.page-about {
  position: relative;
  display: block;
  background: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  font-weight: var(--weight-body);
  overflow-x: clip;
}

/* 阅读进度细线 */
.page-about .about-progress {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: color-mix(in srgb, var(--color-line) 70%, transparent);
  z-index: 60;
  pointer-events: none;
}

.page-about .about-progress::after {
  content: "";
  display: block;
  height: 100%;
  width: calc(var(--meter, 0) * 1%);
  background: var(--color-accent);
  transition: width 120ms linear;
}

/* 进场动效：仅在脚本就绪时启用 */
:where(html[data-js-ready]) .page-about [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
}

.page-about [data-reveal] {
  transition: opacity 260ms cubic-bezier(0.22, 0.61, 0.36, 1),
    transform 260ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

:where(html[data-js-ready]) .page-about [data-reveal].is-revealed {
  opacity: 1;
  transform: translateY(0);
}

/* 面包屑 */
.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-4) 0 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
}

.page-about .breadcrumb a {
  color: var(--color-primary);
  text-decoration: none;
}

.page-about .breadcrumb a:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* 开场 */
.page-about .about-open {
  padding: var(--space-8) 0 var(--section-y);
}

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

.page-about .about-open__head .kicker {
  display: block;
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.page-about .about-open__title {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-3xl);
  line-height: 1.08;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-about .about-open__side {
  border-left: 4px solid var(--color-accent);
  padding-left: var(--space-4);
}

.page-about .about-open__side .lede {
  margin: 0 0 var(--space-3);
  font-size: var(--text-lg);
  line-height: 1.55;
  color: var(--color-ink-soft);
}

.page-about .about-open__note {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  font-variant-numeric: tabular-nums;
}

/* 叙事段落通用 */
.page-about .about-seg {
  padding: var(--section-y) 0;
  border-top: var(--border-thin) solid var(--color-line);
}

.page-about .about-seg--identity {
  border-top: 3px double var(--color-line);
}

.page-about .about-seg__stamp {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.page-about .about-seg__no {
  display: inline-block;
  padding: 2px var(--space-2);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
}

.page-about .about-seg__title {
  margin: 0 0 var(--space-6);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-2xl);
  line-height: 1.22;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  max-width: 26ch;
}

.page-about .about-seg__title--wide {
  max-width: 34ch;
}

.page-about .about-seg .prose p {
  margin: 0 0 var(--space-4);
  max-width: var(--measure);
  color: var(--color-ink);
}

.page-about .about-seg .prose p:last-child {
  margin-bottom: 0;
}

.page-about .about-seg .prose strong {
  font-weight: var(--weight-heading);
  background: var(--color-highlight);
  padding: 0 2px;
}

/* 第一段 7:5 布局 */
.page-about .about-seg__layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
}

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

.page-about .figure--tall {
  aspect-ratio: 3 / 4;
  overflow: hidden;
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
}

.page-about .figure--square {
  aspect-ratio: 1 / 1;
  overflow: hidden;
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
}

.page-about .figure--wide {
  aspect-ratio: 20 / 9;
  overflow: hidden;
  background: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
}

.page-about .figure--tall img,
.page-about .figure--square img,
.page-about .figure--wide img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}

.page-about .figure__caption {
  margin-top: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  line-height: 1.5;
  color: var(--color-ink-muted);
}

/* 第二段：窄栏 + 侧注 */
.page-about .about-why {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
}

.page-about .about-why__text p {
  margin: 0 0 var(--space-4);
  max-width: 62ch;
  color: var(--color-ink);
}

.page-about .about-why__text p:last-child {
  margin-bottom: 0;
}

.page-about .about-why__aside {
  border-left: 4px solid var(--color-accent);
  padding-left: var(--space-4);
}

.page-about .about-why__aside .mono-label {
  display: block;
  margin: var(--space-4) 0 var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.page-about .about-why__aside .mono-label:first-child {
  margin-top: 0;
}

.page-about .about-why__big {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: var(--color-primary);
  font-variant-numeric: tabular-nums;
}

.page-about .about-why__small {
  margin: 0 0 var(--space-4);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}

.page-about .about-why__small:last-child {
  margin-bottom: 0;
}

/* 第三段：深色密集口径区 */
.page-about .about-ruler {
  padding: var(--section-y-lg) 0;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.page-about .about-ruler__stamp {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-contrast-accent);
}

.page-about .about-ruler__no {
  display: inline-block;
  padding: 2px var(--space-2);
  background: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
}

.page-about .about-ruler__title {
  margin: 0 0 var(--space-4);
  max-width: 28ch;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-2xl);
  line-height: 1.22;
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.page-about .about-ruler__intro {
  margin: 0 0 var(--space-6);
  max-width: 68ch;
  font-size: var(--text-base);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
}

.page-about .about-ruler__figure {
  margin: 0 0 var(--space-6);
}

.page-about .about-ruler__figure .figure__caption {
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}

.page-about .about-keys {
  margin: 0;
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.page-about .about-keys__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-1);
  padding: var(--space-4) 0;
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.page-about .about-keys__row .mono-label {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.page-about .about-keys__val {
  display: block;
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1.15;
  letter-spacing: 0.01em;
  color: var(--color-contrast-accent);
  font-variant-numeric: tabular-nums;
}

.page-about .about-keys__txt {
  display: block;
  margin: 0;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-contrast-ink);
}

.page-about .about-ruler__tail {
  margin: var(--space-6) 0 0;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
}

.page-about .about-ruler__tail .link-underline {
  color: var(--color-contrast-accent);
}

/* 第四段：三阶段 */
.page-about .about-phases {
  padding: var(--section-y) 0;
  border-top: 3px double var(--color-line);
}

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

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

.page-about .about-phase__sum {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  grid-template-areas:
    "idx name sign"
    "hint hint hint";
  gap: var(--space-1) var(--space-3);
  align-items: baseline;
  padding: var(--space-4) 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-phase__sum::marker {
  content: "";
}

.page-about .about-phase__idx {
  grid-area: idx;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.page-about .about-phase__name {
  grid-area: name;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1.2;
  color: var(--color-ink);
}

.page-about .about-phase__hint {
  grid-area: hint;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  line-height: 1.6;
  color: var(--color-ink-muted);
}

.page-about .about-phase__sign {
  grid-area: sign;
  position: relative;
  width: 18px;
  height: 18px;
  align-self: center;
}

.page-about .about-phase__sign::before,
.page-about .about-phase__sign::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--color-ink-soft);
  transform: translate(-50%, -50%);
}

.page-about .about-phase__sign::before {
  width: 12px;
  height: 1px;
}

.page-about .about-phase__sign::after {
  width: 1px;
  height: 12px;
  transition: transform 160ms ease;
}

.page-about .about-phase[open] .about-phase__sign::after {
  transform: translate(-50%, -50%) scaleY(0);
}

.page-about .about-phase[open] .about-phase__name {
  color: var(--color-primary);
}

.page-about .about-phase__body {
  padding: 0 0 var(--space-6);
}

.page-about .about-phase__body p {
  margin: 0 0 var(--space-3);
  max-width: 68ch;
  font-size: var(--text-base);
  line-height: 1.75;
  color: var(--color-ink);
}

.page-about .about-phase__body p:last-child {
  margin-bottom: 0;
}

/* 第五段：团队 */
.page-about .about-team {
  padding: var(--section-y) 0;
  border-top: var(--border-thin) solid var(--color-line);
}

.page-about .about-team__layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
}

.page-about .about-team__body .prose p {
  margin: 0 0 var(--space-4);
  max-width: 62ch;
  color: var(--color-ink);
}

.page-about .about-team__body .prose p:last-child {
  margin-bottom: 0;
}

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

/* 第六段：行动出口 */
.page-about .about-next {
  padding: var(--section-y) 0 var(--section-y-lg);
  border-top: 3px double var(--color-line);
  background: var(--color-surface-alt);
}

.page-about .about-next__lead {
  margin: 0 0 var(--space-6);
  max-width: 62ch;
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

.page-about .about-next__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-3);
}

.page-about .about-next__card {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-6) var(--space-4) var(--space-8);
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-top: 4px solid var(--color-primary);
  border-radius: var(--radius-sm);
  color: var(--color-ink);
  text-decoration: none;
  transition: background 160ms ease, border-color 160ms ease;
}

.page-about .about-next__card:nth-child(2) {
  border-top-color: var(--color-accent);
}

.page-about .about-next__card:hover,
.page-about .about-next__card:focus-visible {
  background: var(--color-primary-soft);
  border-color: var(--color-primary);
  border-top-color: var(--color-primary);
}

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

.page-about .about-next__card--contrast {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-line);
  border-top-color: var(--color-contrast-accent);
}

.page-about .about-next__card--contrast:hover,
.page-about .about-next__card--contrast:focus-visible {
  background: color-mix(in srgb, var(--color-contrast-surface) 88%, var(--color-contrast-accent));
  border-color: var(--color-contrast-accent);
}

.page-about .about-next__tag {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.page-about .about-next__card--contrast .about-next__tag {
  color: var(--color-contrast-accent);
}

.page-about .about-next__name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  line-height: 1.2;
  letter-spacing: var(--tracking-heading);
}

.page-about .about-next__desc {
  font-size: var(--text-sm);
  line-height: 1.75;
  color: var(--color-ink-soft);
}

.page-about .about-next__card--contrast .about-next__desc {
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
}

.page-about .about-next__tail {
  margin: var(--space-6) 0 0;
  max-width: 68ch;
  font-size: var(--text-base);
  line-height: 1.75;
  color: var(--color-ink);
}

.page-about .about-next__tail .link-underline {
  color: var(--color-primary);
}

/* 中等宽度：出现非对称栅格 */
@media (min-width: 720px) {
  .page-about .about-open__inner {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-8);
  }

  .page-about .about-open__title {
    font-size: var(--text-4xl);
  }

  .page-about .about-seg__layout {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-8);
  }

  .page-about .about-seg__figure {
    margin-top: var(--space-8);
  }

  .page-about .about-why {
    grid-template-columns: minmax(0, 6fr) minmax(0, 4fr);
    gap: var(--space-8);
  }

  .page-about .about-why__aside {
    margin-top: var(--space-2);
  }

  .page-about .about-keys__row {
    grid-template-columns: minmax(0, 2fr) minmax(0, 3fr) minmax(0, 7fr);
    gap: var(--space-4);
    align-items: baseline;
  }

  .page-about .about-keys__val {
    font-size: var(--text-lg);
    text-align: right;
  }

  .page-about .about-phase__sum {
    grid-template-columns: minmax(0, 2fr) minmax(0, 3fr) minmax(0, 6fr) auto;
    grid-template-areas: "idx name hint sign";
    gap: var(--space-4);
    align-items: baseline;
    padding: var(--space-6) 0;
  }

  .page-about .about-team__layout {
    grid-template-columns: minmax(0, 8fr) minmax(0, 4fr);
    gap: var(--space-8);
  }

  .page-about .about-team__figure {
    margin-top: var(--space-6);
  }

  .page-about .about-next__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 4fr) minmax(0, 3fr);
    gap: var(--space-4);
  }
}

@media (min-width: 1080px) {
  .page-about .about-open__title {
    max-width: 20ch;
  }

  .page-about .about-seg__title {
    font-size: var(--text-3xl);
  }

  .page-about .about-ruler__title {
    font-size: var(--text-3xl);
  }
}

/* 降低动效偏好 */
@media (prefers-reduced-motion: reduce) {
  .page-about [data-reveal],
  :where(html[data-js-ready]) .page-about [data-reveal],
  :where(html[data-js-ready]) .page-about [data-reveal].is-revealed {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .page-about .about-progress::after {
    transition: none;
  }

  .page-about .about-phase__sign::after {
    transition: none;
  }
}

.page-about {
  --meter: 1rem;
}