.page-about {
  font-family: var(--font-body);
  color: var(--color-ink);
  background: var(--color-paper);
  line-height: 1.75;
}

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

/* 面包屑 */
.page-about .breadcrumb {
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 18px 24px 4px;
}

.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.05em;
  color: var(--color-muted);
}

.page-about .breadcrumb a {
  color: var(--color-link);
  text-decoration: none;
}

.page-about .breadcrumb a:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* 对开薄册：框景首屏 */
.page-about .story-spread {
  padding: 12px 24px 44px;
}

.page-about .story-spread__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 32px 26px;
  border: 2px solid var(--color-frame);
  background: var(--color-paper);
  box-shadow: 8px 8px 0 rgba(23, 42, 58, 0.08);
  position: relative;
}

.page-about .story-spread__grid::before {
  content: "";
  position: absolute;
  top: 7px;
  right: 7px;
  bottom: 7px;
  left: 7px;
  border: 1px solid var(--color-border);
  pointer-events: none;
  z-index: 0;
}

.page-about .story-spread__grid > * {
  position: relative;
  z-index: 1;
}

.page-about .story-spread__spine {
  width: calc(100% - 24px);
  height: 2px;
  margin: 0 auto;
  background: linear-gradient(90deg, transparent, var(--color-border) 15%, var(--color-border) 85%, transparent);
}

/* 左叶：版本号 */
.page-about .spread-leaf__eyebrow {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin: 0 0 14px;
}

.page-about .spread-leaf__version {
  display: inline-block;
  background: linear-gradient(135deg, var(--color-amber) 0%, #F0752C 60%, #E8432C 100%);
  color: var(--color-frame);
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 6vw, 4.8rem);
  font-weight: 300;
  line-height: 1.1;
  letter-spacing: -0.02em;
  padding: 6px 18px 12px;
  margin: 0 0 24px;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 12px), calc(100% - 12px) 100%, 0 100%);
}

.page-about .spread-leaf__meta {
  list-style: none;
  margin: 0;
  padding: 0;
  border-left: 2px solid var(--color-border);
  padding-left: 18px;
}

.page-about .spread-leaf__meta li {
  position: relative;
  font-size: 13px;
  color: var(--color-muted);
  margin: 7px 0;
}

.page-about .spread-leaf__meta li::before {
  content: "";
  position: absolute;
  left: -21px;
  top: 50%;
  width: 7px;
  height: 7px;
  transform: translateY(-50%);
  background: var(--color-amber);
  border-radius: 1px;
}

.page-about .spread-leaf__barcode {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  color: var(--color-muted);
  margin: 30px 0 0;
  padding-top: 14px;
  border-top: 1px dashed var(--color-border);
}

/* 右叶：叙事 */
.page-about .spread-leaf__eyebrow--right {
  margin-bottom: 6px;
}

.page-about .story-spread__leaf--right h1 {
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.5rem);
  font-weight: 300;
  letter-spacing: -0.02em;
  line-height: 1.28;
  color: var(--color-frame);
  margin: 0 0 18px;
}

.page-about .spread-deck {
  font-size: 16px;
  font-weight: 700;
  line-height: 1.6;
  color: var(--color-frame);
  border-left: 4px solid var(--color-amber);
  background: var(--color-paper-layered);
  padding: 12px 16px;
  margin: 0 0 16px;
}

.page-about .spread-body {
  font-size: 15px;
  color: var(--color-ink);
  margin: 0 0 18px;
}

.page-about .story-figure {
  margin: 18px 0 0;
  border: 1px solid var(--color-border);
  background: var(--color-paper-layered);
  box-shadow: 6px 6px 0 rgba(23, 42, 58, 0.08);
}

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

.page-about .story-figure figcaption {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--color-muted);
  padding: 9px 12px;
  border-top: 1px solid var(--color-border);
}

/* 页面内目录 */
.page-about .story-toc {
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  background: var(--color-paper-layered);
}

.page-about .story-toc ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 28px;
  list-style: none;
  margin: 0;
  padding: 14px 0;
}

.page-about .story-toc a {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  font-size: 14px;
  font-weight: 700;
  color: var(--color-ink);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  padding-bottom: 2px;
  transition: color var(--transition), border-color var(--transition);
}

.page-about .story-toc a:hover,
.page-about .story-toc a[data-active="true"] {
  color: var(--color-link);
  border-bottom-color: var(--color-cyan);
}

.page-about .story-toc a span {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  color: var(--color-purple);
}

/* 章节标题 */
.page-about .section-head {
  display: flex;
  align-items: flex-end;
  gap: 16px;
  border-bottom: 2px solid var(--color-frame);
  margin-bottom: 28px;
  padding-bottom: 14px;
  position: relative;
}

.page-about .section-head::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 88px;
  height: 2px;
  background: linear-gradient(90deg, var(--color-amber) 0%, #E8432C 100%);
}

.page-about .section-head__num {
  font-family: var(--font-mono);
  font-size: clamp(2.6rem, 5vw, 3.8rem);
  font-weight: 100;
  line-height: 1;
  color: rgba(23, 42, 58, 0.22);
  flex-shrink: 0;
}

.page-about .section-head__copy {
  flex: 1;
}

.page-about .section-head__copy h2 {
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 2.4vw, 1.95rem);
  font-weight: 300;
  letter-spacing: -0.01em;
  color: var(--color-frame);
  margin: 2px 0 0;
}

.page-about .section-kicker {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin: 0;
}

/* 01 哈尔滨记事卡 */
.page-about .note-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
}

.page-about .note-card {
  position: relative;
  background: var(--color-paper);
  border: 1px solid var(--color-border);
  padding: 28px 26px;
  box-shadow: var(--shadow-card);
}

.page-about .note-card--main {
  isolation: isolate;
}

.page-about .note-card--main::before {
  content: "";
  position: absolute;
  right: 8px;
  bottom: -8px;
  width: calc(100% - 16px);
  height: 100%;
  background: var(--color-paper-layered);
  border: 1px solid var(--color-border);
  z-index: -1;
  transform: translate(6px, 6px);
}

.page-about .note-card--main p {
  font-size: 15px;
  margin: 0 0 14px;
}

.page-about .note-card--aside {
  background: var(--color-frame);
  border-color: var(--color-frame);
  color: #FFFFFF;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
}

.page-about .note-card__title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-neon);
  margin: 0 0 18px;
}

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

.page-about .note-list dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #8899A6;
  margin-top: 16px;
}

.page-about .note-list dd {
  margin: 2px 0 0;
  font-size: 15px;
  font-weight: 700;
  color: #FFFFFF;
}

/* 02 版本演进 */
.page-about .ruler {
  height: 12px;
  margin: 24px 0 8px;
  border-top: 1px solid var(--color-border);
  background-image: repeating-linear-gradient(
    90deg,
    var(--color-border) 0 1px,
    transparent 1px 12px
  );
}

.page-about .version-item {
  display: grid;
  grid-template-columns: 34px 1fr;
  column-gap: 14px;
  padding: 10px 0 18px;
  border-bottom: 1px dashed var(--color-border);
}

.page-about .version-item__label {
  grid-column: 2;
  grid-row: 1;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-purple);
  margin: 0 0 4px;
}

.page-about .version-item__rail {
  grid-column: 1;
  grid-row: 1 / span 3;
  position: relative;
  display: flex;
  justify-content: center;
}

.page-about .version-item__rail::before {
  content: "";
  position: absolute;
  top: 12px;
  bottom: -18px;
  left: 50%;
  width: 2px;
  transform: translateX(-50%);
  background: var(--color-border);
}

.page-about .version-item:last-child .version-item__rail::before {
  bottom: auto;
  height: calc(100% - 12px);
}

.page-about .version-item__mark {
  position: relative;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  border: 2px solid var(--color-cyan);
  background: var(--color-paper);
  z-index: 1;
  transition: background var(--transition), box-shadow var(--transition);
}

.page-about .version-item__content {
  grid-column: 2;
  grid-row: 2 / span 3;
}

.page-about .version-item__content h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 400;
  color: var(--color-frame);
  margin: 0 0 6px;
  transition: color var(--transition);
}

.page-about .version-item__content p {
  font-size: 15px;
  margin: 0 0 8px;
}

.page-about .version-item:hover .version-item__mark,
.page-about .version-item:focus-within .version-item__mark {
  background: var(--color-cyan);
  box-shadow: 0 0 0 4px rgba(0, 184, 176, 0.22);
}

.page-about .version-item:hover .version-item__content h3,
.page-about .version-item:focus-within .version-item__content h3 {
  color: var(--color-link);
}

.page-about .version-item:focus-visible {
  outline: 2px solid var(--color-cyan);
  outline-offset: 4px;
}

.page-about .version-item--current .version-item__mark {
  background: var(--color-cyan);
}

.page-about .version-item--current .version-item__label {
  color: var(--color-cyan-text);
  font-weight: 700;
}

.page-about .version-item summary {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-link);
  cursor: pointer;
  margin-top: 6px;
  list-style: none;
}

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

.page-about .version-item summary::before {
  content: "+";
  display: inline-block;
  width: 16px;
  height: 16px;
  line-height: 14px;
  text-align: center;
  border: 1px solid var(--color-cyan);
  border-radius: 50%;
  font-size: 11px;
  color: var(--color-cyan);
  transition: background var(--transition), color var(--transition);
}

.page-about .version-item details[open] summary::before {
  content: "−";
  background: var(--color-cyan);
  color: #FFFFFF;
}

.page-about .version-item details ul {
  margin: 8px 0 4px;
  padding-left: 20px;
}

.page-about .version-item details li {
  font-size: 14px;
  margin-bottom: 4px;
}

.page-about .version-figure {
  margin: 28px 0 0;
  border: 1px solid var(--color-border);
  background: var(--color-paper);
  box-shadow: var(--shadow-paper);
}

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

.page-about .version-figure figcaption {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--color-muted);
  padding: 9px 12px;
  border-top: 1px solid var(--color-border);
}

/* 03 团队组织 */
.page-about .team-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.page-about .team-copy p {
  font-size: 15px;
  margin: 0 0 14px;
}

.page-about .team-roles {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  border-top: 1px solid var(--color-border);
}

.page-about .team-roles li {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 12px 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 15px;
}

.page-about .team-roles__num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-purple);
}

.page-about .team-figure {
  margin: 0;
  border: 1px solid var(--color-border);
  background: var(--color-frame);
  box-shadow: 8px 8px 0 rgba(23, 42, 58, 0.08);
}

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

.page-about .team-figure figcaption {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: #FFFFFF;
  padding: 9px 12px;
  border-top: 1px solid rgba(185, 192, 200, 0.35);
}

/* 04 数据规模 */
.page-about .data-panel--about {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: var(--color-border);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-card);
}

.page-about .data-panel--about .data-cell {
  background: var(--color-paper);
  padding: 22px 16px;
  border: 0;
}

.page-about .data-panel--about .data-cell:first-child {
  background: linear-gradient(135deg, var(--color-amber) 0%, #F0752C 100%);
}

.page-about .data-panel--about .data-cell:first-child .data-cell__label,
.page-about .data-panel--about .data-cell:first-child .data-cell__value {
  color: var(--color-frame);
}

.page-about .data-cell__label {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--color-muted);
  margin-bottom: 8px;
}

.page-about .data-cell__value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.3rem, 2.4vw, 1.9rem);
  font-weight: 700;
  line-height: 1.1;
  color: var(--color-frame);
}

.page-about .data-cell__value--cyan {
  color: var(--color-cyan-text);
}

.page-about .data-cell__value--purple {
  color: var(--color-purple-text);
}

.page-about .data-note {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--color-muted);
  border-top: 1px dashed var(--color-border);
  padding-top: 12px;
  margin: 22px 0 26px;
}

.page-about .data-closing {
  font-size: 16px;
  margin: 0;
}

/* 05 合规与安全 */
.page-about .compliance-section {
  margin-top: 48px;
}

.page-about .section-head--dark {
  border-bottom-color: rgba(185, 192, 200, 0.35);
}

.page-about .section-head--dark .section-head__num {
  color: rgba(255, 255, 255, 0.16);
}

.page-about .section-head--dark .section-head__copy h2 {
  color: #FFFFFF;
}

.page-about .section-head--dark .section-kicker {
  color: #8899A6;
}

.page-about .compliance-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 36px;
}

.page-about .compliance-block h3 {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 400;
  color: var(--color-neon);
  margin: 0 0 12px;
}

.page-about .compliance-block p {
  font-size: 15px;
  color: #D3DAE0;
  margin: 0 0 14px;
}

.page-about .compliance-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

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

.page-about .compliance-list dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #8899A6;
  margin-top: 16px;
}

.page-about .compliance-list dd {
  margin: 2px 0 0;
  font-size: 15px;
  font-weight: 700;
  color: #FFFFFF;
}

.page-about .compliance-note {
  font-size: 13px;
  color: #8899A6;
  border-top: 1px solid rgba(185, 192, 200, 0.35);
  padding-top: 14px;
  margin-top: 18px;
}

.page-about .compliance-section .text-link {
  color: var(--color-neon);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .compliance-section .text-link:hover {
  color: #FFFFFF;
}

/* 桌面断点：对开薄册与多列栅格 */
@media (min-width: 840px) {
  .page-about .story-spread__grid {
    grid-template-columns: 1fr 1fr;
    column-gap: 64px;
    gap: 0;
  }

  .page-about .story-spread__spine {
    display: none;
  }

  .page-about .story-spread__grid::after {
    content: "";
    position: absolute;
    top: 36px;
    bottom: 36px;
    left: 50%;
    width: 2px;
    transform: translateX(-1px);
    background: var(--color-border);
    z-index: 0;
  }

  .page-about .note-grid {
    grid-template-columns: 1.35fr 0.65fr;
    gap: 26px;
  }

  .page-about .version-item {
    grid-template-columns: 150px 44px 1fr;
    column-gap: 0;
  }

  .page-about .version-item__label {
    grid-column: 1;
    grid-row: 1;
    text-align: right;
    padding-top: 5px;
    padding-right: 16px;
    margin: 0;
  }

  .page-about .version-item__rail {
    grid-column: 2;
    grid-row: 1 / span 3;
  }

  .page-about .version-item__content {
    grid-column: 3;
    grid-row: 1 / span 3;
    padding-left: 8px;
  }

  .page-about .team-grid {
    grid-template-columns: 1.05fr 0.95fr;
    gap: 36px;
    align-items: start;
  }

  .page-about .data-panel--about {
    grid-template-columns: repeat(3, 1fr);
  }

  .page-about .compliance-grid {
    grid-template-columns: 0.9fr 1.1fr;
    gap: 56px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition: none !important;
  }
}