.page-about {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  padding-bottom: 0;
}

.page-about .about-top {
  padding-top: 24px;
}

.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-2);
}

.page-about .breadcrumb a {
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--t-fast), border-color var(--t-fast);
}

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

.page-about .breadcrumb__sep {
  color: var(--line);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding: 32px 0 30px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__kicker {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-hero__kicker::before {
  content: "";
  flex: none;
  width: 28px;
  height: 1px;
  background: var(--cyan);
}

.page-about .about-hero h1 {
  margin: 0 0 20px;
  max-width: 20ch;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(28px, 6.4vw, 54px);
  line-height: 1.12;
  letter-spacing: -0.02em;
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 34em;
  padding-left: 14px;
  border-left: 2px solid var(--cyan);
  font-size: 15.5px;
  line-height: 1.8;
}

.page-about .about-hero__stats {
  list-style: none;
  margin: 28px 0 0;
  padding: 1px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-hero__stats li {
  background: var(--panel);
  padding: 14px 15px;
}

.page-about .ab-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 26px;
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.01em;
  color: var(--cyan);
}

.page-about .ab-num--orange {
  color: var(--orange);
}

.page-about .ab-num--amber {
  color: var(--amber);
}

.page-about .ab-num__unit {
  margin-left: 3px;
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 400;
  color: var(--ink-2);
}

.page-about .ab-label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.55;
  color: var(--ink-2);
}

/* ---------- 主体布局 ---------- */

.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  padding-bottom: 48px;
}

.page-about .rail-index {
  display: flex;
  gap: 2px;
  overflow-x: auto;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
  scrollbar-width: none;
}

.page-about .rail-index::-webkit-scrollbar {
  display: none;
}

.page-about .rail-index__link {
  flex: none;
  padding: 6px 10px;
  border: 1px solid var(--line);
  background: var(--panel);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--ink-2);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--t-fast), border-color var(--t-fast), background var(--t-fast);
}

.page-about .rail-index__link:hover,
.page-about .rail-index__link[aria-current="true"] {
  color: var(--cyan);
  border-color: var(--cyan);
  background: var(--cyan-a08);
}

.page-about .about-body {
  min-width: 0;
  padding-top: 4px;
}

/* ---------- 面板目录 ---------- */

.page-about .panel-toc {
  margin-top: 20px;
  border: 1px solid var(--line);
  background: var(--panel);
}

.page-about .panel-toc__caption {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 11px 15px;
  border-bottom: 1px solid var(--line);
  background: var(--panel-2);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-2);
}

.page-about .panel-toc__row {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  align-items: center;
  gap: 4px 12px;
  padding: 12px 15px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  color: var(--ink);
  transition: background var(--t-fast);
}

.page-about .panel-toc__row:last-child {
  border-bottom: 0;
}

.page-about .panel-toc__row:hover {
  background: var(--panel-2);
}

.page-about .panel-toc__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-2);
  transition: color var(--t-fast);
}

.page-about .panel-toc__row:hover .panel-toc__idx {
  color: var(--cyan);
}

.page-about .panel-toc__name {
  font-size: 15px;
  font-weight: 500;
  line-height: 1.45;
}

.page-about .panel-toc__meta {
  grid-column: 2;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-2);
}

/* ---------- 面板 ---------- */

.page-about .panel {
  margin-top: 20px;
  border: 1px solid var(--line);
  background: var(--panel);
  scroll-margin-top: 130px;
}

.page-about .panel__head {
  padding: 18px 16px 15px;
  border-bottom: 1px solid var(--line);
  background:
    linear-gradient(90deg, var(--cyan-a08), rgba(41, 231, 200, 0) 46%),
    var(--panel-2);
}

.page-about .panel__idx {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--cyan);
}

.page-about .panel__title {
  margin: 8px 0 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(21px, 4.6vw, 28px);
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.page-about .panel__note {
  margin: 8px 0 0;
  font-size: 13.5px;
  line-height: 1.6;
  color: var(--ink-2);
}

.page-about .panel__body {
  padding: 18px 16px 22px;
}

.page-about .panel__body p {
  margin: 0 0 12px;
  font-size: 15px;
  line-height: 1.78;
}

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

.page-about .lead-line {
  font-weight: 500;
  padding-left: 12px;
  border-left: 2px solid var(--cyan);
}

.page-about .sub-h {
  margin: 18px 0 8px;
  font-size: 15.5px;
  font-weight: 500;
  line-height: 1.5;
  color: var(--ink);
}

.page-about .sub-h:first-child {
  margin-top: 0;
}

.page-about .cta-line {
  margin-top: 18px;
}

/* ---------- 时间轴 ---------- */

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

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: var(--line);
}

.page-about .timeline__item {
  position: relative;
  padding: 0 0 22px 28px;
}

.page-about .timeline__item:last-child {
  padding-bottom: 0;
}

.page-about .timeline__dot {
  position: absolute;
  left: 0;
  top: 6px;
  width: 9px;
  height: 9px;
  background: var(--panel);
  border: 1px solid var(--ink-2);
  transform: rotate(45deg);
  transition: background var(--t-fast), border-color var(--t-fast);
}

.page-about .timeline__item:hover .timeline__dot {
  background: var(--cyan);
  border-color: var(--cyan);
}

.page-about .timeline__item:last-child .timeline__dot {
  background: var(--orange);
  border-color: var(--orange);
}

.page-about .timeline__time {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--amber);
}

.page-about .tl-card h3 {
  margin: 0 0 5px;
  font-size: 15.5px;
  font-weight: 500;
  line-height: 1.5;
}

.page-about .tl-card p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--ink-2);
}

/* ---------- 图文两栏 ---------- */

.page-about .ab-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 20px;
}

.page-about .media-frame {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--panel-2);
}

.page-about .media-frame img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .media-frame__cap {
  display: block;
  padding: 10px 12px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.65;
  letter-spacing: 0.02em;
  color: var(--ink-2);
}

.page-about .media-frame--panorama {
  margin-bottom: 20px;
}

/* ---------- 筛选与联赛卡片 ---------- */

.page-about .tag-filter {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 14px;
}

.page-about .tag-filter__btn {
  padding: 7px 13px;
  border: 1px solid var(--line);
  background: transparent;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-2);
  cursor: pointer;
  transition: color var(--t-fast), border-color var(--t-fast), background var(--t-fast);
}

.page-about .tag-filter__btn:hover {
  color: var(--ink);
  border-color: var(--ink-2);
}

.page-about .tag-filter__btn.is-active {
  color: var(--bg);
  background: var(--cyan);
  border-color: var(--cyan);
}

.page-about .tag-filter__count {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-2);
}

.page-about .league-board {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  padding: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .league-card {
  background: var(--panel);
  padding: 16px 15px;
}

.page-about .league-card[hidden] {
  display: none;
}

.page-about .league-card__title {
  display: flex;
  align-items: center;
  gap: 9px;
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.page-about .league-card p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--ink-2);
}

.page-about .lg-dot {
  flex: none;
  width: 9px;
  height: 9px;
  background: var(--ink-2);
}

.page-about .lg-dot--cyan {
  background: var(--cyan);
}

.page-about .lg-dot--orange {
  background: var(--orange);
}

.page-about .lg-dot--amber {
  background: var(--amber);
}

.page-about .lg-dot--muted {
  background: var(--ink-2);
}

/* ---------- 指标块 ---------- */

.page-about .metrics {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  padding: 1px;
  margin-top: 20px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .metric {
  background: var(--panel-2);
  padding: 16px 15px;
}

.page-about .metric__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(26px, 5.4vw, 36px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--amber);
}

.page-about .metric__num--cyan {
  color: var(--cyan);
}

.page-about .metric__num--orange {
  color: var(--orange);
  font-size: clamp(22px, 4.6vw, 30px);
}

.page-about .metric__unit {
  margin-left: 4px;
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 400;
  color: var(--ink-2);
}

.page-about .metric__label {
  display: block;
  margin-top: 10px;
  font-size: 13.5px;
  line-height: 1.6;
  color: var(--ink-2);
}

/* ---------- 后续入口 ---------- */

.page-about .next-links {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  padding: 1px;
  margin-top: 20px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .next-link {
  display: block;
  padding: 18px 16px;
  background: var(--panel-2);
  text-decoration: none;
  color: var(--ink);
  transition: background var(--t-fast);
}

.page-about .next-link:hover {
  background: var(--panel);
}

.page-about .next-link__k {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .next-link__t {
  display: block;
  margin: 9px 0 6px;
  font-size: 16px;
  font-weight: 500;
  line-height: 1.45;
}

.page-about .next-link__d {
  display: block;
  font-size: 13.5px;
  line-height: 1.68;
  color: var(--ink-2);
}

/* ---------- 响应式 ---------- */

@media (min-width: 640px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

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

  .page-about .panel__head {
    padding: 22px 22px 18px;
  }

  .page-about .panel__body {
    padding: 22px 22px 26px;
  }
}

@media (min-width: 820px) {
  .page-about .ab-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 24px;
    align-items: start;
  }

  .page-about .panel-toc__row {
    grid-template-columns: 48px minmax(0, 1fr) auto;
    align-items: center;
  }

  .page-about .panel-toc__meta {
    grid-column: 3;
  }
}

@media (min-width: 1040px) {
  .page-about .about-top {
    padding-top: 34px;
  }

  .page-about .about-hero {
    padding: 40px 0 36px;
  }

  .page-about .about-layout {
    grid-template-columns: var(--rail) minmax(0, 1fr);
    gap: 30px;
    padding-bottom: 80px;
  }

  .page-about .rail-index {
    position: sticky;
    top: 128px;
    align-self: start;
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    max-height: calc(100vh - 180px);
    padding: 0;
    border-bottom: 0;
    border-left: 1px solid var(--line);
  }

  .page-about .rail-index__link {
    border: 0;
    border-left: 2px solid transparent;
    background: transparent;
    margin-left: -1px;
    padding: 9px 8px;
    text-align: center;
    letter-spacing: 0.06em;
  }

  .page-about .rail-index__link:hover,
  .page-about .rail-index__link[aria-current="true"] {
    border-left-color: var(--cyan);
    background: var(--cyan-a08);
  }

  .page-about .about-body {
    padding-top: 0;
  }

  .page-about .panel-toc {
    margin-top: 0;
  }

  .page-about .panel {
    margin-top: 24px;
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition-duration: 0.01ms !important;
  }
}