.page-about {
  --about-rail: 1.15rem;
  --about-marker: 2.3rem;
  --about-inline: clamp(1rem, 4vw, 1.6rem);
  color: var(--cloud);
  padding-bottom: clamp(2rem, 6vw, 4rem);
}

/* ---------- 面包屑上边距 ---------- */
.page-about .crumbs {
  padding-top: clamp(1.2rem, 4vw, 2.4rem);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(1.5rem, 5vw, 3rem) clamp(2.2rem, 7vw, 4.5rem);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(1.6rem, 5vw, 3rem);
  align-items: end;
}

.page-about .about-hero__copy {
  min-width: 0;
}

.page-about .about-hero h1 {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.06;
  font-size: clamp(2rem, 5.4vw, 3.6rem);
  margin: 0.45rem 0 0;
  max-width: 20ch;
  color: var(--cloud);
}

.page-about .about-hero .lede {
  margin: clamp(0.9rem, 2.5vw, 1.3rem) 0 0;
  max-width: 40rem;
  font-size: clamp(0.98rem, 1.5vw, 1.08rem);
  line-height: 1.85;
  color: var(--slate);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: clamp(1.4rem, 4vw, 2.2rem) 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem 1.75rem;
}

.page-about .about-hero__facts li {
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
  padding-left: 0.7rem;
  border-left: 2px solid var(--line);
}

.page-about .about-hero__facts b {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(1.4rem, 3vw, 1.95rem);
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-hero__facts span {
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--slate);
  max-width: 9rem;
}

.page-about .about-hero__media {
  margin: 0;
  position: relative;
  border: 1px solid var(--line);
  background: var(--panel);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
  overflow: hidden;
}

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

/* ---------- 时间轴 ---------- */
.page-about .about-timeline {
  position: relative;
  padding-block: clamp(0.5rem, 2vw, 1.2rem) clamp(1rem, 4vw, 2rem);
}

.page-about .timeline {
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: var(--about-rail);
  width: 1px;
  background: linear-gradient(
    to bottom,
    rgba(44, 58, 110, 0) 0%,
    var(--line) 6%,
    var(--line) 68%,
    rgba(35, 230, 200, 0.55) 100%
  );
  transform: translateX(-0.5px);
  z-index: 0;
}

.page-about .timeline::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    to bottom,
    rgba(154, 166, 201, 0.05) 0 1px,
    transparent 1px 4.5rem
  );
  pointer-events: none;
  z-index: 0;
}

.page-about .stage {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  padding-left: calc(var(--about-rail) + 3rem);
  padding-bottom: clamp(2.6rem, 6vw, 4rem);
  z-index: 1;
}

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

.page-about .stage__marker {
  position: absolute;
  top: 0;
  left: calc(var(--about-rail) - (var(--about-marker) / 2));
  width: var(--about-marker);
  height: var(--about-marker);
  display: grid;
  place-items: center;
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--slate);
  background: var(--ink);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease),
    background-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
  z-index: 2;
}

.page-about .stage.is-in .stage__marker {
  color: var(--cyan);
  border-color: rgba(35, 230, 200, 0.55);
  background: rgba(35, 230, 200, 0.1);
  box-shadow: 0 0 0 4px rgba(35, 230, 200, 0.07);
}

.page-about .stage__body {
  min-width: 0;
}

.page-about .stage__body h2 {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.01em;
  line-height: 1.25;
  font-size: clamp(1.3rem, 2.6vw, 1.78rem);
  margin: 0 0 0.9rem;
  color: var(--cloud);
}

.page-about .stage__body p {
  margin: 0 0 0.9rem;
  font-size: 0.97rem;
  line-height: 1.88;
  color: var(--slate);
  max-width: 42rem;
}

.page-about .stage__body p:last-of-type {
  margin-bottom: 0;
}

.page-about .stage__link {
  margin-top: 1.1rem;
}

.page-about .stage__link a {
  display: inline-block;
  font-size: 0.85rem;
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(35, 230, 200, 0.4);
  padding-bottom: 2px;
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .stage__link a:hover,
.page-about .stage__link a:focus-visible {
  color: var(--cyan-lift);
  border-color: var(--cyan-lift);
}

/* 阶段内图片 */
.page-about .stage__media {
  margin: clamp(1.3rem, 3.5vw, 1.9rem) 0 0;
  border: 1px solid var(--line);
  background: var(--panel);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
  overflow: hidden;
}

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

/* 培训条形图 */
.page-about .train {
  list-style: none;
  margin: clamp(1.2rem, 3vw, 1.7rem) 0 0;
  padding: 0;
  display: grid;
  gap: 0.7rem;
}

.page-about .train__item {
  display: grid;
  grid-template-columns: minmax(6.5rem, 9rem) 1fr;
  align-items: center;
  gap: 0.75rem;
}

.page-about .train__label {
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--slate);
}

.page-about .train__track {
  display: block;
  height: 0.7rem;
  background: rgba(44, 58, 110, 0.55);
  border-left: 2px solid var(--line);
}

.page-about .train__fill {
  display: block;
  height: 100%;
  width: 0;
  transform-origin: left center;
  transition: width 0.7s var(--ease);
}

.page-about .train__fill--a {
  background: linear-gradient(90deg, rgba(255, 154, 60, 0.35), var(--amber));
}

.page-about .train__fill--b {
  background: linear-gradient(90deg, rgba(35, 230, 200, 0.3), var(--cyan));
}

.page-about .train__fill--c {
  background: linear-gradient(90deg, rgba(255, 61, 127, 0.3), var(--magenta));
}

.page-about .stage.is-in .train__fill--a { width: 74%; }
.page-about .stage.is-in .train__fill--b { width: 92%; }
.page-about .stage.is-in .train__fill--c { width: 63%; }

.page-about .train__item:nth-child(2) .train__fill { transition-delay: 0.12s; }
.page-about .train__item:nth-child(3) .train__fill { transition-delay: 0.24s; }

/* 留痕节点链 */
.page-about .trace {
  margin: clamp(1.3rem, 3.5vw, 1.9rem) 0 0;
  padding: clamp(0.9rem, 2.5vw, 1.3rem) clamp(0.8rem, 2.5vw, 1.2rem) clamp(0.4rem, 1.5vw, 0.7rem);
  background: rgba(22, 32, 74, 0.65);
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
}

.page-about .trace__svg {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .trace__dot {
  transform-box: fill-box;
  transform-origin: center;
  transform: scale(0);
  transition: transform 0.45s var(--ease);
}

.page-about .trace.is-in .trace__dot {
  transform: scale(1);
}

.page-about .trace__node:nth-child(2) .trace__dot { transition-delay: 0.06s; }
.page-about .trace__node:nth-child(3) .trace__dot { transition-delay: 0.12s; }
.page-about .trace__node:nth-child(4) .trace__dot { transition-delay: 0.18s; }
.page-about .trace__node:nth-child(5) .trace__dot { transition-delay: 0.24s; }
.page-about .trace__node:nth-child(6) .trace__dot { transition-delay: 0.3s; }
.page-about .trace__node:nth-child(7) .trace__dot { transition-delay: 0.36s; }

.page-about .trace__cap {
  display: block;
  margin-top: 0.35rem;
  font-size: 0.72rem;
  letter-spacing: 0.02em;
  color: var(--slate);
}

/* ---------- 收束段 ---------- */
.page-about .about-close {
  position: relative;
  margin-top: clamp(2rem, 6vw, 3.5rem);
  padding-block: clamp(2.2rem, 6vw, 4rem) clamp(1rem, 3vw, 1.6rem);
  background: linear-gradient(180deg, rgba(22, 32, 74, 0.9), rgba(5, 7, 15, 0.95));
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-close::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  width: clamp(3rem, 12vw, 7rem);
  height: 3px;
  background: var(--cyan);
}

.page-about .about-close__inner {
  display: grid;
  gap: clamp(1rem, 3vw, 1.4rem);
}

.page-about .about-close h2 {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.015em;
  line-height: 1.2;
  font-size: clamp(1.5rem, 3.4vw, 2.1rem);
  margin: 0;
  color: var(--cloud);
  max-width: 22ch;
}

.page-about .about-close p {
  margin: 0;
  font-size: 0.97rem;
  line-height: 1.88;
  color: var(--slate);
  max-width: 46rem;
}

.page-about .about-close__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 0.4rem;
}

/* ---------- 窄屏：单列堆叠，禁止横向溢出 ---------- */
@media (max-width: 33rem) {
  .page-about .about-hero__facts {
    flex-direction: column;
    gap: 0.7rem;
  }

  .page-about .about-hero__facts span {
    max-width: none;
  }

  .page-about .train__item {
    grid-template-columns: 1fr;
    gap: 0.3rem;
  }
}

/* ---------- 桌面端：轴线居中的左右交替 ---------- */
@media (min-width: 60rem) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    align-items: center;
  }

  .page-about .about-hero__media {
    margin-bottom: -1.6rem;
  }

  .page-about .timeline::before {
    left: 50%;
  }

  .page-about .stage {
    grid-template-columns: 1fr 4.5rem 1fr;
    padding-left: 0;
  }

  .page-about .stage__marker {
    position: static;
    grid-column: 2;
    grid-row: 1;
    justify-self: center;
    align-self: start;
    margin-top: 0.2rem;
    background: var(--ink);
  }

  .page-about .stage--left .stage__body {
    grid-column: 1;
    grid-row: 1;
    padding-right: 1.6rem;
  }

  .page-about .stage--right .stage__body {
    grid-column: 3;
    grid-row: 1;
    padding-left: 1.6rem;
  }

  .page-about .stage--right .stage__media {
    width: calc(100% + 3rem);
    margin-left: -3rem;
  }

  .page-about .stage--left .stage__media,
  .page-about .stage--left .trace {
    width: calc(100% + 3rem);
    margin-right: -3rem;
  }
}

@media (min-width: 78rem) {
  .page-about .about-hero h1 {
    max-width: 22ch;
  }
}

/* ---------- 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .page-about .trace__dot {
    transform: scale(1);
    transition: none;
  }

  .page-about .train__fill {
    transition: none;
  }

  .page-about .stage.is-in .train__fill--a { width: 74%; }
  .page-about .stage.is-in .train__fill--b { width: 92%; }
  .page-about .stage.is-in .train__fill--c { width: 63%; }
}