.page-about {
  --about-radius: 18px;
  --about-pad: clamp(1.25rem, 4vw, 4.5rem);
  color: var(--c-fog);
  font-family: var(--font-body);
}

.page-about .breadcrumb {
  padding-block: 1.5rem 0;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(2.5rem, 8vw, 6rem) clamp(2rem, 6vw, 4.5rem);
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -22%;
  right: -14%;
  width: clamp(260px, 44vw, 620px);
  height: clamp(260px, 44vw, 620px);
  background: linear-gradient(142deg, rgba(27, 38, 80, 0.95), rgba(23, 31, 61, 0.18));
  border-radius: 46% 54% 38% 62% / 52% 42% 58% 48%;
  transform: rotate(-12deg);
  z-index: 0;
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: -4%;
  bottom: 8%;
  width: 42%;
  height: 1px;
  background: linear-gradient(90deg, var(--c-copper), rgba(198, 242, 74, 0.55), transparent);
  transform: rotate(-5deg);
  transform-origin: left center;
  z-index: 0;
  pointer-events: none;
}

.page-about .hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 4rem);
}

.page-about .hero-copy .lede {
  max-width: 34em;
  margin: 1.25rem 0 0;
  color: var(--c-index);
  font-size: var(--step-0);
  line-height: 1.8;
}

.page-about .hero-stats {
  display: grid;
  border-top: 1px solid var(--line);
}

.page-about .hero-stat {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .hero-stat .stat-value {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 5vw, 2.25rem);
  font-weight: 300;
  letter-spacing: 0.06em;
  line-height: 1;
  color: var(--c-fog);
}

.page-about .hero-stat .stat-value--lime {
  color: var(--c-lime);
}

.page-about .hero-stat .stat-value--amber {
  color: var(--c-amber);
}

.page-about .hero-stat .stat-label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--c-index);
  text-align: right;
}

/* ---------- 双栏主体 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 4.5rem);
  padding-block: clamp(2.5rem, 7vw, 6rem);
}

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

.page-about .index-head {
  margin: 0 0 1rem;
  color: var(--c-copper);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.page-about .index-list {
  list-style: none;
  margin: 0 0 1.25rem;
  padding: 0 0 0 1.15rem;
  border-left: 1px solid var(--c-copper);
}

.page-about .index-list li {
  position: relative;
}

.page-about .index-list li::before {
  content: "";
  position: absolute;
  left: -1.15rem;
  top: 50%;
  width: 7px;
  height: 1px;
  background: var(--c-copper);
  opacity: 0.7;
}

.page-about .index-list a {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  padding: 0.45rem 0;
  color: var(--c-index);
  font-size: 0.92rem;
  text-decoration: none;
  transition: color 200ms ease, transform 200ms ease;
}

.page-about .index-list a:hover,
.page-about .index-list a:focus-visible {
  color: var(--c-fog);
  transform: translateX(4px);
}

.page-about .index-list a:hover .idx-num,
.page-about .index-list a:focus-visible .idx-num {
  color: var(--c-lime);
}

.page-about .idx-num {
  color: var(--c-copper);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  transition: color 200ms ease;
}

.page-about .index-note {
  margin: 0;
  color: var(--c-index);
  font-size: 0.78rem;
  line-height: 1.7;
  max-width: 22em;
}

/* ---------- 章节通用 ---------- */
.page-about .about-sec {
  padding-block: clamp(2rem, 5vw, 3.25rem);
  border-top: 1px solid var(--line-soft);
  scroll-margin-top: 6rem;
}

.page-about .about-body > .about-sec:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .sec-marker {
  margin: 0 0 0.9rem;
  color: var(--c-copper);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.page-about .about-sec h2 {
  margin: 0 0 1.15rem;
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(1.7rem, 4.4vw, 2.6rem);
  letter-spacing: 0.05em;
  line-height: 1.18;
  max-width: 22ch;
}

.page-about .about-sec p {
  max-width: 38em;
  line-height: 1.8;
  color: rgba(242, 244, 248, 0.84);
}

.page-about .sec-lede {
  margin: 0 0 1.5rem;
  color: var(--c-index) !important;
  font-size: 0.95rem;
}

/* ---------- 自述 ---------- */
.page-about .self-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 2.75rem);
}

.page-about .self-copy p + p {
  margin-top: 1rem;
}

.page-about .bound-list {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.75rem;
}

.page-about .bound-list li {
  display: flex;
  gap: 0.85rem;
  align-items: baseline;
  color: var(--c-index);
  font-size: 0.92rem;
  line-height: 1.75;
}

.page-about .bound-key {
  flex: none;
  min-width: 2.6rem;
  color: var(--c-lime);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
}

.page-about .bound-key--off {
  color: var(--c-amber);
}

.page-about .media-frame {
  margin: 0;
  border-radius: var(--about-radius);
  overflow: hidden;
  border: 1px solid var(--line-soft);
  background: linear-gradient(150deg, rgba(27, 38, 80, 0.6), rgba(18, 22, 28, 0.9));
}

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

.page-about .self-figure img {
  aspect-ratio: 3 / 4;
}

/* ---------- 分工 ---------- */
.page-about .team-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .team-row {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.5rem 1rem;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--line-soft);
  align-items: baseline;
}

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

.page-about .team-num {
  font-size: 1.35rem;
  line-height: 1;
  color: var(--c-copper);
  letter-spacing: 0.04em;
}

.page-about .team-name {
  font-family: var(--font-display);
  font-size: 1.05rem;
  letter-spacing: 0.08em;
  color: var(--c-fog);
}

.page-about .team-duty {
  grid-column: 1 / -1;
  color: var(--c-index);
  font-size: 0.9rem;
  line-height: 1.75;
}

/* ---------- 流程折叠组 ---------- */
.page-about .flow-group {
  border-top: 1px solid var(--line);
}

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

.page-about .flow-step summary {
  list-style: none;
  cursor: pointer;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: baseline;
  gap: 0.35rem 1rem;
  padding: 1.05rem 0;
  transition: color 180ms ease;
}

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

.page-about .flow-step summary:hover .step-title,
.page-about .flow-step summary:focus-visible .step-title {
  color: var(--c-lime);
}

.page-about .step-num {
  color: var(--c-copper);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
}

.page-about .step-title {
  font-family: var(--font-display);
  font-size: clamp(1.15rem, 2.6vw, 1.5rem);
  font-weight: 300;
  letter-spacing: 0.08em;
  color: var(--c-fog);
  transition: color 180ms ease;
}

.page-about .step-hint {
  grid-column: 2 / 3;
  color: var(--c-index);
  font-size: 0.78rem;
  line-height: 1.6;
}

.page-about .step-toggle {
  position: relative;
  justify-self: end;
  align-self: center;
  width: 14px;
  height: 14px;
  flex: none;
}

.page-about .step-toggle::before,
.page-about .step-toggle::after {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 14px;
  height: 1.5px;
  background: var(--c-index);
  transition: transform 200ms ease, background 200ms ease;
}

.page-about .step-toggle::after {
  transform: rotate(90deg);
}

.page-about .flow-step[open] .step-toggle::before {
  background: var(--c-lime);
}

.page-about .flow-step[open] .step-toggle::after {
  transform: rotate(0deg);
}

.page-about .step-body {
  margin: 0 0 1.25rem 0;
  padding: 1rem 1.15rem;
  border-radius: 4px 18px 18px 18px;
  background: linear-gradient(160deg, rgba(27, 38, 80, 0.9), rgba(23, 31, 61, 0.5));
  border-left: 2px solid var(--c-copper);
}

.page-about .step-body p {
  margin: 0;
  max-width: 42em;
  color: rgba(242, 244, 248, 0.78);
  font-size: 0.92rem;
  line-height: 1.85;
}

/* ---------- 版本时间轴 ---------- */
.page-about .version-figure {
  margin-bottom: clamp(1.75rem, 4vw, 2.75rem);
}

.page-about .timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 1.5rem;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 0.6rem;
  bottom: 0.6rem;
  width: 1px;
  background: linear-gradient(180deg, var(--c-copper), rgba(181, 96, 58, 0.12));
}

.page-about .tl-item {
  position: relative;
  padding-bottom: 1.75rem;
}

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

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -1.5rem;
  top: 0.5rem;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--c-ink);
  border: 1px solid var(--c-copper);
  transition: background 200ms ease, border-color 200ms ease, box-shadow 200ms ease;
}

.page-about .tl-item:hover::before {
  background: var(--c-lime);
  border-color: var(--c-lime);
  box-shadow: 0 0 0 4px rgba(198, 242, 74, 0.14);
}

.page-about .tl-era {
  margin: 0 0 0.35rem;
  color: var(--c-copper);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
}

.page-about .tl-item h3 {
  margin: 0 0 0.4rem;
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 300;
  letter-spacing: 0.06em;
  color: var(--c-fog);
  display: flex;
  align-items: center;
  gap: 0.7rem;
  flex-wrap: wrap;
}

.page-about .tl-item p {
  margin: 0;
  max-width: 40em;
  color: var(--c-index);
  font-size: 0.92rem;
  line-height: 1.8;
}

/* ---------- 协作 ---------- */
.page-about .partner-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .partner-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1.25rem;
}

.page-about .partner-steps li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.9rem;
  align-items: baseline;
}

.page-about .ps-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.85rem;
  height: 1.85rem;
  border-radius: 50%;
  border: 1px solid var(--c-copper);
  color: var(--c-copper);
  font-size: 0.7rem;
  letter-spacing: 0.05em;
}

.page-about .partner-steps h3 {
  margin: 0 0 0.35rem;
  font-family: var(--font-display);
  font-size: 1.08rem;
  font-weight: 300;
  letter-spacing: 0.08em;
  color: var(--c-fog);
}

.page-about .partner-steps p {
  margin: 0;
  max-width: 38em;
  color: var(--c-index);
  font-size: 0.9rem;
  line-height: 1.8;
}

.page-about .partner-contact {
  margin: 1.75rem 0 0;
  padding-top: 1.1rem;
  border-top: 1px solid var(--line-soft);
  color: var(--c-index) !important;
  font-size: 0.9rem;
}

.page-about .partner-contact a {
  color: var(--c-lime);
  text-decoration: none;
  border-bottom: 1px solid rgba(198, 242, 74, 0.45);
}

.page-about .partner-contact a:hover,
.page-about .partner-contact a:focus-visible {
  border-bottom-color: var(--c-lime);
}

/* ---------- 页尾 ---------- */
.page-about .about-outro {
  margin-top: clamp(2rem, 5vw, 3.25rem);
  padding: clamp(1.75rem, 4vw, 2.5rem) clamp(1.25rem, 4vw, 2.5rem);
  border-radius: var(--about-radius);
  background: linear-gradient(140deg, rgba(27, 38, 80, 0.9), rgba(18, 22, 28, 0.85));
  border: 1px solid var(--line-soft);
}

.page-about .outro-line {
  margin: 0 0 1.25rem;
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 3vw, 1.7rem);
  font-weight: 300;
  letter-spacing: 0.06em;
  line-height: 1.4;
  color: var(--c-fog);
  max-width: 24ch;
}

.page-about .outro-actions {
  display: grid;
  gap: 1.25rem;
}

.page-about .about-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
}

.page-about .about-links a {
  color: var(--c-index);
  font-size: 0.82rem;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 180ms ease, border-color 180ms ease;
}

.page-about .about-links a:hover,
.page-about .about-links a:focus-visible {
  color: var(--c-fog);
  border-bottom-color: var(--c-copper);
}

/* ---------- 平板 ---------- */
@media (min-width: 760px) {
  .page-about .self-grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .team-row {
    grid-template-columns: 5rem minmax(0, 12rem) minmax(0, 1fr);
    gap: 0.5rem 1.5rem;
    align-items: baseline;
  }

  .page-about .team-duty {
    grid-column: 3 / 4;
  }

  .page-about .flow-step summary {
    grid-template-columns: 3.5rem minmax(0, 1fr) auto auto;
  }

  .page-about .step-hint {
    grid-column: 2 / 3;
  }

  .page-about .step-body {
    margin-left: 3.5rem;
  }

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

  .page-about .outro-actions {
    grid-template-columns: auto minmax(0, 1fr);
    align-items: center;
    gap: 2rem;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 960px) {
  .page-about .hero-grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 0.9fr);
    align-items: end;
  }

  .page-about .about-layout {
    grid-template-columns: minmax(170px, 220px) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: 5.5rem;
  }

  .page-about .partner-figure {
    position: sticky;
    top: 5.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .index-list a,
  .page-about .step-toggle::before,
  .page-about .step-toggle::after,
  .page-about .tl-item::before,
  .page-about .about-links a {
    transition: none;
  }
}