/* ===== 平台介绍页 · page-about ===== */

.page-about {
  --about-accent-line: rgba(30, 74, 117, .55);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding-top: clamp(104px, 15vw, 168px);
  padding-bottom: clamp(28px, 5vw, 52px);
}

.page-about .crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 22px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--muted);
}

.page-about .crumbs a {
  color: var(--muted);
  text-decoration: none;
  transition: color var(--fast) var(--ease);
}

.page-about .crumbs a:hover,
.page-about .crumbs a:focus-visible {
  color: var(--cyan);
}

.page-about .about-hero__eyebrow {
  margin: 0 0 16px;
  color: var(--cyan);
  letter-spacing: .14em;
}

.page-about .about-hero h1 {
  max-width: 22ch;
  margin: 0 0 22px;
  font-family: var(--font-title);
  font-weight: 900;
  font-size: clamp(1.75rem, 5.2vw, 3.4rem);
  line-height: 1.14;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .about-hero__lede {
  max-width: 66ch;
  margin: 0 0 30px;
  font-family: var(--font-body);
  font-size: clamp(1rem, 1.6vw, 1.0625rem);
  line-height: 1.85;
  color: var(--muted);
}

.page-about .about-scopes {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-scopes li {
  padding: 4px 11px;
  border: 1px solid var(--line);
  background: var(--ink-800);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--muted);
}

/* ---------- 区块通用 ---------- */
.page-about .about-sec {
  padding-block: clamp(40px, 7vw, 84px);
}

.page-about .about-sec__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  padding-bottom: 14px;
  margin-bottom: clamp(22px, 4vw, 38px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-sec__head h2 {
  margin: 0;
  font-family: var(--font-title);
  font-weight: 900;
  font-size: clamp(1.35rem, 3.2vw, 2.1rem);
  line-height: 1.25;
  letter-spacing: -0.01em;
  color: var(--text);
}

.page-about .about-lead {
  max-width: 68ch;
  margin: 0 0 clamp(22px, 4vw, 34px);
  font-size: 1rem;
  line-height: 1.85;
  color: var(--muted);
}

/* ---------- 平台概览 ---------- */
.page-about .about-overview {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 4vw, 44px);
  align-items: start;
}

.page-about .about-overview__text p {
  margin: 0 0 16px;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .about-overview__text p:last-child {
  margin-bottom: 0;
}

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

.page-about .about-stats li {
  padding: 20px 18px;
  background: var(--ink-800);
}

.page-about .about-stats__num {
  display: block;
  margin-bottom: 10px;
  font-size: clamp(1.6rem, 3.6vw, 2.3rem);
  line-height: 1;
  color: var(--amber);
}

.page-about .about-stats__num em,
.page-about .about-fact__num em {
  font-style: normal;
  font-size: .55em;
  margin-left: 2px;
}

.page-about .about-stats__label {
  display: block;
  font-size: .875rem;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 数据来源 ---------- */
.page-about .about-sources {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 4vw, 44px);
  align-items: start;
}

.page-about .about-sources__text p {
  margin: 0;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .about-steps {
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: about-step;
}

.page-about .about-steps li {
  position: relative;
  padding: 16px 0 16px 46px;
  border-bottom: 1px solid var(--about-accent-line);
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .about-steps li:first-child {
  border-top: 1px solid var(--about-accent-line);
}

.page-about .about-steps li::before {
  counter-increment: about-step;
  content: "0" counter(about-step);
  position: absolute;
  left: 0;
  top: 17px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--cyan);
}

.page-about .about-steps strong {
  display: inline-block;
  margin-right: 8px;
  font-weight: 500;
  color: var(--text);
}

.page-about .about-sources__figure {
  margin: 0;
}

/* ---------- 团队与分工 ---------- */
.page-about .team-list {
  margin: 0 0 clamp(26px, 4vw, 40px);
  padding: 0;
  list-style: none;
}

.page-about .team-item {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 8px 14px;
  padding: 18px 0;
  border-bottom: 1px solid var(--about-accent-line);
  outline: none;
  transition: border-color var(--fast) var(--ease);
}

.page-about .team-item:first-child {
  border-top: 1px solid var(--about-accent-line);
}

.page-about .team-item:hover,
.page-about .team-item:focus-visible {
  border-color: var(--cyan);
}

.page-about .team-item__name {
  grid-column: 1;
  font-weight: 500;
  font-size: 1rem;
  color: var(--text);
}

.page-about .team-item__count {
  grid-column: 2;
  text-align: right;
  font-size: 1rem;
  color: var(--amber);
  white-space: nowrap;
}

.page-about .team-item__bar {
  grid-column: 1 / -1;
  display: block;
  height: 6px;
  border: 1px solid var(--line);
  background: var(--ink-850);
}

.page-about .team-item__bar span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--amber), #FFDFA0);
  transition: filter var(--fast) var(--ease);
}

.page-about .team-item:hover .team-item__bar span {
  filter: brightness(1.12);
}

.page-about .team-item__tags {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.page-about .chip {
  padding: 2px 8px;
  border: 1px solid var(--line);
  background: var(--ink-850);
  font-family: var(--font-mono);
  font-size: 11px;
  font-style: normal;
  letter-spacing: .04em;
  color: var(--muted);
}

.page-about .about-team__figure {
  margin: 0;
}

/* ---------- 版本演进 ---------- */
.page-about .about-timeline-figure {
  margin: 0 0 clamp(26px, 4vw, 42px);
}

.page-about .tl-index {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 26px;
}

.page-about .tl-index a {
  padding: 4px 11px;
  border: 1px solid var(--line);
  background: var(--ink-800);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--muted);
  text-decoration: none;
  transition: color var(--fast) var(--ease), border-color var(--fast) var(--ease);
}

.page-about .tl-index a:hover,
.page-about .tl-index a:focus-visible {
  color: var(--cyan);
  border-color: var(--cyan);
}

.page-about .timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 30px;
  list-style: none;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 13px;
  top: 6px;
  bottom: 6px;
  width: 1px;
  background: var(--line);
}

.page-about .tl-node {
  position: relative;
  padding-bottom: 18px;
}

.page-about .tl-node__dot {
  position: absolute;
  left: -21px;
  top: 20px;
  width: 9px;
  height: 9px;
  border: 1px solid var(--line);
  background: var(--ink-900);
  transform: rotate(45deg);
  transition: background var(--base) var(--ease), border-color var(--base) var(--ease);
}

.page-about .tl-node:hover .tl-node__dot,
.page-about .tl-node:focus-within .tl-node__dot {
  border-color: var(--cyan);
  background: var(--cyan);
}

.page-about .tl-node__box {
  border: 1px solid var(--line);
  border-left-width: 2px;
  background: var(--ink-800);
  box-shadow: var(--panel-shadow);
  transition: border-color var(--base) var(--ease);
}

.page-about .tl-node__box:hover,
.page-about .tl-node__box:focus-within {
  border-color: var(--cyan);
}

.page-about .tl-node__box[open] {
  border-left-color: var(--cyan);
}

.page-about .tl-node__box summary {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .tl-node__box summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1;
  color: var(--muted);
  transition: color var(--fast) var(--ease);
}

.page-about .tl-node__box[open] summary::after {
  content: "–";
  color: var(--cyan);
}

.page-about .tl-node__ver {
  flex: none;
  padding: 2px 8px;
  border: 1px solid var(--cyan-deep);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--cyan);
}

.page-about .tl-node__title {
  font-size: 1rem;
  font-weight: 500;
  line-height: 1.5;
  color: var(--text);
}

.page-about .tl-node__body {
  margin: 0;
  padding: 12px 16px 18px;
  border-top: 1px solid var(--about-accent-line);
}

.page-about .tl-node__body p {
  margin: 0;
  font-size: .9375rem;
  line-height: 1.85;
  color: var(--muted);
}

/* ---------- 资质与合作 ---------- */
.page-about .about-trust {
  padding: clamp(24px, 4vw, 42px);
  background: var(--paper);
  border: 1px solid var(--line);
}

.page-about .about-trust__intro {
  max-width: 62ch;
  margin: 0;
  font-size: .9375rem;
  line-height: 1.85;
  color: var(--ink-800);
}

.page-about .about-trust__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(20px, 3vw, 32px);
  margin-top: clamp(24px, 4vw, 36px);
}

.page-about .about-trust__item {
  padding-top: 16px;
  border-top: 2px solid var(--cyan-deep);
}

.page-about .about-trust__num {
  display: block;
  margin-bottom: 10px;
  font-size: clamp(1.5rem, 3vw, 2rem);
  line-height: 1;
  color: var(--ink-900);
}

.page-about .about-trust__num em {
  font-style: normal;
  font-size: .6em;
  margin-left: 2px;
}

.page-about .about-trust__label {
  display: block;
  font-size: .875rem;
  line-height: 1.75;
  color: var(--ink-800);
}

/* ---------- 延伸入口 ---------- */
.page-about .about-links {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  border: 1px solid var(--line);
  background: var(--line);
}

.page-about .about-links a {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 20px 18px;
  background: var(--ink-800);
  color: var(--text);
  text-decoration: none;
  transition: background var(--fast) var(--ease);
}

.page-about .about-links a:hover,
.page-about .about-links a:focus-visible {
  background: var(--ink-850);
}

.page-about .about-links a .idx {
  color: var(--cyan);
}

.page-about .about-links strong {
  font-size: .9375rem;
  font-weight: 500;
  line-height: 1.65;
}

.page-about .about-links__arrow {
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--muted);
  transition: color var(--fast) var(--ease), transform var(--fast) var(--ease);
}

.page-about .about-links a:hover .about-links__arrow,
.page-about .about-links a:focus-visible .about-links__arrow {
  color: var(--cyan);
  transform: translateX(4px);
}

/* ---------- 响应式 ---------- */
@media (min-width: 560px) {
  .page-about .about-stats {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

@media (min-width: 900px) {
  .page-about .about-overview {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

  .page-about .about-sources {
    grid-template-columns: minmax(0, 6fr) minmax(0, 6fr);
  }

  .page-about .about-sources__figure {
    position: sticky;
    top: 110px;
  }

  .page-about .about-trust__grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .page-about .about-links {
    grid-template-columns: repeat(4, 1fr);
  }

  /* 时间线左右交替 */
  .page-about .timeline {
    padding-left: 0;
  }

  .page-about .timeline::before {
    left: 50%;
    top: 0;
    bottom: 0;
  }

  .page-about .tl-node {
    width: calc(50% - 36px);
    padding-bottom: 28px;
  }

  .page-about .tl-node:nth-child(odd) {
    margin-right: auto;
  }

  .page-about .tl-node:nth-child(even) {
    margin-left: auto;
  }

  .page-about .tl-node:nth-child(odd) .tl-node__dot {
    left: auto;
    right: -40px;
  }

  .page-about .tl-node:nth-child(even) .tl-node__dot {
    left: -40px;
  }

  /* 团队职责关键词浮层 */
  .page-about .team-item__tags {
    position: absolute;
    right: 0;
    top: 50%;
    z-index: 3;
    flex-wrap: nowrap;
    padding: 6px 10px;
    border: 1px solid var(--line);
    background: var(--ink-850);
    opacity: 0;
    pointer-events: none;
    transform: translateY(-50%) translateX(8px);
    transition: opacity var(--fast) var(--ease), transform var(--fast) var(--ease), border-color var(--fast) var(--ease);
  }

  .page-about .team-item:hover .team-item__tags,
  .page-about .team-item:focus-within .team-item__tags,
  .page-about .team-item:focus-visible .team-item__tags {
    opacity: 1;
    transform: translateY(-50%) translateX(0);
    border-color: var(--cyan);
  }
}

@media (min-width: 1100px) {
  .page-about .about-hero h1 {
    max-width: 24ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .tl-node__dot,
  .page-about .about-links__arrow,
  .page-about .team-item__tags,
  .page-about .team-item__bar span {
    transition: none;
  }
}