover::before,
  .page-about .about-rail__link:focus-visible::before {
    background: var(--c-cyan);
    border-color: var(--c-cyan);
  }
}

@media (min-width: 1080px) {
  .page-about .topic-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: 1ms !important;
    animation-duration: 1ms !important;
  }
}