.page-about {
  background: var(--ink);
  color: var(--cold);
}

.page-about .breadcrumb {
  padding-top: 18px;
  font-size: 0.78rem;
  letter-spacing: 0.05em;
}

.page-about .breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  color: var(--muted);
}

.page-about .breadcrumb-list a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.page-about .breadcrumb-list a:hover,
.page-about .breadcrumb-list a:focus-visible {
  color: var(--mint);
  border-bottom-color: var(--mint);
}

.page-about .breadcrumb-item span[aria-current="page"] {
  color: var(--cold);
}

.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 26px;
  padding: 24px 0 58px;
}

/* ---------- 左侧索引栏 ---------- */
.page-about .about-rail {
  border-top: 1px solid var(--steel);
  padding-top: 16px;
}

.page-about .rail-title {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--muted);
}

.page-about .rail-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px;
  margin: 0 0 20px;
  padding: 0;
  list-style: none;
}

.page-about .rail-link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 7px 9px;
  border-left: 2px solid var(--steel);
  color: var(--cold);
  font-size: 0.88rem;
  text-decoration: none;
  transition: border-color 0.2s ease, color 0.2s ease, background 0.2s ease;
}

.page-about .rail-link span {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--muted);
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible {
  border-left-color: var(--mint);
  color: var(--mint);
  background: rgba(57, 245, 200, 0.06);
}

.page-about .rail-link:hover span,
.page-about .rail-link:focus-visible span {
  color: var(--mint);
}

.page-about .rail-stage {
  display: grid;
  gap: 0;
  margin-bottom: 4px;
}

.page-about .stage-tick {
  position: relative;
  padding: 0 0 13px 16px;
  border-left: 1px solid var(--steel);
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.5;
}

.page-about .stage-tick:last-child {
  padding-bottom: 2px;
}

.page-about .stage-tick::before {
  content: "";
  position: absolute;
  left: -4px;
  top: 5px;
  width: 7px;
  height: 7px;
  background: var(--steel);
}

.page-about .stage-tick b {
  font-family: var(--font-mono);
  font-weight: 400;
  color: var(--steel);
  margin-right: 6px;
}

.page-about .stage-tick--on {
  color: var(--mint);
}

.page-about .stage-tick--on::before {
  background: var(--mint);
}

.page-about .stage-tick--on b {
  color: var(--mint);
}

/* ---------- 首屏 ---------- */
.page-about .about-flow {
  min-width: 0;
}

.page-about .hero-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 22px;
  padding-bottom: 8px;
}

.page-about .hero-title {
  margin: 10px 0 16px;
  font-family: var(--font-display);
  font-size: clamp(1.9rem, 4.8vw, 3.2rem);
  line-height: 1.18;
  letter-spacing: -0.02em;
  color: var(--cold);
}

.page-about .hero-lead {
  margin: 0 0 22px;
  max-width: 48ch;
  font-size: 1rem;
  line-height: 1.9;
  color: var(--muted);
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .media-frame {
  margin: 0;
  border: 1px solid var(--steel);
  background: var(--graphite);
  overflow: hidden;
}

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

.page-about .media-frame figcaption {
  padding: 9px 11px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  line-height: 1.6;
  color: var(--muted);
  border-top: 1px solid var(--steel);
}

.page-about .hero-media {
  align-self: end;
}

/* ---------- 章节通用 ---------- */
.page-about .about-block {
  margin-top: 34px;
  padding-top: 26px;
  border-top: 1px solid var(--steel);
}

.page-about .block-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 14px;
  margin-bottom: 16px;
}

.page-about .block-num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  color: var(--orange);
}

.page-about .block-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 2.8vw, 1.9rem);
  line-height: 1.35;
  letter-spacing: -0.01em;
  color: var(--cold);
}

.page-about .copy p {
  margin: 0 0 14px;
  max-width: 66ch;
  font-size: 1rem;
  line-height: 1.9;
  color: var(--cold);
}

.page-about .note {
  margin: 14px 0 0;
  font-size: 0.78rem;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .pull {
  margin: 20px 0 0;
  padding: 18px 20px;
  border-left: 3px solid var(--mint);
  background: var(--graphite);
  font-size: 1.02rem;
  line-height: 1.85;
  color: var(--cold);
}

/* ---------- 团队 ---------- */
.page-about .team-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin-top: 18px;
}

.page-about .team-card {
  padding: 18px 16px 16px;
  border: 1px solid var(--steel);
  background: var(--graphite);
  transition: border-color 0.22s ease, transform 0.22s ease;
}

.page-about .team-card:hover,
.page-about .team-card:focus-within {
  border-color: var(--mint);
  transform: translateY(-3px);
}

.page-about .team-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.8rem;
  line-height: 1;
  color: var(--mint);
}

.page-about .team-role {
  margin: 10px 0 8px;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  color: var(--cold);
}

.page-about .team-duty {
  margin: 0;
  font-size: 0.84rem;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .meter {
  display: flex;
  height: 6px;
  margin-top: 18px;
  background: var(--steel);
  overflow: hidden;
}

.page-about .meter span {
  display: block;
  height: 100%;
}

.page-about .meter .m1 {
  width: 59%;
  background: var(--mint);
}

.page-about .meter .m2 {
  width: 26%;
  background: var(--orange);
}

.page-about .meter .m3 {
  width: 15%;
  background: var(--muted);
}

/* ---------- 流程 ---------- */
.page-about .flow-card {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
  margin-top: 6px;
}

.page-about .process {
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .process-step {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  padding: 15px 0;
  border-top: 1px solid var(--steel);
}

.page-about .process-step:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .process-num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.1em;
  color: var(--mint);
  padding-top: 3px;
}

.page-about .process-step h3 {
  margin: 0 0 6px;
  font-size: 0.98rem;
  color: var(--cold);
  letter-spacing: 0.01em;
}

.page-about .process-step p {
  margin: 0;
  font-size: 0.88rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .paper-block {
  margin: 24px 0 4px;
  padding: 22px 20px;
  background: var(--paper);
  color: var(--ink);
  border-radius: var(--radius);
}

.page-about .paper-block .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--glass);
}

.page-about .rhythm {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  margin-top: 14px;
}

.page-about .rhythm-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.5rem;
  line-height: 1.1;
  color: var(--glass);
}

.page-about .rhythm-label {
  display: block;
  margin-top: 5px;
  font-size: 0.78rem;
  line-height: 1.6;
  color: #3d4a46;
}

.page-about .paper-note {
  margin: 16px 0 0;
  padding-top: 14px;
  border-top: 1px solid rgba(11, 14, 13, 0.16);
  font-size: 0.82rem;
  line-height: 1.8;
  color: #3d4a46;
}

/* ---------- 跨端 ---------- */
.page-about .cross-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  margin-top: 18px;
}

.page-about .cross-card {
  display: grid;
  align-content: start;
  gap: 12px;
  padding: 20px 18px;
  border: 1px solid var(--steel);
  background: var(--graphite);
  transition: border-color 0.2s ease;
}

.page-about .cross-card:hover {
  border-color: var(--mint);
}

.page-about .cross-card h3 {
  margin: 0;
  font-size: 1rem;
  letter-spacing: 0.02em;
  color: var(--cold);
}

.page-about .cross-card ul {
  display: grid;
  gap: 9px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .cross-card li {
  position: relative;
  padding-left: 15px;
  font-size: 0.88rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .cross-card li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 6px;
  height: 6px;
  background: var(--mint);
}

/* ---------- 演进时间线 ---------- */
.page-about .phases {
  margin: 20px 0 0;
  padding: 0 0 0 2px;
  list-style: none;
  border-left: 1px solid var(--steel);
}

.page-about .phase {
  position: relative;
  padding-left: 20px;
}

.page-about .phase::before {
  content: "";
  position: absolute;
  left: -6px;
  top: 19px;
  width: 10px;
  height: 10px;
  background: var(--ink);
  border: 2px solid var(--steel);
  transition: border-color 0.2s ease;
}

.page-about .phase[open]::before {
  border-color: var(--mint);
}

.page-about .phase summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 12px;
  padding: 13px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .phase-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  color: var(--orange);
}

.page-about .phase-name {
  font-size: 1rem;
  color: var(--cold);
  transition: color 0.2s ease;
}

.page-about .phase summary:hover .phase-name,
.page-about .phase[open] .phase-name {
  color: var(--mint);
}

.page-about .phase-body {
  max-width: 62ch;
  padding: 0 0 16px;
  font-size: 0.9rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .city-media {
  margin-top: 18px;
}

/* ---------- 合作与联系 ---------- */
.page-about .eco-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px 14px;
  margin-top: 20px;
}

.page-about .eco-item {
  padding: 14px 0 12px;
  border-top: 1px solid var(--steel);
}

.page-about .eco-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.45rem;
  line-height: 1.1;
  color: var(--mint);
}

.page-about .eco-label {
  display: block;
  margin-top: 6px;
  font-size: 0.78rem;
  line-height: 1.6;
  color: var(--muted);
}

.page-about .contact-slab {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
  margin-top: 22px;
  padding: 20px 18px;
  border: 1px solid var(--steel);
  background: var(--graphite);
}

.page-about .contact-slab h3 {
  margin: 0 0 8px;
  font-size: 1rem;
  color: var(--cold);
}

.page-about .contact-slab p {
  margin: 0;
  font-size: 0.88rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .contact-rows {
  display: grid;
  gap: 8px;
  padding-top: 14px;
  border-top: 1px solid var(--steel);
}

.page-about .contact-rows p {
  font-size: 0.85rem;
  color: var(--cold);
  word-break: break-word;
}

.page-about .contact-rows .k {
  display: inline-block;
  min-width: 46px;
  margin-right: 8px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.page-about .end-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
  margin-top: 24px;
}

.page-about .to-top {
  margin-left: auto;
  padding-bottom: 4px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid var(--steel);
  transition: color 0.2s ease, border-color 0.2s ease;
}

.page-about .to-top:hover,
.page-about .to-top:focus-visible {
  color: var(--mint);
  border-bottom-color: var(--mint);
}

/* ---------- 桌面端 ---------- */
@media (min-width: 900px) {
  .page-about .about-shell {
    grid-template-columns: minmax(190px, 30fr) minmax(0, 70fr);
    gap: 46px;
    align-items: start;
    padding-top: 32px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 88px;
  }

  .page-about .rail-list {
    grid-template-columns: minmax(0, 1fr);
    margin-bottom: 24px;
  }

  .page-about .about-block {
    margin-top: 42px;
    padding-top: 30px;
  }
}

@media (min-width: 820px) {
  .page-about .hero-split {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 1fr);
    gap: 36px;
    align-items: end;
  }
}

@media (min-width: 700px) {
  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 14px;
  }

  .page-about .flow-card {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1fr);
    gap: 22px;
    align-items: start;
  }

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

@media (min-width: 760px) {
  .page-about .cross-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
  }

  .page-about .contact-slab {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr);
    align-items: start;
    padding: 22px 20px;
  }

  .page-about .contact-rows {
    padding-top: 0;
    border-top: 0;
  }
}

@media (min-width: 980px) {
  .page-about .eco-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}
</