.page-about {
  --about-rail: 104px;
  --about-pb-top: clamp(28px, 4vw, 44px);
  --about-pb-pad: clamp(20px, 3vw, 36px);
  position: relative;
  background: var(--ink);
  color: var(--paper);
}

.page-about .num {
  font-family: var(--font-mono);
  letter-spacing: 0;
  font-variant-numeric: tabular-nums;
}

/* ---------- 面包屑 ---------- */
.page-about .about-top {
  padding-top: 28px;
  padding-bottom: 6px;
}

.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 12px;
  color: var(--mist);
}

.page-about .breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--moss);
}

/* ---------- 框景首屏 ---------- */
.page-about .about-hero {
  position: relative;
  margin-top: 22px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: clamp(40px, 7vw, 96px) 0 clamp(36px, 5vw, 72px);
}

.page-about .about-hero__inner {
  position: relative;
  display: grid;
  gap: clamp(18px, 3vw, 30px);
}

.page-about .about-hero__kicker {
  margin: 0;
  color: var(--gold);
  letter-spacing: .18em;
}

.page-about .about-hero__title {
  margin: 0;
  max-width: 20ch;
  line-height: 1.1;
  letter-spacing: -0.035em;
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 64ch;
  color: var(--paper);
  opacity: .88;
}

.page-about .about-hero__stats {
  list-style: none;
  margin: 0;
  padding: clamp(20px, 3vw, 30px) 0 0;
  border-top: 1px solid var(--line);
  display: grid;
  gap: 20px;
}

.page-about .stat {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-left: 14px;
  border-left: 2px solid var(--moss);
}

.page-about .stat__num {
  font-size: clamp(34px, 5vw, 52px);
  line-height: 1;
  color: var(--gold);
}

.page-about .stat__label {
  font-size: 14px;
  line-height: 1.7;
  color: var(--mist);
}

.page-about .about-hero__side {
  display: none;
}

@media (min-width: 720px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 28px;
  }
}

@media (min-width: 980px) {
  .page-about .about-hero__side {
    display: block;
    position: absolute;
    right: clamp(16px, 4vw, 48px);
    top: clamp(40px, 7vw, 96px);
    letter-spacing: .34em;
    color: var(--moss);
  }
}

/* ---------- 章节索引 ---------- */
.page-about .chapter-index {
  padding: 30px 0 6px;
}

.page-about .chapter-index__label {
  margin: 0 0 14px;
  color: var(--mist);
  letter-spacing: .22em;
}

.page-about .chapter-index__list {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  margin: 0;
  padding: 0;
}

.page-about .chapter-index__list a {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  font-size: 14px;
  color: var(--paper);
  text-decoration: none;
}

.page-about .chapter-index__list a .num {
  font-size: 12px;
  color: var(--gold);
}

/* ---------- 主体布局 + 左侧时间轴 ---------- */
.page-about .about-layout {
  padding-bottom: clamp(56px, 9vw, 120px);
}

.page-about .time-rail {
  display: none;
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    display: grid;
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(28px, 4vw, 64px);
    align-items: start;
  }

  .page-about .time-rail {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    position: sticky;
    top: calc(var(--header-h) + 36px);
    padding: 10px 0 30px;
  }

  .page-about .time-rail__label {
    color: var(--moss);
    letter-spacing: .3em;
  }

  .page-about .time-rail__list {
    position: relative;
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 22px;
  }

  .page-about .time-rail__list::before {
    content: "";
    position: absolute;
    top: 10px;
    bottom: 10px;
    left: 50%;
    width: 1px;
    background: var(--moss);
    transform: translateX(-50%);
  }
}

.page-about .time-node {
  position: relative;
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 1px solid var(--moss);
  background: var(--ink);
  color: var(--mist);
  font-family: var(--font-mono);
  font-size: 10px;
  text-decoration: none;
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease),
    background-color var(--dur) var(--ease);
}

.page-about .time-node:hover,
.page-about .time-node:focus-visible {
  border-color: var(--cyan);
  color: var(--cyan);
}

.page-about .time-node[data-active="true"] {
  background: var(--cyan);
  border-color: var(--cyan);
  color: var(--ink);
}

/* ---------- 章节通用 ---------- */
.page-about .chapter {
  padding: clamp(40px, 7vw, 88px) 0;
  border-top: 1px solid var(--line);
}

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

.page-about .section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 14px;
  margin: 0 0 clamp(20px, 3vw, 34px);
}

.page-about .section-head__index {
  font-size: 13px;
  color: var(--gold);
}

.page-about .section-head__dash {
  display: inline-block;
  width: clamp(28px, 5vw, 58px);
  height: 2px;
  background: var(--gold);
  transform: translateY(-5px);
}

.page-about .section-head__title {
  margin: 0;
  letter-spacing: -0.02em;
}

.page-about .prose {
  max-width: 70ch;
}

.page-about .prose p {
  margin: 0 0 1.2em;
  color: var(--paper);
}

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

.page-about .chapter__lead {
  margin-bottom: clamp(22px, 3vw, 34px);
  max-width: 62ch;
}

.page-about .chapter__body {
  display: grid;
  gap: clamp(24px, 4vw, 48px);
}

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

.page-about .chapter__media img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(.88) contrast(1.06);
}

.page-about .media-frame--portrait img {
  aspect-ratio: 5 / 6;
}

.page-about .media-frame--wide {
  margin-top: clamp(30px, 5vw, 56px);
}

.page-about .media-frame--wide img {
  aspect-ratio: 16 / 9;
}

@media (min-width: 860px) {
  .page-about .chapter__body--media {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, .8fr);
    align-items: start;
  }

  .page-about .chapter__body--media-rev {
    grid-template-columns: minmax(0, .85fr) minmax(0, 1.3fr);
    align-items: center;
  }
}

/* ---------- 术语卡 ---------- */
.page-about .term {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  margin-top: 6px;
  padding: 10px 14px;
  border: 1px dashed var(--line-strong);
  background: rgba(38, 51, 47, .55);
}

.page-about .term__key {
  appearance: none;
  background: none;
  border: 0;
  padding: 0;
  font: inherit;
  color: var(--cyan);
  border-bottom: 1px solid currentColor;
  cursor: pointer;
}

.page-about .term__body {
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 团队分工 ---------- */
.page-about .team-grid {
  display: grid;
  gap: 18px;
  margin-top: clamp(20px, 3vw, 32px);
}

.page-about .team-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 3px solid var(--moss);
  padding: 22px 20px 24px;
  transition: border-left-color var(--dur-slow) var(--ease), background-color var(--dur-slow) var(--ease);
}

.page-about .team-card:hover {
  border-left-color: var(--cyan);
  background: #2b3a35;
}

.page-about .team-card__num {
  display: block;
  margin-bottom: 12px;
  font-size: 12px;
  color: var(--cyan);
}

.page-about .team-card h3 {
  margin: 0 0 10px;
  letter-spacing: -0.01em;
}

.page-about .team-card p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--mist);
}

@media (min-width: 760px) {
  .page-about .team-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 24px;
    padding-bottom: 34px;
  }
}

@media (min-width: 1100px) {
  .page-about .team-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    padding-bottom: 56px;
  }

  .page-about .team-card:nth-child(1) { transform: translateY(0); }
  .page-about .team-card:nth-child(2) { transform: translateY(34px); }
  .page-about .team-card:nth-child(3) { transform: translateY(10px); }
  .page-about .team-card:nth-child(4) { transform: translateY(44px); }
}

/* ---------- 工序：纸张叠层 ---------- */
.page-about .process-board {
  position: relative;
  margin-top: clamp(26px, 4vw, 42px);
  padding: var(--about-pb-top) var(--about-pb-pad) clamp(26px, 3vw, 38px);
  background: var(--paper-2);
  color: var(--ink);
  box-shadow: 9px 9px 0 rgba(168, 92, 60, .45), 18px 18px 0 rgba(168, 92, 60, .16);
}

.page-about .process-line {
  display: none;
  color: var(--clay);
}

.page-about .flow {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 26px;
}

.page-about .flow__step {
  display: block;
  outline: none;
}

.page-about .flow__dot {
  display: none;
}

.page-about .flow__title {
  margin: 0 0 8px;
  font-size: 17px;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .flow__desc {
  margin: 0 0 10px;
  font-size: 13px;
  line-height: 1.75;
  color: #3d4b46;
}

.page-about .flow__time {
  margin: 0;
  color: var(--clay);
  letter-spacing: .06em;
  transition: opacity var(--dur-slow) var(--ease);
}

@media (min-width: 900px) {
  .page-about .flow {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 16px;
  }

  .page-about .process-line {
    display: block;
    position: absolute;
    top: calc(var(--about-pb-top) + 6px);
    left: var(--about-pb-pad);
    width: calc(100% - var(--about-pb-pad) * 2);
    height: 2px;
  }

  .page-about .flow__dot {
    display: block;
    width: 13px;
    height: 13px;
    margin-bottom: 14px;
    border-radius: 50%;
    background: var(--clay);
    box-shadow: 0 0 0 3px var(--paper-2);
    position: relative;
    z-index: 1;
  }

  .page-about .flow__step {
    cursor: default;
  }

  .page-about .flow__time {
    opacity: 0;
  }

  .page-about .flow__step:hover .flow__time,
  .page-about .flow__step:focus .flow__time,
  .page-about .flow__step:focus-within .flow__time {
    opacity: 1;
  }
}

/* ---------- 未来三件事 ---------- */
.page-about .next-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .next-item {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 16px;
  padding: clamp(22px, 3vw, 32px) 0;
  border-top: 1px solid var(--line);
}

.page-about .next-item:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .next-item__num {
  font-size: 20px;
  line-height: 1.2;
  color: var(--cyan);
}

.page-about .next-item h3 {
  margin: 0 0 10px;
  letter-spacing: -0.01em;
}

.page-about .next-item p {
  margin: 0;
  max-width: 66ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist);
}

@media (min-width: 860px) {
  .page-about .next-item {
    grid-template-columns: 92px minmax(0, 1fr);
    gap: 28px;
  }

  .page-about .next-item__num {
    font-size: 30px;
  }
}

/* ---------- 合作对接 ---------- */
.page-about .join-panel {
  display: grid;
  gap: clamp(18px, 3vw, 26px);
  padding: clamp(26px, 4vw, 46px);
  border: 1px solid var(--line-strong);
  background: linear-gradient(140deg, rgba(59, 224, 206, .12), rgba(10, 31, 26, 0) 62%);
}

.page-about .join-panel__lede {
  margin: 0;
  max-width: 62ch;
  letter-spacing: -0.01em;
}

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

.page-about .join-list li {
  position: relative;
  padding-left: 24px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .join-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .78em;
  width: 11px;
  height: 2px;
  background: var(--gold);
}

.page-about .join-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

@media (prefers-reduced-motion: reduce) {
  .page-about .time-node,
  .page-about .team-card,
  .page-about .flow__time {
    transition: none;
  }
}