.page-about {
  background: var(--ink-950);
  color: var(--cool-50);
  padding-bottom: clamp(56px, 8vw, 104px);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: clamp(34px, 5.5vw, 78px) 0 clamp(40px, 6vw, 78px);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  z-index: 0;
  left: -34%;
  right: -8%;
  top: -72%;
  height: 224%;
  background: var(--ink-900);
  transform: rotate(-8.5deg);
  transform-origin: 34% 50%;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  z-index: 1;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan-400) 22%, var(--cyan-400) 64%, transparent);
  opacity: 0.55;
}

.page-about .about-hero > .container {
  position: relative;
  z-index: 2;
}

.page-about .breadcrumb {
  margin-bottom: clamp(24px, 4vw, 46px);
}

.page-about .about-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(32px, 5.4vw, 64px);
  line-height: 1.05;
  letter-spacing: -0.012em;
  margin: 0 0 var(--sp-3);
  max-width: 17ch;
}

.page-about .lead {
  max-width: 34em;
  font-size: clamp(15px, 1.4vw, 17px);
  line-height: 1.85;
  margin: 0;
  color: rgba(241, 247, 244, 0.9);
}

.page-about .hero-facts {
  list-style: none;
  margin: 0;
  padding: var(--sp-4) 0 0;
  border-top: 1px dashed var(--ink-700);
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3) clamp(24px, 5vw, 64px);
}

.page-about .hero-facts .stat-value {
  font-family: var(--font-num);
  font-size: clamp(22px, 2.6vw, 32px);
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--cyan-400);
}

.page-about .hero-facts .stat-label {
  color: var(--slate-500);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  font-family: var(--font-num);
}

/* ---------- 双栏骨架 ---------- */

.page-about .about-shell {
  margin-top: clamp(38px, 6vw, 74px);
}

/* ---------- 左窄栏赛季刻度 ---------- */

.page-about .about-rail__inner {
  position: sticky;
  top: 132px;
  padding-right: var(--sp-3);
}

.page-about .rail-label {
  font-family: var(--font-num);
  font-size: 11.5px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--slate-500);
  margin: 0 0 var(--sp-3);
}

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

.page-about .rail-node {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 9px 0 9px 20px;
}

.page-about .rail-node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 10px;
  height: 1px;
  background: var(--slate-700);
  transition: width var(--dur-2) var(--ease), background var(--dur-2) var(--ease);
}

.page-about .rail-node[aria-current="true"]::before {
  width: 17px;
  height: 2px;
  background: var(--cyan-400);
}

.page-about .rail-year {
  font-family: var(--font-num);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--cool-50);
}

.page-about .rail-node[aria-current="true"] .rail-year {
  color: var(--cyan-400);
}

.page-about .rail-tag {
  font-family: var(--font-num);
  font-size: 11.5px;
  letter-spacing: 0.04em;
  color: var(--slate-500);
}

/* ---------- 右宽区连续画布 ---------- */

.page-about .about-stream > section {
  padding-bottom: clamp(36px, 5.5vw, 72px);
}

.page-about .about-stream > section:last-of-type {
  padding-bottom: 0;
}

.page-about .about-sec-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(23px, 2.9vw, 37px);
  line-height: 1.16;
  letter-spacing: -0.008em;
  margin: 0 0 var(--sp-3);
  max-width: 24ch;
}

.page-about .about-sec-title::before {
  content: "";
  display: block;
  width: 22px;
  height: 2px;
  background: var(--cyan-400);
  margin-bottom: 15px;
}

.page-about .about-body p {
  max-width: 36em;
  font-size: 16px;
  line-height: 1.85;
  margin: 0 0 var(--sp-3);
  color: rgba(241, 247, 244, 0.88);
}

.page-about .about-body a {
  color: var(--cyan-200);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.page-about .about-body a:hover,
.page-about .about-body a:focus-visible {
  color: var(--cyan-400);
}

.page-about .about-note {
  font-family: var(--font-num);
  font-size: 12.5px;
  line-height: 1.75;
  letter-spacing: 0.04em;
  color: rgba(241, 247, 244, 0.5);
  max-width: 54em;
  margin: var(--sp-3) 0 0;
}

/* ---------- 六步流程（折叠） ---------- */

.page-about .flow-list {
  list-style: none;
  margin: var(--sp-4) 0 0;
  padding: 0;
}

.page-about .flow-step {
  position: relative;
  padding-bottom: var(--sp-2);
}

.page-about .flow-step::before {
  content: "";
  display: block;
  height: 5px;
  background-image: repeating-linear-gradient(90deg, var(--ink-700) 0 1px, transparent 1px 11px);
  opacity: 0.9;
  margin-bottom: var(--sp-1);
}

.page-about .flow-step.log-item {
  background: transparent;
  border: 0;
  border-radius: 0;
}

.page-about .flow-trigger {
  display: flex;
  align-items: baseline;
  gap: var(--sp-3);
  width: 100%;
  padding: var(--sp-2) 0 var(--sp-1);
  background: none;
  border: 0;
  color: inherit;
  text-align: left;
  cursor: pointer;
  font: inherit;
}

.page-about .flow-no {
  font-family: var(--font-num);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--cyan-400);
  flex: 0 0 auto;
}

.page-about .flow-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(17px, 1.8vw, 21px);
  letter-spacing: -0.004em;
  flex: 1 1 auto;
  min-width: 0;
  color: var(--cool-50);
}

.page-about .flow-hint {
  font-family: var(--font-num);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--slate-500);
  flex: 0 0 auto;
}

.page-about .flow-lead {
  max-width: 34em;
  margin: 0 0 var(--sp-2) 0;
  padding-left: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(241, 247, 244, 0.74);
}

.page-about .flow-panel {
  padding: 0 0 var(--sp-3) 0;
}

.page-about .flow-panel p {
  margin: 0;
  max-width: 34em;
  font-family: var(--font-num);
  font-size: 13px;
  line-height: 1.8;
  letter-spacing: 0.03em;
  color: rgba(241, 247, 244, 0.56);
}

/* ---------- 时间线横幅 ---------- */

.page-about .about-banner {
  position: relative;
  margin: 0 0 var(--sp-6);
  border-radius: var(--r-md);
  overflow: hidden;
  background: var(--ink-900);
}

.page-about .about-banner img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 1920 / 720;
  object-fit: cover;
}

.page-about .about-banner figcaption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: var(--sp-4) var(--sp-4) var(--sp-3);
  background: linear-gradient(to top, rgba(5, 19, 15, 0.92), rgba(5, 19, 15, 0));
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan-200);
}

/* ---------- 赛季刻度横线 ---------- */

.page-about .season-line {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  position: relative;
}

.page-about .season-node {
  position: relative;
  padding: 0 16px 0 0;
  outline: none;
}

.page-about .season-node::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 30px;
  height: 1px;
  background: var(--ink-700);
}

.page-about .season-year {
  display: block;
  font-family: var(--font-num);
  font-size: 13px;
  line-height: 20px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--slate-500);
  transition: color var(--dur-2) var(--ease);
}

.page-about .season-dot {
  position: absolute;
  left: 0;
  top: 26px;
  width: 9px;
  height: 9px;
  box-sizing: border-box;
  border-radius: 50%;
  background: var(--ink-800);
  border: 1px solid var(--ink-700);
  transition: background var(--dur-2) var(--ease), border-color var(--dur-2) var(--ease);
}

.page-about .season-node--now .season-dot {
  background: var(--cyan-400);
  border-color: var(--cyan-400);
  box-shadow: 0 0 0 4px rgba(53, 240, 200, 0.14);
}

.page-about .season-note {
  display: block;
  margin-top: 16px;
  max-height: 3.4em;
  overflow: hidden;
  font-size: 12.5px;
  line-height: 1.68;
  color: rgba(241, 247, 244, 0.6);
  transition: max-height var(--dur-3) var(--ease), color var(--dur-2) var(--ease);
}

.page-about .season-node:hover .season-note,
.page-about .season-node:focus-visible .season-note,
.page-about .season-node:focus-within .season-note {
  max-height: 12em;
  color: rgba(241, 247, 244, 0.88);
}

.page-about .season-node:hover .season-year,
.page-about .season-node:focus-visible .season-year {
  color: var(--cyan-200);
}

/* ---------- 版本演进 ---------- */

.page-about .ver-wrap {
  position: relative;
  margin-top: var(--sp-4);
}

.page-about .ver-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  border-radius: var(--r-md);
  opacity: 0.09;
  pointer-events: none;
}

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

.page-about .ver-wrap .filter-bar,
.page-about .ver-wrap .ver-list {
  position: relative;
  z-index: 1;
}

.page-about .filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--sp-2);
  padding-bottom: var(--sp-3);
  margin-bottom: var(--sp-3);
  border-bottom: 1px solid var(--ink-700);
}

.page-about .filter-capsule {
  font-family: var(--font-num);
  font-size: 12.5px;
  letter-spacing: 0.06em;
}

.page-about .filter-count {
  margin-left: auto;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--slate-500);
}

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

.page-about .ver-row.filter-item {
  display: grid;
  grid-template-columns: minmax(66px, 92px) minmax(0, 1fr) auto;
  gap: var(--sp-2) var(--sp-3);
  align-items: baseline;
  padding: var(--sp-3) 0;
  border-bottom: 1px dashed var(--ink-700);
}

.page-about .ver-no {
  font-family: var(--font-num);
  font-size: clamp(17px, 1.9vw, 23px);
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--cyan-400);
  justify-self: start;
  padding-bottom: 2px;
  border-bottom: 2px solid rgba(53, 240, 200, 0.32);
}

.page-about .ver-body {
  display: flex;
  flex-direction: column;
  gap: 5px;
  min-width: 0;
}

.page-about .ver-head {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: -0.004em;
  color: var(--cool-50);
}

.page-about .ver-desc {
  font-size: 14px;
  line-height: 1.75;
  color: rgba(241, 247, 244, 0.72);
  max-width: 36em;
}

.page-about .ver-row .badge {
  white-space: nowrap;
}

/* ---------- 分工 ---------- */

.page-about .unit-list {
  list-style: none;
  margin: var(--sp-4) 0 0;
  padding: 0;
}

.page-about .unit-row {
  display: grid;
  grid-template-columns: 78px minmax(0, 1fr);
  gap: 6px var(--sp-4);
  padding: var(--sp-3) 0;
  border-top: 1px solid var(--ink-700);
}

.page-about .unit-count {
  grid-row: span 2;
  font-family: var(--font-num);
  font-size: clamp(28px, 3.4vw, 42px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--amber-500);
}

.page-about .unit-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.004em;
  color: var(--cool-50);
}

.page-about .unit-desc {
  margin: 0;
  max-width: 34em;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(241, 247, 244, 0.78);
}

/* ---------- 边界清单 ---------- */

.page-about .nope-list {
  list-style: none;
  margin: var(--sp-4) 0 0;
  padding: 0;
  display: grid;
  gap: var(--sp-3);
}

.page-about .nope-list li {
  position: relative;
  padding-left: 28px;
  max-width: 36em;
  font-size: 15.5px;
  line-height: 1.85;
  color: rgba(241, 247, 244, 0.86);
}

.page-about .nope-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 14px;
  height: 1px;
  background: var(--signal-600);
}

/* ---------- 90+ 分割线与收束 ---------- */

.page-about .about-tickline {
  height: 9px;
  margin: var(--sp-5) 0 var(--sp-5);
  background-image: repeating-linear-gradient(90deg, var(--ink-700) 0 1px, transparent 1px 26px);
}

.page-about .about-outro {
  padding-top: var(--sp-2);
}

.page-about .about-outro .about-sec-title {
  max-width: 18ch;
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  margin-top: var(--sp-4);
}

/* ---------- 响应式 ---------- */

@media (max-width: 980px) {
  .page-about .ver-row.filter-item {
    grid-template-columns: minmax(0, 1fr) auto;
  }

  .page-about .ver-no {
    grid-column: 1 / -1;
  }
}

@media (max-width: 900px) {
  .page-about .about-rail {
    margin-bottom: var(--sp-5);
  }

  .page-about .about-rail__inner {
    position: static;
    padding-right: 0;
    border-bottom: 1px solid var(--ink-700);
    padding-bottom: var(--sp-3);
  }

  .page-about .rail-list {
    display: flex;
    gap: 20px;
    overflow-x: auto;
    padding-bottom: 6px;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

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

  .page-about .rail-node {
    flex: 0 0 auto;
    white-space: nowrap;
    padding: 8px 0 8px 18px;
  }

  .page-about .about-shell {
    margin-top: clamp(28px, 6vw, 48px);
  }
}

@media (max-width: 760px) {
  .page-about .about-hero::before {
    left: -52%;
    right: -24%;
    top: -58%;
    height: 200%;
    transform: rotate(-7deg);
  }

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

  .page-about .hero-facts {
    gap: var(--sp-3) var(--sp-4);
  }

  .page-about .season-line {
    grid-template-columns: none;
    grid-auto-flow: column;
    grid-auto-columns: 62%;
    overflow-x: auto;
    padding-bottom: var(--sp-3);
    scroll-snap-type: x proximity;
    -webkit-overflow-scrolling: touch;
  }

  .page-about .season-node {
    scroll-snap-align: start;
    padding-right: 22px;
  }

  .page-about .season-note {
    max-height: none;
    overflow: visible;
  }

  .page-about .ver-row.filter-item {
    grid-template-columns: minmax(0, 1fr);
    gap: 8px;
  }

  .page-about .ver-row .badge {
    justify-self: start;
  }

  .page-about .unit-row {
    grid-template-columns: 60px minmax(0, 1fr);
    gap: 6px var(--sp-3);
  }

  .page-about .flow-trigger {
    flex-wrap: wrap;
    gap: var(--sp-2);
  }

  .page-about .flow-hint {
    margin-left: auto;
  }
}

@media (max-width: 480px) {
  .page-about .about-title {
    max-width: 100%;
  }

  .page-about .flow-hint {
    display: none;
  }

  .page-about .filter-count {
    margin-left: 0;
    width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .season-note,
  .page-about .season-dot,
  .page-about .season-year,
  .page-about .rail-node::before {
    transition: none;
  }
}