.page-about {
  --about-rail-w: 216px;
  --about-gap: clamp(28px, 4vw, 56px);
  --about-line: rgba(11, 23, 48, 0.14);
  --about-num: rgba(11, 23, 48, 0.13);
  background: var(--paper);
  color: var(--ink);
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-top: clamp(112px, 15vw, 176px);
  padding-bottom: clamp(56px, 8vw, 104px);
  background:
    radial-gradient(circle at 82% 12%, rgba(22, 163, 74, 0.28), transparent 46%),
    radial-gradient(circle at 8% 84%, rgba(242, 98, 42, 0.16), transparent 44%),
    var(--ink);
  color: var(--paper);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(53, 214, 196, 0.08) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(53, 214, 196, 0.08) 1px, transparent 1px);
  background-size: 72px 72px;
  pointer-events: none;
}

.page-about .about-hero .wrap {
  position: relative;
  z-index: 1;
}

.page-about .about-hero__crumbs {
  margin-bottom: clamp(28px, 4vw, 48px);
}

.page-about .about-hero__crumbs a {
  color: var(--steel);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color var(--t-fast), color var(--t-fast);
}

.page-about .about-hero__crumbs a:hover,
.page-about .about-hero__crumbs a:focus-visible {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

.page-about .about-hero__crumbs span {
  color: var(--steel);
}

.page-about .about-hero__crumbs [aria-current="page"] {
  color: var(--paper);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(32px, 5vw, 64px);
}

.page-about .about-hero h1 {
  margin: 18px 0 0;
  font-size: clamp(34px, 6.4vw, 76px);
  line-height: 1.02;
  letter-spacing: -0.025em;
  font-weight: 700;
  max-width: 15em;
}

.page-about .about-hero .lede {
  margin-top: 24px;
  max-width: 34em;
  font-size: clamp(15px, 1.4vw, 18px);
  line-height: 1.75;
  color: rgba(245, 246, 241, 0.86);
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1px;
  margin: clamp(32px, 4vw, 44px) 0 0;
  background: rgba(30, 44, 72, 0.9);
  border: 1px solid var(--grid);
}

.page-about .about-fact {
  padding: 16px 18px;
  background: rgba(6, 13, 28, 0.72);
}

.page-about .about-fact dt {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--steel);
}

.page-about .about-fact dd {
  margin: 8px 0 0;
  font-size: 14px;
  color: rgba(245, 246, 241, 0.9);
}

.page-about .about-fact__num {
  font-family: var(--font-mono);
  font-size: 26px;
  font-weight: 700;
  color: var(--lime);
  font-variant-numeric: tabular-nums;
  margin-right: 4px;
}

/* ---------- 图片块 ---------- */
.page-about .about-figure {
  position: relative;
  margin: 0;
  overflow: hidden;
  background: var(--midnight);
  border: 1px solid var(--grid);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.92);
  transition: filter var(--t-mid);
}

.page-about .about-figure--hero {
  aspect-ratio: 11 / 7;
}

.page-about .about-figure--side {
  aspect-ratio: 3 / 2;
}

.page-about .about-figure--panel {
  aspect-ratio: 2 / 1;
}

.page-about .about-figure::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(22, 163, 74, 0.42), rgba(22, 163, 74, 0.1));
  opacity: 0;
  transition: opacity var(--t-fast);
  pointer-events: none;
}

.page-about .about-figure:hover::after,
.page-about .about-figure:focus-within::after {
  opacity: 1;
}

.page-about .about-figure__cap {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 14px 16px 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--paper);
  background: linear-gradient(180deg, transparent, rgba(6, 13, 28, 0.88) 62%);
  z-index: 2;
}

/* ---------- 轨道 + 内容流 ---------- */
.page-about .about-shell {
  display: grid;
  gap: var(--about-gap);
  padding-block: clamp(52px, 8vw, 104px);
}

.page-about .about-rail__label {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--steel);
  text-transform: uppercase;
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 6px;
  scrollbar-width: thin;
}

.page-about .about-rail__item {
  flex: 0 0 auto;
}

.page-about .about-rail__node {
  display: block;
  padding: 9px 14px;
  text-decoration: none;
  color: var(--ink);
  border: 1px solid var(--grid);
  border-radius: 999px;
  white-space: nowrap;
  transition: border-color var(--t-fast), background var(--t-fast), color var(--t-fast);
}

.page-about .about-rail__node:hover,
.page-about .about-rail__node:focus-visible {
  border-color: var(--pitch);
  background: rgba(22, 163, 74, 0.1);
}

.page-about .about-rail__no {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  color: var(--pitch-deep);
  margin-right: 6px;
  font-variant-numeric: tabular-nums;
}

.page-about .about-rail__title {
  font-size: 14px;
  font-weight: 600;
}

.page-about .about-rail__tags,
.page-about .about-rail__foot {
  display: none;
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  padding-top: clamp(36px, 5vw, 64px);
  scroll-margin-top: 120px;
  border-top: 1px solid var(--about-line);
  transition: background-color var(--t-mid);
}

.page-about .about-chapter:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-chapter:target {
  background: rgba(22, 163, 74, 0.05);
}

.page-about .about-chapter__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  flex-wrap: wrap;
}

.page-about .about-chapter__num {
  font-family: var(--font-mono);
  font-size: clamp(46px, 9vw, 104px);
  font-weight: 200;
  line-height: 0.85;
  letter-spacing: -0.04em;
  color: var(--about-num);
  font-variant-numeric: tabular-nums;
  flex: 0 0 auto;
}

.page-about .about-chapter__title {
  margin: 0;
  font-size: clamp(23px, 3.4vw, 40px);
  line-height: 1.16;
  letter-spacing: -0.02em;
  max-width: 18em;
}

.page-about .about-chapter__lede {
  margin: 20px 0 0;
  max-width: 40em;
  font-size: 16px;
  line-height: 1.75;
  color: var(--pitch-deep);
}

.page-about .about-chapter__grid {
  display: grid;
  gap: clamp(22px, 3.6vw, 44px);
  margin-top: clamp(22px, 3vw, 34px);
}

.page-about .about-chapter__text p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.8;
}

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

.page-about .about-chapter__note {
  margin: 0;
  padding: 16px 0 16px 18px;
  border-left: 3px solid var(--stand);
  font-size: 15px;
  line-height: 1.75;
  color: var(--pitch-deep);
  background: linear-gradient(90deg, rgba(242, 98, 42, 0.08), transparent 72%);
}

/* ---------- 时间线 ---------- */
.page-about .about-timeline {
  margin-top: clamp(24px, 3vw, 36px);
  padding: 20px 16px;
  background: var(--ink);
  border: 1px solid var(--grid);
  background-image:
    linear-gradient(to right, rgba(53, 214, 196, 0.07) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(53, 214, 196, 0.07) 1px, transparent 1px);
  background-size: 48px 48px;
}

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

/* ---------- 阶段卡片 ---------- */
.page-about .about-phases {
  list-style: none;
  margin: clamp(24px, 3vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-phase {
  padding: 20px 20px 22px;
  border: 1px solid var(--grid);
  border-top: 3px solid var(--pitch);
  background: rgba(255, 255, 255, 0.5);
  transition: border-color var(--t-fast), background-color var(--t-fast);
}

.page-about .about-phase:hover {
  border-color: var(--pitch);
  background: rgba(22, 163, 74, 0.07);
}

.page-about .about-phase__step {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--stand);
}

.page-about .about-phase__name {
  margin: 0 0 10px;
  font-size: 18px;
  line-height: 1.35;
}

.page-about .about-phase p:last-child {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(11, 23, 48, 0.82);
}

.page-about .about-chapter__grid--phases {
  margin-top: clamp(26px, 3.4vw, 40px);
}

/* ---------- 引言 ---------- */
.page-about .about-quote {
  margin: clamp(40px, 6vw, 80px) 0;
  padding: clamp(24px, 4vw, 40px) 0 clamp(24px, 4vw, 40px) clamp(20px, 3vw, 34px);
  border-left: 5px solid var(--pitch);
  border-top: 1px solid var(--about-line);
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-quote p {
  margin: 0;
  max-width: 20em;
  font-size: clamp(22px, 4vw, 42px);
  line-height: 1.28;
  font-weight: 700;
  letter-spacing: -0.025em;
  color: var(--ink);
}

/* ---------- 去向 ---------- */
.page-about .about-next {
  background: var(--midnight);
  color: var(--paper);
  padding-block: clamp(44px, 6vw, 84px);
  border-top: 4px solid var(--pitch);
}

.page-about .about-next__title {
  margin: 0 0 clamp(24px, 3vw, 36px);
  font-size: clamp(24px, 3.4vw, 40px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--paper);
}

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

.page-about .about-next__link {
  display: block;
  padding: 20px 18px;
  background: var(--ink);
  text-decoration: none;
  color: var(--paper);
  transition: background-color var(--t-fast), box-shadow var(--t-fast);
}

.page-about .about-next__link:hover,
.page-about .about-next__link:focus-visible {
  background: rgba(22, 163, 74, 0.18);
  box-shadow: inset 0 0 0 1px var(--lime);
}

.page-about .about-next__k {
  display: block;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.page-about .about-next__d {
  display: block;
  margin-top: 8px;
  font-size: 14px;
  line-height: 1.65;
  color: var(--steel);
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 720px) {
  .page-about .about-phases {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

@media (min-width: 960px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr);
    align-items: end;
  }

  .page-about .about-shell {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 116px;
  }

  .page-about .about-rail__list {
    display: block;
    overflow: visible;
    padding-bottom: 0;
    border-left: 1px solid var(--about-line);
  }

  .page-about .about-rail__item + .about-rail__item {
    margin-top: 2px;
  }

  .page-about .about-rail__node {
    position: relative;
    border: 0;
    border-radius: 0;
    padding: 12px 8px 12px 20px;
    border-left: 3px solid transparent;
    margin-left: -1px;
    white-space: normal;
  }

  .page-about .about-rail__node::before {
    content: "";
    position: absolute;
    left: 0;
    top: 18px;
    width: 7px;
    height: 7px;
    background: var(--grid);
    transform: translateX(-4px);
    transition: background-color var(--t-fast);
  }

  .page-about .about-rail__node:hover,
  .page-about .about-rail__node:focus-visible {
    border-left-color: var(--pitch);
    background: rgba(22, 163, 74, 0.07);
  }

  .page-about .about-rail__node:hover::before,
  .page-about .about-rail__node:focus-visible::before {
    background: var(--pitch);
  }

  .page-about .about-rail__no {
    display: block;
    margin: 0 0 2px;
    font-size: 11px;
    letter-spacing: 0.1em;
  }

  .page-about .about-rail__title {
    display: block;
    font-size: 15px;
  }

  .page-about .about-rail__tags {
    display: block;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    font-size: 12px;
    line-height: 1.6;
    color: var(--steel);
    transition: max-height var(--t-mid), opacity var(--t-mid), margin-top var(--t-mid);
  }

  .page-about .about-rail__node:hover .about-rail__tags,
  .page-about .about-rail__node:focus-visible .about-rail__tags {
    max-height: 80px;
    opacity: 1;
    margin-top: 6px;
  }

  .page-about .about-rail__foot {
    display: block;
    margin: 18px 0 0;
    padding-top: 14px;
    border-top: 1px solid var(--about-line);
    font-family: var(--font-mono);
    font-size: 11px;
    line-height: 1.7;
    letter-spacing: 0.06em;
    color: var(--steel);
  }

  .page-about .about-chapter__grid {
    grid-template-columns: repeat(12, minmax(0, 1fr));
    align-items: start;
  }

  .page-about .about-chapter__text {
    grid-column: 1 / 7;
  }

  .page-about .about-chapter__note {
    grid-column: 8 / 13;
  }

  .page-about .about-figure--side {
    grid-column: 7 / 13;
    margin-top: 40px;
  }

  .page-about .about-chapter--flip .about-chapter__text {
    grid-column: 7 / 13;
    order: 2;
  }

  .page-about .about-chapter--flip .about-chapter__note {
    grid-column: 1 / 6;
    order: 1;
  }

  .page-about .about-chapter--flip .about-figure--side {
    grid-column: 1 / 7;
    order: 3;
  }

  .page-about .about-chapter__grid--phases .about-chapter__text {
    grid-column: 1 / 6;
  }

  .page-about .about-chapter__grid--phases .about-figure--panel {
    grid-column: 6 / 13;
    margin-top: 36px;
  }

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

@media (min-width: 1200px) {
  .page-about .about-chapter__text p {
    font-size: 17px;
  }
}
<<<END>>>