.page-about {
  --about-space: clamp(3.25rem, 8vw, 7rem);
  --about-cut: 13px;
  --about-panel: #0C2B47;
  display: block;
  color: var(--mist);
  padding-bottom: clamp(2.5rem, 7vw, 5.5rem);
}

.page-about .lede {
  color: var(--mist);
  opacity: 0.92;
}

/* ---------- 扉页 ---------- */
.page-about .frontis {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.75rem, 5vw, 3.25rem);
  padding-top: clamp(1.75rem, 5vw, 3.5rem);
  padding-bottom: clamp(2rem, 5vw, 3.5rem);
}

.page-about .frontis__title {
  margin: 0.65rem 0 1rem;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(1.85rem, 7.6vw, 3.5rem);
  line-height: 1.14;
  letter-spacing: -0.015em;
  color: var(--mist);
  max-width: 22ch;
}

.page-about .frontis__lede {
  margin: 0 0 0.9rem;
}

.page-about .frontis__more {
  margin: 0;
  max-width: 40ch;
  font-size: 0.95rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .frontis__side {
  position: relative;
  padding: 1.5rem 1.35rem 1.35rem;
  background: linear-gradient(155deg, var(--grad-a), var(--grad-b));
  clip-path: var(--cut-corners);
  border: 1px solid var(--line);
}

.page-about .frontis__side-tag {
  display: block;
  margin: 0 0 1.1rem;
  color: var(--cyan);
}

.page-about .frontis__facts {
  margin: 0;
  display: grid;
  gap: 0.9rem;
}

.page-about .frontis__fact {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 0.7rem;
  border-bottom: 1px solid var(--line-soft);
}

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

.page-about .frontis__fact dt {
  font-size: 0.82rem;
  color: var(--muted);
  letter-spacing: 0.04em;
}

.page-about .frontis__fact dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--signal);
  white-space: nowrap;
}

/* ---------- 分隔 ---------- */
.page-about .divider-slash {
  margin-bottom: clamp(1.5rem, 4vw, 2.5rem);
}

/* ---------- 章节骨架 ---------- */
.page-about .dossier {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.1rem;
  padding-bottom: var(--about-space);
}

.page-about .dossier__rail {
  display: flex;
  align-items: center;
  gap: 0.7rem;
}

.page-about .dossier__num {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--cyan);
  letter-spacing: 0.06em;
}

.page-about .dossier__label {
  font-size: 0.75rem;
  letter-spacing: 0.36em;
  color: var(--muted);
}

.page-about .dossier__title {
  margin: 0 0 1rem;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(1.4rem, 5vw, 2.1rem);
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--mist);
}

.page-about .dossier__after {
  margin: 1.35rem 0 0;
  max-width: 38ch;
  font-size: 0.95rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .dossier__after a,
.page-about .colgrid__foot a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 1px;
}

.page-about .dossier__after a:hover,
.page-about .colgrid__foot a:hover {
  color: var(--signal);
  border-bottom-color: var(--signal);
}

.page-about .dossier__after a:focus-visible,
.page-about .colgrid__foot a:focus-visible,
.page-about .nextgrid__card:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

/* ---------- 01 栏目 ---------- */
.page-about .colgrid {
  margin-top: 1.6rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.85rem;
}

.page-about .colgrid__item {
  background: var(--about-panel);
  border: 1px solid var(--line-soft);
  clip-path: var(--cut-corners);
  transition: border-color 260ms var(--ease), transform 260ms var(--ease);
}

.page-about .colgrid__item:hover {
  border-color: var(--line-strong);
  transform: translateY(-2px);
}

.page-about .colgrid__item[open] {
  border-color: var(--line-strong);
  background: linear-gradient(160deg, var(--grad-a), var(--grad-b));
}

.page-about .colgrid__item summary {
  cursor: pointer;
  padding: 1.05rem 1.15rem;
  font-family: var(--font-head);
  font-weight: 600;
  font-size: 1rem;
  color: var(--mist);
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.7rem;
}

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

.page-about .colgrid__item summary::before {
  content: "+";
  flex: none;
  width: 1.15rem;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  color: var(--signal);
  transition: transform 260ms var(--ease);
}

.page-about .colgrid__item[open] summary::before {
  content: "−";
}

.page-about .colgrid__item .disclosure__body {
  padding: 0 1.15rem 1.15rem 2.9rem;
}

.page-about .colgrid__item .disclosure__body p {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .colgrid__foot {
  margin: 1.5rem 0 0;
  max-width: 40ch;
  font-size: 0.93rem;
  line-height: 1.85;
  color: var(--muted);
}

/* ---------- 02 时间轴 ---------- */
.page-about .version-visual {
  margin: 1.75rem 0 1.5rem;
  border: 1px solid var(--line-soft);
  clip-path: var(--cut-corners);
  overflow: hidden;
  background: linear-gradient(140deg, var(--grad-a), var(--grad-b));
}

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

.page-about .timeline {
  list-style: none;
  margin: 0;
  padding: 0.25rem 0 0;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 14px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan), rgba(47, 211, 224, 0.06));
}

.page-about .timeline__node {
  position: relative;
  padding: 0 0 1.5rem 2.1rem;
}

.page-about .timeline__node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.4rem;
  width: 11px;
  height: 11px;
  background: var(--muted);
  border: 1px solid var(--ink);
  transition: background 240ms var(--ease), box-shadow 240ms var(--ease);
}

.page-about .timeline__node:hover::before,
.page-about .timeline__node:focus-within::before {
  background: var(--signal);
  box-shadow: 0 0 0 4px rgba(255, 201, 60, 0.14);
}

.page-about .timeline__ver {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--cyan);
  margin-bottom: 0.3rem;
  transition: color 240ms var(--ease);
}

.page-about .timeline__node:hover .timeline__ver {
  color: var(--signal);
}

.page-about .timeline__sum {
  margin: 0;
  font-size: 0.97rem;
  line-height: 1.8;
  color: var(--mist);
  max-width: 42ch;
}

.page-about .timeline__more {
  margin: 0.35rem 0 0;
  max-width: 44ch;
  font-size: 0.88rem;
  line-height: 1.8;
  color: var(--muted);
  transition: opacity 280ms var(--ease);
}

/* ---------- 03 团队 ---------- */
.page-about .dossier__main--split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.75rem;
}

.page-about .crew {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  display: grid;
  gap: 1.1rem;
}

.page-about .crew__item {
  padding-left: 0.95rem;
  border-left: 2px solid var(--line);
  transition: border-color 240ms var(--ease);
}

.page-about .crew__item:hover {
  border-left-color: var(--cyan);
}

.page-about .crew__name {
  display: block;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.02rem;
  color: var(--mist);
  margin-bottom: 0.35rem;
}

.page-about .crew__desc {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .crew__note {
  margin: 1.5rem 0 0;
  padding: 0.9rem 1.1rem;
  font-size: 0.9rem;
  line-height: 1.8;
  color: var(--signal);
  background: rgba(255, 201, 60, 0.06);
  border-left: 2px solid var(--signal);
}

.page-about .crew-visual {
  margin: 0;
  border: 1px solid var(--line-soft);
  clip-path: var(--cut-corners);
  overflow: hidden;
  background: var(--graphite);
}

.page-about .crew-visual img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1 / 1;
  object-fit: cover;
}

.page-about .crew-visual figcaption,
.page-about .arch-visual figcaption {
  padding: 0.75rem 1rem;
  font-size: 0.8rem;
  line-height: 1.7;
  color: var(--muted);
  background: var(--ink);
}

/* ---------- 04 协作 ---------- */
.page-about .statgrid {
  margin-top: 1.6rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.85rem;
}

.page-about .statgrid__cell {
  padding: 1.25rem 1.15rem;
  background: var(--graphite);
  border: 1px solid var(--line-soft);
  clip-path: var(--cut-corners);
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  transition: border-color 260ms var(--ease), background 260ms var(--ease);
}

.page-about .statgrid__cell:hover {
  border-color: var(--line-strong);
  background: var(--about-panel);
}

.page-about .statgrid__num {
  font-family: var(--font-mono);
  font-size: clamp(1.9rem, 7vw, 2.6rem);
  font-weight: 700;
  line-height: 1;
  color: var(--signal);
}

.page-about .statgrid__label {
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--muted);
}

/* ---------- 05 归档 ---------- */
.page-about .dossier__main--split-rev .arch-visual {
  order: -1;
}

.page-about .arch-list {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.85rem;
}

.page-about .arch-list li {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.6rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--line-soft);
  font-size: 0.92rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .arch-list__key {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  padding: 0.15rem 0.5rem;
  color: var(--ink);
  background: var(--cyan);
}

.page-about .arch-visual {
  margin: 0;
  border: 1px solid var(--line-soft);
  clip-path: var(--cut-corners);
  overflow: hidden;
  background: var(--graphite);
}

.page-about .arch-visual img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

/* ---------- 下一步 ---------- */
.page-about .next {
  padding-top: clamp(0.5rem, 3vw, 1.5rem);
  padding-bottom: clamp(1.5rem, 5vw, 3rem);
  border-top: 1px solid var(--line-soft);
}

.page-about .next__title {
  margin: 0.6rem 0 1.6rem;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(1.25rem, 4.5vw, 1.85rem);
  line-height: 1.35;
  color: var(--mist);
  max-width: 26ch;
}

.page-about .nextgrid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.85rem;
}

.page-about .nextgrid__card {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding: 1.2rem 1.15rem;
  background: var(--about-panel);
  border: 1px solid var(--line-soft);
  clip-path: var(--cut-corners);
  text-decoration: none;
  transition: transform 240ms var(--ease), border-color 240ms var(--ease),
    background 240ms var(--ease);
}

.page-about .nextgrid__card:hover {
  transform: translateY(-2px);
  border-color: var(--cyan);
  background: linear-gradient(150deg, var(--grad-a), var(--grad-b));
}

.page-about .nextgrid__kicker {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1rem;
  color: var(--signal);
}

.page-about .nextgrid__text {
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .nextgrid__card:hover .nextgrid__text {
  color: var(--mist);
}

/* ---------- 桌面 ---------- */
@media (min-width: 760px) {
  .page-about .frontis {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
  }

  .page-about .dossier {
    grid-template-columns: 72px minmax(0, 1fr);
    column-gap: clamp(1.25rem, 3vw, 2.5rem);
  }

  .page-about .dossier__rail {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
    padding-top: 0.5rem;
  }

  .page-about .dossier__label {
    writing-mode: vertical-rl;
    letter-spacing: 0.5em;
  }

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

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

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

  .page-about .dossier__main--split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
    gap: clamp(1.5rem, 3.5vw, 3rem);
  }

  .page-about .dossier__main--split-rev {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

  .page-about .dossier__main--split-rev .arch-visual {
    order: 0;
  }

  .page-about .version-visual {
    grid-column: 2;
  }

  .page-about .timeline {
    grid-column: 2;
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    column-gap: 1.5rem;
    padding-top: 0.5rem;
  }

  .page-about .timeline::before {
    left: 5px;
    right: 5px;
    top: 5px;
    bottom: auto;
    width: auto;
    height: 1px;
    background: linear-gradient(90deg, var(--cyan), rgba(47, 211, 224, 0.06));
  }

  .page-about .timeline__node {
    padding: 1.6rem 0 1.5rem 0;
  }

  .page-about .timeline__node::before {
    left: 0;
    top: 0;
    width: 11px;
    height: 11px;
  }

  .page-about .timeline__more {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
  }

  .page-about .timeline__node:hover .timeline__more,
  .page-about .timeline__node:focus-within .timeline__more {
    max-height: 7rem;
    opacity: 1;
  }
}

@media (min-width: 1060px) {
  .page-about .nextgrid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .dossier__main--split {
    grid-template-columns: minmax(0, 8fr) minmax(0, 4fr);
  }

  .page-about .dossier__main--split-rev {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .colgrid__item,
  .page-about .statgrid__cell,
  .page-about .nextgrid__card,
  .page-about .timeline__node::before,
  .page-about .timeline__ver,
  .page-about .timeline__more {
    transition: none;
  }

  .page-about .colgrid__item:hover,
  .page-about .nextgrid__card:hover {
    transform: none;
  }

  .page-about .timeline__more {
    max-height: none;
    opacity: 1;
  }
}