.page-about {
  --about-line: rgba(79, 124, 91, 0.34);
  --about-ink-soft: rgba(10, 31, 51, 0.74);
  background: var(--fog);
  color: var(--abyss);
}

/* ---------- 首屏 ---------- */
.page-about__hero {
  position: relative;
  overflow: hidden;
  background: var(--abyss);
  color: var(--paper);
  padding: calc(var(--header-h) + clamp(2.2rem, 7vw, 4.5rem)) 0 clamp(2.6rem, 7vw, 4.2rem);
}

.page-about__hero-grid {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 84% 6%, rgba(31, 224, 208, 0.22), transparent 50%),
    radial-gradient(circle at 4% 94%, rgba(79, 124, 91, 0.36), transparent 46%);
}

.page-about__hero-grid::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(24deg, rgba(198, 208, 217, 0.075) 0 1px, transparent 1px 54px);
}

.page-about__hero-inner {
  position: relative;
  z-index: 1;
}

.page-about__crumb {
  margin: 0 0 clamp(1.2rem, 4vw, 2rem);
}

.page-about__crumb a {
  color: var(--cyan);
  text-decoration: none;
}

.page-about__title {
  margin: 0.55rem 0 0;
  max-width: 17em;
  font-size: clamp(1.95rem, 6.2vw, 3.75rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.page-about__lede {
  margin: clamp(1rem, 3vw, 1.5rem) 0 0;
  max-width: 46em;
  font-size: clamp(1rem, 2.2vw, 1.0625rem);
  line-height: 1.75;
  color: rgba(245, 248, 250, 0.78);
}

.page-about__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.1rem 1.5rem;
  margin: clamp(1.8rem, 5vw, 2.8rem) 0 0;
  padding-top: clamp(1.2rem, 4vw, 1.8rem);
  border-top: 1px solid var(--line);
}

.page-about__stat dt {
  margin: 0 0 0.25rem;
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--silver);
}

.page-about__stat dd {
  margin: 0;
  font-size: clamp(1.35rem, 4vw, 1.85rem);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--cyan);
}

/* ---------- 通栏图 ---------- */
.page-about__wide {
  margin: 0;
  background: var(--abyss);
}

.page-about__wide img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.page-about__wide-cap {
  display: block;
  padding: 0.85rem var(--gutter) 1.1rem;
  background: var(--void);
  color: var(--silver);
  font-size: 13px;
  line-height: 1.65;
}

/* ---------- 正文分屏 ---------- */
.page-about__body {
  padding: clamp(2.4rem, 7vw, 4.5rem) 0 clamp(3rem, 9vw, 6rem);
}

.page-about__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.6rem, 5vw, 2.6rem);
  align-items: start;
}

/* ---------- 左侧章节索引 ---------- */
.page-about__rail {
  padding-left: 0.9rem;
  border-left: 2px solid rgba(79, 124, 91, 0.5);
}

.page-about__rail-title {
  margin: 0 0 0.75rem;
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--moss);
}

.page-about__index {
  display: flex;
  flex-wrap: nowrap;
  gap: 0.35rem 0.6rem;
  margin: 0;
  padding: 0 0 0.45rem;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
}

.page-about__index li {
  min-width: 0;
}

.page-about__index .index-link {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
  padding: 0.45rem 0.6rem;
  border-left: 3px solid transparent;
  border-radius: 0 6px 6px 0;
  font-size: 13.5px;
  line-height: 1.45;
  color: rgba(10, 31, 51, 0.58);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--speed) var(--ease), background-color var(--speed) var(--ease), border-color var(--speed) var(--ease);
}

.page-about__index .index-link:hover {
  color: var(--abyss);
  background: rgba(31, 224, 208, 0.08);
}

.page-about__index .index-link:focus-visible {
  outline: 2px solid var(--coral);
  outline-offset: 2px;
}

.page-about__index .index-link.is-current {
  color: var(--abyss);
  border-left-color: var(--cyan);
  background: rgba(31, 224, 208, 0.12);
}

.page-about__idx {
  font-size: 11px;
  letter-spacing: 0.05em;
  color: var(--moss);
}

.page-about__index .index-link.is-current .page-about__idx {
  color: var(--coral);
}

/* ---------- 右侧叙事正文 ---------- */
.page-about__content {
  min-width: 0;
}

.page-about__section {
  padding: clamp(1.7rem, 4.5vw, 2.6rem) 0;
  border-top: 1px solid var(--about-line);
  scroll-margin-top: calc(var(--header-h) + 1.5rem);
}

.page-about__content > .page-about__section:first-child {
  padding-top: 0;
  border-top: 0;
}

.page-about__no {
  margin: 0 0 0.5rem;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--coral);
}

.page-about__h2 {
  margin: 0 0 clamp(0.85rem, 2.5vw, 1.2rem);
  max-width: 20em;
  font-size: clamp(1.45rem, 4.2vw, 2.05rem);
  font-weight: 900;
  line-height: 1.26;
  letter-spacing: -0.02em;
}

.page-about__p {
  margin: 0 0 0.95rem;
  max-width: 56em;
  font-size: 1rem;
  line-height: 1.75;
  color: var(--about-ink-soft);
}

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

.page-about__p a {
  color: var(--moss);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about__p a:hover {
  color: var(--coral);
}

/* ---------- 服务卡片 ---------- */
.page-about__cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.85rem;
  margin-top: clamp(1.1rem, 3vw, 1.6rem);
}

.page-about__card {
  padding: 1rem 1.1rem 1.15rem;
  background: var(--paper);
  border-left: 3px solid var(--moss);
  border-radius: 0 var(--notch) var(--notch) 0;
  box-shadow: 0 12px 28px -24px rgba(10, 31, 51, 0.5);
}

.page-about__card:nth-child(3n + 2) {
  border-left-color: var(--cyan);
}

.page-about__card:nth-child(3n) {
  border-left-color: var(--moss);
  background: rgba(167, 243, 237, 0.24);
}

.page-about__card h3 {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  margin: 0 0 0.4rem;
  font-size: 1rem;
  font-weight: 900;
  letter-spacing: -0.01em;
}

.page-about__card h3 .mono {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--coral);
}

.page-about__card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.68;
  color: rgba(10, 31, 51, 0.72);
}

.page-about__card p a {
  color: var(--moss);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about__card p a:hover {
  color: var(--coral);
}

/* ---------- 团队 ---------- */
.page-about__team {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.9rem;
  margin: clamp(1rem, 3vw, 1.5rem) 0 0;
  padding: 0;
  list-style: none;
}

.page-about__team li {
  padding-top: 0.85rem;
  border-top: 1px solid var(--about-line);
}

.page-about__team-num {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 1.7rem;
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--abyss);
}

.page-about__team h3 {
  margin: 0 0 0.4rem;
  font-size: 0.95rem;
  font-weight: 900;
  color: var(--moss);
}

.page-about__team p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.68;
  color: var(--about-ink-soft);
}

/* ---------- 图文块 ---------- */
.page-about__figure {
  margin: clamp(1.2rem, 3.5vw, 1.8rem) 0 0;
}

.page-about__figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
}

.page-about__figure figcaption {
  margin-top: 0.65rem;
  font-size: 13px;
  line-height: 1.65;
  color: rgba(10, 31, 51, 0.58);
}

/* ---------- 阶段轨迹 ---------- */
.page-about__phases {
  display: grid;
  gap: 0.55rem;
  margin: clamp(1rem, 3vw, 1.5rem) 0 0;
  padding: 0;
  list-style: none;
}

.page-about__phase {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.9rem;
  padding: 0.9rem 1rem;
  background: var(--paper);
  border-left: 3px solid var(--moss);
  border-radius: 0 var(--notch) var(--notch) 0;
  transition: border-color var(--speed) var(--ease), box-shadow var(--speed) var(--ease), transform var(--speed) var(--ease);
}

.page-about__phase:hover,
.page-about__phase:focus-within {
  border-left-color: var(--coral);
  transform: translateY(-2px);
  box-shadow: 0 16px 32px -26px rgba(10, 31, 51, 0.7);
}

.page-about__phase:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.page-about__phase-no {
  padding-top: 2px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--moss);
}

.page-about__phase-title {
  margin: 0 0 0.28rem;
  font-size: 0.98rem;
  font-weight: 900;
  letter-spacing: -0.01em;
}

.page-about__phase-brief {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.65;
  color: var(--about-ink-soft);
}

.page-about__phase-more {
  max-height: 0;
  margin: 0;
  overflow: hidden;
  opacity: 0;
  font-size: 0.875rem;
  line-height: 1.65;
  color: rgba(10, 31, 51, 0.56);
  transition: max-height var(--speed) var(--ease), opacity var(--speed) var(--ease), margin-top var(--speed) var(--ease);
}

.page-about__phase:hover .page-about__phase-more,
.page-about__phase:focus-within .page-about__phase-more {
  max-height: 7rem;
  margin-top: 0.4rem;
  opacity: 1;
}

.page-about__phase-more a {
  color: var(--moss);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 合作与地区 ---------- */
.page-about__partners {
  display: grid;
  gap: 0;
  margin: clamp(1rem, 3vw, 1.5rem) 0 0;
  padding: 0;
  list-style: none;
}

.page-about__partners li {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  padding: 0.7rem 0.15rem;
  border-bottom: 1px solid var(--about-line);
}

.page-about__partners .mono {
  flex: 0 0 auto;
  min-width: 4.6rem;
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--moss);
  letter-spacing: -0.01em;
}

.page-about__partners span:last-child {
  font-size: 0.9375rem;
  line-height: 1.6;
  color: var(--about-ink-soft);
}

/* ---------- 合作入口 ---------- */
.page-about__coop {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.3rem;
  margin-top: clamp(1rem, 3vw, 1.4rem);
  padding: clamp(1.1rem, 3vw, 1.6rem);
  background: var(--paper);
  border-left: 3px solid var(--cyan);
  border-radius: 0 var(--notch) var(--notch) 0;
}

.page-about__coop h3 {
  margin: 0 0 0.55rem;
  font-size: 0.95rem;
  font-weight: 900;
}

.page-about__coop ul {
  display: grid;
  gap: 0.35rem;
  margin: 0 0 1rem;
  padding-left: 1.1rem;
}

.page-about__coop li {
  font-size: 0.9rem;
  line-height: 1.62;
  color: var(--about-ink-soft);
}

.page-about__coop .btn {
  margin-top: 0.2rem;
}

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about__team {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.1rem;
  }
}

@media (min-width: 760px) {
  .page-about__coop {
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
}

@media (min-width: 960px) {
  .page-about__grid {
    grid-template-columns: minmax(168px, 22%) minmax(0, 1fr);
    gap: clamp(2rem, 4.5vw, 4.2rem);
  }

  .page-about__rail {
    position: sticky;
    top: calc(var(--header-h) + 1.6rem);
  }

  .page-about__index {
    flex-wrap: wrap;
    overflow-x: visible;
    gap: 0.15rem 0.4rem;
    padding-bottom: 0;
  }

  .page-about__index li {
    flex: 1 1 100%;
  }

  .page-about__index .index-link {
    white-space: normal;
  }

  .page-about__cards {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about__index .index-link,
  .page-about__phase,
  .page-about__phase-more {
    transition: none;
  }

  .page-about__phase:hover,
  .page-about__phase:focus-within {
    transform: none;
  }
}