.page-about {
  position: relative;
  background:
    radial-gradient(120% 55% at 84% -8%, rgba(140, 196, 255, 0.13), transparent 62%),
    linear-gradient(180deg, var(--navy-deep) 0%, var(--navy) 40%, var(--navy) 100%);
  color: var(--snow);
}

/* ---------- 面包屑 ---------- */
.page-about .about-breadcrumb {
  padding-top: var(--sp-4);
}

.page-about .about-breadcrumb .breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--sp-1);
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist);
}

.page-about .about-breadcrumb li + li::before {
  content: '/';
  margin-right: var(--sp-1);
  color: var(--line);
}

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

.page-about .about-breadcrumb a:hover,
.page-about .about-breadcrumb a:focus-visible {
  color: var(--white);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: var(--sp-3) 0 var(--sp-5);
}

.page-about .about-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-4);
  align-items: start;
}

.page-about .about-hero h1 {
  margin: var(--sp-2) 0 var(--sp-3);
  font-family: var(--font-display);
  font-size: clamp(34px, 6.4vw, 64px);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--white);
}

.page-about .about-lead {
  margin: 0 0 var(--sp-3);
  max-width: 46ch;
  font-size: 16px;
  line-height: 1.85;
  color: var(--snow);
}

.page-about .about-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
}

.page-about .about-hero-media {
  position: relative;
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line-soft);
}

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

.page-about .about-hero-media::after {
  content: '';
  position: absolute;
  inset: auto 0 0 0;
  height: 4px;
  background: linear-gradient(
    90deg,
    var(--link) 0 20%,
    var(--white) 20% 40%,
    var(--red) 40% 60%,
    var(--green) 60% 80%,
    var(--yellow) 80% 100%
  );
}

/* ---------- 左右分屏主体 ---------- */
.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-4);
  padding-bottom: var(--sp-6);
}

/* ---------- 左侧台阶索引 ---------- */
.page-about .about-rail {
  display: none;
}

.page-about .about-rail-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 2px;
}

.page-about .about-rail-node {
  position: relative;
  display: block;
  min-height: 44px;
  padding: 12px var(--sp-2) 12px var(--sp-3);
  text-decoration: none;
  color: var(--mist);
  transition: color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.page-about .about-rail-node::before {
  content: '';
  position: absolute;
  left: 0;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: var(--orange);
  opacity: 0;
  transform: scaleY(0.35);
  transform-origin: center;
  transition: opacity 0.2s var(--ease), transform 0.2s var(--ease);
}

.page-about .about-rail-node:hover::before,
.page-about .about-rail-node:focus-visible::before {
  opacity: 1;
  transform: scaleY(1);
}

.page-about .about-rail-node:focus-visible {
  outline: 2px solid var(--link);
  outline-offset: 3px;
}

.page-about .about-rail-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--line);
  transition: color 0.2s var(--ease);
}

.page-about .about-rail-label {
  display: block;
  margin-top: 3px;
  font-size: 14px;
  font-weight: 500;
  line-height: 1.45;
  color: inherit;
  transition: color 0.2s var(--ease);
}

.page-about .about-rail-node:hover .about-rail-num,
.page-about .about-rail-node:focus-visible .about-rail-num {
  color: var(--orange);
}

.page-about .about-rail-node:hover .about-rail-label,
.page-about .about-rail-node:focus-visible .about-rail-label {
  color: var(--white);
}

@media (min-width: 900px) {
  .page-about .about-rail {
    display: block;
    position: sticky;
    top: calc(var(--header-h) + var(--sp-4));
    align-self: start;
    padding-left: 0;
  }

  .page-about .about-rail::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--line-soft);
  }

  .page-about .about-rail::after {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 2px;
    height: 100%;
    background: linear-gradient(180deg, var(--orange), var(--yellow));
    transform: scaleY(0);
    transform-origin: top;
    opacity: 0.9;
    pointer-events: none;
  }
}

@supports (animation-timeline: scroll()) {
  @media (min-width: 900px) and (prefers-reduced-motion: no-preference) {
    .page-about .about-rail::after {
      animation: aboutRailFill linear both;
      animation-timeline: scroll(root block);
    }
  }
}

@keyframes aboutRailFill {
  from {
    transform: scaleY(0);
  }
  to {
    transform: scaleY(1);
  }
}

/* ---------- 右侧连续叙事 ---------- */
.page-about .about-flow {
  display: block;
  min-width: 0;
}

.page-about .about-chapter {
  padding: var(--sp-5) 0 0;
  border-top: 1px solid var(--line-soft);
  margin-top: var(--sp-5);
  scroll-margin-top: calc(var(--header-h) + var(--sp-3));
}

.page-about .about-chapter:first-of-type {
  margin-top: 0;
  padding-top: 0;
  border-top: 0;
}

.page-about .about-chapter h2 {
  margin: var(--sp-2) 0 var(--sp-3);
  font-family: var(--font-display);
  font-size: clamp(24px, 3.6vw, 40px);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--white);
}

.page-about .about-chapter h3 {
  margin: 0 0 var(--sp-1);
  font-size: 17px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--white);
}

.page-about .about-chapter p {
  margin: 0 0 var(--sp-2);
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--snow);
}

.page-about .about-chapter p a {
  color: var(--link);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-chapter p a:hover,
.page-about .about-chapter p a:focus-visible {
  color: var(--white);
}

.page-about .about-quote {
  margin: var(--sp-4) 0 0;
  padding: var(--sp-1) 0 var(--sp-1) var(--sp-3);
  border-left: 3px solid var(--yellow);
  max-width: 40ch;
  font-size: clamp(19px, 2.6vw, 28px);
  font-weight: 700;
  line-height: 1.45;
  color: var(--white);
}

/* ---------- 三条主线 ---------- */
.page-about .about-lines {
  margin: var(--sp-3) 0 var(--sp-3);
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-line {
  display: grid;
  grid-template-columns: 3px minmax(0, 1fr);
  gap: var(--sp-3);
  padding: var(--sp-3) 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-line-bar {
  display: block;
  align-self: stretch;
  background: var(--link);
}

.page-about .about-line:nth-child(2) .about-line-bar {
  background: var(--yellow);
}

.page-about .about-line:nth-child(3) .about-line-bar {
  background: var(--green);
}

.page-about .about-line h3 {
  margin-bottom: var(--sp-1);
}

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

/* ---------- 家庭能力 ---------- */
.page-about .about-caps {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: var(--sp-3) 0 var(--sp-3);
  padding: 1px;
  list-style: none;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.page-about .about-caps li {
  background: var(--navy-2);
  padding: var(--sp-3);
}

.page-about .about-caps strong {
  display: block;
  margin-bottom: var(--sp-1);
  font-size: 15px;
  font-weight: 700;
  color: var(--yellow);
}

.page-about .about-caps span {
  display: block;
  font-size: 14px;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 图片块 ---------- */
.page-about .about-figure {
  margin: var(--sp-3) 0;
  border: 1px solid var(--line-soft);
}

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

.page-about .about-figure figcaption {
  padding: 10px var(--sp-2);
  border-top: 1px solid var(--line-soft);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.5;
  letter-spacing: 0.03em;
  color: var(--mist);
}

/* ---------- 三段流程 ---------- */
.page-about .about-steps {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-4);
  margin: var(--sp-3) 0 var(--sp-3);
  padding: 0;
  list-style: none;
  counter-reset: aboutStep;
}

.page-about .about-steps li {
  padding-top: var(--sp-2);
  border-top: 2px solid var(--line);
}

.page-about .about-steps li::before {
  counter-increment: aboutStep;
  content: '0' counter(aboutStep);
  display: block;
  margin-bottom: var(--sp-1);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--link);
}

.page-about .about-steps p {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 协作数字 ---------- */
.page-about .about-counters {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--sp-3) var(--sp-2);
  margin: var(--sp-4) 0 var(--sp-3);
  padding: var(--sp-3) 0 0;
  list-style: none;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-counter {
  border-left: 2px solid var(--line);
  padding-left: var(--sp-2);
}

.page-about .about-counter-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(28px, 5vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: var(--white);
}

.page-about .about-counter-label {
  display: block;
  margin-top: var(--sp-1);
  font-size: 13px;
  line-height: 1.5;
  color: var(--mist);
}

/* ---------- 收束动作 ---------- */
.page-about .about-close {
  margin-top: var(--sp-4);
  padding: var(--sp-4) var(--sp-3);
  background: var(--navy-2);
  border-left: 3px solid var(--orange);
}

.page-about .about-close-title {
  margin: 0 0 var(--sp-1);
  font-size: clamp(20px, 2.6vw, 26px);
  font-weight: 700;
  color: var(--white);
  max-width: none;
}

.page-about .about-close-text {
  margin: 0 0 var(--sp-3);
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
  max-width: 52ch;
}

.page-about .about-close-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-caps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

  .page-about .about-counters {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    padding: var(--sp-4) 0 var(--sp-6);
  }

  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: var(--sp-5);
    align-items: end;
  }

  .page-about .about-body {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
    gap: var(--sp-6);
    align-items: start;
  }

  .page-about .about-chapter {
    padding-top: var(--sp-6);
    margin-top: var(--sp-6);
  }

  .page-about .about-chapter:first-of-type {
    padding-top: 0;
    margin-top: 0;
  }

  .page-about .about-close {
    padding: var(--sp-5) var(--sp-4);
  }
}