.page-about {
  --stage-indent: 32px;
  --rail-x: 9px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  background:
    radial-gradient(120% 140% at 88% 0%, rgba(255, 106, 31, .18) 0%, rgba(255, 106, 31, 0) 54%),
    linear-gradient(160deg, var(--ink) 0%, var(--ink-2) 100%);
  color: var(--paper);
  border-bottom: 3px solid var(--signal);
  padding: clamp(28px, 5vw, 48px) 0 clamp(40px, 7vw, 76px);
}

.page-about .hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(28px, 5vw, 56px);
  align-items: start;
}

.page-about .hero-copy .eyebrow {
  color: var(--signal);
  letter-spacing: .16em;
  margin-bottom: 14px;
}

.page-about .about-hero h1 {
  font-family: var(--font-display);
  font-size: clamp(28px, 5vw, 52px);
  line-height: 1.14;
  letter-spacing: -0.02em;
  font-weight: 800;
  margin: 0 0 20px;
  max-width: 22ch;
}

.page-about .hero-lede {
  font-size: 16px;
  line-height: 1.85;
  color: rgba(247, 242, 232, .82);
  max-width: 46ch;
  margin: 0 0 14px;
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.page-about .hero-side {
  border-top: 1px solid rgba(247, 242, 232, .22);
}

.page-about .side-block {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 2px;
  border-bottom: 1px solid rgba(247, 242, 232, .14);
}

.page-about .side-key {
  font-size: 13px;
  color: rgba(247, 242, 232, .72);
}

.page-about .side-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(20px, 3vw, 26px);
  font-weight: 700;
  color: var(--signal);
}

/* ---------- 章节骨架 ---------- */
.page-about .section-block {
  padding: clamp(44px, 7vw, 84px) 0 clamp(20px, 3vw, 36px);
}

.page-about .section-lede {
  max-width: 42ch;
  color: var(--ink-2);
  line-height: 1.85;
  margin: 18px 0 26px;
}

/* ---------- 时间线导航 ---------- */
.page-about .timeline-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  padding: 16px 0;
  border-top: var(--hair);
  border-bottom: var(--hair);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  margin-bottom: clamp(24px, 4vw, 40px);
}

.page-about .timeline-nav a {
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px dashed var(--line);
  padding-bottom: 2px;
  transition: color 160ms var(--ease), border-color 160ms var(--ease);
}

.page-about .timeline-nav a:hover,
.page-about .timeline-nav a:focus-visible {
  color: var(--signal-deep);
  border-bottom-color: var(--signal);
}

/* ---------- 时间线主体 ---------- */
.page-about .timeline {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 4px 0 4px var(--stage-indent);
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: var(--rail-x);
  top: 0;
  bottom: 0;
  width: 1px;
  background: linear-gradient(180deg, var(--line) 0%, var(--line) 82%, rgba(217, 224, 228, 0) 100%);
}

.page-about .t-stage {
  position: relative;
  margin-bottom: clamp(20px, 3vw, 32px);
}

.page-about .t-stage:last-child {
  margin-bottom: 0;
}

.page-about .t-dot {
  position: absolute;
  left: -28px;
  top: 20px;
  width: 11px;
  height: 11px;
  border: 2px solid var(--signal);
  border-radius: 50%;
  background: var(--paper);
  transition: background 160ms var(--ease);
}

.page-about .t-body {
  background: var(--card);
  border: var(--hair);
  padding: clamp(18px, 3vw, 26px);
  transition: border-color 180ms var(--ease), box-shadow 180ms var(--ease);
}

.page-about .t-body .index-code {
  color: var(--muted);
  display: block;
  margin-bottom: 8px;
}

.page-about .t-title {
  font-family: var(--font-display);
  font-size: clamp(20px, 2.6vw, 27px);
  line-height: 1.28;
  letter-spacing: -0.01em;
  margin: 0 0 12px;
  color: var(--ink);
}

.page-about .t-summary {
  margin: 0;
  line-height: 1.85;
  color: var(--ink-2);
  max-width: 44ch;
}

.page-about .t-details {
  margin-top: 14px;
  border-top: 1px dashed var(--line);
  padding-top: 12px;
}

.page-about .t-details summary {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--signal-deep);
  cursor: pointer;
  list-style: none;
}

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

.page-about .t-details summary::before {
  content: "+ ";
  font-weight: 700;
}

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

.page-about .t-details p {
  margin: 10px 0 0;
  line-height: 1.85;
  color: var(--muted);
  max-width: 46ch;
}

.page-about .t-stage:target .t-body {
  border-color: var(--signal);
  box-shadow: var(--shade);
}

.page-about .t-stage:target .t-dot {
  background: var(--signal);
}

.page-about .timeline-figure {
  margin: clamp(30px, 5vw, 48px) 0 0;
}

/* ---------- 版本区 ---------- */
.page-about .version-section .filter-bar {
  margin-bottom: 20px;
}

.page-about .version-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: var(--hair);
}

.page-about .v-card {
  background: var(--card);
  padding: 20px 18px 22px;
}

.page-about .v-code {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--muted);
  margin: 0 0 10px;
}

.page-about .v-count {
  margin: 0 0 10px;
  font-size: 13px;
  color: var(--ink-2);
}

.page-about .v-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(26px, 3.4vw, 34px);
  font-weight: 700;
  color: var(--signal-deep);
  margin-right: 4px;
}

.page-about .v-note {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--ink-2);
}

.page-about .version-figure {
  margin: clamp(26px, 4vw, 40px) 0 0;
}

/* ---------- 服务网络 ---------- */
.page-about .network-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 4vw, 44px);
  align-items: start;
}

.page-about .network-figure {
  margin: 0;
}

.page-about .network-copy p {
  margin: 0 0 22px;
  line-height: 1.85;
  color: var(--ink-2);
  max-width: 44ch;
}

.page-about .network-list {
  list-style: none;
  margin: 0 0 26px;
  padding: 0;
  border-top: var(--hair);
}

.page-about .network-list li {
  padding: 16px 0;
  border-bottom: var(--hair);
}

.page-about .n-key {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--ink);
  margin-bottom: 6px;
}

.page-about .n-val {
  display: block;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

/* ---------- 三条规矩 ---------- */
.page-about .craft-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border-top: var(--hair);
  border-bottom: var(--hair);
}

.page-about .craft-item {
  background: var(--paper);
  padding: clamp(22px, 3vw, 30px) clamp(18px, 2.4vw, 26px);
}

.page-about .craft-index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--signal);
  margin: 0 0 12px;
}

.page-about .craft-title {
  font-family: var(--font-display);
  font-size: clamp(18px, 2.2vw, 22px);
  line-height: 1.32;
  color: var(--ink);
  margin: 0 0 12px;
}

.page-about .craft-item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-2);
}

/* ---------- 合作与认证 ---------- */
.page-about .partner-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: var(--hair);
}

.page-about .partner-card {
  border: 0;
  padding: clamp(22px, 3vw, 30px);
}

.page-about .partner-title {
  font-family: var(--font-display);
  font-size: clamp(19px, 2.3vw, 24px);
  line-height: 1.3;
  margin: 0 0 12px;
  color: var(--ink);
}

.page-about .partner-card p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-2);
}

.page-about .partner-card--ink .partner-title {
  color: var(--paper);
}

.page-about .partner-card--ink p {
  color: rgba(247, 242, 232, .82);
}

.page-about .partner-cta {
  margin-top: 18px;
}

.page-about .partner-cta a {
  color: var(--signal);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .04em;
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 106, 31, .5);
  padding-bottom: 2px;
}

/* ---------- 数据带 ---------- */
.page-about .data-band {
  background: var(--ink);
  color: var(--paper);
  margin-top: clamp(44px, 7vw, 84px);
  border-top: 3px solid var(--signal);
  border-bottom: 1px solid rgba(247, 242, 232, .14);
}

.page-about .band-inner {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: rgba(247, 242, 232, .14);
  padding: 0;
}

.page-about .band-item {
  background: var(--ink);
  padding: 22px 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-about .band-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(22px, 3.2vw, 30px);
  font-weight: 700;
  color: var(--signal);
  letter-spacing: -0.01em;
}

.page-about .band-label {
  font-size: 13px;
  color: rgba(247, 242, 232, .74);
}

/* ---------- 收尾 ---------- */
.page-about .closing-section {
  padding: clamp(44px, 7vw, 84px) 0 clamp(48px, 7vw, 88px);
}

.page-about .closing-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: var(--hair);
}

.page-about .next-card {
  border: 0;
  text-decoration: none;
  display: block;
  padding: clamp(20px, 2.8vw, 28px);
  transition: background 160ms var(--ease);
}

.page-about .next-card .index-code {
  color: var(--muted);
  display: block;
  margin-bottom: 10px;
}

.page-about .next-card h3 {
  font-family: var(--font-display);
  font-size: clamp(18px, 2.2vw, 22px);
  line-height: 1.32;
  color: var(--ink);
  margin: 0 0 10px;
}

.page-about .next-card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .next-card:hover,
.page-about .next-card:focus-visible {
  background: var(--signal-soft);
}

/* ---------- 图片容器约束 ---------- */
.page-about .media-frame img {
  width: 100%;
  height: auto;
  display: block;
  object-fit: cover;
}

.page-about .timeline-figure {
  max-width: 520px;
}

/* ---------- 平板 ---------- */
@media (min-width: 720px) {
  .page-about .version-grid {
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  }

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

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

  .page-about .partner-card--ink {
    grid-column: 1 / -1;
  }

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

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

/* ---------- 桌面 ---------- */
@media (min-width: 960px) {
  .page-about .hero-grid {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, .8fr);
  }

  .page-about .hero-side {
    padding-top: 6px;
  }

  .page-about .timeline {
    padding-left: 40px;
  }

  .page-about .t-dot {
    left: -36px;
  }

  .page-about .t-stage:nth-child(1) .t-body {
    width: 62%;
  }

  .page-about .t-stage:nth-child(2) .t-body {
    width: 74%;
    margin-left: 4%;
  }

  .page-about .t-stage:nth-child(3) .t-body {
    width: 86%;
    margin-left: 8%;
  }

  .page-about .t-stage:nth-child(4) .t-body {
    width: 100%;
    margin-left: 0;
  }

  .page-about .network-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
  }

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

  .page-about .partner-card--ink {
    grid-column: auto;
  }

  .page-about .partner-cta a {
    border-bottom-color: rgba(255, 106, 31, .8);
  }
}

@media (min-width: 1120px) {
  .page-about .timeline-figure {
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
  }

  .page-about .timeline-nav {
    gap: 0 34px;
  }
}