.page-about {
  --ab-radius-sm: 14px;
  --ab-toc-w: 236px;
  color: var(--c-text);
  background: var(--c-deep);
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumbs {
  padding-top: 26px;
}
.page-about .breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--f-data);
  font-size: 13px;
  color: var(--c-muted);
}
.page-about .breadcrumb-list a {
  color: var(--c-muted);
  text-decoration: none;
  transition: color var(--t-fast);
}
.page-about .breadcrumb-list a:hover,
.page-about .breadcrumb-list a:focus-visible {
  color: var(--c-green);
}
.page-about .breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  margin-right: 8px;
  color: var(--c-line);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: 34px 0 46px;
  overflow: hidden;
}
.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(34, 52, 92, 0.5) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(34, 52, 92, 0.35) 1px, transparent 1px);
  background-size: 68px 68px;
  -webkit-mask-image: radial-gradient(130% 90% at 12% 0%, #000 0%, transparent 72%);
  mask-image: radial-gradient(130% 90% at 12% 0%, #000 0%, transparent 72%);
  pointer-events: none;
}
.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
}
.page-about .about-hero__title {
  margin: 14px 0 18px;
  font-size: clamp(28px, 6.4vw, 46px);
  line-height: 1.16;
  font-weight: 900;
  letter-spacing: -0.02em;
  max-width: 22ch;
}
.page-about .about-hero__lead {
  margin: 0;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--c-muted);
}
.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 30px 0 0;
  padding: 0;
  list-style: none;
}
.page-about .about-hero__facts li {
  flex: 1 1 136px;
  padding: 14px 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--ab-radius-sm);
  background: linear-gradient(180deg, rgba(22, 41, 76, 0.7), rgba(10, 20, 48, 0.55));
}
.page-about .about-hero__facts .mono {
  display: block;
  font-family: var(--f-data);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--c-ice);
}
.page-about .about-hero__facts li:first-child .mono {
  color: var(--c-green);
}
.page-about .about-hero__facts small {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.5;
  color: var(--c-muted);
}

/* ---------- 主体两栏 ---------- */
.page-about .about-layout {
  display: grid;
  gap: 28px;
  padding-bottom: 72px;
}

/* ---------- 章节索引 ---------- */
.page-about .about-toc {
  padding: 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-card);
  background: rgba(16, 32, 63, 0.6);
}
.page-about .about-toc__title {
  margin: 0 0 12px;
  padding-left: 10px;
  font-family: var(--f-data);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--c-muted);
  text-transform: uppercase;
}
.page-about .about-toc__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 2px;
}
.page-about .about-toc__list a {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 9px 10px;
  border-left: 2px solid transparent;
  border-radius: 10px;
  font-size: 14px;
  line-height: 1.5;
  color: var(--c-muted);
  text-decoration: none;
  transition: color var(--t-fast), background var(--t-fast), border-color var(--t-fast);
}
.page-about .about-toc__list a .mono {
  font-family: var(--f-data);
  font-size: 12px;
  color: var(--c-line);
  transition: color var(--t-fast);
}
.page-about .about-toc__list a:hover,
.page-about .about-toc__list a:focus-visible {
  color: var(--c-text);
  background: rgba(53, 240, 154, 0.08);
  border-left-color: var(--c-green);
}
.page-about .about-toc__list a:hover .mono,
.page-about .about-toc__list a:focus-visible .mono {
  color: var(--c-green);
}

/* ---------- 章节通用 ---------- */
.page-about .about-sections {
  min-width: 0;
}
.page-about .about-chapter {
  padding: 40px 0;
  border-top: 1px solid var(--c-line);
  scroll-margin-top: 112px;
}
.page-about .about-chapter:first-child {
  padding-top: 6px;
  border-top: 0;
}
.page-about .about-chapter:last-child {
  padding-bottom: 8px;
}
.page-about .about-chapter__head {
  display: flex;
  gap: 14px;
  align-items: baseline;
  margin-bottom: 22px;
}
.page-about .about-chapter__num {
  flex: none;
  font-family: var(--f-data);
  font-size: 26px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--c-green);
}
.page-about .about-chapter__title {
  margin: 0;
  font-size: clamp(22px, 4.6vw, 30px);
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.01em;
}
.page-about .about-prose p {
  margin: 0 0 16px;
  max-width: 68ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--c-text);
}
.page-about .about-prose p:last-child {
  margin-bottom: 0;
}

/* ---------- 字段分区 ---------- */
.page-about .about-fields {
  display: grid;
  gap: 14px;
  margin-top: 26px;
}
.page-about .about-field {
  padding: 16px 18px;
  border: 1px solid var(--c-line);
  border-radius: var(--ab-radius-sm);
  background: rgba(16, 32, 63, 0.55);
  transition: border-color var(--t-fast), transform var(--t-fast);
}
.page-about .about-field:hover {
  border-color: var(--c-green);
  transform: translateY(-1px);
}
.page-about .about-field .pill {
  font-family: var(--f-data);
  font-size: 12px;
  letter-spacing: 0.06em;
}
.page-about .about-field p {
  margin: 12px 0 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--c-muted);
}

/* ---------- 说明块 ---------- */
.page-about .about-note {
  margin-top: 26px;
  padding: 16px 18px;
  border-left: 3px solid var(--c-ice);
  border-radius: var(--ab-radius-sm);
  background: rgba(116, 216, 255, 0.06);
}
.page-about .about-note--boundary {
  border-left-color: var(--c-amber);
  background: rgba(255, 165, 61, 0.06);
}
.page-about .about-note__label {
  margin: 0 0 8px;
  font-family: var(--f-data);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--c-amber);
}
.page-about .about-note--boundary .about-note__label {
  color: var(--c-amber);
}
.page-about .about-note p:last-child {
  margin: 0;
  max-width: 68ch;
  font-size: 14px;
  line-height: 1.78;
  color: var(--c-muted);
}

/* ---------- 图像 ---------- */
.page-about .about-figure {
  margin: 28px 0 0;
}
.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--c-line);
  border-radius: var(--r-card);
  background: var(--c-panel);
}
.page-about .about-figure figcaption {
  margin-top: 10px;
  max-width: 66ch;
  font-size: 13px;
  line-height: 1.68;
  color: var(--c-muted);
}

/* ---------- 折叠面板 ---------- */
.page-about .about-fold {
  display: grid;
  gap: 10px;
  margin-top: 28px;
}
.page-about .fold {
  border: 1px solid var(--c-line);
  border-radius: var(--ab-radius-sm);
  background: rgba(6, 12, 31, 0.65);
  transition: border-color var(--t-fast);
}
.page-about .fold:hover {
  border-color: #2c4370;
}
.page-about .fold[open] {
  border-color: rgba(53, 240, 154, 0.45);
  background: rgba(16, 32, 63, 0.6);
}
.page-about .fold summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 15px 18px;
  cursor: pointer;
  list-style: none;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.5;
  color: var(--c-text);
}
.page-about .fold summary::-webkit-details-marker {
  display: none;
}
.page-about .fold summary::after {
  content: "+";
  flex: none;
  font-family: var(--f-data);
  font-size: 18px;
  line-height: 1;
  color: var(--c-green);
}
.page-about .fold[open] summary {
  color: var(--c-green);
}
.page-about .fold[open] summary::after {
  content: "−";
}
.page-about .fold summary:focus-visible {
  outline: 2px solid var(--c-green);
  outline-offset: -2px;
  border-radius: var(--ab-radius-sm);
}
.page-about .fold p {
  margin: 0;
  padding: 0 18px 16px;
  max-width: 68ch;
  font-size: 14px;
  line-height: 1.78;
  color: var(--c-muted);
}

/* ---------- 版本时间线 ---------- */
.page-about .about-timeline-wrap {
  margin-top: 4px;
  padding: 22px 20px 8px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-card);
  background:
    linear-gradient(180deg, rgba(22, 41, 76, 0.55), rgba(6, 12, 31, 0.75));
}
.page-about .about-timeline-svg {
  display: block;
  width: 100%;
  height: auto;
  max-height: 168px;
  margin: 0 0 26px;
}
.page-about .about-timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 28px;
  list-style: none;
}
.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 26px;
  width: 2px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--c-violet), var(--c-ice) 55%, var(--c-amber));
}
.page-about .about-timeline li {
  position: relative;
  padding-bottom: 26px;
}
.page-about .about-timeline li:last-child {
  padding-bottom: 6px;
}
.page-about .about-timeline li::before {
  content: "";
  position: absolute;
  left: -28px;
  top: 3px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--c-deep);
  border: 2px solid var(--c-ice);
}
.page-about .about-timeline li.is-current::before {
  border-color: var(--c-green);
  box-shadow: 0 0 0 4px rgba(53, 240, 154, 0.16);
}
.page-about .about-timeline__meta {
  margin: 0 0 6px;
  font-family: var(--f-data);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--c-amber);
}
.page-about .about-timeline li.is-current .about-timeline__meta {
  color: var(--c-green);
}
.page-about .about-timeline__title {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.005em;
}
.page-about .about-timeline__desc {
  margin: 0;
  max-width: 62ch;
  font-size: 14px;
  line-height: 1.78;
  color: var(--c-muted);
}

/* ---------- 团队卡片 ---------- */
.page-about .about-team {
  display: grid;
  gap: 14px;
  margin-top: 24px;
}
.page-about .about-team__card {
  padding: 18px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-card);
  background: linear-gradient(160deg, rgba(22, 41, 76, 0.72), rgba(10, 20, 48, 0.6));
  transition: border-color var(--t-fast), transform var(--t-fast);
}
.page-about .about-team__card:hover {
  border-color: var(--c-green);
  transform: translateY(-1px);
}
.page-about .about-team__card h3 {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 700;
}
.page-about .about-team__tag {
  margin: 0 0 12px;
  font-family: var(--f-data);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-violet);
}
.page-about .about-team__card p:last-child {
  margin: 0;
  font-size: 14px;
  line-height: 1.74;
  color: var(--c-muted);
}

/* ---------- 原则卡片 ---------- */
.page-about .about-principles {
  display: grid;
  gap: 14px;
  margin-top: 24px;
}
.page-about .about-principle {
  display: flex;
  gap: 14px;
  padding: 18px;
  border: 1px solid var(--c-line);
  border-left: 3px solid var(--c-green);
  border-radius: var(--ab-radius-sm);
  background: rgba(16, 32, 63, 0.5);
}
.page-about .about-principle svg {
  flex: none;
  width: 24px;
  height: 24px;
  margin-top: 2px;
  stroke: var(--c-green);
}
.page-about .about-principle h3 {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
}
.page-about .about-principle p {
  margin: 0;
  max-width: 60ch;
  font-size: 14px;
  line-height: 1.78;
  color: var(--c-muted);
}

/* ---------- 引导链接 ---------- */
.page-about .about-next {
  display: grid;
  gap: 12px;
  margin-top: 24px;
}
.page-about .about-next a {
  display: block;
  padding: 18px;
  border: 1px solid var(--c-line);
  border-radius: var(--ab-radius-sm);
  font-size: 14px;
  line-height: 1.72;
  color: var(--c-muted);
  text-decoration: none;
  transition: border-color var(--t-fast), background var(--t-fast), color var(--t-fast);
}
.page-about .about-next a span {
  display: block;
  margin-bottom: 6px;
  font-family: var(--f-data);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--c-ice);
}
.page-about .about-next a:hover,
.page-about .about-next a:focus-visible {
  border-color: var(--c-green);
  background: rgba(53, 240, 154, 0.06);
  color: var(--c-text);
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 720px) {
  .page-about .about-fields {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-team {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-next {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-hero {
    padding: 52px 0 60px;
  }
  .page-about .about-timeline-wrap {
    padding: 28px 28px 12px;
  }
}

/* ---------- 桌面：固定章节索引 ---------- */
@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: var(--ab-toc-w) minmax(0, 1fr);
    gap: 56px;
  }
  .page-about .about-toc {
    position: sticky;
    top: 104px;
    padding: 18px 14px;
  }
  .page-about .about-chapter {
    padding: 52px 0;
  }
  .page-about .about-chapter:first-child {
    padding-top: 4px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-field,
  .page-about .about-team__card {
    transition: none;
  }
  .page-about .about-field:hover,
  .page-about .about-team__card:hover {
    transform: none;
  }
}