.page-about {
  --about-rail: 104px;
  --about-gap: 40px;
  --about-num: clamp(1.9rem, 4.4vw, 3rem);
  background: var(--ink);
  color: var(--mist);
}

/* ---------- 容器 ---------- */
.page-about .about-shell {
  max-width: var(--shell);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}

.page-about .about-shell--body {
  padding-bottom: clamp(64px, 9vw, 120px);
}

/* ---------- 封面 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(30px, 5vw, 56px) 0 clamp(40px, 6vw, 76px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: -8%;
  right: -8%;
  bottom: -140px;
  height: 260px;
  background: linear-gradient(90deg, var(--cyan-2), var(--cyan) 46%, rgba(53, 242, 192, 0) 82%);
  opacity: 0.09;
  transform: rotate(-6deg);
  pointer-events: none;
}

.page-about .about-hero .crumb {
  position: relative;
  z-index: 1;
}

.page-about .about-hero__grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 40px;
  margin-top: clamp(26px, 4vw, 44px);
}

.page-about .about-hero__vol {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  color: var(--brass);
  margin-bottom: 16px;
}

.page-about .about-hero__title {
  font-size: clamp(2.1rem, 5.4vw, 4.4rem);
  font-weight: 300;
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--paper);
  max-width: 17ch;
}

.page-about .about-hero__lede {
  margin-top: clamp(20px, 2.6vw, 30px);
  max-width: 40ch;
  font-size: 1.0625rem;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 3vw, 34px);
}

.page-about .about-hero__index {
  border-top: 1px solid var(--line);
}

.page-about .about-hero__index-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-hero__index-row dt {
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  color: var(--mist-2);
}

.page-about .about-hero__index-row dd {
  font-size: 0.9375rem;
  color: var(--paper);
  white-space: nowrap;
}

.page-about .about-hero__index-row .num {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--cyan);
}

/* ---------- 左侧竖向轨道 ---------- */
.page-about .about-rail-col {
  display: none;
}

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

.page-about .about-rail a {
  display: block;
  padding: 7px 0 7px 14px;
  border-left: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  color: var(--mist-2);
  text-decoration: none;
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .about-rail a:hover,
.page-about .about-rail a.is-active {
  color: var(--cyan);
  border-left-color: var(--cyan);
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  padding: clamp(40px, 6vw, 76px) 0;
  border-top: 1px solid var(--line);
}

.page-about .about-sec:first-child {
  border-top: 0;
  padding-top: clamp(36px, 5vw, 64px);
}

.page-about .about-sec__head {
  display: flex;
  align-items: baseline;
  gap: clamp(14px, 2vw, 24px);
  margin-bottom: clamp(20px, 3vw, 30px);
}

.page-about .about-sec__no {
  flex: none;
  font-family: var(--font-mono);
  font-size: clamp(2.2rem, 6vw, 4rem);
  font-weight: 700;
  line-height: 0.92;
  letter-spacing: 0.02em;
  color: rgba(53, 242, 192, 0.18);
}

.page-about .about-sec__title {
  font-size: clamp(1.3rem, 2.8vw, 2rem);
  font-weight: 700;
  line-height: 1.26;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-sec__body > p {
  max-width: 42ch;
  font-size: 1.0625rem;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .about-sec__body > p + p {
  margin-top: 16px;
}

.page-about .about-sec__body a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--line-cyan);
  transition: border-color var(--t-fast), color var(--t-fast);
}

.page-about .about-sec__body a:hover {
  border-bottom-color: var(--cyan);
}

.page-about .about-sec__foot {
  margin-top: clamp(24px, 3vw, 34px);
  padding-top: 18px;
  border-top: 1px solid var(--line-soft);
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--mist-2);
  max-width: 46ch;
}

/* ---------- 引言块 ---------- */
.page-about .about-pullquote {
  margin-top: clamp(24px, 3vw, 34px);
  padding: 22px 0 22px 22px;
  border-left: 2px solid var(--clay);
}

.page-about .about-pullquote p {
  max-width: 26ch;
  font-size: clamp(1.05rem, 2vw, 1.3rem);
  line-height: 1.6;
  color: var(--paper);
}

/* ---------- 图文两栏 ---------- */
.page-about .about-split {
  display: grid;
  gap: 30px;
  margin-top: clamp(24px, 3vw, 34px);
}

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

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  object-fit: cover;
  background: var(--ink-2);
}

.page-about .about-figure figcaption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  color: var(--mist-2);
}

.page-about .about-figure--wide {
  margin-top: clamp(26px, 3.4vw, 40px);
  position: relative;
}

.page-about .about-figure--wide::before {
  content: "";
  position: absolute;
  inset: 12px -10px -12px 14px;
  border: 1px solid var(--line-soft);
  pointer-events: none;
}

/* ---------- 团队分工 ---------- */
.page-about .about-team {
  border: 1px solid var(--line);
}

.page-about .about-team__row {
  padding: 20px 18px;
  border-bottom: 1px solid var(--line);
  background: var(--ink-2);
  transition: background var(--t-mid);
}

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

.page-about .about-team__row:hover {
  background: var(--ink-3);
}

.page-about .about-team__role {
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-team__role span {
  display: block;
  margin-top: 5px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 400;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .about-team__desc {
  margin-top: 10px;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--mist-2);
}

/* ---------- 流程步骤 ---------- */
.page-about .about-steps {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  margin-top: clamp(24px, 3vw, 34px);
  border: 1px solid var(--line);
  counter-reset: aboutStep;
}

.page-about .about-step {
  position: relative;
  padding: 22px 18px 24px;
  border-bottom: 1px solid var(--line);
  background: var(--ink-2);
  transition: background var(--t-mid);
}

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

.page-about .about-step::after {
  content: "";
  position: absolute;
  inset: 0;
  border: 1px solid transparent;
  pointer-events: none;
  transition: border-color var(--t-mid);
}

.page-about .about-step:hover::after {
  border-color: var(--cyan);
}

.page-about .about-step__no {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .about-step__title {
  margin-top: 12px;
  font-size: 1rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-step__desc {
  margin-top: 8px;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--mist-2);
}

/* ---------- 版本时间轴 ---------- */
.page-about .about-versions {
  margin-top: clamp(24px, 3vw, 34px);
  border-left: 1px solid var(--line);
  padding-left: 26px;
}

.page-about .about-node {
  position: relative;
  border-bottom: 1px solid var(--line-soft);
  padding: 12px 0;
}

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

.page-about .about-node::before {
  content: "";
  position: absolute;
  left: -31px;
  top: 22px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  border: 1px solid var(--cyan-2);
  background: var(--ink);
  transition: background var(--t-mid), border-color var(--t-mid), box-shadow var(--t-mid);
}

.page-about .about-node[open]::before {
  background: var(--cyan);
  border-color: var(--cyan);
  box-shadow: 0 0 0 4px rgba(53, 242, 192, 0.14);
}

.page-about .about-node__sum {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 4px 0;
  cursor: pointer;
  list-style: none;
}

.page-about .about-node__sum::-webkit-details-marker {
  display: none;
}

.page-about .about-node__sum::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--cyan);
}

.page-about .about-node[open] .about-node__sum::after {
  content: "–";
}

.page-about .about-node__ver {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.14em;
  color: var(--brass);
  border: 1px solid rgba(217, 164, 65, 0.42);
  padding: 3px 8px;
  white-space: nowrap;
}

.page-about .about-node__name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-node__body {
  max-width: 44ch;
  margin: 8px 0 6px;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--mist-2);
}

/* ---------- 数字卡 ---------- */
.page-about .about-metrics {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: clamp(24px, 3vw, 34px);
  border: 1px solid var(--line);
  border-right: 0;
  border-bottom: 0;
}

.page-about .about-metric {
  position: relative;
  padding: 22px 18px 24px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--ink-2);
  transition: background var(--t-mid), box-shadow var(--t-mid);
}

.page-about .about-metric:hover {
  background: var(--ink-3);
  box-shadow: inset 0 0 0 1px var(--line-cyan);
}

.page-about .about-metric__num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--about-num);
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--cyan);
}

.page-about .about-metric__label {
  display: block;
  margin-top: 10px;
  font-size: 0.875rem;
  color: var(--mist);
}

.page-about .about-metric__note {
  margin-top: 10px;
  font-size: 0.75rem;
  line-height: 1.65;
  color: var(--mist-2);
  overflow: hidden;
  max-height: 140px;
  transition: max-height var(--t-slow), opacity var(--t-mid);
}

/* ---------- 赛段说明 ---------- */
.page-about .about-segments__title {
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-segments__lede {
  margin-top: 10px;
  max-width: 36ch;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--mist-2);
}

.page-about .about-segment-list {
  margin-top: 22px;
  border-top: 1px solid var(--line);
}

.page-about .about-segment {
  display: grid;
  gap: 6px;
  padding: 14px 0 14px 14px;
  border-bottom: 1px solid var(--line-soft);
  border-left: 2px solid var(--clay);
}

.page-about .about-segment b {
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-segment span {
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--mist-2);
}

/* ---------- 合作 ---------- */
.page-about .about-partners {
  display: grid;
  gap: 1px;
  margin-top: clamp(24px, 3vw, 34px);
}

.page-about .about-partner {
  padding: 24px 20px 26px;
  border: 1px solid var(--line);
  background: var(--ink-2);
  position: relative;
  transition: border-color var(--t-mid), background var(--t-mid);
}

.page-about .about-partner::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 16px;
  height: 16px;
  border-left: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--ink);
}

.page-about .about-partner:hover {
  border-color: var(--line-cyan);
  background: var(--ink-3);
}

.page-about .about-partner__tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  color: var(--cyan);
}

.page-about .about-partner__title {
  margin-top: 12px;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-partner__desc {
  margin-top: 10px;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--mist-2);
}

/* ---------- 加入与联络 ---------- */
.page-about .about-join {
  display: grid;
  gap: 26px;
}

.page-about .about-join__col {
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.page-about .about-join__col--alt {
  border-top-color: var(--line-cyan);
}

.page-about .about-join__title {
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-join__list {
  margin-top: 16px;
}

.page-about .about-join__list li {
  display: grid;
  gap: 5px;
  padding: 13px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-join__list b {
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--cyan);
}

.page-about .about-join__list span {
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--mist-2);
}

.page-about .about-join__col--alt p {
  margin-top: 14px;
  max-width: 42ch;
  font-size: 0.9375rem;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .about-join__col--alt a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--line-cyan);
}

.page-about .about-cta {
  display: grid;
  gap: 20px;
  margin-top: clamp(30px, 4vw, 46px);
  padding: clamp(22px, 3vw, 32px) clamp(20px, 3.2vw, 34px);
  background: linear-gradient(100deg, var(--ink-2), var(--ink-3) 62%);
  border: 1px solid var(--line);
  border-left: 3px solid var(--clay);
}

.page-about .about-cta__text {
  max-width: 32ch;
  font-size: clamp(1rem, 1.8vw, 1.2rem);
  line-height: 1.6;
  color: var(--paper);
}

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

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

  .page-about .about-step {
    border-right: 1px solid var(--line);
  }

  .page-about .about-step:nth-child(2n) {
    border-right: 0;
  }

  .page-about .about-partners {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
  }
}

@media (min-width: 760px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 1fr);
    column-gap: clamp(32px, 5vw, 72px);
    align-items: end;
  }

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

  .page-about .about-team__row {
    display: grid;
    grid-template-columns: 148px minmax(0, 1fr);
    column-gap: 24px;
    align-items: start;
    padding: 24px 22px;
  }

  .page-about .about-team__desc {
    margin-top: 0;
  }
}

@media (min-width: 900px) {
  .page-about .about-split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.08fr);
    column-gap: clamp(28px, 4vw, 56px);
    align-items: start;
  }

  .page-about .about-split--reverse {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  }

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

  .page-about .about-step {
    border-right: 1px solid var(--line);
  }

  .page-about .about-step:nth-child(2n) {
    border-right: 1px solid var(--line);
  }

  .page-about .about-step:nth-child(3n) {
    border-right: 0;
  }

  .page-about .about-step:nth-last-child(-n + 3) {
    border-bottom: 0;
  }

  .page-about .about-steps {
    border-bottom: 0;
  }

  .page-about .about-step:nth-last-child(-n + 3) {
    border-bottom: 1px solid var(--line);
  }

  .page-about .about-step:nth-last-child(-n + 3):nth-child(n + 4) {
    border-bottom: 0;
  }

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

  .page-about .about-join {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
    column-gap: clamp(30px, 4vw, 60px);
  }

  .page-about .about-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    column-gap: 32px;
  }

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

@media (min-width: 1080px) {
  .page-about .about-shell--body {
    display: grid;
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: var(--about-gap);
    align-items: start;
  }

  .page-about .about-rail-col {
    display: block;
  }

  .page-about .about-rail {
    position: sticky;
    top: 128px;
    padding-top: 8px;
  }

  .page-about .about-stream {
    min-width: 0;
  }
}

@media (hover: hover) and (pointer: fine) {
  .page-about .about-metric__note {
    max-height: 0;
    opacity: 0;
    margin-top: 0;
  }

  .page-about .about-metric:hover .about-metric__note,
  .page-about .about-metric:focus-within .about-metric__note {
    max-height: 140px;
    opacity: 1;
    margin-top: 10px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-metric,
  .page-about .about-step,
  .page-about .about-partner,
  .page-about .about-node::before,
  .page-about .about-metric__note,
  .page-about .about-rail a {
    transition: none;
  }
}
</main>