.page-about {
  --ab-rail: 88px;
  --ab-radius: 20px;
  --ab-pad: clamp(20px, 3.4vw, 48px);
  display: block;
  background: var(--sand);
  color: var(--rock);
}

.page-about .breadcrumb {
  padding-top: clamp(14px, 2.4vw, 26px);
}

/* ---------- 档案封面 ---------- */

.page-about .about-cover {
  padding-bottom: clamp(24px, 4vw, 52px);
}

.page-about .about-cover__grid {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.4vw, 44px);
  align-items: end;
  padding-top: clamp(18px, 3vw, 40px);
}

.page-about .about-cover__title {
  margin: 14px 0 0;
  color: var(--ink);
  max-width: 15em;
}

.page-about .about-cover__lede {
  margin: clamp(16px, 2.4vw, 26px) 0 0;
  max-width: 46em;
}

.page-about .about-cover__anno {
  display: none;
}

.page-about .about-cover__meta {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px 24px;
  margin: 0;
  padding-top: 22px;
  border-top: var(--hair);
}

.page-about .about-meta__row {
  min-width: 0;
}

.page-about .about-meta__row dt {
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--rock-2);
  margin-bottom: 5px;
}

.page-about .about-meta__row dd {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(17px, 2vw, 21px);
  font-weight: 700;
  color: var(--ink);
  letter-spacing: -0.01em;
}

.page-about .about-cover__figure {
  margin: clamp(26px, 4vw, 52px) 0 0;
}

.page-about .about-cover__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 2 / 1;
  object-fit: cover;
}

/* ---------- 主体：年份轴 + 连续画布 ---------- */

.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 36px);
  padding-bottom: clamp(40px, 6vw, 88px);
}

.page-about .about-stream {
  min-width: 0;
}

.page-about .about-rail {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px 14px;
  padding-bottom: 10px;
  border-bottom: var(--hair-soft);
}

.page-about .about-rail__label {
  margin: 0 6px 0 0;
  font-size: 12px;
  letter-spacing: 0.24em;
  color: var(--rock-2);
  white-space: nowrap;
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px 14px;
}

.page-about .about-rail__link {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  letter-spacing: 0.04em;
  color: var(--rock-2);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}

.page-about .about-rail__link::before {
  content: "";
  width: 12px;
  height: 1px;
  background: var(--gold);
  opacity: 0.45;
  transition: width var(--dur) var(--ease), opacity var(--dur) var(--ease);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link.is-active {
  color: var(--ink);
}

.page-about .about-rail__link:hover::before,
.page-about .about-rail__link.is-active::before {
  width: 24px;
  opacity: 1;
}

/* ---------- 章节骨架 ---------- */

.page-about .about-section {
  padding: clamp(34px, 5vw, 70px) 0;
  border-top: var(--hair-soft);
}

.page-about .about-section:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-section--light {
  margin: clamp(18px, 2.6vw, 34px) 0;
  padding: clamp(30px, 4.4vw, 60px) var(--ab-pad);
  background: var(--sand-2);
  border-top: 0;
  border-radius: var(--ab-radius);
}

.page-about .section-head {
  max-width: 730px;
}

.page-about .about-sub {
  margin: clamp(28px, 4vw, 46px) 0 0;
  font-size: clamp(17px, 2vw, 20px);
  font-weight: 700;
  color: var(--ink);
  letter-spacing: 0.02em;
}

.page-about .about-sub-note {
  margin: 14px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--rock-2);
  max-width: 60ch;
}

/* ---------- 版本筛选与版本条目 ---------- */

.page-about .filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 26px 0 4px;
}

.page-about .filter-btn {
  appearance: none;
  border: 1px solid rgba(74, 74, 74, 0.22);
  background: transparent;
  color: var(--rock);
  font: inherit;
  font-size: 14px;
  line-height: 1;
  padding: 9px 16px;
  border-radius: 999px;
  cursor: pointer;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .filter-btn:hover {
  border-color: var(--gold);
  color: var(--ink);
}

.page-about .filter-btn[aria-pressed="true"] {
  background: var(--green);
  border-color: var(--green);
  color: var(--sand-2);
}

.page-about .about-versions {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
}

.page-about .about-version {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  padding: clamp(20px, 2.6vw, 30px) 0;
  border-bottom: var(--hair-soft);
}

.page-about [data-tags][hidden] {
  display: none !important;
}

.page-about .about-version__badge {
  display: flex;
  flex-direction: row;
  align-items: baseline;
  gap: 12px;
}

.page-about .about-version__code {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(22px, 3vw, 28px);
  font-weight: 700;
  color: var(--gold-deep);
  letter-spacing: -0.01em;
}

.page-about .about-version__year {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 13px;
  letter-spacing: 0.18em;
  color: var(--rock-2);
}

.page-about .about-version__title {
  margin: 0 0 10px;
  font-size: clamp(18px, 2.2vw, 22px);
  font-weight: 700;
  color: var(--ink);
  line-height: 1.4;
}

.page-about .about-version__body p {
  margin: 0;
  font-size: 16px;
  line-height: 1.85;
  color: var(--rock);
  max-width: 62ch;
}

.page-about .about-version__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 34px;
  margin: 16px 0 0;
}

.page-about .about-version__facts > div {
  display: flex;
  align-items: baseline;
  gap: 9px;
}

.page-about .about-version__facts dt {
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--rock-2);
}

.page-about .about-version__facts dd {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  font-weight: 700;
  color: var(--ink);
}

/* ---------- 核定流程 ---------- */

.page-about .about-flow {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
}

.page-about .about-flow > li {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 4px 16px;
  padding: 18px 0;
  border-bottom: var(--hair-soft);
}

.page-about .about-flow > li:first-child {
  border-top: var(--hair-soft);
}

.page-about .about-flow__num {
  grid-row: 1 / span 2;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 20px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--gold);
}

.page-about .about-flow__title {
  margin: 0;
  font-size: 17px;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: 0.02em;
}

.page-about .about-flow__text {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--rock);
}

.page-about .about-params {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* ---------- 覆盖结构 ---------- */

.page-about .about-coverage {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 52px);
  align-items: start;
}

.page-about .about-layers {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
}

.page-about .about-layers > li {
  display: grid;
  grid-template-columns: 62px minmax(0, 1fr);
  gap: 2px 14px;
  padding: 15px 0;
  border-top: var(--hair-soft);
}

.page-about .about-layers__num {
  grid-row: 1 / span 2;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(24px, 3.2vw, 32px);
  font-weight: 700;
  line-height: 1.15;
  color: var(--gold);
}

.page-about .about-layers__name {
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-layers__desc {
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--rock-2);
}

.page-about .about-coverage__graphic {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.page-about .about-ring {
  display: block;
  width: 100%;
  max-width: 300px;
  height: auto;
}

.page-about .about-ring__c {
  fill: none;
}

.page-about .about-ring__c--1 {
  stroke: var(--gold);
  stroke-width: 9;
}

.page-about .about-ring__c--2 {
  stroke: var(--gold-deep);
  stroke-width: 8;
}

.page-about .about-ring__c--3 {
  stroke: var(--teal);
  stroke-width: 7;
}

.page-about .about-ring__c--4 {
  stroke: var(--earth);
  stroke-width: 6;
}

.page-about .about-ring__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 42px;
  font-weight: 700;
  letter-spacing: -0.02em;
  fill: var(--ink);
  text-anchor: middle;
}

.page-about .about-ring__cap {
  font-size: 12px;
  letter-spacing: 0.2em;
  fill: var(--rock-2);
  text-anchor: middle;
}

.page-about .about-ring__legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
  width: 100%;
  max-width: 300px;
}

.page-about .about-ring__legend li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12.5px;
  color: var(--rock-2);
  letter-spacing: 0.03em;
}

.page-about .about-ring__dot {
  width: 16px;
  height: 3px;
  flex: 0 0 auto;
  border-radius: 2px;
}

.page-about .about-ring__dot--1 { background: var(--gold); }
.page-about .about-ring__dot--2 { background: var(--gold-deep); }
.page-about .about-ring__dot--3 { background: var(--teal); }
.page-about .about-ring__dot--4 { background: var(--earth); }

.page-about .about-coverage__figure {
  margin: clamp(30px, 4vw, 54px) 0 0;
}

.page-about .about-coverage__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

/* ---------- 工作组 ---------- */

.page-about .about-teams {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 3vw, 34px);
}

.page-about .about-team {
  padding-top: 16px;
  border-top: var(--hair);
}

.page-about .about-team__code {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--gold-deep);
}

.page-about .about-team__title {
  margin: 0 0 9px;
  font-size: clamp(18px, 2.2vw, 21px);
  font-weight: 700;
  color: var(--ink);
  line-height: 1.4;
}

.page-about .about-team__text {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--rock);
}

.page-about .about-team__meta {
  margin: 12px 0 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--rock-2);
}

.page-about .about-teams__figure {
  margin: clamp(30px, 4vw, 54px) 0 0;
}

.page-about .about-teams__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 14 / 9;
  object-fit: cover;
}

/* ---------- 合作生态 ---------- */

.page-about .about-eco {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 2.8vw, 32px);
}

.page-about .about-eco__item {
  padding-top: 16px;
  border-top: var(--hair-soft);
}

.page-about .about-eco__title {
  margin: 0 0 9px;
  font-size: 17px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-eco__item p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--rock);
}

.page-about .about-eco__meta {
  margin-top: 12px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: 0.05em;
  color: var(--rock-2);
}

/* ---------- 收束区块 ---------- */

.page-about .about-close {
  background: var(--green);
  color: var(--sand-2);
  padding: clamp(46px, 6.5vw, 92px) 0 clamp(44px, 6vw, 84px);
  margin-bottom: clamp(36px, 5vw, 72px);
}

.page-about .about-close__anno {
  color: var(--gold);
}

.page-about .about-close__body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
  margin-top: 20px;
}

.page-about .about-close__num {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(68px, 10vw, 132px);
  font-weight: 700;
  line-height: 0.85;
  color: var(--gold);
  letter-spacing: -0.03em;
}

.page-about .about-close__title {
  margin: 0 0 14px;
  font-size: clamp(21px, 2.8vw, 30px);
  font-weight: 700;
  line-height: 1.38;
  color: var(--sand-2);
}

.page-about .about-close__text {
  margin: 0;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(251, 246, 236, 0.82);
  max-width: 60ch;
}

.page-about .about-close__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 24px 0 0;
}

.page-about .about-close .btn--ghost {
  color: var(--sand-2);
  border-color: rgba(251, 246, 236, 0.42);
  background: transparent;
}

.page-about .about-close .btn--ghost:hover {
  color: var(--gold);
  border-color: var(--gold);
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .about-version {
    grid-template-columns: 128px minmax(0, 1fr);
    gap: clamp(20px, 3vw, 42px);
  }

  .page-about .about-version__badge {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }

  .page-about .about-team {
    padding-left: 2px;
  }

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

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

@media (min-width: 900px) {
  .page-about .about-cover__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
  }

  .page-about .about-cover__meta {
    padding-top: 0;
    border-top: 0;
    border-left: var(--hair);
    padding-left: clamp(20px, 2.6vw, 34px);
  }

  .page-about .about-coverage {
    grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
    gap: clamp(32px, 4vw, 60px);
  }

  .page-about .about-close__body {
    grid-template-columns: 160px minmax(0, 1fr);
    gap: clamp(28px, 4vw, 56px);
    align-items: start;
  }
}

@media (min-width: 1000px) {
  .page-about .about-body {
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: clamp(28px, 3.4vw, 52px);
  }

  .page-about .about-rail {
    display: block;
    position: sticky;
    top: 116px;
    align-self: start;
    padding: 0 0 0 16px;
    border-bottom: 0;
    border-left: var(--hair-soft);
  }

  .page-about .about-rail__label {
    writing-mode: vertical-rl;
    margin: 0 0 16px;
    letter-spacing: 0.34em;
  }

  .page-about .about-rail__list {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 2px;
  }
}

@media (min-width: 1100px) {
  .page-about .about-cover__anno {
    display: block;
    position: absolute;
    right: clamp(16px, 2.6vw, 38px);
    top: clamp(10px, 2vw, 26px);
    margin: 0;
  }

  .page-about .about-cover__main {
    padding-right: 46px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .filter-btn,
  .page-about .about-rail__link,
  .page-about .about-rail__link::before {
    transition: none;
  }
}