.page-about {
  --about-side: 250px;
  --about-sticky: 96px;
  background: var(--c-ink);
  color: var(--c-fog);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding: 28px 0 64px;
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  z-index: -1;
  inset: -25% -12% -25% 32%;
  background: linear-gradient(155deg, var(--c-ink-soft) 0%, var(--c-charcoal) 100%);
  clip-path: polygon(30% 0, 100% 0, 100% 100%, 0 100%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  z-index: -1;
  top: -5%;
  bottom: -5%;
  left: 27%;
  width: 1px;
  background: linear-gradient(180deg, transparent, var(--c-orange) 35%, var(--c-orange) 65%, transparent);
  transform: rotate(7deg);
  transform-origin: top center;
  opacity: .55;
}

.page-about .about-hero__grid {
  display: grid;
  gap: 36px;
  padding-top: 36px;
}

.page-about .about-hero__kicker {
  margin: 0 0 18px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-orange);
}

.page-about .about-hero h1 {
  margin: 0 0 22px;
  max-width: 15em;
  font-size: clamp(30px, 6.2vw, 58px);
  line-height: 1.16;
  font-weight: 800;
  letter-spacing: -.01em;
  color: var(--c-paper);
}

.page-about .about-hero__lead-text {
  margin: 0;
  max-width: 36em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--fog-70);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.page-about .about-figures {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  background: var(--line-soft);
  border: 1px solid var(--line);
}

.page-about .about-figure-cell {
  padding: 16px 14px 18px;
  background: var(--c-charcoal);
}

.page-about .about-figure__label {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--fog-50);
}

.page-about .about-figure__value {
  margin: 0;
  font-family: var(--f-mono);
  font-size: 24px;
  line-height: 1.1;
  color: var(--c-cyan);
}

/* ---------- 版面骨架 ---------- */

.page-about .about-layout {
  display: grid;
  gap: 32px;
  padding-bottom: 72px;
}

.page-about .about-toc {
  align-self: start;
}

.page-about .about-toc__title {
  margin: 0 0 12px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-brass);
}

.page-about .about-toc__list {
  display: flex;
  gap: 6px;
  margin: 0;
  padding: 0 0 6px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-toc__item {
  margin: 0;
  flex: 0 0 auto;
}

.page-about .about-toc__link {
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding: 9px 13px;
  border-left: 2px solid transparent;
  font-size: 14px;
  line-height: 1.5;
  color: var(--fog-50);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--t-base) var(--ease), background var(--t-fast) var(--ease), border-color var(--t-base) var(--ease);
}

.page-about .about-toc__num {
  font-family: var(--f-mono);
  font-size: 12px;
  color: var(--c-brass);
  transition: color var(--t-base) var(--ease);
}

.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  color: var(--c-paper);
  background: var(--orange-soft);
  border-left-color: var(--c-orange);
}

.page-about .about-toc__link:hover .about-toc__num,
.page-about .about-toc__link:focus-visible .about-toc__num {
  color: var(--c-orange);
}

/* ---------- 章节 ---------- */

.page-about .about-chapter {
  padding-top: 36px;
  border-top: 1px solid var(--line-soft);
  scroll-margin-top: 92px;
}

.page-about .about-chapter + .about-chapter {
  margin-top: 64px;
}

.page-about .about-chapter__head {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 22px;
}

.page-about .about-chapter__num {
  flex: 0 0 auto;
  padding-top: 3px;
  font-family: var(--f-mono);
  font-size: 26px;
  line-height: 1;
  color: var(--c-orange);
}

.page-about .about-chapter__title {
  margin: 0;
  font-size: 23px;
  line-height: 1.35;
  font-weight: 800;
  color: var(--c-paper);
}

.page-about .about-chapter > p {
  margin: 0 0 18px;
  max-width: 38em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--fog-70);
}

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

/* ---------- 说明牌 ---------- */

.page-about .about-plates {
  display: grid;
  gap: 14px;
  margin-top: 26px;
}

.page-about .about-plate {
  padding: 20px 20px 22px;
  background: var(--c-charcoal);
  border: 1px solid var(--line);
  border-left: 3px solid var(--c-brass);
  box-shadow: 6px 8px 0 -2px var(--c-shadow);
  transition: transform var(--t-base) var(--ease), box-shadow var(--t-slow) var(--ease), border-left-color var(--t-base) var(--ease);
}

.page-about .about-plate:hover {
  transform: translateY(-2px);
  box-shadow: 8px 10px 0 -2px var(--c-shadow);
  border-left-color: var(--c-orange);
}

.page-about .about-plate__title {
  margin: 0 0 10px;
  font-size: 16px;
  font-weight: 700;
  color: var(--c-paper);
}

.page-about .about-plate__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--fog-70);
}

/* ---------- 时间轴 ---------- */

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

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line);
  background: var(--c-charcoal);
}

.page-about .about-figure figcaption {
  margin-top: 12px;
  padding-left: 14px;
  border-left: 1px solid var(--c-brass);
  font-size: 14px;
  line-height: 1.75;
  color: var(--fog-50);
}

.page-about .about-figure--wide {
  margin: 26px 0 0;
}

.page-about .about-timeline {
  display: flex;
  gap: 14px;
  margin: 26px 0 0;
  padding: 6px 2px 18px;
  list-style: none;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  scrollbar-width: thin;
}

.page-about .tl-node {
  position: relative;
  flex: 0 0 240px;
  padding: 26px 18px 20px;
  background: var(--c-charcoal);
  border: 1px solid var(--line);
  scroll-snap-align: start;
  transition: transform var(--t-base) var(--ease), border-color var(--t-base) var(--ease), background var(--t-slow) var(--ease);
}

.page-about .tl-node::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 18px;
  width: 38px;
  height: 2px;
  background: var(--c-orange);
}

.page-about .tl-node:hover {
  transform: translateY(-2px);
  border-color: var(--c-orange);
  background: var(--orange-soft);
}

.page-about .tl-node__num {
  display: block;
  margin-bottom: 10px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-cyan);
}

.page-about .tl-node__title {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
  color: var(--c-paper);
}

.page-about .tl-node__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--fog-70);
  opacity: .78;
  transition: opacity var(--t-base) var(--ease);
}

.page-about .tl-node:hover .tl-node__text {
  opacity: 1;
}

/* ---------- 四道工序 ---------- */

.page-about .about-process {
  display: grid;
  gap: 24px;
  margin-top: 26px;
}

.page-about .about-steps {
  display: grid;
  gap: 12px;
}

.page-about .about-step {
  padding: 20px 18px 22px;
  background: var(--c-ink-soft);
  border: 1px solid var(--line);
  transition: border-color var(--t-base) var(--ease);
}

.page-about .about-step:hover {
  border-color: var(--c-graphite);
}

.page-about .about-step__num {
  display: block;
  margin-bottom: 12px;
  font-family: var(--f-mono);
  font-size: 20px;
  color: var(--c-orange);
}

.page-about .about-step__title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 700;
  color: var(--c-paper);
}

.page-about .about-step__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--fog-70);
}

.page-about .about-figure--tall img {
  box-shadow: 10px 12px 0 -3px var(--c-shadow);
}

/* ---------- 内蒙古节点 ---------- */

.page-about .about-node {
  display: grid;
  gap: 24px;
  margin-top: 26px;
}

.page-about .about-node__figure img {
  box-shadow: 10px 12px 0 -3px var(--c-shadow);
}

.page-about .about-node__text > p {
  margin: 0 0 18px;
  max-width: 38em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--fog-70);
}

.page-about .about-term {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px;
  margin-top: 22px;
  padding: 18px 20px 20px;
  background: var(--c-charcoal);
  border: 1px solid var(--line);
  border-left: 3px solid var(--c-cyan);
}

.page-about .about-term__num {
  font-family: var(--f-mono);
  font-size: 34px;
  line-height: 1;
  color: var(--c-cyan);
}

.page-about .about-term__unit {
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--fog-50);
}

.page-about .about-term__text {
  flex: 1 1 100%;
  margin: 6px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--fog-70);
}

/* ---------- 团队 ---------- */

.page-about .about-team {
  display: grid;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-team__item {
  padding: 22px 20px 24px;
  background: var(--c-charcoal);
  border: 1px solid var(--line);
  border-top: 2px solid var(--c-brass);
  transition: border-top-color var(--t-base) var(--ease), transform var(--t-base) var(--ease);
}

.page-about .about-team__item:hover {
  transform: translateY(-2px);
  border-top-color: var(--c-orange);
}

.page-about .about-team__value {
  display: block;
  margin-bottom: 8px;
  font-family: var(--f-mono);
  font-size: 38px;
  line-height: 1;
  color: var(--c-paper);
}

.page-about .about-team__unit {
  margin-left: 6px;
  font-size: 14px;
  color: var(--fog-50);
}

.page-about .about-team__title {
  margin: 0 0 12px;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--c-orange);
}

.page-about .about-team__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--fog-70);
}

/* ---------- 下一步 ---------- */

.page-about .about-next {
  display: grid;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-next__item {
  display: block;
  padding: 20px 22px;
  background: var(--c-charcoal);
  border: 1px solid var(--line);
  text-decoration: none;
  transition: transform var(--t-base) var(--ease), border-color var(--t-base) var(--ease), background var(--t-fast) var(--ease);
}

.page-about .about-next__item:hover,
.page-about .about-next__item:focus-visible {
  transform: translateY(-2px);
  border-color: var(--c-orange);
  background: var(--orange-soft);
}

.page-about .about-next__tag {
  display: block;
  margin-bottom: 6px;
  font-size: 17px;
  font-weight: 700;
  color: var(--c-paper);
}

.page-about .about-next__desc {
  display: block;
  font-size: 14px;
  line-height: 1.7;
  color: var(--fog-50);
}

.page-about .entry-bar {
  margin-top: 32px;
}

/* ---------- 响应式 ---------- */

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

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

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

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

@media (min-width: 700px) {
  .page-about .about-figures {
    gap: 1px;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    padding: 36px 0 86px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1fr) 288px;
    gap: 56px;
    align-items: end;
    padding-top: 60px;
  }

  .page-about .about-layout {
    grid-template-columns: var(--about-side) minmax(0, 1fr);
    gap: 60px;
    padding-bottom: 112px;
  }

  .page-about .about-toc {
    position: sticky;
    top: var(--about-sticky);
  }

  .page-about .about-toc__list {
    display: block;
    overflow: visible;
    padding: 0;
    border-left: 1px solid var(--line);
  }

  .page-about .about-toc__item {
    display: block;
  }

  .page-about .about-chapter {
    padding-top: 44px;
  }

  .page-about .about-chapter + .about-chapter {
    margin-top: 88px;
  }

  .page-about .about-chapter__num {
    font-size: 34px;
  }

  .page-about .about-chapter__title {
    font-size: 31px;
  }

  .page-about .about-process {
    grid-template-columns: minmax(0, 1fr) 300px;
    gap: 36px;
    align-items: start;
  }

  .page-about .about-node {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1fr);
    gap: 36px;
    align-items: start;
  }

  .page-about .about-team {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 14px;
  }

  .page-about .about-figure--wide {
    margin-top: 30px;
  }
}

@media (max-width: 899px) {
  .page-about .about-hero::after {
    display: none;
  }

  .page-about .about-hero::before {
    inset: -20% -30% -20% 18%;
  }
}

@media (max-width: 420px) {
  .page-about .about-figure__value {
    font-size: 20px;
  }

  .page-about .about-figure-cell {
    padding: 14px 10px 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-plate,
  .page-about .tl-node,
  .page-about .about-team__item,
  .page-about .about-next__item,
  .page-about .tl-node__text {
    transition: none;
  }

  .page-about .about-plate:hover,
  .page-about .tl-node:hover,
  .page-about .about-team__item:hover,
  .page-about .about-next__item:hover,
  .page-about .about-next__item:focus-visible {
    transform: none;
  }
}