.page-about {
  display: block;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-block: var(--space-8) var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset-inline-end: -10%;
  inset-block-start: -22%;
  width: 44%;
  height: 96%;
  background: var(--color-primary-soft);
  border-radius: var(--radius-lg);
  transform: rotate(-7deg);
  opacity: 0.5;
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero > .container {
  position: relative;
  z-index: 1;
}

.page-about .crumbs {
  margin-block-end: var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

.page-about .about-hero__grid {
  display: grid;
  gap: var(--space-4);
}

.page-about .about-hero__title {
  margin-block: var(--space-2) 0;
  font-size: var(--text-3xl);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  max-width: 20ch;
}

.page-about .about-hero__intro {
  margin-block-start: var(--space-3);
  font-size: var(--text-lg);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
  max-width: 48ch;
}

.page-about .about-hero__quote {
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink);
  border-inline-start: 3px solid var(--color-primary);
  padding-inline-start: var(--space-3);
}

.page-about .about-hero__quote-src {
  margin-block-start: var(--space-2);
  padding-inline-start: var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3) var(--space-2);
  margin: var(--space-6) 0 0;
  padding-block-start: var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
  list-style: none;
}

.page-about .about-facts > li {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  min-width: 0;
}

.page-about .about-facts__val {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: 1.05;
  color: var(--color-primary);
  font-variant-numeric: tabular-nums;
}

.page-about .about-facts__key {
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

/* ---------- 通用小节 ---------- */
.page-about .sec-head {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  margin-block-end: var(--space-3);
}

.page-about .sec-head h2 {
  font-size: var(--text-2xl);
  line-height: var(--leading-heading);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  letter-spacing: var(--tracking-heading);
}

.page-about .about-lead {
  max-width: var(--measure);
  margin-block-end: var(--space-4);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

/* ---------- 01 定位 ---------- */
.page-about .about-position__grid {
  display: grid;
  gap: var(--space-4);
}

.page-about .about-position__text p {
  max-width: var(--measure);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.page-about .about-position__text p + p {
  margin-block-start: var(--space-3);
}

.page-about .about-position__figure {
  margin: 0;
}

.page-about .about-boundary {
  margin-block-start: var(--space-6);
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.page-about .about-boundary__list {
  display: grid;
  gap: var(--space-2);
  margin-block-start: var(--space-2);
  list-style: none;
}

.page-about .about-boundary__list li {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  font-size: var(--text-base);
  color: var(--color-ink);
  padding-block-end: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-about .about-boundary__list li:last-child {
  padding-block-end: 0;
  border-bottom: 0;
}

.page-about .about-boundary__list .num {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
  flex: none;
}

/* ---------- 02 发展阶段 ---------- */
.page-about .about-stages__figure {
  margin: 0 0 var(--space-4);
}

.page-about .about-stages__accordion {
  border-top: var(--border-thin) solid var(--color-line);
}

.page-about .accordion__item {
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-about .accordion__item > summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-3);
  padding-block: var(--space-3);
  cursor: pointer;
  list-style: none;
}

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

.page-about .accordion__item > summary::after {
  content: "＋";
  margin-inline-start: auto;
  color: var(--color-ink-muted);
  font-size: var(--text-base);
  line-height: 1;
}

.page-about .accordion__item[open] > summary::after {
  content: "－";
  color: var(--color-primary);
}

.page-about .accordion__item > summary:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.page-about .about-stage__num {
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-primary);
  flex: none;
}

.page-about .about-stage__name {
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
}

.page-about .about-stage__code {
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
  padding-block: calc(var(--space-1) / 2);
  padding-inline: var(--space-1);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
}

.page-about .accordion__body {
  padding-block: 0 var(--space-4);
}

.page-about .accordion__body p {
  max-width: var(--measure);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-about .accordion__body p + p {
  margin-block-start: var(--space-2);
}

/* ---------- 03 能力边界 ---------- */
.page-about .about-capability__grid {
  display: grid;
  gap: var(--space-3);
}

.page-about .about-capability__col {
  padding: var(--space-3);
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.page-about .about-capability__col h3 {
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
}

.page-about .about-capability__col--in h3 {
  color: var(--color-primary);
}

.page-about .about-capability__col--out h3 {
  color: var(--color-ink-soft);
}

.page-about .about-capability__col ul {
  display: grid;
  gap: var(--space-2);
  margin-block-start: var(--space-3);
  list-style: none;
}

.page-about .about-capability__col li {
  display: grid;
  gap: var(--space-1);
  padding-block-end: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-about .about-capability__col li:last-child {
  padding-block-end: 0;
  border-bottom: 0;
}

.page-about .about-capability__col li strong {
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
}

.page-about .about-capability__col li span {
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-about .about-capability__figure {
  margin: var(--space-4) 0 0;
  max-width: calc(var(--space-8) * 9);
}

/* ---------- 04 运营原则 ---------- */
.page-about .about-principles__list {
  display: grid;
  gap: var(--space-6);
  margin: 0;
  padding: var(--space-4) 0 0;
  border-top: var(--border-thin) solid var(--color-line);
  list-style: none;
}

.page-about .about-principle {
  display: grid;
  gap: var(--space-2);
}

.page-about .about-principle__num {
  font-size: var(--text-2xl);
  line-height: 1;
  color: var(--color-primary);
  font-variant-numeric: tabular-nums;
}

.page-about .about-principle__title {
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  margin-block-end: var(--space-2);
}

.page-about .about-principle__text {
  max-width: var(--measure);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-about .about-principle__example {
  margin-block-start: var(--space-2);
  padding-inline-start: var(--space-2);
  border-inline-start: 2px solid var(--color-highlight);
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-muted);
}

.page-about .about-principle:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: var(--space-2);
}

.page-about .about-principle .about-principle__example {
  transition: max-height 240ms ease, opacity 240ms ease, margin-block-start 240ms ease;
}

/* ---------- 05 主体与服务覆盖 ---------- */
.page-about .about-subject__grid {
  display: grid;
  gap: var(--space-4);
}

.page-about .about-subject__text p {
  max-width: 46ch;
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.page-about .about-subject__text p + p {
  margin-block-start: var(--space-3);
}

.page-about .about-subject__pairs {
  border-top: var(--border-thin) solid var(--color-line);
}

.page-about .about-subject__pairs .pair {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-1);
  padding-block: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-about .about-subject__pairs .pair__key {
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.page-about .about-subject__pairs .pair__val {
  font-size: var(--text-base);
  color: var(--color-ink);
  word-break: break-word;
}

/* ---------- 06 去向 ---------- */
.page-about .about-next__list {
  display: grid;
  margin: 0;
  padding: 0;
  border-top: var(--border-thin) solid var(--color-line);
  list-style: none;
}

.page-about .about-next__list > li {
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-about .about-next__link {
  display: grid;
  gap: var(--space-1);
  padding-block: var(--space-3);
  text-decoration: none;
  color: inherit;
}

.page-about .about-next__link:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.page-about .about-next__name {
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  letter-spacing: var(--tracking-heading);
}

.page-about .about-next__link:hover .about-next__name,
.page-about .about-next__link:focus-visible .about-next__name {
  color: var(--color-primary);
}

.page-about .about-next__desc {
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-hero__title {
    font-size: var(--text-4xl);
  }

  .page-about .about-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .about-boundary__list li:nth-last-child(-n + 2) {
    padding-block-end: 0;
    border-bottom: 0;
  }

  .page-about .about-subject__pairs .pair {
    grid-template-columns: minmax(0, 1fr) minmax(0, 2fr);
    gap: var(--space-3);
    align-items: baseline;
  }

  .page-about .about-next__link {
    grid-template-columns: minmax(0, 220px) minmax(0, 1fr);
    gap: var(--space-4);
    align-items: baseline;
  }
}

@media (min-width: 860px) {
  .page-about .about-capability__grid {
    grid-template-columns: 1fr 1fr;
    gap: 0;
    border: var(--border-thin) solid var(--color-line);
    border-radius: var(--radius-md);
    overflow: hidden;
  }

  .page-about .about-capability__col {
    background: transparent;
    border: 0;
    border-radius: 0;
    padding: var(--space-4);
  }

  .page-about .about-capability__col + .about-capability__col {
    border-inline-start: var(--border-thin) solid var(--color-line);
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    padding-block: var(--space-8) var(--space-6);
  }

  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-6);
    align-items: end;
  }

  .page-about .about-position__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-about .about-subject__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-about .about-principle {
    grid-template-columns: calc(var(--space-8) + var(--space-4)) minmax(0, 1fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-about .about-principle__num {
    text-align: end;
  }
}

@media (hover: hover) and (pointer: fine) and (min-width: 900px) {
  .page-about .about-principle__example {
    max-height: 0;
    margin-block-start: 0;
    opacity: 0;
    overflow: hidden;
  }

  .page-about .about-principle:hover .about-principle__example,
  .page-about .about-principle:focus-within .about-principle__example,
  .page-about .about-principle:focus .about-principle__example {
    max-height: 10em;
    margin-block-start: var(--space-2);
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-principle .about-principle__example {
    transition: none;
  }

  .page-about [data-reveal] {
    opacity: 1;
    transform: none;
  }
}