.page-about {
  --about-narrow: 640px;
  overflow-x: hidden;
}

.page-about .crumbs {
  padding-top: 20px;
}

.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
}

/* 首屏声明 */
.page-about .about-open {
  position: relative;
  padding: clamp(28px, 6vw, 64px) 0 clamp(34px, 6vw, 68px);
  background:
    radial-gradient(120% 90% at 100% 0%, rgba(0, 102, 255, .24), transparent 58%),
    repeating-linear-gradient(112deg, rgba(180, 255, 58, .055) 0 2px, transparent 2px 28px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-open-grid {
  display: grid;
  gap: 32px;
}

.page-about .about-open-main h1 {
  margin: 12px 0 18px;
  font-size: clamp(32px, 6.2vw, 62px);
  line-height: .98;
  letter-spacing: -.03em;
  font-weight: 800;
  text-wrap: balance;
}

.page-about .about-lead {
  margin: 0 0 26px;
  max-width: 62ch;
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.75;
  color: var(--silver);
}

.page-about .about-stat-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-stat-row li {
  padding: 14px 14px 16px;
  background: var(--ink);
}

.page-about .about-stat-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(20px, 3vw, 28px);
  letter-spacing: .02em;
  color: var(--lime);
}

.page-about .about-stat-label {
  display: block;
  margin-top: 4px;
  font-size: 13px;
  color: var(--muted);
}

.page-about .about-index {
  align-self: start;
  padding: 20px 20px 22px;
  background: rgba(18, 26, 42, .92);
  border: 1px solid var(--line-strong);
  border-left: 3px solid var(--lime);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

.page-about .about-index-list {
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 2px;
  counter-reset: about-idx;
}

.page-about .about-index-list li {
  counter-increment: about-idx;
  border-bottom: 1px solid var(--line);
}

.page-about .about-index-list a {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 10px 2px;
  font-size: 15px;
  color: var(--silver);
  text-decoration: none;
  transition: color .15s var(--ease);
}

.page-about .about-index-list a::before {
  content: "0" counter(about-idx);
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--blue-2);
}

.page-about .about-index-list a:hover {
  color: var(--lime);
}

.page-about .about-index-note {
  margin: 16px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

/* 正文流程：窄栏叙述 + 右侧版本卡片 */
.page-about .about-flow {
  display: grid;
  gap: 44px;
  padding: clamp(40px, 7vw, 76px) 0 clamp(24px, 4vw, 40px);
}

.page-about .about-block h2 {
  margin: 10px 0 16px;
  font-size: clamp(24px, 3.6vw, 36px);
  line-height: 1.1;
  letter-spacing: -.025em;
  font-weight: 800;
}

.page-about .about-block p {
  margin: 0 0 16px;
  max-width: 68ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--silver);
}

/* 研究板注释 */
.page-about .board {
  display: grid;
  gap: 12px;
  margin: 22px 0 0;
  padding-left: 16px;
  border-left: 2px solid var(--blue);
}

.page-about .board-note {
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .board-body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--silver);
}

/* 版本时间轴卡片 */
.page-about .about-tl-card {
  align-self: start;
  padding: 22px 20px 24px;
  background: linear-gradient(180deg, var(--ink-2), var(--ink));
  border: 1px solid var(--line-strong);
  border-top: 3px solid var(--blue);
}

.page-about .about-side-title {
  margin: 10px 0 8px;
  font-size: clamp(22px, 3vw, 28px);
  line-height: 1.12;
  letter-spacing: -.02em;
  font-weight: 800;
}

.page-about .about-side-lead {
  margin: 0 0 20px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .about-timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 24px;
  list-style: none;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 18px;
  width: 2px;
  background: linear-gradient(180deg, rgba(0, 102, 255, .85), var(--cyan) 62%, var(--lime));
}

.page-about .about-timeline > li {
  position: relative;
  padding-bottom: 22px;
}

.page-about .about-timeline > li::before {
  content: "";
  position: absolute;
  left: -24px;
  top: 5px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--blue-2);
}

.page-about .about-timeline > li:last-child::before {
  border-color: var(--lime);
  box-shadow: 0 0 0 4px rgba(180, 255, 58, .15);
}

.page-about .tl-title {
  margin: 8px 0 6px;
  font-size: 17px;
  line-height: 1.35;
  letter-spacing: -.01em;
  font-weight: 700;
}

.page-about .about-timeline p {
  margin: 0 0 8px;
  font-size: 14px;
  line-height: 1.72;
  color: var(--silver);
}

/* 折叠展开通用 */
.page-about details summary {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  list-style: none;
  font-size: 13px;
  font-family: var(--font-mono);
  letter-spacing: .01em;
  color: var(--blue-2);
}

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

.page-about details summary::before {
  content: "+";
  font-family: var(--font-mono);
  color: var(--lime);
  font-size: 14px;
}

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

.page-about details[open] > p {
  margin-top: 10px;
}

/* 团队角色 */
.page-about .role-grid {
  display: grid;
  gap: 12px;
  margin: 22px 0 26px;
}

.page-about .role {
  padding: 14px 16px 16px;
  background: var(--ink-2);
  border: 1px solid var(--line);
  transition: border-color .15s var(--ease), transform .15s var(--ease);
}

.page-about .role:hover {
  transform: translateY(-4px);
  border-color: var(--blue);
}

.page-about .role summary {
  justify-content: space-between;
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 700;
  color: var(--paper);
}

.page-about .role summary::before {
  order: 3;
}

.page-about .role-name {
  flex: 1 1 auto;
}

.page-about .role-count {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--muted);
  padding: 2px 8px;
  border: 1px solid var(--line-strong);
}

.page-about .role[open] {
  border-color: rgba(0, 102, 255, .6);
}

.page-about .role p {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.76;
  color: var(--silver);
}

/* 反馈步骤 */
.page-about .feedback-flow {
  display: grid;
  gap: 10px;
  margin-top: 22px;
}

.page-about .feedback-step {
  padding: 14px 16px;
  background: rgba(18, 26, 42, .72);
  border: 1px solid var(--line);
  border-left: 2px solid var(--line-strong);
  transition: border-color .18s var(--ease);
}

.page-about .feedback-step:hover,
.page-about .feedback-step[open] {
  border-left-color: var(--lime);
}

.page-about .feedback-step summary {
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 700;
  color: var(--paper);
}

.page-about .feedback-num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--lime);
  margin-right: 10px;
}

.page-about .feedback-name {
  flex: 1 1 auto;
}

.page-about .feedback-step p {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.76;
  color: var(--silver);
}

/* 合作生态 */
.page-about .about-network {
  margin-top: clamp(24px, 5vw, 48px);
  padding: clamp(40px, 7vw, 80px) 0;
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(0, 102, 255, .1), transparent 62%);
}

.page-about .network-grid {
  display: grid;
  gap: 30px;
}

.page-about .network-copy h2 {
  margin: 10px 0 16px;
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1.08;
  letter-spacing: -.025em;
  font-weight: 800;
}

.page-about .network-copy p {
  margin: 0 0 18px;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--silver);
}

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

.page-about .network-list li {
  padding: 12px 14px;
  font-size: 15px;
  line-height: 1.7;
  color: var(--silver);
  border: 1px solid var(--line);
  border-left: 3px solid var(--blue);
  background: rgba(11, 14, 20, .55);
}

.page-about .network-list .data-key {
  margin-right: 8px;
}

/* 服务范围（冷白反向分区） */
.page-about .about-service {
  padding: clamp(40px, 7vw, 80px) 0;
}

.page-about .service-grid {
  display: grid;
  gap: 30px;
}

.page-about .service-copy h2 {
  margin: 10px 0 16px;
  font-size: clamp(26px, 4vw, 38px);
  line-height: 1.1;
  letter-spacing: -.025em;
  font-weight: 800;
  color: var(--ink);
}

.page-about .service-copy p {
  margin: 0 0 16px;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--ink-2);
}

.page-about .service-contact {
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  border-top: 2px solid var(--ink);
}

.page-about .service-contact li {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  padding: 12px 2px;
  border-bottom: 1px solid rgba(11, 14, 20, .14);
}

.page-about .service-key {
  flex: 0 0 84px;
  font-size: 13px;
  color: var(--blue);
}

.page-about .service-val {
  flex: 1 1 200px;
  font-size: 15px;
  color: var(--ink);
  word-break: break-word;
}

.page-about .service-visual {
  align-self: start;
}

.page-about .about-svg {
  display: block;
  width: 100%;
  max-width: 560px;
  height: auto;
  overflow: visible;
}

.page-about .about-svg-line {
  stroke: var(--blue);
  stroke-width: 1.5;
  opacity: .45;
}

.page-about .about-svg-node circle {
  fill: #ffffff;
  stroke: var(--blue);
  stroke-width: 1.5;
  transition: fill .25s var(--ease), stroke .25s var(--ease);
}

.page-about .about-svg-node text {
  fill: var(--ink-2);
  font-family: var(--font-mono);
  font-size: 13px;
}

.page-about .about-svg-node:hover circle {
  fill: var(--lime);
  stroke: var(--ink);
}

.page-about .about-svg-node:hover text {
  fill: var(--blue);
}

.page-about .service-cap {
  margin: 14px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

/* 收尾自述 */
.page-about .about-close {
  padding: clamp(40px, 7vw, 80px) 0 clamp(48px, 8vw, 88px);
  border-top: 1px solid var(--line);
}

.page-about .about-close-inner {
  max-width: 760px;
}

.page-about .about-quote {
  margin: 0 0 24px;
  padding: 4px 0 4px 22px;
  border-left: 4px solid var(--lime);
  font-size: clamp(20px, 2.8vw, 30px);
  line-height: 1.45;
  letter-spacing: -.015em;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-close p {
  margin: 0 0 26px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--silver);
}

.page-about .about-close-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* 响应式 */
@media (min-width: 720px) {
  .page-about .about-stat-row {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .board {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 20px;
    align-items: start;
  }

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

@media (min-width: 960px) {
  .page-about .about-open-grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, .85fr);
    gap: 56px;
    align-items: start;
  }

  .page-about .network-grid,
  .page-about .service-grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 48px;
    align-items: start;
  }
}

@media (min-width: 1000px) {
  .page-about .about-flow {
    grid-template-columns: minmax(0, var(--about-narrow)) minmax(0, 1fr);
    column-gap: 56px;
    row-gap: 48px;
  }

  .page-about .about-block {
    grid-column: 1;
  }

  .page-about .about-block--origin {
    grid-row: 1;
  }

  .page-about .about-block--team {
    grid-row: 2;
  }

  .page-about .about-block--feedback {
    grid-row: 3;
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about .role,
  .page-about .feedback-step,
  .page-about .about-svg-node circle {
    transition: none;
  }

  .page-about .role:hover {
    transform: none;
  }
}