.page-about {
  --a-muted: rgba(167, 180, 194, 0.8);
  --a-pad: clamp(52px, 8vw, 108px);
  background: var(--ice);
  color: var(--frost);
  font-family: var(--font-body);
  overflow-x: clip;
}

.page-about .section {
  padding: var(--a-pad) 0;
}

.page-about img {
  max-width: 100%;
}

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

.page-about .chapter-no {
  display: block;
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(34px, 6vw, 62px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--lava);
}

.page-about .section h2 {
  margin: 14px 0 0;
  font-family: var(--font-head);
  font-size: clamp(26px, 4.2vw, 44px);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: -0.02em;
  max-width: 18em;
}

.page-about .a-lede {
  margin: 18px 0 0;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.85;
  color: var(--a-muted);
}

.page-about h3 {
  font-family: var(--font-head);
  font-weight: 700;
}

/* ---------- HERO ---------- */

.page-about .a-hero {
  position: relative;
  padding: clamp(20px, 4vw, 40px) 0 clamp(48px, 7vw, 92px);
  background:
    radial-gradient(90% 72% at 88% 4%, rgba(91, 75, 214, 0.3), transparent 62%),
    radial-gradient(72% 62% at 4% 104%, rgba(255, 90, 31, 0.14), transparent 64%),
    linear-gradient(176deg, var(--ink) 0%, var(--ice) 66%);
  border-bottom: 1px solid var(--line-soft);
}

.page-about .a-hero__inner {
  position: relative;
}

.page-about .a-hero__crumb {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--a-muted);
}

.page-about .a-hero__crumb a {
  color: var(--a-muted);
  text-decoration: none;
}

.page-about .a-hero__crumb a:hover,
.page-about .a-hero__crumb a:focus-visible {
  color: var(--lava);
}

.page-about .a-hero__grid {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
  margin-top: clamp(26px, 5vw, 54px);
}

.page-about .a-hero__title {
  margin: 10px 0 0;
  font-family: var(--font-head);
  font-size: clamp(44px, 10.5vw, 88px);
  font-weight: 900;
  line-height: 0.94;
  letter-spacing: -0.03em;
}

.page-about .a-hero__side-kicker {
  margin: 0 0 12px;
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--silver);
}

.page-about .a-hero__index {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .a-hero__index a {
  display: flex;
  align-items: baseline;
  gap: 12px;
  min-height: 44px;
  padding: 0 0 6px;
  border-bottom: 1px solid var(--line-soft);
  font-size: 14px;
  color: var(--a-muted);
  text-decoration: none;
  transition: color 0.18s ease;
}

.page-about .a-hero__index span {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--lava);
}

.page-about .a-hero__index a:hover,
.page-about .a-hero__index a:focus-visible {
  color: var(--frost);
}

.page-about .a-hero__lead {
  margin: clamp(28px, 4vw, 46px) 0 0;
  max-width: 34em;
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.85;
  color: rgba(242, 246, 250, 0.88);
}

.page-about .a-facts {
  list-style: none;
  margin: clamp(30px, 5vw, 54px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: rgba(167, 180, 194, 0.18);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .a-facts li {
  background: rgba(6, 20, 32, 0.72);
  padding: 18px 16px 20px;
}

.page-about .a-facts__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(30px, 4.6vw, 48px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--lava);
}

.page-about .a-facts__label {
  display: block;
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--a-muted);
}

/* ---------- 01 发展历程 ---------- */

.page-about .a-stages {
  background: var(--ice);
}

.page-about .a-stages__media {
  margin-top: clamp(28px, 4vw, 46px);
}

.page-about .a-timeline {
  list-style: none;
  margin: clamp(30px, 4vw, 52px) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .a-tl-node {
  position: relative;
  padding: 22px 0 24px 34px;
  border-left: 1px solid var(--line);
}

.page-about .a-tl-node:last-child {
  padding-bottom: 0;
}

.page-about .a-tl-dot {
  position: absolute;
  top: 27px;
  left: -5px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--ivory);
  box-shadow: 0 0 0 4px var(--ice);
}

.page-about .a-tl-num {
  display: inline-block;
  padding: 2px 7px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--electric);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.page-about .a-tl-node h3 {
  margin: 12px 0 0;
  font-size: 19px;
  line-height: 1.35;
  color: var(--frost);
}

.page-about .a-tl-node p {
  margin: 10px 0 0;
  max-width: 32em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--a-muted);
}

.page-about .a-tl-node:hover .a-tl-num,
.page-about .a-tl-node:focus-within .a-tl-num {
  background: var(--lava);
  border-color: var(--lava);
  color: var(--ink);
}

/* ---------- 02 六个板块 ---------- */

.page-about .a-blocks-zone {
  background: linear-gradient(180deg, var(--ice) 0%, var(--steel) 130%);
}

.page-about .a-blocks {
  margin-top: clamp(28px, 4vw, 48px);
  display: grid;
  gap: 1px;
  background: rgba(167, 180, 194, 0.2);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .a-block {
  position: relative;
  z-index: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 26px 22px 30px;
  background: rgba(6, 20, 32, 0.6);
  transition: background 0.2s ease, transform 0.2s ease;
}

.page-about .a-block:hover,
.page-about .a-block:focus-within {
  z-index: 2;
  background: var(--steel);
  transform: translateY(-4px);
}

.page-about .a-block__no {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--electric);
}

.page-about .a-block h3 {
  margin: 0;
  font-size: 20px;
  line-height: 1.3;
  color: var(--frost);
}

.page-about .a-block p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--a-muted);
}

.page-about .a-block__link {
  margin-top: auto;
  padding-top: 12px;
  align-self: flex-start;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--ember);
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 138, 61, 0.4);
}

.page-about .a-block__link:hover,
.page-about .a-block__link:focus-visible {
  color: var(--lava);
  border-bottom-color: var(--lava);
}

/* ---------- 纸面区块 ---------- */

.page-about .a-zone--paper {
  --a-muted: rgba(11, 30, 51, 0.68);
  background: var(--frost);
  color: var(--ink);
  clip-path: polygon(0 40px, 100% 0, 100% 100%, 0 100%);
  padding-top: calc(var(--a-pad) + 40px);
}

.page-about .a-zone--paper .chapter-no {
  color: var(--lava-deep);
}

/* ---------- 03 青训梯队 ---------- */

.page-about .a-youth__grid {
  display: grid;
  gap: clamp(28px, 4vw, 52px);
  margin-top: clamp(26px, 4vw, 46px);
}

.page-about .a-youth__text p {
  margin: 0 0 16px;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.85;
}

.page-about .a-youth__list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  border-top: 1px solid rgba(11, 30, 51, 0.16);
}

.page-about .a-youth__list li {
  display: grid;
  gap: 6px;
  padding: 14px 0;
  border-bottom: 1px solid rgba(11, 30, 51, 0.16);
  font-size: 15px;
  line-height: 1.75;
  color: rgba(11, 30, 51, 0.78);
}

.page-about .a-youth__list .mono {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--turf-deep);
}

.page-about .a-youth__media {
  margin: 0;
}

.page-about .a-youth__media .media__label {
  color: rgba(11, 30, 51, 0.6);
}

/* ---------- 04 团队 ---------- */

.page-about .a-team-zone {
  background: var(--ink);
}

.page-about .a-team {
  display: grid;
  gap: clamp(26px, 4vw, 40px);
  margin-top: clamp(28px, 4vw, 48px);
}

.page-about .a-team__item {
  border-top: 1px solid var(--line-strong);
  padding-top: 18px;
}

.page-about .a-team__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(46px, 7vw, 72px);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--frost);
}

.page-about .a-team__item h3 {
  margin: 14px 0 0;
  font-size: 18px;
  color: var(--lava);
}

.page-about .a-team__item p {
  margin: 10px 0 0;
  max-width: 30em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--a-muted);
}

/* ---------- 05 更新节奏 ---------- */

.page-about .a-rhythm-zone {
  background: linear-gradient(180deg, var(--ink) 0%, var(--ice) 100%);
}

.page-about .a-rhythm {
  margin-top: clamp(26px, 4vw, 46px);
  border-top: 1px solid var(--line);
}

.page-about .a-rhythm__row {
  display: grid;
  gap: 10px;
  padding: 20px 2px;
  border-bottom: 1px solid var(--line-soft);
  transition: background 0.18s ease, box-shadow 0.18s ease;
}

.page-about .a-rhythm__row:hover,
.page-about .a-rhythm__row:focus-within {
  background: rgba(53, 224, 208, 0.07);
  box-shadow: inset 3px 0 0 var(--lava);
}

.page-about .a-rhythm__tag {
  justify-self: start;
  display: inline-block;
  padding: 5px 9px;
  border-radius: var(--radius);
  background: var(--turf);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.1em;
  white-space: nowrap;
}

.page-about .a-rhythm__title {
  margin: 0;
  font-size: 18px;
  line-height: 1.35;
  color: var(--frost);
}

.page-about .a-rhythm__desc {
  margin: 0;
  max-width: 40em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--a-muted);
}

/* ---------- 06 合作生态 ---------- */

.page-about .a-details {
  margin-top: 18px;
  background: rgba(255, 255, 255, 0.62);
  border: 1px solid rgba(11, 30, 51, 0.16);
  border-radius: var(--radius);
}

.page-about .a-details summary {
  display: flex;
  align-items: baseline;
  gap: 12px;
  min-height: 44px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
  font-size: 16px;
  font-weight: 700;
  line-height: 1.55;
  color: var(--ink);
}

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

.page-about .a-details summary::before {
  content: "+";
  flex: none;
  font-family: var(--font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--lava-deep);
}

.page-about .a-details[open] summary::before {
  content: "−";
}

.page-about .a-details summary:hover {
  background: rgba(47, 191, 113, 0.1);
}

.page-about .a-details__body {
  padding: 0 18px 20px 42px;
}

.page-about .a-details__body p {
  margin: 0;
  max-width: 36em;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(11, 30, 51, 0.76);
}

/* ---------- 收口 ---------- */

.page-about .a-outro {
  padding: clamp(56px, 8vw, 110px) 0 clamp(64px, 9vw, 124px);
  background:
    radial-gradient(80% 90% at 82% 8%, rgba(91, 75, 214, 0.34), transparent 62%),
    linear-gradient(180deg, var(--ink), #040d16);
  border-top: 1px solid var(--line);
}

.page-about .a-outro__inner {
  position: relative;
}

.page-about .a-outro__big {
  margin: 14px 0 0;
  max-width: 20em;
  font-family: var(--font-head);
  font-size: clamp(24px, 3.8vw, 40px);
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: -0.02em;
  color: var(--frost);
}

.page-about .a-outro__text {
  margin: 18px 0 0;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.85;
  color: var(--a-muted);
}

.page-about .a-outro .btn {
  margin-top: 30px;
}

/* ---------- 断点 ---------- */

@media (min-width: 620px) {
  .page-about .a-youth__list li {
    grid-template-columns: 120px minmax(0, 1fr);
    gap: 4px 18px;
    align-items: baseline;
  }
}

@media (min-width: 700px) {
  .page-about .a-blocks {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .a-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (min-width: 860px) {
  .page-about .a-timeline {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 0 26px;
  }

  .page-about .a-tl-node {
    padding: 46px 8px 0 0;
    border-left: 0;
  }

  .page-about .a-tl-node::before {
    content: "";
    position: absolute;
    top: 30px;
    left: 0;
    right: -26px;
    height: 1px;
    background: var(--line);
  }

  .page-about .a-tl-node:last-child::before {
    right: 0;
    background: linear-gradient(90deg, var(--line), transparent 70%);
  }

  .page-about .a-tl-num {
    position: absolute;
    top: 0;
    left: 0;
  }

  .page-about .a-tl-dot {
    top: 26px;
    left: 0;
  }

  .page-about .a-rhythm__row {
    grid-template-columns: 158px minmax(0, 1fr) minmax(0, 1.4fr);
    align-items: baseline;
    gap: 6px 24px;
    padding: 22px 8px;
  }
}

@media (min-width: 900px) {
  .page-about .a-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    align-items: end;
    gap: 40px;
  }

  .page-about .a-youth__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.92fr);
    align-items: start;
  }
}

@media (min-width: 1060px) {
  .page-about .a-blocks {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .a-hero__lead {
    max-width: 40em;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .a-block,
  .page-about .a-tl-num {
    transition: none;
  }

  .page-about .a-block:hover,
  .page-about .a-block:focus-within {
    transform: none;
  }
}