.page-about {
  --about-rail: 240px;
  --about-line: rgba(28, 37, 51, 0.14);
  --about-line-strong: rgba(28, 37, 51, 0.24);
  --about-text-soft: rgba(28, 37, 51, 0.84);
  background: var(--k8-ink-900);
  color: var(--k8-paper);
  font-family: var(--k8-body);
  overflow-x: hidden;
}

.page-about .page-about__crumb {
  background: var(--k8-ink-900);
  padding-top: 18px;
}

.page-about .k8-crumbs__item a {
  color: var(--k8-line);
  text-decoration: none;
  transition: color 160ms ease;
}

.page-about .k8-crumbs__item a:hover {
  color: var(--k8-paper);
}

.page-about .k8-crumbs__item a[aria-current="page"] {
  color: var(--k8-cyan);
}

.page-about .k8-crumbs__sep {
  color: rgba(143, 163, 184, 0.5);
}

/* 首屏 */
.page-about .about-hero {
  background-color: var(--k8-ink-900);
  background-image:
    linear-gradient(rgba(143, 163, 184, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(143, 163, 184, 0.08) 1px, transparent 1px);
  background-size: 64px 64px;
  padding: clamp(28px, 5vw, 64px) clamp(20px, 5vw, 56px) clamp(36px, 5vw, 64px);
  border-bottom: 1px solid var(--k8-mist);
}

.page-about .about-hero__inner {
  display: grid;
  gap: 32px;
  max-width: 1420px;
  margin: 0 auto;
}

.page-about .about-hero__eyebrow {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  font-family: var(--k8-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--k8-cyan);
}

.page-about .about-hero__eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--k8-cyan);
}

.page-about .about-hero__title {
  margin: 0 0 20px;
  font-family: var(--k8-display);
  font-weight: 800;
  font-size: clamp(30px, 4.4vw, 52px);
  line-height: 1.16;
  letter-spacing: -0.02em;
  color: var(--k8-paper);
  max-width: 18em;
}

.page-about .about-hero__lead {
  margin: 0 0 28px;
  max-width: 40em;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.8;
  color: rgba(242, 245, 247, 0.78);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .about-hero__figure {
  margin: 0;
  border: 1px solid var(--k8-mist);
  background: var(--k8-ink-800);
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  max-width: 1420px;
  margin: 36px auto 0;
  background: var(--k8-mist);
  border: 1px solid var(--k8-mist);
}

.page-about .about-hero__stat {
  background: var(--k8-ink-900);
  padding: 18px 20px;
}

.page-about .about-hero__stat dt {
  margin: 0 0 8px;
  font-family: var(--k8-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--k8-line);
}

.page-about .about-hero__stat dd {
  margin: 0;
  font-size: clamp(26px, 3.2vw, 36px);
  font-weight: 800;
  line-height: 1;
  color: var(--k8-cyan);
}

/* 正文画布 */
.page-about .about-doc {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  background: var(--k8-paper);
  color: var(--k8-graphite);
}

.page-about .about-rail {
  background: var(--k8-ink-800);
  padding: 24px 20px 28px;
  border-bottom: 1px solid var(--k8-mist);
}

.page-about .about-rail__title {
  margin: 0 0 14px;
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--k8-cyan-dark);
}

.page-about .about-rail__list {
  display: flex;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__item {
  flex: 0 0 auto;
}

.page-about .about-rail__link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 12px;
  border: 1px solid var(--k8-mist);
  text-decoration: none;
  color: var(--k8-line);
  white-space: nowrap;
  transition: color 160ms ease, border-color 160ms ease;
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--k8-cyan);
  border-color: var(--k8-cyan-dark);
}

.page-about .about-rail__year {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--k8-paper);
}

.page-about .about-rail__label {
  font-size: 12px;
}

.page-about .about-doc__body {
  min-width: 0;
  padding: 36px clamp(20px, 5vw, 68px) 64px;
}

.page-about .about-chapter {
  max-width: 960px;
  padding: 40px 0;
  border-top: 1px solid var(--about-line);
  scroll-margin-top: 88px;
}

.page-about .about-chapter:first-child {
  padding-top: 8px;
  border-top: 0;
}

.page-about .about-chapter__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 22px;
}

.page-about .about-chapter__index {
  flex: 0 0 auto;
  padding: 3px 8px;
  border: 1px solid var(--k8-cyan-dark);
  font-size: 12px;
  line-height: 1.2;
  letter-spacing: 0.08em;
  color: var(--k8-cyan-dark);
}

.page-about .about-chapter__title {
  margin: 0;
  font-family: var(--k8-display);
  font-weight: 800;
  font-size: clamp(22px, 2.6vw, 32px);
  line-height: 1.24;
  letter-spacing: -0.01em;
  color: var(--k8-graphite);
}

.page-about .about-chapter__body > p,
.page-about .about-chapter__note {
  max-width: 42em;
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.82;
  color: var(--about-text-soft);
}

.page-about .about-chapter h3 {
  margin: 0 0 6px;
  font-family: var(--k8-display);
  font-size: 17px;
  font-weight: 700;
  color: var(--k8-graphite);
}

.page-about .about-chapter__note {
  margin-top: 26px;
  font-size: 15px;
}

.page-about .about-chapter__note a {
  color: var(--k8-violet);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-chapter__note a:hover {
  color: var(--k8-cyan-dark);
}

.page-about .about-chapter__figure {
  margin: 26px 0 0;
  border: 1px solid var(--about-line);
  background: #ffffff;
}

.page-about .about-chapter__figure figcaption {
  padding: 10px 14px 12px;
  border-top: 1px solid var(--about-line);
  font-family: var(--k8-mono);
  font-size: 12px;
  letter-spacing: 0.02em;
  color: var(--k8-line);
}

/* 变更等级 */
.page-about .about-levels {
  display: grid;
  gap: 1px;
  list-style: none;
  margin: 24px 0 8px;
  padding: 0;
  background: var(--about-line);
}

.page-about .about-levels__item {
  padding: 20px 20px 22px;
  background: var(--k8-paper);
  border-top: 2px solid var(--k8-line);
}

.page-about .about-levels__item--major {
  border-top-color: var(--k8-orange);
}

.page-about .about-levels__item--normal {
  border-top-color: var(--k8-cyan-dark);
}

.page-about .about-levels__item--fix {
  border-top-color: var(--k8-violet);
}

.page-about .about-levels__tag {
  display: inline-block;
  margin-bottom: 10px;
  padding: 3px 8px;
  font-family: var(--k8-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--k8-graphite);
  background: rgba(28, 37, 51, 0.07);
}

.page-about .about-levels__item--major .about-levels__tag {
  background: var(--k8-orange-pale);
}

.page-about .about-levels__item--fix .about-levels__tag {
  background: rgba(124, 92, 255, 0.16);
}

.page-about .about-levels p {
  margin: 0;
  font-size: 15px;
  line-height: 1.76;
  color: var(--about-text-soft);
}

/* 栏目记录表 */
.page-about .about-table {
  width: 100%;
  margin: 22px 0 18px;
  border-collapse: collapse;
  font-size: 15px;
  table-layout: auto;
}

.page-about .about-table caption {
  padding-bottom: 10px;
  text-align: left;
  font-family: var(--k8-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--k8-line);
}

.page-about .about-table th,
.page-about .about-table td {
  padding: 12px 10px 12px 0;
  text-align: left;
  vertical-align: middle;
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-table thead th {
  padding-bottom: 8px;
  font-family: var(--k8-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--k8-line);
  border-bottom-color: var(--about-line-strong);
  white-space: nowrap;
}

.page-about .about-table tbody th {
  font-weight: 600;
  color: var(--k8-graphite);
}

.page-about .about-table td.k8-mono {
  width: 84px;
  font-weight: 700;
  color: var(--k8-cyan-dark);
}

.page-about .about-table__bar {
  display: block;
  height: 6px;
  min-width: 4px;
  background: linear-gradient(90deg, var(--k8-cyan-dark), var(--k8-cyan));
}

.page-about .about-bar--100 { width: 100%; }
.page-about .about-bar--76 { width: 76%; }
.page-about .about-bar--71 { width: 71%; }
.page-about .about-bar--65 { width: 65%; }
.page-about .about-bar--53 { width: 53%; }

/* 更新节奏 */
.page-about .about-cadence {
  display: grid;
  gap: 1px;
  margin: 24px 0;
  background: var(--about-line);
}

.page-about .about-cadence__item {
  padding: 22px 20px 24px;
  background: var(--k8-paper);
}

.page-about .about-cadence__period {
  display: block;
  margin-bottom: 10px;
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--k8-cyan-dark);
}

.page-about .about-cadence__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.74;
  color: var(--about-text-soft);
}

/* 服务对象 */
.page-about .about-audience {
  display: grid;
  gap: 18px;
  list-style: none;
  margin: 22px 0 24px;
  padding: 0;
}

.page-about .about-audience > li {
  padding: 4px 0 4px 16px;
  border-left: 2px solid var(--k8-cyan-dark);
}

.page-about .about-audience .k8-tag {
  display: inline-block;
  margin-bottom: 10px;
  padding: 2px 8px;
  font-family: var(--k8-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--k8-ink-800);
  background: rgba(15, 168, 149, 0.16);
}

.page-about .about-audience > li:nth-child(2) {
  border-left-color: var(--k8-violet);
}

.page-about .about-audience > li:nth-child(2) .k8-tag {
  background: rgba(124, 92, 255, 0.16);
}

.page-about .about-audience > li:nth-child(3) {
  border-left-color: var(--k8-orange);
}

.page-about .about-audience > li:nth-child(3) .k8-tag {
  background: var(--k8-orange-pale);
}

.page-about .about-audience p {
  margin: 0;
  font-size: 15px;
  line-height: 1.74;
  color: var(--about-text-soft);
}

/* 里程碑 */
.page-about .about-milestones__filter {
  margin: 18px 0 20px;
}

.page-about .about-milestones {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--about-line);
}

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

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

.page-about .about-milestone {
  background: transparent;
}

.page-about .about-milestone__summary {
  position: relative;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 18px 40px 18px 0;
  list-style: none;
  cursor: pointer;
}

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

.page-about .about-milestone__summary::after {
  content: "+";
  position: absolute;
  right: 6px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--k8-mono);
  font-size: 20px;
  line-height: 1;
  color: var(--k8-cyan-dark);
}

.page-about .about-milestone[open] .about-milestone__summary::after {
  content: "-";
}

.page-about .about-milestone__year {
  flex: 0 0 68px;
  font-size: 20px;
  font-weight: 700;
  color: var(--k8-graphite);
}

.page-about .about-milestone__title {
  font-family: var(--k8-display);
  font-size: 17px;
  font-weight: 700;
  color: var(--k8-graphite);
}

.page-about .about-milestone__badge {
  margin-left: auto;
  padding: 3px 8px;
  font-family: var(--k8-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  white-space: nowrap;
  color: var(--k8-ink-900);
  background: var(--k8-orange);
}

.page-about .about-milestone__desc {
  margin: 0 0 20px 82px;
  max-width: 38em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--about-text-soft);
}

.page-about .about-milestones__item--current {
  background: rgba(255, 138, 61, 0.09);
}

/* 查阅入口 */
.page-about .about-chapter--end {
  border-top: 1px solid var(--about-line);
}

.page-about .about-links {
  display: grid;
  gap: 1px;
  margin-top: 8px;
  background: var(--about-line);
  border: 1px solid var(--about-line);
}

.page-about .about-links__item {
  display: block;
  padding: 22px 20px 24px;
  text-decoration: none;
  color: inherit;
  background: var(--k8-paper);
  transition: background-color 180ms ease;
}

.page-about .about-links__num {
  display: block;
  margin-bottom: 10px;
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--k8-cyan-dark);
}

.page-about .about-links__title {
  display: block;
  margin-bottom: 6px;
  font-family: var(--k8-display);
  font-size: 18px;
  font-weight: 700;
  color: var(--k8-graphite);
  transition: color 180ms ease;
}

.page-about .about-links__desc {
  display: block;
  font-size: 14px;
  line-height: 1.7;
  color: var(--about-text-soft);
  transition: color 180ms ease;
}

.page-about .about-links__item:hover,
.page-about .about-links__item:focus-visible {
  background: var(--k8-ink-900);
}

.page-about .about-links__item:hover .about-links__title,
.page-about .about-links__item:focus-visible .about-links__title,
.page-about .about-links__item:hover .about-links__num,
.page-about .about-links__item:focus-visible .about-links__num {
  color: var(--k8-cyan);
}

.page-about .about-links__item:hover .about-links__desc,
.page-about .about-links__item:focus-visible .about-links__desc {
  color: rgba(242, 245, 247, 0.74);
}

/* 响应式 */
@media (min-width: 600px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .about-levels {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

  .page-about .about-audience {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 22px;
  }

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

@media (min-width: 900px) {
  .page-about .about-hero__inner {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
    gap: 56px;
    align-items: end;
  }
}

@media (min-width: 960px) {
  .page-about .about-doc {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    background: linear-gradient(to right, var(--k8-ink-800) var(--about-rail), var(--k8-paper) var(--about-rail));
  }

  .page-about .about-rail {
    position: sticky;
    top: 76px;
    align-self: start;
    max-height: calc(100vh - 92px);
    overflow-y: auto;
    background: transparent;
    border-bottom: 0;
    padding: 56px 24px 48px;
  }

  .page-about .about-rail__list {
    position: relative;
    flex-direction: column;
    gap: 0;
    padding: 0 0 0 22px;
    overflow: visible;
  }

  .page-about .about-rail__list::before {
    content: "";
    position: absolute;
    left: 0;
    top: 10px;
    bottom: 10px;
    width: 1px;
    background: var(--k8-mist);
  }

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

  .page-about .about-rail__item::before {
    content: "";
    position: absolute;
    left: -26px;
    top: 19px;
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--k8-cyan-dark);
  }

  .page-about .about-rail__link {
    display: block;
    padding: 10px 0;
    border: 0;
    white-space: normal;
  }

  .page-about .about-rail__year {
    display: block;
    font-size: 18px;
  }

  .page-about .about-rail__label {
    display: block;
    margin-top: 2px;
    font-size: 12px;
    color: var(--k8-line);
  }

  .page-about .about-doc__body {
    padding: 64px clamp(36px, 5vw, 76px) 88px;
  }

  .page-about .about-chapter {
    padding: 52px 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__link,
  .page-about .about-links__item,
  .page-about .about-links__title,
  .page-about .about-links__desc,
  .page-about .about-links__num {
    transition: none;
  }
}