.page-about {
  position: relative;
  background: var(--bg);
  color: var(--ink);
  overflow-x: clip;
}

.page-about::before {
  content: "";
  position: absolute;
  inset: -80px -12% auto -12%;
  height: 620px;
  background:
    radial-gradient(58% 52% at 16% 0%, rgba(34, 224, 214, 0.16), transparent 70%),
    radial-gradient(48% 46% at 84% 6%, rgba(255, 122, 47, 0.10), transparent 72%);
  pointer-events: none;
  z-index: 0;
}

.page-about .about-shell {
  position: relative;
  z-index: 1;
}

.page-about .breadcrumb {
  margin-top: 26px;
  margin-bottom: 20px;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--ink-dim);
}

.page-about .breadcrumb a {
  color: var(--ink-dim);
  text-decoration: none;
  border-bottom: 1px solid rgba(157, 170, 198, 0.35);
}

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

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding-bottom: clamp(34px, 6vw, 68px);
}

.page-about .about-hero .section-tag {
  margin-bottom: 16px;
}

.page-about .about-hero h1 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(30px, 7.4vw, 58px);
  line-height: 1.1;
  letter-spacing: 0.01em;
  margin: 0 0 18px;
  max-width: 16ch;
}

.page-about .about-hero .lede {
  max-width: 64ch;
  color: var(--ink-dim);
  line-height: 1.85;
  margin: 0;
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  padding: 1px;
  margin: clamp(28px, 6vw, 48px) 0 0;
  list-style: none;
  background: var(--line);
  border-radius: var(--r-md);
  overflow: hidden;
}

.page-about .about-facts li {
  display: flex;
  flex-direction: column;
  gap: 7px;
  padding: 18px 16px;
  background: var(--panel);
}

.page-about .about-facts__num {
  font-family: var(--font-num);
  font-size: clamp(26px, 6.4vw, 40px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--cyan);
}

.page-about .about-facts li:nth-child(2) .about-facts__num {
  color: var(--mint);
}

.page-about .about-facts__label {
  font-size: 13px;
  line-height: 1.6;
  color: var(--ink-dim);
}

/* ---------- 主体与索引 ---------- */

.page-about .about-body {
  display: block;
}

.page-about .about-index {
  margin: 0 0 30px;
}

.page-about .about-index__head {
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--muted);
  margin: 0 0 10px;
}

.page-about .about-index__list {
  display: flex;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-index__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink-dim);
  font-size: 13px;
  white-space: nowrap;
  text-decoration: none;
  transition: color 0.2s var(--ease), background 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .about-index__link .u-num {
  font-size: 11px;
  color: var(--cyan-deep);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  color: var(--ink);
  background: var(--panel-2);
  border-color: var(--mint);
  outline: none;
}

/* ---------- 章节 ---------- */

.page-about .about-sec {
  position: relative;
  padding-block: clamp(44px, 7.5vw, 88px);
  border-top: 1px solid var(--line);
}

.page-about .about-sec .h-section {
  margin: 0 0 20px;
  max-width: 24ch;
}

.page-about .about-sec .h-sub {
  margin: 0 0 10px;
}

.page-about .about-copy p {
  margin: 0 0 14px;
  max-width: 66ch;
  color: var(--ink-dim);
  line-height: 1.85;
}

.page-about .about-copy strong {
  color: var(--ink);
  font-weight: 500;
}

.page-about .about-copy a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(34, 224, 214, 0.4);
}

.page-about .about-copy a:hover {
  border-bottom-color: var(--mint);
}

.page-about .lede-grid {
  display: grid;
  gap: 26px;
}

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

.page-about .plate__kicker {
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--amber);
  margin: 0 0 12px;
}

.page-about .plate__foot {
  margin: 14px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

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

.page-about .ticklist li {
  position: relative;
  padding-left: 18px;
  margin-bottom: 10px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-dim);
}

.page-about .ticklist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--grad-cyan);
}

/* ---------- 图片 ---------- */

.page-about .img-frame {
  margin: 28px 0 0;
}

.page-about .img-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--r-lg);
}

.page-about .tl-figure {
  margin-bottom: 34px;
}

/* ---------- 三段分工 ---------- */

.page-about .phase-grid {
  display: grid;
  gap: 12px;
  margin-top: 34px;
}

.page-about .phase {
  position: relative;
  padding: 22px 20px;
  border-radius: var(--r-lg);
  background: var(--panel);
  border-top: 2px solid var(--cyan);
}

.page-about .phase--b {
  border-top-color: var(--orange);
}

.page-about .phase--c {
  border-top-color: var(--amber);
}

.page-about .phase__k {
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--ink-dim);
  margin: 0 0 10px;
}

.page-about .phase__t {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 500;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .phase__d {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--ink-dim);
}

/* ---------- 赛区点阵 ---------- */

.page-about .zones {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
}

.page-about .zones__item {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 14px 16px 18px;
  border-radius: var(--r-md);
  background: var(--panel);
  border: 1px solid transparent;
  transition: border-color 0.2s var(--ease), transform 0.2s var(--ease), background 0.2s var(--ease);
}

.page-about .zones__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 16px;
  bottom: 16px;
  width: 3px;
  border-radius: 3px;
  background: var(--grad-cyan);
}

.page-about .zones__item:hover,
.page-about .zones__item:focus-within {
  background: var(--panel-2);
  border-color: rgba(111, 243, 228, 0.4);
  transform: translateY(-2px);
}

.page-about .zones__idx {
  font-family: var(--font-num);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--cyan-deep);
}

.page-about .zones__name {
  font-size: 15px;
  font-weight: 500;
  color: var(--ink);
}

.page-about .zones__duty {
  font-size: 13px;
  line-height: 1.65;
  color: var(--ink-dim);
}

/* ---------- 版本时间线 ---------- */

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

.page-about .tl::before {
  content: "";
  position: absolute;
  left: 14px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  border-radius: 2px;
  background: linear-gradient(180deg, rgba(34, 224, 214, 0.08), rgba(34, 224, 214, 0.55), rgba(255, 122, 47, 0.4));
}

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

.page-about .tl__node {
  position: relative;
  padding-left: 44px;
  margin-bottom: 6px;
}

.page-about .tl__node::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 16px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--cyan-deep);
  box-shadow: 0 0 0 4px rgba(34, 224, 214, 0.08);
  transition: border-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}

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

.page-about .tl__node--now::before {
  border-color: var(--orange);
  background: radial-gradient(circle, var(--orange) 0 4px, var(--bg) 5px);
}

.page-about .tl__node > summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  padding: 12px 34px 12px 0;
  cursor: pointer;
  list-style: none;
  position: relative;
  border-bottom: 1px solid var(--line);
}

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

.page-about .tl__node > summary::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: 10px;
  font-family: var(--font-num);
  font-size: 18px;
  line-height: 1;
  color: var(--ink-dim);
}

.page-about .tl__node[open] > summary::after {
  content: "–";
  color: var(--orange);
}

.page-about .tl__node > summary:hover .tl__name {
  color: var(--cyan);
}

.page-about .tl__idx {
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--cyan-deep);
}

.page-about .tl__name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 600;
  color: var(--ink);
  transition: color 0.2s var(--ease);
}

.page-about .tl__body {
  padding: 4px 0 18px;
}

.page-about .tl__body p {
  margin: 0;
  max-width: 62ch;
  font-size: 14px;
  line-height: 1.85;
  color: var(--ink-dim);
}

/* ---------- 合作方 ---------- */

.page-about .partner-grid {
  display: grid;
  gap: 12px;
  margin-top: 30px;
}

.page-about .partner {
  padding: 24px 22px;
  border-radius: var(--r-lg);
  background: var(--panel);
  border-left: 3px solid var(--cyan);
}

.page-about .partner--b {
  border-left-color: var(--orange);
}

.page-about .partner__num {
  font-family: var(--font-num);
  font-size: clamp(30px, 7vw, 46px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--cyan);
  margin: 0 0 12px;
}

.page-about .partner--b .partner__num {
  color: var(--orange);
}

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

.page-about .partner__list li {
  position: relative;
  padding-left: 16px;
  margin-bottom: 9px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-dim);
}

.page-about .partner__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 6px;
  border-radius: 1px;
  background: var(--muted);
}

/* ---------- 复盘 ---------- */

.page-about .review-grid {
  display: grid;
  gap: 26px;
}

.page-about .review-grid .img-frame {
  margin-top: 0;
}

/* ---------- 服务与支持 ---------- */

.page-about .about-sec--last {
  border-bottom: 1px solid var(--line);
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-actions .btn {
  text-decoration: none;
}

/* ---------- 响应式 ---------- */

@media (min-width: 620px) {
  .page-about .about-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

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

@media (min-width: 900px) {
  .page-about .about-body {
    display: grid;
    grid-template-columns: 176px minmax(0, 1fr);
    gap: clamp(28px, 4vw, 60px);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--status-h) + 22px);
    margin: 0;
    padding-top: 4px;
  }

  .page-about .about-index__list {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    padding: 0;
  }

  .page-about .about-index__link {
    display: flex;
    padding: 8px 10px;
    border-radius: var(--r-sm);
    border-color: transparent;
    background: transparent;
    font-size: 13px;
  }

  .page-about .about-index__link:hover,
  .page-about .about-index__link:focus-visible {
    border-color: transparent;
    background: var(--panel);
  }

  .page-about .lede-grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    gap: 40px;
  }

  .page-about .review-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: 40px;
    align-items: start;
  }

  .page-about .tl__node {
    padding-left: 52px;
  }

  .page-about .tl::before {
    left: 15px;
  }

  .page-about .tl__node::before {
    left: 7px;
  }

  .page-about .about-sec {
    padding-block: clamp(60px, 6vw, 110px);
  }

  .page-about .about-sec .h-section {
    font-size: clamp(28px, 3.4vw, 42px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .zones__item,
  .page-about .tl__name,
  .page-about .about-index__link,
  .page-about .tl__node::before {
    transition: none;
  }

  .page-about .zones__item:hover {
    transform: none;
  }
}