.page-about {
  --about-rail: 168px;
  --about-cut: 26px;
  background: var(--c-bg);
  color: var(--c-white);
  font-family: var(--font-body);
  overflow-x: hidden;
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-family: var(--font-display);
  letter-spacing: -.01em;
  margin: 0;
}

.page-about p {
  margin: 0;
}

.page-about .shell {
  width: min(var(--shell), 100% - var(--gutter) * 2);
  margin-inline: auto;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding-block: clamp(1.5rem, 4vw, 3rem) clamp(2.5rem, 6vw, 4.5rem);
  position: relative;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--violet-55) 38%, var(--c-amber) 62%, transparent);
  opacity: .55;
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(1.75rem, 4vw, 3rem);
  margin-top: 1.75rem;
}

.page-about .about-hero__title {
  font-size: var(--step-6);
  line-height: 1.08;
  margin-top: .9rem;
  text-transform: none;
}

.page-about .about-hero__title br {
  display: none;
}

.page-about .about-hero__lead .lede {
  margin-top: 1.25rem;
  color: var(--text-soft);
  max-width: 56ch;
  line-height: 1.85;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  margin-top: 1.75rem;
}

.page-about .about-hero__figure {
  position: relative;
  --cut: var(--about-cut);
}

.page-about .about-hero__figure::before {
  content: "";
  position: absolute;
  inset: -14px -14px auto auto;
  width: 46%;
  height: 3px;
  background: var(--c-violet);
  transform: rotate(-12deg);
  transform-origin: right top;
  opacity: .7;
  pointer-events: none;
}

.page-about .about-hero__caption {
  margin-top: .7rem;
  font-family: var(--font-mono);
  font-size: var(--step-1);
  color: var(--c-grey);
  letter-spacing: .02em;
}

.page-about .about-hero__figures {
  list-style: none;
  margin: clamp(2rem, 5vw, 3.5rem) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-fig {
  background: var(--c-bg);
  padding: 1.15rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: .3rem;
}

.page-about .about-fig__num {
  font-family: var(--font-mono);
  font-size: var(--step-4);
  color: var(--c-amber);
  line-height: 1;
  letter-spacing: -.02em;
}

.page-about .about-fig__label {
  font-size: var(--step-1);
  color: var(--c-grey);
}

/* ---------- 时间轴 ---------- */

.page-about .about-timeline {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
  background: var(--c-black);
}

.page-about .about-timeline .section-head__title {
  font-size: var(--step-5);
  line-height: 1.18;
}

.page-about .about-timeline__layout {
  display: grid;
  gap: 1.5rem;
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 .5rem;
  display: flex;
  gap: .5rem;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__item {
  display: flex;
  align-items: baseline;
  gap: .5rem;
  white-space: nowrap;
  padding: .45rem .85rem;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--c-grey);
  text-decoration: none;
  font-size: var(--step-1);
  transition: border-color .25s var(--ease), color .25s var(--ease), background-color .25s var(--ease);
}

.page-about .about-rail__item:hover,
.page-about .about-rail__item:focus-visible {
  color: var(--c-white);
  border-color: var(--c-violet);
  background: var(--violet-12);
}

.page-about .about-rail__year {
  font-family: var(--font-mono);
  color: var(--c-violet);
  font-weight: 600;
}

.page-about .about-rail__label {
  font-size: .8125rem;
}

.page-about .about-stream {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  min-width: 0;
}

.page-about .about-era {
  position: relative;
  background: var(--c-surface);
  padding: 1.5rem 1.35rem;
  clip-path: polygon(0 0, calc(100% - var(--about-cut)) 0, 100% var(--about-cut), 100% 100%, 0 100%);
}

.page-about .about-era::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 3px;
  height: 52px;
  background: var(--c-violet);
}

.page-about .about-era__inner {
  display: grid;
  gap: .85rem;
}

.page-about .about-era__year {
  font-family: var(--font-mono);
  font-size: clamp(1.9rem, 1.2rem + 2.4vw, 2.75rem);
  font-weight: 700;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px var(--violet-55);
  letter-spacing: -.03em;
  margin: 0;
}

.page-about .about-era__meta {
  display: flex;
  align-items: center;
  gap: .6rem;
  margin-bottom: .55rem;
}

.page-about .about-era__phase {
  font-family: var(--font-mono);
  font-size: .8125rem;
  color: var(--c-grey);
  letter-spacing: .04em;
}

.page-about .about-era__title {
  font-size: var(--step-3);
  line-height: 1.35;
  margin-bottom: .6rem;
}

.page-about .about-era__body p {
  color: var(--text-soft);
  line-height: 1.85;
  font-size: var(--step-2);
  max-width: 62ch;
}

.page-about .about-era__figure {
  --cut: 20px;
  margin: 0;
}

/* ---------- 资料来源 ---------- */

.page-about .about-source {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
}

.page-about .about-source .section-head__title {
  font-size: var(--step-5);
  line-height: 1.18;
}

.page-about .about-source__lede {
  margin-top: 1.25rem;
  color: var(--text-soft);
  max-width: 62ch;
  line-height: 1.85;
}

.page-about .about-flow {
  list-style: none;
  margin: clamp(2rem, 4vw, 2.75rem) 0 0;
  padding: 0;
  display: grid;
  gap: 1.1rem;
}

.page-about .about-flow__step {
  position: relative;
  padding: 1.15rem 1.2rem;
  border-left: 2px solid var(--violet-30);
  background: linear-gradient(90deg, var(--violet-12), transparent 70%);
}

.page-about .about-flow__no {
  font-family: var(--font-mono);
  font-size: .8125rem;
  color: var(--c-amber);
  letter-spacing: .08em;
  display: block;
  margin-bottom: .5rem;
}

.page-about .about-flow__title {
  font-size: var(--step-3);
  margin-bottom: .4rem;
}

.page-about .about-flow__step p {
  color: var(--c-grey);
  font-size: var(--step-1);
  line-height: 1.75;
}

.page-about .about-source__figure {
  --cut: 22px;
  margin: clamp(2rem, 4vw, 3rem) 0 0;
}

/* ---------- 规模数字 ---------- */

.page-about .about-numbers {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
}

.page-about .about-numbers .section-head__title {
  font-size: var(--step-5);
  line-height: 1.18;
}

.page-about .about-numbers__grid {
  list-style: none;
  margin: clamp(1.75rem, 4vw, 2.5rem) 0 0;
  padding: 1px;
  display: grid;
  gap: 1px;
  background: var(--line);
}

.page-about .about-number {
  background: var(--c-black);
  padding: 1.5rem 1.35rem;
  display: flex;
  flex-direction: column;
  gap: .5rem;
}

.page-about .about-number__num {
  font-family: var(--font-mono);
  font-size: var(--step-5);
  line-height: 1;
  color: var(--c-cyan);
  letter-spacing: -.03em;
}

.page-about .about-number__label {
  font-size: var(--step-2);
  font-weight: 600;
}

.page-about .about-number__desc {
  font-size: var(--step-1);
  color: var(--c-grey);
  line-height: 1.75;
}

/* ---------- 分类标签页 ---------- */

.page-about .about-cats {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
}

.page-about .about-cats .section-head__title {
  font-size: var(--step-5);
  line-height: 1.18;
}

.page-about .about-cats__lede {
  margin-top: 1.25rem;
  color: var(--text-soft);
  max-width: 62ch;
  line-height: 1.85;
}

.page-about .about-tabs {
  margin-top: clamp(1.75rem, 4vw, 2.5rem);
}

.page-about .about-tabs .tabs {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}

.page-about .about-tabs .tab {
  font-family: var(--font-mono);
  font-size: .8125rem;
  letter-spacing: .02em;
  padding: .5rem .9rem;
  border: 1px solid var(--line-strong);
  background: transparent;
  color: var(--c-grey);
  border-radius: 2px;
  cursor: pointer;
  transition: color .22s var(--ease), border-color .22s var(--ease), background-color .22s var(--ease);
}

.page-about .about-tabs .tab:hover,
.page-about .about-tabs .tab:focus-visible {
  color: var(--c-white);
  border-color: var(--violet-55);
}

.page-about .about-tabs .tab[aria-selected="true"] {
  color: var(--c-black);
  background: var(--c-amber);
  border-color: var(--c-amber);
}

.page-about .about-tabs__panels {
  margin-top: 1.5rem;
}

.page-about .about-cat {
  background: var(--c-surface);
  padding: 1.5rem 1.35rem;
  clip-path: polygon(0 0, calc(100% - 20px) 0, 100% 20px, 100% 100%, 0 100%);
  border-top: 2px solid var(--c-violet);
}

.page-about .about-cat__title {
  font-size: var(--step-3);
  margin-bottom: .65rem;
}

.page-about .about-cat__text {
  color: var(--text-soft);
  line-height: 1.85;
  font-size: var(--step-2);
  max-width: 68ch;
}

/* ---------- 服务 ---------- */

.page-about .about-service {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
}

.page-about .about-service__grid {
  display: grid;
  gap: clamp(1.75rem, 4vw, 3rem);
}

.page-about .about-service .section-head__title {
  font-size: var(--step-5);
  line-height: 1.18;
}

.page-about .about-service__col .lede {
  margin-top: 1.25rem;
  color: var(--text-soft);
  line-height: 1.85;
  max-width: 56ch;
}

.page-about .about-service__note {
  margin-top: 1rem;
  padding-left: 1rem;
  border-left: 2px solid var(--c-amber);
  font-size: var(--step-1);
  color: var(--c-grey);
  line-height: 1.75;
}

.page-about .about-service__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1.1rem;
}

.page-about .about-service__item {
  display: grid;
  grid-template-columns: 14px minmax(0, 1fr);
  gap: .9rem;
  padding-bottom: 1.1rem;
  border-bottom: 1px dashed var(--line);
}

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

.page-about .about-service__item .dot {
  margin-top: .55rem;
}

.page-about .about-service__title {
  font-size: var(--step-3);
  margin-bottom: .35rem;
}

.page-about .about-service__item p {
  color: var(--c-grey);
  font-size: var(--step-1);
  line-height: 1.75;
}

/* ---------- 合作渠道 ---------- */

.page-about .about-partner {
  padding-block: clamp(2.5rem, 6vw, 4.5rem);
  background: var(--c-black);
}

.page-about .about-partner .section-head__title {
  font-size: var(--step-5);
  line-height: 1.18;
}

.page-about .about-partner__grid {
  margin-top: clamp(1.75rem, 4vw, 2.5rem);
  display: grid;
  gap: 1rem;
}

.page-about .about-partner__card {
  position: relative;
  padding: 1.6rem 1.35rem;
  background: var(--c-surface);
  border-left: 3px solid var(--c-violet);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 22px), calc(100% - 22px) 100%, 0 100%);
}

.page-about .about-partner__card:nth-child(2) {
  border-left-color: var(--c-amber);
}

.page-about .about-partner__card:nth-child(3) {
  border-left-color: var(--c-cyan);
}

.page-about .about-partner__num {
  font-family: var(--font-mono);
  font-size: var(--step-4);
  display: block;
  margin-bottom: .7rem;
  color: var(--c-white);
  letter-spacing: -.02em;
}

.page-about .about-partner__card h3 {
  font-size: var(--step-3);
  margin-bottom: .5rem;
}

.page-about .about-partner__card p {
  color: var(--c-grey);
  font-size: var(--step-1);
  line-height: 1.8;
}

/* ---------- 收尾 ---------- */

.page-about .about-cta {
  padding-block: clamp(2.5rem, 6vw, 4rem);
}

.page-about .about-cta__inner {
  display: grid;
  gap: 1.5rem;
  padding: clamp(1.5rem, 4vw, 2.5rem) clamp(1.35rem, 3vw, 2.25rem);
  border: 1px solid var(--violet-30);
  background: linear-gradient(135deg, var(--violet-12), transparent 58%);
  clip-path: polygon(0 0, calc(100% - 32px) 0, 100% 32px, 100% 100%, 32px 100%, 0 calc(100% - 32px));
}

.page-about .about-cta__title {
  font-size: var(--step-4);
  line-height: 1.3;
  margin-bottom: .7rem;
}

.page-about .about-cta__text p {
  color: var(--text-soft);
  line-height: 1.8;
  max-width: 52ch;
}

.page-about .about-cta__links {
  display: flex;
  flex-wrap: wrap;
  gap: .7rem;
  align-content: start;
}

/* ---------- 响应式 ---------- */

@media (max-width: 599px) {
  .page-about .about-hero__figure::before {
    display: none;
  }

  .page-about .about-cta__inner {
    clip-path: none;
    border-radius: 2px;
  }
}

@media (min-width: 600px) {
  .page-about .about-hero__figures {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

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

  .page-about .about-era__inner {
    grid-template-columns: 92px minmax(0, 1fr);
    gap: 1.5rem;
    align-items: start;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: center;
  }

  .page-about .about-hero__title br {
    display: inline;
  }

  .page-about .about-hero__figures {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-service__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-flow {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 1.6rem;
  }

  .page-about .about-flow__step {
    padding: 1rem .9rem 1rem 1rem;
  }

  .page-about .about-flow__step::after {
    content: "";
    position: absolute;
    right: -.95rem;
    top: 2.1rem;
    width: 1.1rem;
    height: 1px;
    background: var(--c-violet);
    transform: rotate(-12deg);
    opacity: .8;
  }

  .page-about .about-flow__step:last-child::after {
    display: none;
  }

  .page-about .about-cta__inner {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    align-items: center;
  }

  .page-about .about-cta__links {
    justify-content: flex-end;
  }
}

@media (min-width: 960px) {
  .page-about .about-timeline__layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 3rem;
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--topbar-h) + 88px);
    align-self: start;
  }

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

  .page-about .about-rail__item {
    border: 0;
    border-left: 2px solid var(--line);
    border-radius: 0;
    padding: .7rem 0 .7rem 1.1rem;
    flex-direction: column;
    align-items: flex-start;
    gap: .2rem;
    position: relative;
  }

  .page-about .about-rail__item::before {
    content: "";
    position: absolute;
    left: -5px;
    top: 1.15rem;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--c-bg);
    border: 2px solid var(--line-strong);
  }

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

  .page-about .about-rail__year {
    font-size: var(--step-3);
  }

  .page-about .about-era {
    padding: 2rem 2rem 2rem 1.75rem;
  }

  .page-about .about-era__inner {
    grid-template-columns: 116px minmax(0, 1fr);
    gap: 2rem;
  }

  .page-about .about-numbers__grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (min-width: 1180px) {
  .page-about {
    --about-rail: 184px;
  }

  .page-about .about-cat {
    padding: 1.9rem 2rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: .01ms !important;
  }
}