.page-about {
  --about-scale-w: 200px;
  --about-radius: 2px;
}

.page-about .container {
  position: relative;
}

.page-about .about-top-anchor {
  display: block;
  height: 1px;
  scroll-margin-top: 96px;
}

/* ============ 首屏 ============ */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: 40px 0 32px;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -60px;
  right: -12%;
  width: 52%;
  height: 340px;
  background: radial-gradient(closest-side, rgba(53, 230, 210, 0.16), rgba(53, 230, 210, 0) 72%);
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero .container {
  z-index: 1;
}

.page-about .breadcrumb {
  margin-bottom: 30px;
}

.page-about .breadcrumb a {
  color: var(--slate-mute);
  text-decoration: none;
  transition: color 0.2s var(--ease);
}

.page-about .breadcrumb a:hover {
  color: var(--signal-cyan);
}

.page-about .about-hero-grid {
  row-gap: 40px;
}

.page-about .about-h1 {
  font-size: clamp(36px, 8vw, 76px);
  line-height: 1.03;
  letter-spacing: -0.03em;
  font-weight: 800;
  margin: 18px 0 0;
  max-width: 13em;
  color: var(--paper-white);
}

.page-about .about-h1 em {
  font-style: normal;
  color: var(--signal-cyan);
}

.page-about .about-lede {
  margin: 26px 0 0;
  max-width: 30em;
  color: var(--paper-white);
  opacity: 0.88;
}

.page-about .about-snapshot {
  padding: 24px 22px;
  align-self: start;
}

.page-about .about-snapshot-list {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-snapshot-list li {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--hairline);
}

.page-about .about-snapshot-list li:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.page-about .about-snapshot-list .stat-figure {
  min-width: 86px;
  font-size: 26px;
  color: var(--pulse-orange);
  letter-spacing: -0.01em;
}

.page-about .about-snapshot-list .stat-label {
  font-size: 13px;
  color: var(--slate-mute);
}

/* ============ 主体两栏 ============ */
.page-about .about-body {
  display: grid;
  gap: 36px;
  padding-top: 24px;
  padding-bottom: 40px;
}

/* 左侧刻度尺 */
.page-about .about-scale {
  display: none;
}

.page-about .about-chapters {
  min-width: 0;
  display: grid;
  gap: 0;
}

/* ============ 章节 ============ */
.page-about .about-chapter {
  min-width: 0;
  padding: 0 0 64px;
  scroll-margin-top: 96px;
}

.page-about .about-chapter + .about-chapter {
  border-top: 1px solid var(--hairline);
  padding-top: 48px;
}

.page-about .about-chapter:last-child {
  padding-bottom: 16px;
}

.page-about .about-chapter-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(24px, 3.6vw, 40px);
  line-height: 1.18;
  letter-spacing: -0.018em;
  color: var(--paper-white);
  margin: 20px 0 24px;
  max-width: 17em;
}

.page-about .about-claim {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(28px, 5.6vw, 58px);
  line-height: 1.08;
  letter-spacing: -0.025em;
  color: var(--paper-white);
  margin: 22px 0 30px;
  max-width: 12em;
}

.page-about .about-claim strong {
  font-weight: 800;
  color: var(--signal-cyan);
}

.page-about .about-prose {
  max-width: 36em;
  font-size: 16px;
  line-height: 1.85;
  color: var(--slate-mute);
}

.page-about .about-prose p {
  margin: 0 0 18px;
}

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

.page-about .about-prose--after {
  margin-top: 28px;
}

/* ============ 图片 ============ */
.page-about .about-figure {
  margin: 32px 0 0;
  border: 1px solid var(--hairline);
  background: var(--deep-indigo);
  overflow: hidden;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about .about-figure--square img {
  aspect-ratio: 4 / 3;
}

/* ============ 数据条 ============ */
.page-about .about-facts {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1px;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}

.page-about .about-facts li {
  background: var(--deep-indigo);
  padding: 20px 18px;
}

.page-about .about-facts .stat-figure {
  display: block;
  font-size: 30px;
  line-height: 1.1;
  color: var(--paper-white);
  letter-spacing: -0.01em;
}

.page-about .about-facts li:nth-child(2) .stat-figure {
  color: var(--signal-cyan);
}

.page-about .about-facts .stat-label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  color: var(--slate-mute);
}

/* ============ 六个大类 ============ */
.page-about .about-cats {
  list-style: none;
  margin: 32px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 12px;
  counter-reset: about-cat;
}

.page-about .about-cats li {
  position: relative;
  counter-increment: about-cat;
  background: var(--deep-indigo);
  border: 2px solid var(--hairline);
  padding: 16px 16px 18px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: 0.01em;
  color: var(--paper-white);
  transition: border-color 0.25s var(--ease), transform 0.25s var(--ease);
}

.page-about .about-cats li::before {
  content: "0" counter(about-cat);
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 400;
  letter-spacing: 0.14em;
  color: var(--signal-cyan);
}

.page-about .about-cats li::after {
  content: "";
  position: absolute;
  inset: -2px;
  border: 2px solid transparent;
  transition: border-color 0.25s var(--ease);
  pointer-events: none;
}

.page-about .about-cats li:hover {
  transform: translateY(-2px);
}

.page-about .about-cats li:hover::after {
  border-color: var(--signal-cyan);
}

.page-about .about-cats li:nth-child(5)::before,
.page-about .about-cats li:nth-child(6)::before {
  color: var(--neon-violet);
}

/* ============ 内联链接 ============ */
.page-about .about-inline-link {
  margin: 28px 0 0;
}

/* ============ 里程碑 ============ */
.page-about .about-milestone-figure {
  margin: 32px 0 0;
  border: 1px solid var(--hairline);
  background: var(--deep-indigo);
  overflow: hidden;
}

.page-about .about-milestone-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  aspect-ratio: 2 / 1;
  object-fit: cover;
}

.page-about .about-milestone-figure figcaption {
  padding: 14px 18px;
  border-top: 1px solid var(--hairline);
  font-size: 13px;
  line-height: 1.7;
  color: var(--slate-mute);
}

.page-about .about-milestones {
  margin-top: 36px;
  border-left: 2px solid var(--hairline);
}

.page-about .about-milestone {
  border-bottom: 1px solid var(--hairline);
}

.page-about .about-milestone summary {
  position: relative;
  list-style: none;
  cursor: pointer;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-areas:
    "num title"
    "num meta";
  align-items: baseline;
  column-gap: 14px;
  row-gap: 4px;
  padding: 20px 12px 20px 26px;
}

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

.page-about .about-milestone summary::before {
  content: "";
  position: absolute;
  left: -8px;
  top: 24px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--void-indigo);
  border: 2px solid var(--signal-cyan);
  transition: background 0.25s var(--ease), border-color 0.25s var(--ease), box-shadow 0.25s var(--ease);
}

.page-about .about-milestone[open] summary::before {
  background: var(--pulse-orange);
  border-color: var(--pulse-orange);
  box-shadow: 0 0 0 5px rgba(255, 122, 47, 0.14);
}

.page-about .about-ms-num {
  grid-area: num;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.12em;
  color: var(--slate-mute);
}

.page-about .about-ms-title {
  grid-area: title;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 19px;
  line-height: 1.35;
  color: var(--paper-white);
  transition: color 0.25s var(--ease);
}

.page-about .about-milestone summary:hover .about-ms-title {
  color: var(--signal-cyan);
}

.page-about .about-milestone[open] .about-ms-title {
  color: var(--pulse-orange);
}

.page-about .about-ms-meta {
  grid-area: meta;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--slate-mute);
}

.page-about .about-ms-body {
  margin: 0;
  padding: 0 24px 24px 26px;
  max-width: 36em;
  font-size: 15px;
  line-height: 1.85;
  color: var(--slate-mute);
}

/* 返回顶部 */
.page-about .about-backtop-wrap {
  margin: 32px 0 0;
}

.page-about .about-backtop {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 16px;
  border: 1px solid var(--hairline);
  color: var(--slate-mute);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  text-decoration: none;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .about-backtop:hover {
  color: var(--signal-cyan);
  border-color: var(--signal-cyan);
}

.page-about .about-backtop-mark {
  color: var(--signal-cyan);
}

/* ============ 合作与加入 ============ */
.page-about .about-partner-grid {
  margin-top: 32px;
  display: grid;
  gap: 16px;
  grid-template-columns: 1fr;
}

.page-about .about-partner-card {
  padding: 26px 24px 24px;
  border-left: 2px solid var(--neon-violet);
}

.page-about .about-partner-card h3 {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 19px;
  letter-spacing: -0.01em;
  color: var(--paper-white);
}

.page-about .about-partner-card p {
  margin: 0 0 20px;
  max-width: 34em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--slate-mute);
}

.page-about .about-contact-strip {
  margin-top: 20px;
  padding: 22px 22px 20px;
  border: 1px solid var(--hairline);
  background: linear-gradient(105deg, rgba(53, 230, 210, 0.08), rgba(255, 122, 47, 0.06) 62%, transparent);
}

.page-about .about-contact-line {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.9;
  color: var(--paper-white);
  word-break: break-word;
}

.page-about .about-contact-line a {
  color: var(--signal-cyan);
  text-decoration: none;
  border-bottom: 2px solid rgba(53, 230, 210, 0.4);
  transition: border-color 0.2s var(--ease);
}

.page-about .about-contact-line a:hover {
  border-bottom-color: var(--signal-cyan);
}

.page-about .about-sep {
  margin: 0 10px;
  color: var(--hairline);
}

.page-about .about-contact-note {
  margin: 10px 0 0;
  font-size: 13px;
  color: var(--slate-mute);
}

/* ============ 平板及以上 ============ */
@media (min-width: 720px) {
  .page-about .about-hero {
    padding: 56px 0 40px;
  }

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

  .page-about .about-contact-strip {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    flex-wrap: wrap;
  }

  .page-about .about-contact-note {
    margin: 0;
  }
}

@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: var(--about-scale-w) minmax(0, 1fr);
    column-gap: 64px;
    align-items: start;
    padding-top: 40px;
  }

  .page-about .about-scale {
    display: block;
    position: sticky;
    top: calc(var(--header-h-scrolled) + 40px);
    padding-left: 18px;
    align-self: start;
  }

  .page-about .about-scale::before {
    content: "";
    position: absolute;
    left: 0;
    top: 8px;
    bottom: 8px;
    width: 2px;
    background: linear-gradient(180deg, var(--signal-cyan), rgba(166, 107, 255, 0.55) 58%, rgba(42, 51, 88, 0));
  }

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

  .page-about .about-scale-list a {
    position: relative;
    display: flex;
    align-items: baseline;
    gap: 10px;
    padding: 9px 0;
    font-family: var(--font-mono);
    font-size: 13px;
    letter-spacing: 0.04em;
    text-decoration: none;
    color: var(--slate-mute);
    transition: color 0.22s var(--ease);
  }

  .page-about .about-scale-list a::before {
    content: "";
    position: absolute;
    left: -18px;
    top: 50%;
    width: 9px;
    height: 2px;
    transform: translateY(-50%);
    background: var(--hairline);
    transition: background 0.22s var(--ease), width 0.22s var(--ease);
  }

  .page-about .about-scale-list a:hover {
    color: var(--paper-white);
  }

  .page-about .about-scale-list a[data-active] {
    color: var(--signal-cyan);
  }

  .page-about .about-scale-list a[data-active]::before {
    width: 16px;
    background: var(--signal-cyan);
  }

  .page-about .about-scale-num {
    font-size: 11px;
    color: inherit;
    opacity: 0.7;
  }

  .page-about .about-chapter {
    padding-bottom: 88px;
  }

  .page-about .about-chapter + .about-chapter {
    padding-top: 64px;
  }

  .page-about .about-ms-body {
    padding-left: 26px;
    padding-right: 48px;
  }
}

/* ============ 窄屏保护 ============ */
@media (max-width: 560px) {
  .page-about .about-cats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-cats li {
    font-size: 15px;
    padding: 14px 12px 16px;
  }

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

  .page-about .about-snapshot-list .stat-figure {
    min-width: 74px;
    font-size: 22px;
  }

  .page-about .about-partner-card {
    padding: 22px 18px 20px;
  }

  .page-about .about-contact-strip {
    padding: 18px 16px;
  }
}

@media (max-width: 400px) {
  .page-about .about-cats {
    grid-template-columns: minmax(0, 1fr);
  }

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