.page-about {
  --about-line: 1px solid var(--grid-line);
  --about-label-top: 32px;
}

/* 面包屑与页面上下文 */
.page-about .breadcrumb {
  padding-top: 20px;
}

.page-about .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 14px;
  color: var(--slate);
}

.page-about .breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--grid-line);
}

.page-about .breadcrumb a {
  color: var(--sea-mid);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--coral-text);
  border-bottom-color: var(--coral-entry);
}

/* 首屏 */
.page-about .about-hero {
  padding-block: clamp(24px, 5vw, 56px) clamp(48px, 8vw, 96px);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(28px, 5vw, 56px);
}

.page-about .about-hero__title {
  margin: 12px 0 24px;
  max-width: 22ch;
  font-size: clamp(2.1rem, 7.5vw, 3.6rem);
  line-height: 1.1;
  letter-spacing: -0.01em;
  font-weight: 800;
  color: var(--ink-abyss);
}

.page-about .about-hero__intro {
  margin: 0 0 1.2em;
  max-width: var(--prose-max);
  font-size: 17px;
  line-height: 1.75;
  color: var(--slate);
}

.page-about .hero-facts {
  display: grid;
  gap: 1px;
  margin: 32px 0 0;
  padding: 0;
  list-style: none;
  background: var(--grid-line);
  border: var(--about-line);
}

.page-about .hero-facts li {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
  background: var(--pearl);
}

.page-about .hero-facts__num {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--ink-abyss);
  letter-spacing: 0;
}

.page-about .hero-facts li span:last-child {
  font-size: 14px;
  line-height: 1.6;
  color: var(--slate);
}

.page-about .about-jump {
  margin-top: 32px;
  padding-top: 16px;
  border-top: var(--about-line);
}

.page-about .about-jump ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-jump a {
  display: inline-flex;
  gap: 8px;
  align-items: baseline;
  padding-bottom: 2px;
  font-size: 14px;
  color: var(--slate);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

.page-about .about-jump a:hover,
.page-about .about-jump a:focus-visible {
  color: var(--ink-abyss);
  border-bottom-color: var(--coral-entry);
}

.page-about .about-jump .mono {
  font-size: 12px;
  color: var(--sea-mid);
}

.page-about .about-hero__figure {
  margin: 0;
  overflow: hidden;
}

.page-about .about-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* 章节骨架：左侧展签 + 右侧正文 */
.page-about .chapter {
  display: grid;
  gap: 24px;
}

.page-about .chapter__title {
  margin: 8px 0 0;
  font-size: clamp(1.6rem, 6vw, 2.6rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  font-weight: 700;
  color: var(--ink-abyss);
}

.page-about .chapter__note {
  margin: 12px 0 0;
  max-width: 42ch;
  font-size: 15px;
  line-height: 1.7;
  color: var(--slate);
}

.page-about .chapter__label--stacked {
  margin-bottom: 32px;
}

.page-about .chapter__body p {
  margin: 0 0 1.2em;
}

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

/* 四类访客 */
.page-about .audience-grid {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .audience-card {
  padding: 24px 20px;
  background: var(--pearl);
  border: var(--about-line);
  border-top: 3px solid var(--ink-deep);
  transition: border-color 0.3s ease, transform 0.3s ease;
}

.page-about .audience-card:hover,
.page-about .audience-card:focus-within {
  border-top-color: var(--coral-entry);
}

.page-about .audience-card .card__meta {
  margin: 0 0 12px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--sea-mid);
}

.page-about .audience-card h3 {
  margin: 0 0 12px;
  font-size: 1.15rem;
  line-height: 1.35;
  font-weight: 600;
  color: var(--ink-abyss);
}

.page-about .audience-card p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--slate);
}

/* 四道工序 */
.page-about .process-figure {
  margin: 0 0 32px;
}

.page-about .process-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .process-intro {
  margin-bottom: 32px;
}

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

.page-about .process__step {
  padding: 20px 20px 18px;
  background: var(--pearl);
  border-left: 3px solid var(--grid-line);
  transition: border-color 0.25s ease, background-color 0.25s ease;
}

.page-about .process__step:hover,
.page-about .process__step:focus-within {
  border-left-color: var(--coral-entry);
  background: #ffffff;
}

.page-about .process__num {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--coral-text);
}

.page-about .process__step h3 {
  margin: 0 0 10px;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--ink-abyss);
}

.page-about .process__step p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--slate);
}

.page-about .process__owner {
  margin: 0;
  padding-top: 12px;
  border-top: 1px dashed var(--grid-line);
  font-size: 13px;
  line-height: 1.6;
  color: var(--sea-mid);
  opacity: 0.78;
  transition: opacity 0.25s ease, color 0.25s ease;
}

.page-about .process__step:hover .process__owner,
.page-about .process__step:focus-within .process__owner {
  opacity: 1;
  color: var(--ink-deep);
}

/* 团队 */
.page-about .team {
  display: grid;
  gap: 28px;
}

.page-about .team-figure {
  margin: 0;
}

.page-about .team-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .team__body p {
  margin: 0 0 1.2em;
  max-width: var(--prose-max);
  font-size: 17px;
  line-height: 1.75;
  color: var(--slate);
}

.page-about .team-stats {
  display: grid;
  gap: 1px;
  margin: 24px 0;
  padding: 0;
  list-style: none;
  background: var(--grid-line);
  border: var(--about-line);
}

.page-about .team-stats li {
  display: flex;
  gap: 16px;
  align-items: baseline;
  padding: 16px;
  background: var(--mist);
}

.page-about .team-stats__num {
  min-width: 4.5em;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--ink-abyss);
}

.page-about .team-stats__label {
  font-size: 14px;
  line-height: 1.6;
  color: var(--slate);
}

/* 发展历程时间轴 */
.page-about .about-timeline {
  display: grid;
  gap: 1px;
  background: var(--grid-line);
  border-top: var(--about-line);
  border-bottom: var(--about-line);
}

.page-about .about-stage {
  position: relative;
  padding: 28px 20px 24px;
  background: var(--pearl);
}

.page-about .about-stage::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: var(--grid-line);
  transition: background-color 0.5s ease;
}

.page-about .about-stage.is-lit::before {
  background: var(--coral-entry);
}

.page-about .about-stage .timeline__time {
  margin: 0 0 14px;
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--sea-mid);
  transition: color 0.4s ease;
}

.page-about .about-stage.is-lit .timeline__time {
  color: var(--coral-text);
}

.page-about .about-stage__name {
  margin: 0 0 12px;
  font-size: 1.25rem;
  line-height: 1.35;
  font-weight: 600;
  color: var(--ink-abyss);
}

.page-about .about-stage__desc {
  margin: 0 0 16px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--slate);
}

.page-about .about-stage__more {
  padding-top: 12px;
  border-top: var(--about-line);
}

.page-about .about-stage__more summary {
  display: flex;
  gap: 8px;
  align-items: center;
  cursor: pointer;
  list-style: none;
  font-size: 14px;
  color: var(--coral-text);
}

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

.page-about .about-stage__more summary::before {
  content: "+";
  font-family: var(--font-mono);
  color: var(--coral-entry);
}

.page-about .about-stage__more[open] summary::before {
  content: "–";
}

.page-about .about-stage__more ul {
  margin: 12px 0 0;
  padding-left: 1.1em;
}

.page-about .about-stage__more li {
  margin-bottom: 6px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--slate);
}

/* 质量承诺与下一步 */
.page-about .pledge {
  display: grid;
  gap: 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .pledge__item {
  padding-left: 20px;
  border-left: 3px solid var(--ink-deep);
}

.page-about .pledge__item h3 {
  margin: 0 0 8px;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--ink-abyss);
}

.page-about .pledge__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--slate);
}

.page-about .pledge__foot {
  margin: 28px 0 0;
  max-width: var(--prose-max);
  font-size: 15px;
  line-height: 1.75;
  color: var(--slate);
}

.page-about .pledge__foot a {
  color: var(--coral-text);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-next {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

/* 平板与桌面 */
@media (min-width: 640px) {
  .page-about .hero-facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

@media (min-width: 760px) {
  .page-about .audience-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
  }

  .page-about .about-hero__figure img {
    aspect-ratio: 5 / 7;
  }

  .page-about .chapter {
    grid-template-columns: minmax(0, 4fr) minmax(0, 7fr);
    gap: clamp(32px, 5vw, 64px);
    align-items: start;
  }

  .page-about .chapter__label {
    position: sticky;
    top: var(--about-label-top);
  }

  .page-about .chapter__label--stacked {
    position: static;
    max-width: 62ch;
    margin-bottom: 40px;
  }

  .page-about .team {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    align-items: start;
    gap: clamp(32px, 5vw, 56px);
  }

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

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

@media (min-width: 1180px) {
  .page-about .audience-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .audience-card:nth-child(even) {
    transform: translateY(16px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .audience-card,
  .page-about .process__step,
  .page-about .about-stage::before {
    transition: none;
  }

  .page-about .audience-card:nth-child(even) {
    transform: none;
  }
}