.page-about {
  --about-index-w: 3.5rem;
  --about-gap: clamp(1.25rem, 4vw, 2.5rem);
  position: relative;
  background-color: var(--ink);
  background-image: linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 72px 100%;
  color: var(--mist);
  font-family: var(--font-body);
  padding-bottom: clamp(2.5rem, 7vw, 5rem);
}

.page-about .breadcrumb {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  padding-top: clamp(1.25rem, 4vw, 2rem);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(1.5rem, 5vw, 3rem) 0 clamp(2.25rem, 6vw, 4rem);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.75rem, 5vw, 3rem);
  align-items: start;
}

.page-about .about-hero__title {
  margin: 0.5rem 0 0;
  font-family: var(--font-title);
  font-weight: 900;
  font-size: clamp(2.6rem, 9vw, 5rem);
  line-height: 0.96;
  letter-spacing: -0.02em;
  color: var(--paper);
}

.page-about .about-hero__lede {
  margin: 1.25rem 0 0;
  max-width: 46ch;
  font-size: clamp(1rem, 1.6vw, 1.125rem);
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: 1.75rem 0 0;
  padding: 1rem 0 0;
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.75rem;
}

.page-about .about-hero__fact {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}

.page-about .about-hero__fact b {
  font-family: var(--font-mono);
  font-size: clamp(1.125rem, 2.4vw, 1.375rem);
  font-weight: 700;
  color: var(--amber);
  letter-spacing: -0.02em;
}

.page-about .about-hero__fact span {
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
  color: var(--steel);
}

.page-about .about-hero__actions {
  margin-top: 1.75rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.page-about .about-hero__figure {
  border: 1px solid var(--line);
  background: var(--grad-deep);
}

/* ---------- 章节通用骨架 ---------- */
.page-about .about-chapter {
  padding: clamp(2.25rem, 6vw, 4rem) 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-chapter--last {
  border-bottom: 0;
}

.page-about .about-chapter__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.25rem;
}

.page-about .about-chapter__index {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
}

.page-about .about-chapter__index .num {
  font-family: var(--font-mono);
  font-size: clamp(1.75rem, 5vw, 2.5rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--amber);
}

.page-about .about-chapter__label {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-chapter__title {
  margin: 0.5rem 0 0;
  font-family: var(--font-title);
  font-weight: 900;
  font-size: clamp(1.5rem, 4.4vw, 2.375rem);
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-chapter__body > p {
  margin: 1rem 0 0;
  max-width: 60ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--mist);
}

.page-about .about-chapter__aside {
  border-top: 1px solid var(--line);
  padding-top: 1rem;
}

.page-about .aside-note {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--steel);
}

.page-about .aside-link {
  display: inline-block;
  margin-top: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  color: var(--amber);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease);
}

.page-about .aside-link:hover,
.page-about .aside-link:focus-visible {
  color: var(--amber-deep);
  border-bottom-color: var(--amber-deep);
}

.page-about .about-chapter__actions {
  margin-top: 1.75rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* ---------- 图片容器 ---------- */
.page-about .media-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .media-frame__caption {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  color: var(--steel);
}

/* ---------- 服务原则卡片 ---------- */
.page-about .principle-grid {
  margin-top: 1.75rem;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .principle-card {
  background: var(--ink-2);
  padding: 1.25rem 1.25rem 1.5rem;
  transition: background var(--t) var(--ease), transform var(--t) var(--ease);
}

.page-about .principle-card:hover {
  background: var(--ink-4);
  transform: translateY(-2px);
}

.page-about .principle-card__step {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  color: var(--amber);
}

.page-about .principle-card__title {
  margin: 0.625rem 0 0;
  font-family: var(--font-title);
  font-size: 1.0625rem;
  font-weight: 800;
  color: var(--paper);
}

.page-about .principle-card__text {
  margin: 0.625rem 0 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--steel);
}

/* ---------- 团队 ---------- */
.page-about .about-team__figure {
  margin: 1.75rem 0 0;
  border: 1px solid var(--line);
  background: var(--ink-2);
}

.page-about .team-grid {
  margin-top: 1.5rem;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
}

.page-about .team-card {
  border: 1px solid var(--line);
  background: var(--ink-2);
  transition: border-color var(--t) var(--ease), transform var(--t) var(--ease);
}

.page-about .team-card:hover {
  border-color: var(--amber);
  transform: translateY(-2px);
}

.page-about .team-card[open] {
  border-color: var(--amber);
}

.page-about .team-card__summary {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-title);
  font-weight: 800;
  font-size: 1rem;
  color: var(--paper);
}

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

.page-about .team-card__mark {
  position: relative;
  flex: none;
  margin-left: auto;
  width: 1.125rem;
  height: 1.125rem;
}

.page-about .team-card__mark::before,
.page-about .team-card__mark::after {
  content: "";
  position: absolute;
  background: var(--amber);
  transition: transform var(--t) var(--ease), opacity var(--t) var(--ease);
}

.page-about .team-card__mark::before {
  left: 0;
  right: 0;
  top: 50%;
  height: 1px;
}

.page-about .team-card__mark::after {
  top: 0;
  bottom: 0;
  left: 50%;
  width: 1px;
}

.page-about .team-card[open] .team-card__mark::after {
  transform: scaleY(0);
  opacity: 0;
}

.page-about .team-card__body {
  padding: 0 1rem 1.125rem;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--steel);
}

/* ---------- 时间线 ---------- */
.page-about .about-timeline__figure {
  margin: 1.75rem 0 0;
  border: 1px solid var(--line);
  background: var(--ink-3);
}

.page-about .about-timeline {
  margin-top: 1.75rem;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.5rem;
}

.page-about .about-timeline__index {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.page-about .about-timeline__year {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  color: var(--steel);
  text-decoration: none;
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--line);
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease);
}

.page-about .about-timeline__year:hover,
.page-about .about-timeline__year:focus-visible {
  color: var(--amber);
  border-color: var(--line-strong);
}

.page-about .about-timeline__list {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0 0 0 1.75rem;
}

.page-about .about-timeline__list::before {
  content: "";
  position: absolute;
  top: 0.5rem;
  bottom: 0.5rem;
  left: 0.3125rem;
  width: 1px;
  background: var(--line-strong);
}

.page-about .about-timeline__item {
  position: relative;
  padding-bottom: 1.75rem;
}

.page-about .about-timeline__item:last-child {
  padding-bottom: 0;
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -1.75rem;
  top: 0.35rem;
  width: 0.6875rem;
  height: 0.6875rem;
  border: 1px solid var(--line-strong);
  background: var(--ink);
  transition: background var(--t) var(--ease), border-color var(--t) var(--ease);
}

.page-about .about-timeline__item:hover::before,
.page-about .about-timeline__item:focus-within::before {
  background: var(--amber);
  border-color: var(--amber);
}

.page-about .about-timeline__marker {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--amber);
}

.page-about .about-timeline__content h3 {
  margin: 0.3rem 0 0;
  font-family: var(--font-title);
  font-size: 1.0625rem;
  font-weight: 800;
  color: var(--paper);
}

.page-about .about-timeline__content p {
  margin: 0.5rem 0 0;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--steel);
}

.page-about .about-timeline__note {
  display: grid;
  grid-template-rows: 0fr;
  opacity: 0;
  padding-left: 0.75rem;
  border-left: 1px solid var(--line);
  transition: grid-template-rows var(--t) var(--ease), opacity var(--t) var(--ease);
}

.page-about .about-timeline__note > * {
  overflow: hidden;
}

.page-about .about-timeline__item:hover .about-timeline__note,
.page-about .about-timeline__item:focus-within .about-timeline__note {
  grid-template-rows: 1fr;
  opacity: 1;
}

.page-about .about-timeline__note {
  color: var(--cyan);
}

/* ---------- 数据 ---------- */
.page-about .about-stats {
  margin-top: 1.75rem;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-stat {
  background: var(--ink-2);
  padding: 1.125rem 1rem 1.25rem;
}

.page-about .about-stat__value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--cyan);
}

.page-about .about-stat__unit {
  display: block;
  margin-top: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--amber);
}

.page-about .about-stat__desc {
  margin: 0.625rem 0 0;
  font-size: 0.8125rem;
  line-height: 1.7;
  color: var(--steel);
}

/* ---------- 主体与联系 ---------- */
.page-about .about-credential {
  margin-top: 1.75rem;
  padding: 1.5rem;
  border: 1px solid var(--line);
  background: var(--grad-deep);
}

.page-about .about-contact {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-contact__row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.75rem;
  padding: 0.875rem 1rem;
  background: var(--ink-2);
}

.page-about .about-contact__key {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--steel);
}

.page-about .about-contact__value {
  font-size: 0.9375rem;
  line-height: 1.6;
  color: var(--paper);
  word-break: break-word;
}

.page-about .copy-btn {
  margin-left: auto;
  flex: none;
  padding: 0.25rem 0.625rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  color: var(--cyan);
  background: none;
  border: 1px solid var(--line-strong);
  cursor: pointer;
  transition: color var(--t) var(--ease), border-color var(--t) var(--ease);
}

.page-about .copy-btn:hover {
  color: var(--amber);
  border-color: var(--amber);
}

.page-about .about-credential__meta {
  margin: 1.25rem 0 0;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  color: var(--mist);
}

.page-about .about-credential__note {
  margin: 0.625rem 0 0;
  font-size: 0.875rem;
  line-height: 1.75;
  color: var(--steel);
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 700px) {
  .page-about .principle-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

/* ---------- 桌面非对称栅格 ---------- */
@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    gap: clamp(2rem, 4vw, 3.5rem);
  }

  .page-about .about-chapter__grid {
    grid-template-columns: var(--about-index-w) minmax(0, 7fr) minmax(0, 4fr);
    gap: 0 clamp(1.5rem, 3vw, 2.5rem);
  }

  .page-about .about-chapter__index {
    grid-column: 1;
    padding-top: 0.4rem;
  }

  .page-about .about-chapter__body {
    grid-column: 2;
  }

  .page-about .about-chapter__aside {
    grid-column: 3;
    border-top: 0;
    border-left: 1px solid var(--line);
    padding-top: 0;
    padding-left: 1.25rem;
  }

  .page-about .about-timeline {
    grid-template-columns: 5.5rem minmax(0, 1fr);
    gap: 2rem;
  }

  .page-about .about-timeline__index {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.375rem;
    position: sticky;
    top: 6rem;
    align-self: start;
  }

  .page-about .about-timeline__year {
    width: 100%;
    text-align: center;
  }
}

@media (min-width: 1100px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* ---------- 降低动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about .principle-card,
  .page-about .team-card,
  .page-about .about-timeline__note,
  .page-about .copy-btn,
  .page-about .aside-link {
    transition: none;
  }

  .page-about .principle-card:hover,
  .page-about .team-card:hover {
    transform: none;
  }
}