.page-about {
  color: var(--text-900);
}

/* ============ Hero ============ */
.page-about .about-hero {
  padding-top: 26px;
  padding-bottom: 52px;
  background:
    radial-gradient(120% 90% at 92% 0%, var(--brand-100) 0%, transparent 58%),
    linear-gradient(180deg, var(--paper) 0%, var(--mist-100) 100%);
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-hero .breadcrumb {
  margin-bottom: 22px;
}

.page-about .about-hero__title {
  margin: 12px 0 20px;
  font-size: clamp(27px, 5.4vw, 48px);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: .01em;
  max-width: 21ch;
  text-wrap: balance;
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 66ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--text-900);
}

.page-about .about-facts {
  margin-top: 36px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-m);
  overflow: hidden;
}

.page-about .about-fact {
  background: var(--paper);
  padding: 18px 18px 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 0;
}

.page-about .about-fact__num {
  font-size: clamp(21px, 3vw, 29px);
  font-weight: 500;
  color: var(--brand-600);
  letter-spacing: .02em;
  line-height: 1.15;
  word-break: break-word;
}

.page-about .about-fact__label {
  font-size: 13px;
  line-height: 1.5;
  color: var(--slate-500);
}

/* ============ 通用图片容器 ============ */
.page-about .about-figure {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-m);
  border: 1px solid var(--line-soft);
  background: var(--mist-100);
  object-fit: cover;
}

/* ============ 定位与边界 ============ */
.page-about .about-scope {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-bottom: 26px;
}

.page-about .about-scope__col {
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-m);
  padding: 24px 22px;
}

.page-about .about-scope__col h3 {
  margin: 0 0 16px;
  font-size: 18px;
  font-weight: 600;
  line-height: 1.4;
}

.page-about .about-scope__col .checklist {
  margin: 0;
}

.page-about .about-scope__col--dont {
  border-color: var(--line-mid);
}

.page-about .about-scope__col--dont .checklist__item::before {
  color: var(--amber-600);
}

.page-about .checklist--x .checklist__item::before {
  color: var(--amber-600);
  content: "—";
}

/* ============ 改版历程 ============ */
.page-about .about-versions__figure {
  margin: 26px 0 32px;
}

.page-about .about-rail {
  list-style: none;
  margin: 0 0 34px;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 4px;
  position: relative;
}

.page-about .about-rail::before {
  content: "";
  position: absolute;
  left: 12%;
  right: 12%;
  top: 55px;
  height: 1px;
  background: var(--slate-300);
  z-index: 0;
}

.page-about .about-rail__node {
  position: relative;
  z-index: 1;
  min-width: 0;
}

.page-about .about-rail__node a {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 8px 2px 6px;
  text-decoration: none;
  color: var(--slate-500);
  transition: color var(--dur-1) var(--ease);
}

.page-about .about-rail__node a:hover {
  color: var(--text-900);
}

.page-about .about-rail__dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--paper);
  border: 2px solid var(--slate-300);
  box-shadow: 0 0 0 4px var(--paper);
  transition:
    background-color var(--dur-2) var(--ease),
    border-color var(--dur-2) var(--ease),
    transform var(--dur-2) var(--ease),
    box-shadow var(--dur-2) var(--ease);
}

.page-about .about-rail__ver {
  font-size: 12px;
  letter-spacing: .02em;
  line-height: 1.3;
}

.page-about .about-rail__name {
  font-size: 12px;
  line-height: 1.4;
  text-align: center;
  word-break: keep-all;
}

.page-about .about-rail__node a[aria-current="true"] {
  color: var(--text-900);
}

.page-about .about-rail__node a[aria-current="true"] .about-rail__dot {
  background: var(--brand-600);
  border-color: var(--brand-600);
  transform: scale(1.35);
  box-shadow: 0 0 0 5px var(--brand-100);
}

.page-about .about-stages {
  display: grid;
}

.page-about .about-stage {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  padding: 26px 0;
  border-top: 1px dashed var(--slate-300);
  scroll-margin-top: 90px;
}

.page-about .about-stage:last-child {
  border-bottom: 1px dashed var(--slate-300);
}

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

.page-about .about-stage__ver {
  font-size: 22px;
  font-weight: 500;
  color: var(--brand-600);
  letter-spacing: .02em;
  line-height: 1.1;
}

.page-about .about-stage__tag {
  display: inline-block;
  font-size: 12px;
  line-height: 1;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--brand-100);
  color: var(--brand-600);
  letter-spacing: .06em;
}

.page-about .about-stage__body h3 {
  margin: 0 0 10px;
  font-size: 19px;
  font-weight: 600;
  line-height: 1.4;
}

.page-about .about-stage__body p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.78;
}

.page-about .about-stage__points {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
  font-size: 14px;
  line-height: 1.72;
  color: var(--slate-500);
}

.page-about .about-stage__points li {
  position: relative;
  padding-left: 16px;
}

.page-about .about-stage__points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .78em;
  width: 7px;
  height: 1px;
  background: var(--slate-300);
}

/* ============ 两轮校对 ============ */
.page-about .about-verify__figure {
  margin: 4px 0 28px;
}

.page-about .about-verify {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

.page-about .about-verify__step {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 26px 22px;
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-m);
  position: relative;
  overflow: hidden;
}

.page-about .about-verify__step::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: var(--brand-600);
}

.page-about .about-verify__step--pass {
  border-color: var(--teal-500);
  box-shadow: 0 14px 34px -26px rgba(15, 176, 138, .85);
}

.page-about .about-verify__step--pass::before {
  background: var(--teal-500);
}

.page-about .about-verify__idx {
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--slate-500);
  text-transform: uppercase;
}

.page-about .about-verify__step h3 {
  margin: 0;
  font-size: 20px;
  font-weight: 600;
  line-height: 1.35;
}

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

.page-about .about-verify__step .checklist {
  margin: 0;
}

.page-about .about-verify__step .badge {
  align-self: flex-start;
}

.page-about .checklist--ok .checklist__item::before {
  color: var(--teal-500);
  content: "✓";
}

/* ============ 更新节奏 ============ */
.page-about .about-cadence {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-bottom: 32px;
}

.page-about .about-cadence__stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 24px 22px 26px;
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-m);
  position: relative;
  overflow: hidden;
}

.page-about .about-cadence__stat::after {
  content: "";
  position: absolute;
  right: -30px;
  bottom: -40px;
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: var(--brand-100);
  opacity: .7;
  z-index: 0;
}

.page-about .about-cadence__stat > * {
  position: relative;
  z-index: 1;
}

.page-about .about-cadence__num {
  font-size: clamp(34px, 6vw, 52px);
  font-weight: 500;
  letter-spacing: .02em;
  color: var(--brand-600);
  line-height: 1;
}

.page-about .about-cadence__unit {
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--slate-500);
}

.page-about .about-cadence__stat p {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--text-900);
}

.page-about .about-cat {
  display: grid;
  grid-template-columns: 1fr;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-cat__item {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 12px;
  align-items: start;
  padding: 20px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-cat__key {
  font-size: 14px;
  font-weight: 500;
  letter-spacing: .08em;
  color: var(--brand-600);
  padding-top: 3px;
}

.page-about .about-cat__item h3 {
  margin: 0 0 6px;
  font-size: 17px;
  font-weight: 600;
  line-height: 1.4;
}

.page-about .about-cat__item p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--slate-500);
}

/* ============ 专题体系 ============ */
.page-about .about-topics__figure {
  margin: 0 0 26px;
}

.page-about .about-topics__filter {
  margin: 0 0 22px;
}

.page-about .topic-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.page-about .topic-cell {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 16px 14px 18px;
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-s);
  min-width: 0;
  transition:
    background-color var(--dur-2) var(--ease),
    border-color var(--dur-2) var(--ease),
    transform var(--dur-2) var(--ease);
}

.page-about .topic-cell:hover {
  background: var(--brand-100);
  border-color: var(--brand-400);
}

.page-about .topic-cell[hidden] {
  display: none;
}

.page-about .topic-cell__idx {
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--brand-600);
}

.page-about .topic-cell__name {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  word-break: break-word;
}

.page-about .topic-cell__text {
  margin: 0;
  font-size: 13px;
  line-height: 1.62;
  color: var(--slate-500);
}

.page-about .about-topics__more {
  margin: 28px 0 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--text-900);
}

.page-about .about-topics__more a {
  color: var(--brand-600);
  text-decoration: none;
  border-bottom: 1px solid var(--brand-100);
  padding-bottom: 1px;
  transition: border-color var(--dur-1) var(--ease);
}

.page-about .about-topics__more a:hover {
  border-bottom-color: var(--brand-600);
}

/* ============ 备案与联络 ============ */
.page-about .about-meta {
  background: var(--ink-900);
  color: var(--on-dark);
}

.page-about .about-meta__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

.page-about .about-meta__eyebrow {
  color: var(--brand-400);
}

.page-about .about-meta__title {
  margin: 10px 0 16px;
  font-size: clamp(21px, 3.6vw, 30px);
  font-weight: 700;
  line-height: 1.32;
  letter-spacing: .01em;
  color: var(--on-dark-strong);
  max-width: 22ch;
}

.page-about .about-meta__text {
  margin: 0 0 22px;
  max-width: 64ch;
  font-size: 15px;
  line-height: 1.78;
  color: var(--on-dark-muted);
}

.page-about .about-meta__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--on-dark-line);
  border: 1px solid var(--on-dark-line);
  border-radius: var(--radius-m);
  overflow: hidden;
}

.page-about .about-meta__list li {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
  background: var(--ink-800);
  min-width: 0;
}

.page-about .about-meta__label {
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--on-dark-muted);
}

.page-about .about-meta__value {
  font-size: 14.5px;
  line-height: 1.6;
  color: var(--on-dark-strong);
  word-break: break-word;
}

.page-about .about-meta__aside {
  padding: 22px 20px 24px;
  background: var(--glass);
  border: 1px solid var(--on-dark-line-strong);
  border-radius: var(--radius-m);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.page-about .about-meta__aside h3 {
  margin: 0 0 14px;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.45;
  color: var(--on-dark-strong);
}

.page-about .about-meta__aside .checklist {
  margin: 0;
}

.page-about .about-meta__aside .checklist__item {
  color: var(--on-dark);
}

.page-about .about-meta__aside .checklist--x .checklist__item::before {
  color: var(--amber-600);
}

.page-about .about-meta__note {
  margin: 18px 0 0;
  font-size: 13.5px;
  line-height: 1.72;
  color: var(--on-dark-muted);
}

.page-about .about-meta__note a {
  color: var(--brand-400);
  text-decoration: none;
  border-bottom: 1px solid rgba(79, 139, 255, .4);
  transition: border-color var(--dur-1) var(--ease);
}

.page-about .about-meta__note a:hover {
  border-bottom-color: var(--brand-400);
}

/* ============ 响应式 ============ */
@media (min-width: 640px) {
  .page-about .about-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-rail::before {
    top: 58px;
  }

  .page-about .about-rail__ver,
  .page-about .about-rail__name {
    font-size: 13px;
  }

  .page-about .about-cadence {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
  }

  .page-about .topic-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 12px;
  }
}

@media (min-width: 800px) {
  .page-about .about-scope {
    grid-template-columns: 1fr 1fr;
    gap: 22px;
  }

  .page-about .about-verify {
    grid-template-columns: 1fr 1fr;
    gap: 20px;
  }

  .page-about .about-stage {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: 32px;
    padding: 32px 0;
  }

  .page-about .about-stage__id {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .page-about .about-stage__ver {
    font-size: 26px;
  }

  .page-about .about-stage__body h3 {
    font-size: 20px;
  }
}

@media (min-width: 900px) {
  .page-about .about-meta__grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    gap: 48px;
    align-items: start;
  }
}

@media (min-width: 1000px) {
  .page-about .topic-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 14px;
  }

  .page-about .about-rail__ver,
  .page-about .about-rail__name {
    font-size: 14px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__dot,
  .page-about .topic-cell,
  .page-about .about-rail__node a,
  .page-about .about-topics__more a,
  .page-about .about-meta__note a {
    transition: none !important;
  }

  .page-about .about-rail__node a[aria-current="true"] .about-rail__dot {
    transform: none;
  }
}