.page-about {
  --about-gap: clamp(22px, 4vw, 44px);
  --about-rule: rgba(242, 247, 244, 0.14);
  background: var(--bg-deep);
  color: var(--ink);
  font-family: var(--font-body);
  line-height: 1.7;
  overflow-x: hidden;
}

.page-about .page-shell {
  max-width: var(--shell);
  margin-inline: auto;
  padding: 18px var(--page-gutter) 56px;
}

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

/* ---------- 首屏框景 ---------- */
.page-about .mission-hero {
  position: relative;
  display: grid;
  gap: 0;
  margin-top: 20px;
  border: 2px solid var(--line-strong);
  background:
    radial-gradient(120% 90% at 8% 0%, rgba(12, 58, 46, 0.95), rgba(4, 23, 19, 0.98) 62%),
    var(--bg-deep);
  box-shadow: 10px 10px 0 rgba(0, 0, 0, 0.45);
}

.page-about .mission-hero::before,
.page-about .mission-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 10px;
  background-image: repeating-linear-gradient(90deg, var(--line-strong) 0 1px, transparent 1px 26px);
  pointer-events: none;
}

.page-about .mission-hero::before { top: 0; }
.page-about .mission-hero::after { bottom: 0; }

.page-about .mission-hero__frame {
  position: relative;
  padding: clamp(30px, 6vw, 56px) clamp(20px, 5vw, 46px) clamp(26px, 5vw, 44px);
  border-bottom: 2px solid var(--about-rule);
}

.page-about .mission-hero__frame::before {
  content: "";
  position: absolute;
  top: 14px;
  left: 14px;
  width: 30px;
  height: 30px;
  border-top: 2px solid var(--cyan);
  border-left: 2px solid var(--cyan);
}

.page-about .mission-hero h1 {
  margin: 14px 0 18px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(30px, 7.2vw, 56px);
  line-height: 1.12;
  letter-spacing: -0.01em;
  max-width: 15em;
}

.page-about .mission-hero .lede {
  max-width: 34em;
  font-size: 16px;
  color: var(--ink);
  margin: 0 0 14px;
}

.page-about .mission-hero__sub {
  max-width: 36em;
  margin: 0 0 26px;
  font-size: 14px;
  color: var(--muted);
}

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

.page-about .mission-hero__board {
  padding: clamp(22px, 4vw, 34px) clamp(20px, 5vw, 46px) clamp(30px, 5vw, 42px);
  background: linear-gradient(160deg, rgba(11, 15, 14, 0.9), rgba(12, 58, 46, 0.72));
}

.page-about .mission-hero__board-label {
  margin: 0 0 16px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .stat-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .stat-item {
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
  padding: 14px 0;
  border-top: 1px solid var(--about-rule);
  transition: border-color 180ms ease;
}

.page-about .stat-item:last-child { border-bottom: 1px solid var(--about-rule); }

.page-about .stat-item__num {
  font-family: var(--font-mono);
  font-size: 34px;
  font-weight: 700;
  line-height: 1;
  color: var(--ink);
  letter-spacing: -0.02em;
}

.page-about .stat-item__num em {
  font-style: normal;
  color: var(--orange);
  margin-left: 2px;
  font-size: 22px;
}

.page-about .stat-item__label {
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--muted);
}

.page-about .stat-item__hint {
  font-size: 13px;
  color: var(--muted);
  opacity: 0.75;
  transition: opacity 180ms ease, color 180ms ease;
}

.page-about .stat-item:hover { border-top-color: var(--cyan); }
.page-about .stat-item:hover .stat-item__hint { opacity: 1; color: var(--ink); }

/* ---------- 左右分屏 ---------- */
.page-about .about-split {
  display: grid;
  gap: var(--about-gap);
  margin-top: clamp(46px, 8vw, 86px);
}

.page-about .about-split__text h2,
.page-about .about-section h2 {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(24px, 4.6vw, 38px);
  line-height: 1.2;
  margin: 10px 0 16px;
  letter-spacing: -0.01em;
}

.page-about .about-split__text p {
  margin: 0 0 14px;
  max-width: 36em;
  font-size: 15px;
}

.page-about .about-split__media {
  border: 2px solid var(--line-strong);
  background: var(--bg-charcoal);
  box-shadow: 8px 8px 0 rgba(0, 0, 0, 0.4);
}

.page-about .about-split__media .image-frame__media img {
  width: 100%;
  object-fit: cover;
  aspect-ratio: 16 / 9;
}

.page-about .image-frame__media--square img { aspect-ratio: 1 / 1; }

.page-about .image-frame__caption {
  padding: 12px 14px 14px;
  font-size: 12.5px;
  color: var(--muted);
  border-top: 1px solid var(--about-rule);
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.page-about .point-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .point-list li {
  display: grid;
  grid-template-columns: 34px 1fr;
  align-items: start;
  gap: 10px;
  font-size: 14px;
  padding-bottom: 12px;
  border-bottom: 1px dashed var(--about-rule);
}

.page-about .point-list__code {
  font-family: var(--font-mono);
  color: var(--cyan);
  font-size: 12px;
  letter-spacing: 0.1em;
  padding-top: 3px;
}

.page-about .team-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .team-item {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 6px 12px;
  padding: 13px 14px;
  background: linear-gradient(90deg, rgba(12, 58, 46, 0.55), rgba(11, 15, 14, 0.35));
  border-left: 3px solid var(--cyan);
}

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

.page-about .team-item strong {
  font-size: 14.5px;
  letter-spacing: 0.02em;
}

.page-about .team-item span:last-child {
  grid-column: 2;
  font-size: 13.5px;
  color: var(--muted);
}

.page-about .about-note {
  margin-top: 20px !important;
  padding: 14px 16px;
  border-left: 3px solid var(--orange);
  background: rgba(255, 138, 61, 0.07);
  font-size: 13.5px !important;
  color: var(--ink);
}

.page-about .divider {
  margin: clamp(40px, 7vw, 72px) 0 0;
}

/* ---------- 章节通用 ---------- */
.page-about .about-section {
  margin-top: clamp(20px, 4vw, 34px);
}

.page-about .about-section__head {
  border-top: 2px solid var(--line-strong);
  padding-top: clamp(22px, 4vw, 34px);
}

.page-about .about-section__lede {
  max-width: 40em;
  margin: 0 0 clamp(24px, 4vw, 36px);
  font-size: 15px;
  color: var(--muted);
}

/* ---------- 内容体系流转 ---------- */
.page-about .flow {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
  counter-reset: flow;
}

.page-about .flow__item {
  position: relative;
  padding: 24px 20px 22px;
  background: linear-gradient(175deg, rgba(12, 58, 46, 0.62), rgba(11, 15, 14, 0.9));
  border: 2px solid var(--about-rule);
  clip-path: polygon(0 14px, 100% 0, 100% 100%, 0 100%);
}

.page-about .flow__item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 58%;
  height: 3px;
}

.page-about .flow__item--a::before { background: var(--cyan); }
.page-about .flow__item--b::before { background: var(--orange); }
.page-about .flow__item--c::before { background: var(--blue); }

.page-about .flow__code {
  display: block;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--muted);
  margin-bottom: 10px;
}

.page-about .flow__item h3 {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 700;
  margin: 0 0 10px;
  letter-spacing: 0.01em;
}

.page-about .flow__item p {
  margin: 0 0 16px;
  font-size: 13.8px;
  color: var(--muted);
}

.page-about .flow__link {
  display: inline-block;
  font-size: 13px;
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 240, 200, 0.45);
  padding-bottom: 2px;
}

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

/* ---------- 数据编辑流程 ---------- */
.page-about .about-section--process .about-section__head {
  border-top-color: var(--cyan);
}

.page-about .process-grid {
  display: grid;
  gap: var(--about-gap);
}

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

.page-about .process-step {
  position: relative;
  padding: 18px 0 18px 22px;
  border-left: 2px solid var(--about-rule);
}

.page-about .process-step::before {
  content: "";
  position: absolute;
  left: -6px;
  top: 24px;
  width: 10px;
  height: 10px;
  background: var(--bg-deep);
  border: 2px solid var(--cyan);
  border-radius: 50%;
}

.page-about .process-step__code {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .process-step h3 {
  font-family: var(--font-display);
  font-size: 17px;
  margin: 6px 0 8px;
  letter-spacing: 0.02em;
}

.page-about .process-step p {
  margin: 0;
  font-size: 13.8px;
  color: var(--muted);
  max-width: 38em;
}

.page-about .process-figure {
  border: 2px solid var(--line-strong);
  background: var(--bg-panel);
  align-self: start;
}

.page-about .process-figure img {
  width: 100%;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

/* ---------- 里程碑 ---------- */
.page-about .milestone-layout {
  display: grid;
  gap: clamp(22px, 4vw, 40px);
}

.page-about .milestone-nav {
  border: 2px solid var(--about-rule);
  padding: 16px 16px 18px;
  background: rgba(11, 15, 14, 0.75);
}

.page-about .milestone-nav__label {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.page-about .milestone-nav__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .milestone-nav__link {
  display: block;
  padding: 9px 10px;
  font-size: 13px;
  color: var(--muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
  transition: color 160ms ease, border-color 160ms ease, background 160ms ease;
}

.page-about .milestone-nav__link:hover,
.page-about .milestone-nav__link[data-active] {
  color: var(--cyan);
  border-left-color: var(--cyan);
  background: rgba(53, 240, 200, 0.06);
}

.page-about .milestone-track {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .milestone-item {
  position: relative;
  padding: 20px 0 22px 20px;
  border-left: 3px solid var(--about-rule);
  transition: border-color 200ms ease;
}

.page-about .milestone-item::before {
  content: "";
  position: absolute;
  left: -9px;
  top: 26px;
  width: 15px;
  height: 15px;
  background: var(--bg-deep);
  border: 3px solid var(--muted);
  transition: border-color 200ms ease, background 200ms ease;
}

.page-about .milestone-item[data-active] { border-left-color: var(--cyan); }
.page-about .milestone-item[data-active]::before {
  border-color: var(--cyan);
  background: var(--bg-panel);
}

.page-about .milestone-item__tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--bg-deep);
  background: var(--muted);
  padding: 2px 8px;
  margin-bottom: 8px;
}

.page-about .milestone-item[data-active] .milestone-item__tag {
  background: var(--cyan);
  color: var(--bg-charcoal);
}

.page-about .milestone-item h3 {
  font-family: var(--font-display);
  font-size: 18px;
  margin: 0 0 8px;
  letter-spacing: 0.01em;
}

.page-about .milestone-item p {
  margin: 0;
  font-size: 13.8px;
  color: var(--muted);
  max-width: 40em;
}

/* ---------- 合作方式 ---------- */
.page-about .coop-grid {
  display: grid;
  gap: 12px;
}

.page-about .coop-card {
  border: 2px solid var(--about-rule);
  background: linear-gradient(170deg, rgba(12, 58, 46, 0.5), rgba(11, 15, 14, 0.85));
  transition: border-color 180ms ease;
}

.page-about .coop-card[open] { border-color: var(--line-strong); }

.page-about .coop-card__summary {
  display: grid;
  grid-template-columns: 58px 1fr 24px;
  align-items: center;
  gap: 10px;
  padding: 16px 16px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-display);
  font-size: 15.5px;
  letter-spacing: 0.02em;
}

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

.page-about .coop-card__summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--cyan);
  text-align: center;
}

.page-about .coop-card[open] .coop-card__summary::after { content: "−"; }

.page-about .coop-card__code {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.12em;
  color: var(--orange);
}

.page-about .coop-card__body {
  padding: 0 16px 18px;
  border-top: 1px solid var(--about-rule);
  margin-top: 2px;
  padding-top: 14px;
}

.page-about .coop-card__body p {
  margin: 0 0 10px;
  font-size: 13.8px;
  color: var(--muted);
  max-width: 40em;
}

.page-about .coop-card__ask {
  border-left: 2px solid var(--yellow);
  padding-left: 10px;
  color: var(--ink) !important;
  font-size: 13px !important;
}

.page-about .coop-cta {
  margin-top: 22px;
  padding: 20px;
  display: grid;
  gap: 14px;
  border: 2px solid var(--line-strong);
  background: linear-gradient(120deg, rgba(255, 138, 61, 0.14), rgba(11, 15, 14, 0.9) 60%);
}

.page-about .coop-cta__text {
  margin: 0;
  font-size: 14px;
  max-width: 30em;
}

/* ---------- 尾部入口 ---------- */
.page-about .about-tail {
  margin-top: clamp(46px, 8vw, 80px);
  border-top: 2px solid var(--line-strong);
  padding-top: 22px;
}

.page-about .about-tail__label {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.page-about .about-tail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-tail__list a {
  display: block;
  padding: 12px 14px;
  font-size: 14px;
  color: var(--ink);
  text-decoration: none;
  background: rgba(12, 58, 46, 0.34);
  border-left: 3px solid var(--about-rule);
  transition: border-color 160ms ease, background 160ms ease;
}

.page-about .about-tail__list a:hover {
  border-left-color: var(--orange);
  background: rgba(12, 58, 46, 0.62);
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about .stat-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0 26px;
  }
  .page-about .stat-item:nth-child(2) { border-top-color: transparent; }
  .page-about .flow { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .page-about .coop-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .page-about .coop-card__summary { grid-template-columns: 1fr 20px; }
  .page-about .coop-card__code { grid-column: 1 / -1; margin-bottom: 4px; }
  .page-about .about-tail__list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 960px) {
  .page-about .page-shell { padding-top: 24px; padding-bottom: 76px; }

  .page-about .mission-hero {
    grid-template-columns: 7fr 5fr;
    align-items: stretch;
    margin-top: 26px;
  }

  .page-about .mission-hero__frame {
    border-bottom: 0;
    border-right: 2px solid var(--about-rule);
    padding: 64px 52px 56px;
  }

  .page-about .mission-hero__frame::after {
    content: "";
    position: absolute;
    right: 14px;
    bottom: 14px;
    width: 30px;
    height: 30px;
    border-bottom: 2px solid var(--cyan);
    border-right: 2px solid var(--cyan);
  }

  .page-about .mission-hero__board {
    padding: 46px 34px 40px;
    clip-path: polygon(10% 0, 100% 0, 100% 100%, 0 100%);
  }

  .page-about .stat-list { grid-template-columns: 1fr; gap: 2px; }
  .page-about .stat-item:nth-child(2) { border-top-color: var(--about-rule); }

  .page-about .about-split {
    grid-template-columns: 5fr 7fr;
    align-items: start;
    gap: clamp(32px, 5vw, 64px);
  }

  .page-about .about-split--reverse { grid-template-columns: 6fr 6fr; }
  .page-about .about-split--reverse .about-split__media { order: -1; }

  .page-about .process-grid { grid-template-columns: 6fr 6fr; align-items: start; }

  .page-about .milestone-layout { grid-template-columns: 260px 1fr; align-items: start; }

  .page-about .milestone-nav {
    position: sticky;
    top: calc(var(--nav-height) + 18px);
  }

  .page-about .coop-cta {
    grid-template-columns: 1fr auto;
    align-items: center;
    padding: 24px 26px;
  }

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