.page-about {
  background: var(--paper);
  color: var(--text-ink);
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-family: var(--font-sans);
  letter-spacing: -0.02em;
}

/* ---------- 首屏框景 ---------- */
.page-about .ab-hero {
  padding: 18px 0 4px;
}

.page-about .ab-hero__inner {
  display: grid;
  gap: 22px;
  padding: 24px 16px 20px;
}

.page-about .ab-hero__kicker {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--slate);
}

.page-about h1 {
  margin: 0 0 14px;
  font-size: 30px;
  line-height: 1.22;
  font-weight: 800;
  color: var(--ink);
}

.page-about .ab-hero__lead {
  margin: 0 0 20px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--text-soft);
}

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

.page-about .ab-hero__facts li {
  background: var(--paper-2);
  padding: 12px 14px;
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.page-about .ab-fact__num {
  flex: none;
  min-width: 74px;
  font-family: var(--font-mono);
  font-size: 17px;
  font-weight: 700;
  color: var(--night);
}

.page-about .ab-fact__label {
  font-size: 14px;
  color: var(--text-soft);
}

.page-about .ab-hero__media {
  margin: 0;
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .ab-hero__media img,
.page-about .ab-figure img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}

/* ---------- 主体：左索引 + 右内容流 ---------- */
.page-about .ab-body {
  display: grid;
  gap: 28px;
  padding: 34px 0 8px;
}

.page-about .ab-index {
  border-left: 2px solid var(--flag-yellow);
  padding-left: 14px;
}

.page-about .ab-index__title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--slate);
}

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

.page-about .ab-index__list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 10px 8px;
  font-size: 14px;
  color: var(--night);
  text-decoration: none;
  border-bottom: 1px dashed var(--line);
  transition: background 0.18s ease, color 0.18s ease;
}

.page-about .ab-index__list a:hover,
.page-about .ab-index__list a:focus-visible {
  background: rgba(111, 211, 232, 0.18);
  color: var(--ink);
}

.page-about .ab-index__num {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  color: var(--flag-blue);
}

.page-about .ab-flow {
  min-width: 0;
}

.page-about .ab-block {
  padding: 26px 0 34px;
  border-top: 1px solid var(--line);
}

.page-about .ab-block:first-child {
  padding-top: 0;
  border-top: 0;
}

.page-about .ab-block + .ab-block {
  margin-top: 4px;
}

/* ---------- 双卡对照 ---------- */
.page-about .ab-duo {
  display: grid;
  gap: 12px;
  margin-top: 22px;
}

.page-about .ab-card {
  position: relative;
  padding: 18px 18px 20px;
  border-radius: var(--radius);
  background: var(--night);
  color: var(--flag-white);
  overflow: hidden;
}

.page-about .ab-card::after {
  content: "";
  position: absolute;
  right: -30px;
  top: -30px;
  width: 90px;
  height: 90px;
  border-radius: 50%;
  background: rgba(111, 211, 232, 0.16);
}

.page-about .ab-card--paper {
  background: var(--paper-2);
  color: var(--text-ink);
  border: 1px solid var(--line);
}

.page-about .ab-card--paper::after {
  background: rgba(46, 111, 191, 0.10);
}

.page-about .ab-card__idx {
  position: relative;
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--flag-yellow);
}

.page-about .ab-card--paper .ab-card__idx {
  color: var(--flag-blue);
}

.page-about .ab-card__title {
  position: relative;
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 700;
  line-height: 1.4;
}

.page-about .ab-card__text {
  position: relative;
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: inherit;
  opacity: 0.86;
}

/* ---------- 数据规模 ---------- */
.page-about .ab-stats {
  display: grid;
  gap: 1px;
  margin-top: 22px;
  background: var(--line-strong);
  border: 1px solid var(--line-strong);
}

.page-about .ab-stat {
  background: var(--paper-2);
  padding: 16px 15px 18px;
}

.page-about .ab-stat__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 30px;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .ab-stat__num span {
  margin-left: 2px;
  font-size: 14px;
  font-weight: 600;
  color: var(--flag-blue);
}

.page-about .ab-stat__label {
  margin: 6px 0 0;
  font-size: 13px;
  line-height: 1.6;
  color: var(--text-soft);
}

/* ---------- 图文错位 ---------- */
.page-about .ab-figure {
  margin: 26px 0 0;
}

.page-about .ab-figure .media-frame {
  border-radius: var(--radius);
  overflow: hidden;
}

/* ---------- 时间轴 ---------- */
.page-about .ab-timeline {
  position: relative;
  margin-top: 22px;
  padding-left: 30px;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--flag-blue), var(--glacier), var(--flag-green));
}

.page-about .ab-node {
  position: relative;
  padding-bottom: 14px;
}

.page-about .ab-node__dot {
  position: absolute;
  left: -30px;
  top: 12px;
  width: 20px;
  height: 20px;
  box-sizing: border-box;
  border-radius: 50%;
  border: 3px solid var(--flag-blue);
  background: var(--paper-2);
}

.page-about .ab-node:last-child .ab-node__dot {
  border-color: var(--flag-yellow);
}

.page-about .ab-node__when {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--slate);
}

.page-about .ab-node__heading {
  margin: 0;
  font-size: 17px;
}

.page-about .ab-node__trigger {
  display: flex;
  width: 100%;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 8px 0 12px;
  background: transparent;
  border: 0;
  border-bottom: 1px solid var(--line);
  cursor: pointer;
  text-align: left;
  font-family: var(--font-sans);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.45;
  color: var(--ink);
  transition: color 0.18s ease;
}

.page-about .ab-node__trigger:hover,
.page-about .ab-node__trigger:focus-visible {
  color: var(--night);
}

.page-about .ab-node__sign {
  position: relative;
  flex: none;
  width: 22px;
  height: 22px;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
}

.page-about .ab-node__sign::before,
.page-about .ab-node__sign::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--flag-blue);
  transform: translate(-50%, -50%);
}

.page-about .ab-node__sign::before {
  width: 10px;
  height: 1.5px;
}

.page-about .ab-node__sign::after {
  width: 1.5px;
  height: 10px;
  transition: transform 0.2s ease;
}

.page-about .ab-node__trigger[aria-expanded="true"] .ab-node__sign::after {
  transform: translate(-50%, -50%) scaleY(0);
}

.page-about .ab-node__panel {
  padding: 10px 0 4px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-soft);
}

.page-about .ab-node__panel p {
  margin: 0;
}

.page-about .ab-tail {
  margin: 18px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-soft);
}

.page-about .ab-tail a {
  color: var(--night);
  text-decoration: underline;
  text-decoration-color: var(--glacier);
  text-underline-offset: 3px;
}

.page-about .ab-tail a:hover,
.page-about .ab-tail a:focus-visible {
  color: var(--flag-blue);
}

/* ---------- 收尾 ---------- */
.page-about .ab-cta {
  padding: 12px 0 56px;
}

.page-about .ab-cta__box {
  position: relative;
  padding: 26px 20px 28px;
  border-radius: var(--radius);
  background: linear-gradient(150deg, var(--ink) 0%, var(--night) 62%, #1B4E7A 100%);
  color: var(--flag-white);
  overflow: hidden;
}

.page-about .ab-cta__box::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--flag-blue), var(--flag-white), var(--flag-red), var(--flag-green), var(--flag-yellow));
}

.page-about .ab-cta__idx {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--glacier);
}

.page-about .ab-cta__title {
  margin: 0 0 12px;
  font-size: 24px;
  font-weight: 800;
  line-height: 1.25;
  color: var(--flag-white);
}

.page-about .ab-cta__text {
  margin: 0 0 20px;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(255, 255, 255, 0.82);
}

.page-about .ab-cta__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about h1 {
    font-size: 36px;
  }

  .page-about .ab-hero__inner {
    padding: 30px 24px 26px;
  }

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

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

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

  .page-about .ab-cta__box {
    padding: 34px 32px 36px;
  }
}

@media (min-width: 900px) {
  .page-about h1 {
    font-size: 44px;
  }

  .page-about .ab-hero__inner {
    grid-template-columns: 1.05fr 0.95fr;
    align-items: center;
    gap: 34px;
    padding: 34px 30px 30px;
  }

  .page-about .ab-body {
    grid-template-columns: 218px minmax(0, 1fr);
    gap: 52px;
    padding-top: 46px;
  }

  .page-about .ab-index {
    position: sticky;
    top: 96px;
  }

  .page-about .ab-block {
    padding: 34px 0 46px;
  }

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

  .page-about .ab-figure--right {
    width: 76%;
    margin-left: auto;
  }

  .page-about .ab-figure--left {
    width: 72%;
    margin-right: auto;
  }
}

@media (min-width: 1180px) {
  .page-about .ab-hero__inner {
    padding: 40px 36px 34px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-index__list a,
  .page-about .ab-node__trigger,
  .page-about .ab-node__sign::after {
    transition: none;
  }
}