.page-about {
  --about-gap: clamp(1.5rem, 3.5vw, 2.75rem);
  --about-h1: clamp(2rem, 5.2vw, 3.7rem);
  --about-sticky: calc(var(--bar-h) + 1.5rem);
  color: var(--ice);
  background: var(--ink-900);
  overflow-x: clip;
}

/* 面包屑 */
.page-about .about-breadcrumb {
  padding-top: clamp(0.9rem, 2.4vw, 1.6rem);
}
.page-about .about-breadcrumb .crumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: var(--fs-annot);
  color: var(--mist);
}
.page-about .about-breadcrumb a {
  color: var(--cyan);
  text-decoration: none;
}
.page-about .about-breadcrumb a:hover,
.page-about .about-breadcrumb a:focus-visible {
  text-decoration: underline;
}
.page-about .about-breadcrumb .crumb-item + .crumb-item::before {
  content: "/";
  margin-right: 0.35rem;
  color: var(--ink-700);
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding: clamp(1.5rem, 4.5vw, 3.5rem) 0 clamp(1.75rem, 4vw, 2.75rem);
}
.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(to right, rgba(139, 163, 184, 0.13) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(139, 163, 184, 0.13) 1px, transparent 1px);
  background-size: 4.5rem 4.5rem;
  -webkit-mask-image: radial-gradient(120% 90% at 18% 0%, #000 28%, transparent 78%);
  mask-image: radial-gradient(120% 90% at 18% 0%, #000 28%, transparent 78%);
  opacity: 0.7;
  pointer-events: none;
}
.page-about .about-hero__grid {
  display: grid;
  gap: var(--about-gap);
}
.page-about .about-hero h1 {
  margin: 0.35rem 0 1rem;
  font-size: var(--about-h1);
  line-height: 1.05;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: var(--ice);
}
.page-about .about-hero .lead {
  margin: 0;
  max-width: 34em;
  font-size: var(--fs-body);
  line-height: 1.78;
  color: var(--ice);
  opacity: 0.9;
}
.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.6rem;
}
.page-about .about-hero__figure {
  margin: 0;
  display: grid;
  gap: 0.55rem;
}
.page-about .about-hero__figure .annot {
  color: var(--mist);
  font-size: var(--fs-annot);
  letter-spacing: 0.04em;
}
.page-about figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

/* 数据条 */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .about-stat {
  background: var(--ink-850);
  padding: clamp(0.85rem, 2vw, 1.3rem) clamp(0.85rem, 2vw, 1.2rem);
}
.page-about .about-stat__value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.45rem, 4.2vw, 2.05rem);
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--amber);
}
.page-about .about-stat:nth-child(2) .about-stat__value {
  color: var(--cyan);
}
.page-about .about-stat:nth-child(3) .about-stat__value {
  color: var(--grass);
}
.page-about .about-stat:nth-child(4) .about-stat__value {
  color: var(--ice);
}
.page-about .about-stat__label {
  display: block;
  margin-top: 0.4rem;
  font-size: var(--fs-annot);
  letter-spacing: 0.04em;
  color: var(--mist);
}

/* 正文双栏 */
.page-about .about-body {
  display: grid;
  gap: var(--about-gap);
  padding: clamp(2rem, 5vw, 3.5rem) 0 clamp(2.5rem, 6vw, 5rem);
}
.page-about .about-side {
  min-width: 0;
}

/* 章节目录 */
.page-about .about-chapters {
  border-left: 0;
  padding-left: 0;
}
.page-about .about-chapters .chapter-title {
  margin: 0 0 0.7rem;
  font-size: var(--fs-annot);
  letter-spacing: 0.22em;
  color: var(--mist);
  text-transform: uppercase;
}
.page-about .about-chapters .chapter-list {
  display: flex;
  gap: 0.4rem;
  margin: 0;
  padding: 0 0 0.4rem;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}
.page-about .about-chapters .chapter-link {
  display: block;
  white-space: nowrap;
  padding: 0.45rem 0.7rem;
  font-size: 0.85rem;
  color: var(--mist);
  text-decoration: none;
  border: 1px solid var(--line);
  background: var(--ink-850);
  transition: color 0.18s ease, border-color 0.18s ease;
}
.page-about .about-chapters .chapter-link:hover,
.page-about .about-chapters .chapter-link:focus-visible {
  color: var(--ice);
  border-color: var(--line-strong);
}
.page-about .about-chapters .chapter-link.is-active {
  color: var(--cyan);
  border-color: var(--line-strong);
  background: var(--ink-800);
}
.page-about .about-chapters .vertical-note {
  display: none;
}

/* 章节 */
.page-about .about-main {
  min-width: 0;
}
.page-about .about-chapter {
  padding: clamp(1.6rem, 3.6vw, 2.5rem) 0;
  border-top: 1px solid var(--line);
  scroll-margin-top: calc(var(--bar-h) + 1.5rem);
}
.page-about .about-chapter:first-of-type {
  padding-top: 0;
  border-top: 0;
}
.page-about .about-chapter__head {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  margin-bottom: 0.95rem;
}
.page-about .about-chapter__num {
  font-family: var(--font-mono);
  font-size: clamp(1.35rem, 3.4vw, 2rem);
  line-height: 1;
  color: var(--cyan);
}
.page-about .about-chapter h2 {
  margin: 0;
  font-size: var(--fs-h2);
  letter-spacing: -0.01em;
  color: var(--ice);
}
.page-about .about-chapter p {
  margin: 0 0 0.9rem;
  max-width: 62ch;
  line-height: 1.78;
  color: var(--ice);
  opacity: 0.92;
}
.page-about .about-chapter p:last-child {
  margin-bottom: 0;
}
.page-about .about-chapter a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 242, 208, 0.4);
}
.page-about .about-chapter a:hover,
.page-about .about-chapter a:focus-visible {
  border-bottom-color: var(--cyan);
}
.page-about .about-inline-link {
  margin-top: 1.1rem;
  font-size: 0.95rem;
  color: var(--mist);
}

/* 资料叠层卡 */
.page-about .about-stack {
  display: grid;
  gap: 0.9rem;
  margin: 1.4rem 0;
}
.page-about .about-stack__card {
  position: relative;
  padding: 1.1rem 1.05rem 1.2rem;
  background: var(--ink-800);
  border: 1px solid var(--line-strong);
  box-shadow: 0.45rem 0.45rem 0 rgba(18, 52, 74, 0.6);
}
.page-about .about-stack__card h3 {
  margin: 0.7rem 0 0.4rem;
  font-size: var(--fs-h3);
  color: var(--ice);
}
.page-about .about-stack__card p {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.7;
  color: var(--mist);
  opacity: 1;
}
.page-about .about-stack__card .tag {
  font-size: var(--fs-tag);
  letter-spacing: 0.08em;
}

.page-about .about-figure {
  margin: 1.4rem 0;
  display: grid;
  gap: 0.55rem;
}
.page-about .about-figure .annot {
  font-size: var(--fs-annot);
  letter-spacing: 0.04em;
  color: var(--mist);
}

/* 时间线 */
.page-about .about-timeline {
  list-style: none;
  margin: 1.4rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.9rem;
}
.page-about .about-timeline__item {
  position: relative;
  padding-top: 0.95rem;
  border-top: 2px solid var(--ink-700);
}
.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  top: -5px;
  left: 0;
  width: 8px;
  height: 8px;
  background: var(--cyan);
}
.page-about .about-timeline__item:last-child::before {
  background: var(--amber);
}
.page-about .about-timeline summary {
  display: grid;
  gap: 0.2rem;
  list-style: none;
  cursor: pointer;
}
.page-about .about-timeline summary::-webkit-details-marker {
  display: none;
}
.page-about .about-timeline__stage {
  font-family: var(--font-mono);
  font-size: var(--fs-annot);
  letter-spacing: 0.08em;
  color: var(--grass);
}
.page-about .about-timeline__label {
  font-size: 1rem;
  font-weight: 700;
  color: var(--ice);
}
.page-about .about-timeline summary::after {
  content: "＋";
  margin-top: 0.15rem;
  font-size: 0.8rem;
  color: var(--mist);
}
.page-about .about-timeline details[open] summary::after {
  content: "－";
  color: var(--cyan);
}
.page-about .about-timeline__body {
  padding-top: 0.5rem;
}
.page-about .about-timeline__body p {
  margin: 0;
  max-width: 40ch;
  font-size: 0.88rem;
  line-height: 1.7;
  color: var(--mist);
  opacity: 1;
}

/* 团队 */
.page-about .about-crew {
  list-style: none;
  margin: 1.3rem 0;
  padding: 0;
  display: grid;
  gap: 0.85rem;
}
.page-about .about-crew__item {
  padding: 0.15rem 0 0.15rem 0.85rem;
  border-left: 2px solid var(--grass);
}
.page-about .about-crew__item h3 {
  margin: 0 0 0.35rem;
  font-size: 1rem;
  letter-spacing: 0.02em;
  color: var(--ice);
}
.page-about .about-crew__item p {
  margin: 0;
  max-width: none;
  font-size: 0.88rem;
  line-height: 1.68;
  color: var(--mist);
  opacity: 1;
}

/* 内容来源 */
.page-about .about-sources {
  list-style: none;
  margin: 1.3rem 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .about-sources li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.9rem;
  align-items: start;
  padding: 1rem 1.05rem;
  background: var(--ink-850);
}
.page-about .about-sources .num {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  line-height: 1.2;
  color: var(--orange);
}
.page-about .about-sources h3 {
  margin: 0 0 0.3rem;
  font-size: 1rem;
  color: var(--ice);
}
.page-about .about-sources p {
  margin: 0;
  max-width: 46ch;
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--mist);
  opacity: 1;
}

/* 体验条目 */
.page-about .about-notes {
  display: grid;
  gap: 1rem;
  margin: 1.3rem 0 0;
}
.page-about .about-note {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.9rem;
  padding-bottom: 1rem;
  border-bottom: 1px dashed var(--line);
}
.page-about .about-note:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}
.page-about .about-note__mark {
  display: block;
  width: 0.6rem;
  height: 0.6rem;
  margin-top: 0.5rem;
  background: var(--cyan);
}
.page-about .about-note:nth-child(2) .about-note__mark {
  background: var(--grass);
}
.page-about .about-note:nth-child(3) .about-note__mark {
  background: var(--orange);
}
.page-about .about-note h3 {
  margin: 0 0 0.3rem;
  font-size: 1rem;
  color: var(--ice);
}
.page-about .about-note p {
  margin: 0;
  max-width: 60ch;
  font-size: 0.92rem;
  line-height: 1.72;
  color: var(--mist);
  opacity: 1;
}

/* 结尾入口 */
.page-about .about-cta {
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  padding: clamp(1.3rem, 3.6vw, 2.1rem);
  background: var(--ink-800);
  border: 1px solid var(--line-strong);
  border-left: 4px solid var(--cyan);
  display: grid;
  gap: 0.75rem;
}
.page-about .about-cta h2 {
  margin: 0;
  font-size: var(--fs-h2);
  letter-spacing: -0.01em;
  color: var(--ice);
}
.page-about .about-cta p {
  margin: 0;
  max-width: 56ch;
  font-size: 0.98rem;
  line-height: 1.75;
  color: var(--mist);
}
.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.35rem;
}

@media (min-width: 34rem) {
  .page-about .about-stack {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
  }
}

@media (min-width: 48rem) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.06fr) minmax(0, 0.94fr);
    align-items: end;
  }
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-stack {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .about-crew {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem 1.25rem;
  }
  .page-about .about-timeline {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
  }
}

@media (min-width: 62rem) {
  .page-about .about-body {
    grid-template-columns: 15rem minmax(0, 1fr);
    align-items: start;
    gap: clamp(2rem, 4vw, 3.25rem);
  }
  .page-about .about-side {
    position: sticky;
    top: var(--about-sticky);
  }
  .page-about .about-chapters {
    border-left: 1px solid var(--line);
    padding-left: 1rem;
  }
  .page-about .about-chapters .chapter-list {
    display: grid;
    gap: 0.1rem;
    overflow: visible;
    padding-bottom: 0;
  }
  .page-about .about-chapters .chapter-link {
    white-space: normal;
    padding: 0.5rem 0.6rem 0.5rem 0.8rem;
    font-size: 0.9rem;
    border: 0;
    border-left: 2px solid transparent;
    background: transparent;
  }
  .page-about .about-chapters .chapter-link:hover,
  .page-about .about-chapters .chapter-link:focus-visible {
    color: var(--ice);
    border-left-color: var(--line-strong);
  }
  .page-about .about-chapters .chapter-link.is-active {
    color: var(--cyan);
    border-left-color: var(--cyan);
    background: linear-gradient(90deg, rgba(53, 242, 208, 0.12), transparent 85%);
  }
  .page-about .about-chapters .vertical-note {
    display: block;
    margin: 1.75rem 0 0;
    writing-mode: vertical-rl;
    letter-spacing: 0.32em;
    font-size: var(--fs-annot);
    color: var(--mist);
  }
  .page-about .about-stack {
    padding-bottom: 2.3rem;
  }
  .page-about .about-stack__card:nth-child(2) {
    transform: translateY(1.1rem);
  }
  .page-about .about-stack__card:nth-child(3) {
    transform: translateY(2.2rem);
  }
  .page-about .about-timeline {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }
}

@media (min-width: 74rem) {
  .page-about .about-crew {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-body {
    grid-template-columns: 17rem minmax(0, 1fr);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-chapters .chapter-link,
  .page-about .about-stack__card {
    transition: none;
    transform: none;
  }
}