.page-about {
  --about-gap: clamp(20px, 3vw, 40px);
  --about-rail: 60px;
  --about-pad: clamp(48px, 7vw, 96px);
  background: var(--paper);
  color: var(--graphite);
}

.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

.page-about .figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding-bottom: clamp(40px, 6vw, 76px);
}

.page-about .about-hero__head {
  max-width: 880px;
  margin-top: clamp(26px, 5vw, 54px);
}

.page-about .about-hero h1 {
  font-family: var(--font-head);
  font-size: var(--fs-xl);
  font-weight: 900;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin: 14px 0 20px;
}

.page-about .about-hero__lede {
  max-width: 46ch;
  font-size: 17px;
  line-height: 1.75;
}

.page-about .about-hero__fig {
  margin: clamp(30px, 4.5vw, 50px) 0 0;
}

.page-about .about-hero__fig img {
  width: 100%;
  height: auto;
  border: 1px solid var(--rule);
}

.page-about .about-marks {
  list-style: none;
  margin: clamp(30px, 4.5vw, 52px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
}

.page-about .about-marks__item {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 18px 16px;
  background: var(--paper-2);
}

.page-about .about-marks__num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 4vw, 40px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-marks__label {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--graphite);
  opacity: 0.78;
}

/* ---------- 区段标题 ---------- */

.page-about .about-head {
  max-width: 780px;
  margin-bottom: clamp(28px, 4vw, 52px);
}

.page-about .about-head h2 {
  font-family: var(--font-head);
  font-size: var(--fs-lg);
  font-weight: 900;
  line-height: 1.18;
  letter-spacing: -0.01em;
  color: var(--ink);
  margin: 12px 0 14px;
}

.page-about .about-head__note {
  font-size: 16px;
  line-height: 1.75;
  color: var(--graphite);
}

/* ---------- 时间线 ---------- */

.page-about .about-tl {
  padding: var(--about-pad) 0;
  border-top: 1px solid var(--rule);
}

.page-about .tl {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .tl::before {
  content: "";
  position: absolute;
  top: 10px;
  bottom: 12px;
  left: calc(var(--about-rail) / 2);
  width: 1px;
  background: linear-gradient(180deg, var(--rule) 0%, var(--gold) 14%, var(--gold) 86%, transparent 100%);
  transform: translateX(-0.5px);
}

.page-about .tl__item {
  display: grid;
  grid-template-columns: var(--about-rail) minmax(0, 1fr);
  gap: 14px;
  padding-bottom: clamp(26px, 4vw, 46px);
}

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

.page-about .tl__rail {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding-top: 4px;
}

.page-about .tl__no {
  font-family: var(--font-mono);
  font-size: clamp(18px, 2.4vw, 26px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.page-about .tl__scale {
  width: 22px;
  height: 22px;
  color: var(--gold);
  background: var(--paper);
  border-radius: 50%;
  flex: 0 0 auto;
}

.page-about .tl__card {
  padding: clamp(18px, 2.4vw, 28px);
  background: var(--paper-2);
  border: 1px solid var(--rule);
}

.page-about .tl__card h3 {
  font-size: clamp(19px, 2vw, 24px);
  font-weight: 800;
  line-height: 1.32;
  color: var(--ink);
  margin: 10px 0 8px;
}

.page-about .tl__card p {
  font-size: 16px;
  line-height: 1.75;
  color: var(--graphite);
}

.page-about .tl__more {
  margin-top: 14px;
  padding-top: 10px;
  border-top: 1px dashed var(--rule);
}

.page-about .tl__more summary {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--jade);
}

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

.page-about .tl__more summary::after {
  content: "+";
  font-size: 16px;
  line-height: 1;
  color: var(--gold);
}

.page-about .tl__more[open] summary::after {
  content: "–";
}

.page-about .tl__more ul {
  margin: 4px 0 0;
  padding-left: 18px;
  display: grid;
  gap: 6px;
  font-size: 15px;
  line-height: 1.7;
  color: var(--graphite);
}

.page-about .tl__more summary:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 3px;
}

/* ---------- 回访沉淀（深色） ---------- */

.page-about .about-return {
  margin-top: clamp(20px, 3vw, 36px);
  padding: var(--about-pad) 0;
  background: var(--ink);
  color: var(--paper);
}

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

.page-about .about-return h2 {
  font-family: var(--font-head);
  font-size: var(--fs-lg);
  font-weight: 900;
  line-height: 1.18;
  color: var(--paper-2);
  margin: 12px 0 16px;
}

.page-about .about-return__copy > p {
  font-size: 16px;
  line-height: 1.78;
  color: rgba(244, 238, 226, 0.84);
  max-width: 48ch;
}

.page-about .about-flow {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .about-flow li {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  gap: 10px;
  padding-top: 10px;
  border-top: 1px solid rgba(200, 162, 74, 0.32);
  font-size: 15px;
  line-height: 1.7;
  color: rgba(244, 238, 226, 0.86);
}

.page-about .about-flow__no {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gold-hi);
  padding-top: 3px;
}

.page-about .about-return__fig img {
  border: 1px solid rgba(200, 162, 74, 0.4);
}

.page-about .about-return .figure__cap {
  color: rgba(244, 238, 226, 0.62);
}

/* ---------- 校对轮次 ---------- */

.page-about .about-audit {
  padding: var(--about-pad) 0;
}

.page-about .about-filter__bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .about-filter__live {
  margin: 14px 0 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--graphite);
  opacity: 0.8;
}

.page-about .about-entries {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
}

.page-about .about-entry {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 14px;
  padding: 14px 16px;
  background: var(--paper-2);
  min-height: 44px;
}

.page-about .about-entry__id {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--vermilion);
}

.page-about .about-entry__name {
  flex: 1 1 220px;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .about-entry__ver {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--graphite);
  opacity: 0.72;
}

/* ---------- 团队与流程 ---------- */

.page-about .about-team {
  padding: var(--about-pad) 0;
  background: var(--paper-2);
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}

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

.page-about .about-roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .about-roles__item {
  padding: 2px 0 2px 16px;
  border-left: 3px solid var(--gold);
}

.page-about .about-roles__no {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--jade);
}

.page-about .about-roles__item h3 {
  font-size: 19px;
  font-weight: 800;
  color: var(--ink);
  margin: 6px 0 6px;
}

.page-about .about-roles__item p {
  font-size: 16px;
  line-height: 1.75;
  color: var(--graphite);
}

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

.page-about .about-team__fig img {
  border: 1px solid var(--rule);
}

.page-about .about-steps {
  list-style: none;
  margin: clamp(28px, 4vw, 48px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--rule);
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}

.page-about .about-steps__item {
  padding: 14px 10px;
  background: var(--paper-2);
  text-align: center;
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
}

.page-about .about-steps__no {
  display: block;
  margin-bottom: 5px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--gold);
}

/* ---------- 范围演进 ---------- */

.page-about .about-scope {
  padding: var(--about-pad) 0;
}

.page-about .about-scope__track {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
}

.page-about .about-scope__stage {
  padding: clamp(20px, 2.6vw, 30px);
  background: var(--paper-2);
  border: 1px solid var(--rule);
}

.page-about .about-scope__v {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--gold);
}

.page-about .about-scope__stage h3 {
  font-size: clamp(19px, 2vw, 24px);
  font-weight: 800;
  line-height: 1.3;
  color: var(--ink);
  margin: 12px 0 8px;
}

.page-about .about-scope__stage p {
  font-size: 16px;
  line-height: 1.75;
  color: var(--graphite);
}

.page-about .about-scope__stage.plate--ink {
  color: var(--paper);
  border-color: var(--ink-2);
}

.page-about .about-scope__stage.plate--ink h3 {
  color: var(--gold-hi);
}

.page-about .about-scope__stage.plate--ink .about-scope__v {
  color: var(--gold-hi);
}

.page-about .about-scope__stage.plate--ink p {
  color: rgba(244, 238, 226, 0.84);
}

/* ---------- 下一步 ---------- */

.page-about .about-next {
  padding: var(--about-pad) 0 clamp(56px, 8vw, 104px);
  background: var(--ink);
  color: var(--paper);
}

.page-about .about-next__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
}

.page-about .about-next h2 {
  font-family: var(--font-head);
  font-size: var(--fs-lg);
  font-weight: 900;
  line-height: 1.18;
  color: var(--paper-2);
  margin: 12px 0 14px;
}

.page-about .about-next__lead p {
  font-size: 16px;
  line-height: 1.78;
  color: rgba(244, 238, 226, 0.82);
  max-width: 44ch;
}

.page-about .about-next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-next__list li {
  position: relative;
  padding-left: 24px;
  font-size: 16px;
  line-height: 1.72;
  color: rgba(244, 238, 226, 0.88);
}

.page-about .about-next__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 13px;
  width: 12px;
  height: 1px;
  background: var(--gold);
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

/* ---------- 响应式 ---------- */

@media (min-width: 720px) {
  .page-about {
    --about-rail: 86px;
  }

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

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

  .page-about .about-steps__item {
    padding: 18px 12px;
  }
}

@media (min-width: 960px) {
  .page-about {
    --about-rail: 112px;
  }

  .page-about .about-return__grid {
    grid-template-columns: 5fr 7fr;
  }

  .page-about .about-team__body {
    grid-template-columns: 7fr 5fr;
  }

  .page-about .about-next__grid {
    grid-template-columns: 5fr 7fr;
  }

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

  .page-about .about-scope__stage:nth-child(2) {
    margin-top: 22px;
  }

  .page-about .about-scope__stage:nth-child(3) {
    margin-top: 44px;
  }
}

@media (min-width: 1200px) {
  .page-about .tl__item {
    gap: 22px;
  }
}