.page-about {
  --about-rail: 288px;
  --about-gap: clamp(24px, 4vw, 56px);
  background: var(--mist);
  color: var(--brown);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  background-color: var(--ink);
  background-image:
    linear-gradient(118deg, rgba(47, 224, 168, 0.16) 0%, rgba(47, 224, 168, 0) 46%),
    linear-gradient(0deg, rgba(255, 106, 31, 0.10) 0%, rgba(255, 106, 31, 0) 38%);
  color: var(--mist);
  padding: clamp(28px, 6vw, 56px) 0 clamp(36px, 6vw, 72px);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  right: -8%;
  top: -30%;
  width: 46%;
  height: 160%;
  background: linear-gradient(180deg, rgba(47, 224, 168, 0.10), rgba(11, 31, 26, 0));
  transform: skewX(-12deg);
  pointer-events: none;
}

.page-about .about-hero .breadcrumbs {
  position: relative;
  z-index: 1;
  margin-bottom: clamp(18px, 3vw, 32px);
}

.page-about .about-hero .breadcrumbs__list,
.page-about .about-hero .breadcrumbs__item {
  color: rgba(201, 210, 206, 0.7);
}

.page-about .about-hero .breadcrumbs a {
  color: var(--silver);
  text-decoration: none;
}

.page-about .about-hero .breadcrumbs a:hover {
  color: var(--mint);
}

.page-about .hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(24px, 4vw, 40px);
  grid-template-columns: 1fr;
}

.page-about .hero-eyebrow {
  color: var(--mint);
  letter-spacing: 0.18em;
  margin: 0 0 14px;
}

.page-about .about-hero h1 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(34px, 7.4vw, 76px);
  line-height: 1.06;
  letter-spacing: 0.035em;
  margin: 0 0 clamp(16px, 2.5vw, 26px);
  max-width: 16em;
}

.page-about .hero-lead {
  color: rgba(237, 240, 238, 0.82);
  max-width: 34em;
  margin: 0;
  font-size: 16px;
  line-height: 1.75;
}

.page-about .hero-side {
  border-top: 1px solid var(--line-dark);
  padding-top: 16px;
}

.page-about .hero-side-label {
  margin: 0 0 12px;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--orange);
}

.page-about .hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 20px;
  margin: 0;
}

.page-about .hero-stat dt {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: rgba(201, 210, 206, 0.72);
  margin-bottom: 4px;
}

.page-about .hero-stat dd {
  margin: 0;
  font-size: 15px;
  color: var(--mist);
}

.page-about .hero-stat dd .mono {
  font-family: var(--font-mono);
  font-size: 26px;
  color: var(--orange);
  letter-spacing: 0.04em;
  margin-right: 2px;
}

/* ---------- 画布与侧栏 ---------- */
.page-about .about-canvas {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--about-gap);
  padding-top: clamp(24px, 4vw, 56px);
  padding-bottom: clamp(32px, 5vw, 72px);
}

.page-about .about-rail {
  background: var(--cream);
  border-top: 3px solid var(--orange);
  padding: 18px 18px 22px;
}

.page-about .rail-title {
  margin: 0 0 14px;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--ink-2);
}

.page-about .rail-stack {
  list-style: none;
  margin: 0 0 14px;
  padding: 0;
  display: grid;
  gap: 8px;
}

.page-about .rail-stack li {
  display: grid;
  grid-template-columns: 10px 1fr auto;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line-light);
}

.page-about .rail-dot {
  width: 10px;
  height: 10px;
  display: block;
}

.page-about .rail-dot--mint { background: var(--mint); }
.page-about .rail-dot--orange { background: var(--orange); }
.page-about .rail-dot--silver { background: var(--silver); }
.page-about .rail-dot--ink { background: var(--ink-3); }

.page-about .rail-num {
  font-family: var(--font-mono);
  font-size: 17px;
  color: var(--ink);
  letter-spacing: 0.06em;
}

.page-about .rail-bar {
  display: flex;
  height: 8px;
  margin-bottom: 14px;
  background: var(--mist);
}

.page-about .rail-bar-seg { display: block; height: 100%; }
.page-about .rail-bar-seg--mint { background: var(--mint); }
.page-about .rail-bar-seg--orange { background: var(--orange); }
.page-about .rail-bar-seg--silver { background: var(--silver); }
.page-about .rail-bar-seg--ink { background: var(--ink-3); }

.page-about .rail-note {
  margin: 0 0 20px;
  font-size: 14px;
  line-height: 1.7;
  color: rgba(26, 21, 18, 0.72);
}

.page-about .rail-index {
  display: grid;
  gap: 2px;
  border-top: 1px solid var(--line-light);
  padding-top: 12px;
}

.page-about .rail-index .index-link {
  display: grid;
  grid-template-columns: 30px 1fr;
  align-items: baseline;
  gap: 8px;
  padding: 8px 6px 8px 0;
  font-size: 14px;
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px solid rgba(26, 21, 18, 0.08);
}

.page-about .rail-index .index-link__num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--orange);
  letter-spacing: 0.08em;
}

.page-about .rail-index .index-link:hover,
.page-about .rail-index .index-link.is-active {
  color: var(--ink);
  box-shadow: inset 2px 0 0 var(--mint);
  padding-left: 8px;
}

/* ---------- 章节通用 ---------- */
.page-about .about-flow {
  min-width: 0;
}

.page-about .about-sec {
  padding: clamp(24px, 4vw, 40px) 0 clamp(28px, 4vw, 48px);
  border-top: 1px solid var(--line-light);
}

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

.page-about .sec-head {
  max-width: 40em;
  margin-bottom: clamp(18px, 3vw, 28px);
}

.page-about .sec-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--orange);
  margin-bottom: 10px;
}

.page-about .sec-head h2 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(24px, 4.4vw, 40px);
  line-height: 1.16;
  letter-spacing: 0.03em;
  margin: 0 0 12px;
  color: var(--ink);
}

.page-about .sec-lead {
  margin: 0;
  font-size: 16px;
  line-height: 1.78;
  color: rgba(26, 21, 18, 0.8);
}

/* ---------- 01 分工 ---------- */
.page-about .crew {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line-light);
  margin-bottom: clamp(20px, 3vw, 32px);
}

.page-about .crew-item {
  background: var(--cream);
  padding: 18px 18px 20px;
  border-left: 2px solid transparent;
}

.page-about .crew-item:nth-child(1) { border-left-color: var(--mint); }
.page-about .crew-item:nth-child(2) { border-left-color: var(--orange); }
.page-about .crew-item:nth-child(3) { border-left-color: var(--silver); }
.page-about .crew-item:nth-child(4) { border-left-color: var(--ink-3); }

.page-about .crew-meta {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--ink-2);
  margin: 0 0 8px;
}

.page-about .crew-item h3 {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: 0.02em;
  margin: 0 0 8px;
  color: var(--ink);
}

.page-about .crew-item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: rgba(26, 21, 18, 0.78);
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 0;
  overflow: hidden;
  background: var(--ink-2);
}

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

.page-about .about-figure--banner img {
  aspect-ratio: 1400 / 600;
}

.page-about .about-figure--tall img {
  aspect-ratio: 800 / 1000;
}

.page-about .about-figure--square {
  margin-bottom: clamp(16px, 3vw, 28px);
  clip-path: polygon(0 0, 100% 3%, 100% 100%, 0 97%);
}

.page-about .about-figure--square img {
  aspect-ratio: 900 / 900;
}

.page-about .about-figure figcaption {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  line-height: 1.65;
  padding: 10px 2px 0;
  color: rgba(26, 21, 18, 0.62);
}

/* ---------- 02 夜间深色区 ---------- */
.page-about .about-sec--night {
  background: var(--ink-2);
  color: var(--mist);
  border-top: 2px solid var(--mint);
  margin-right: calc(var(--gutter) * -1);
  padding: clamp(24px, 4vw, 44px) clamp(18px, 3vw, 36px) clamp(26px, 4vw, 40px);
}

.page-about .sec-head--night h2 {
  color: var(--mist);
}

.page-about .sec-head--night .sec-lead {
  color: rgba(237, 240, 238, 0.76);
}

.page-about .night-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(20px, 3vw, 32px);
  align-items: start;
}

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

.page-about .tl-axis,
.page-about .tl-tick {
  stroke: rgba(201, 210, 206, 0.4);
  stroke-width: 1;
}

.page-about .tl-tick-label,
.page-about .tl-lane {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  fill: rgba(201, 210, 206, 0.75);
}

.page-about .tl-tick-label {
  text-anchor: middle;
  fill: rgba(201, 210, 206, 0.55);
}

.page-about .shift-band rect {
  transition: opacity 200ms ease-out;
}

.page-about .shift-band--mint rect { fill: var(--mint); }
.page-about .shift-band--silver rect { fill: rgba(201, 210, 206, 0.55); }
.page-about .shift-band--orange rect { fill: var(--orange); }

.page-about .shift-band:hover rect {
  opacity: 0.62;
}

.page-about .tl-hint {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: rgba(201, 210, 206, 0.6);
  margin: 4px 0 16px;
}

.page-about .shift-legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .shift-legend li {
  font-size: 15px;
  line-height: 1.7;
  color: rgba(237, 240, 238, 0.82);
  border-top: 1px solid var(--line-dark-soft);
  padding-top: 10px;
}

.page-about .shift-time {
  font-family: var(--font-mono);
  color: var(--mint);
  letter-spacing: 0.06em;
  margin-right: 6px;
}

.page-about .about-sec--night .about-figure {
  background: var(--ink);
}

.page-about .about-sec--night .about-figure figcaption {
  color: rgba(201, 210, 206, 0.6);
}

/* ---------- 03 沿革 ---------- */
.page-about .eras {
  border-bottom: 1px solid var(--line-light);
}

.page-about .era {
  border-top: 1px solid var(--line-light);
}

.page-about .era summary {
  list-style: none;
  cursor: pointer;
  display: grid;
  grid-template-columns: 32px 1fr auto 18px;
  align-items: baseline;
  gap: 10px;
  padding: 14px 0;
}

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

.page-about .era summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--orange);
  text-align: right;
}

.page-about .era[open] summary::after {
  content: "−";
}

.page-about .era-num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--ink-2);
}

.page-about .era-title {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--ink);
}

.page-about .era-meta {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--orange);
  white-space: nowrap;
}

.page-about .era-body {
  padding: 0 0 16px 42px;
}

.page-about .era-body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(26, 21, 18, 0.78);
  max-width: 60ch;
}

/* ---------- 04 伙伴 ---------- */
.page-about .partner-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(18px, 3vw, 32px);
  margin-bottom: 18px;
}

.page-about .partner-block {
  background: var(--cream);
  padding: 20px 18px 22px;
  border-top: 2px solid var(--ink-3);
}

.page-about .partner-count {
  font-family: var(--font-mono);
  font-size: 44px;
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--orange);
  margin: 0 0 10px;
}

.page-about .partner-block h3 {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 800;
  margin: 0 0 8px;
  color: var(--ink);
}

.page-about .partner-block p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(26, 21, 18, 0.78);
}

.page-about .partner-foot {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(26, 21, 18, 0.8);
  max-width: 62ch;
}

.page-about .partner-foot a {
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px solid var(--orange);
  padding-bottom: 1px;
}

.page-about .partner-foot a:hover {
  color: var(--orange);
}

/* ---------- 05 年度 ---------- */
.page-about .about-sec--annual {
  background: var(--cream);
  margin-left: calc(var(--gutter) * -0.5);
  padding-left: clamp(16px, 3vw, 32px);
  padding-right: clamp(16px, 3vw, 32px);
  border-top: 1px solid var(--line-light);
}

.page-about .annual-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(18px, 3vw, 32px);
}

.page-about .annual-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .annual-list li {
  font-size: 15px;
  line-height: 1.8;
  color: rgba(26, 21, 18, 0.8);
  border-top: 1px solid var(--line-light);
  padding-top: 12px;
}

.page-about .annual-key {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--orange);
  margin-bottom: 4px;
}

.page-about .annual-aside {
  border-left: 2px solid var(--mint);
  padding-left: 16px;
}

.page-about .annual-aside p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-2);
}

.page-about .annual-aside a {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--orange);
}

.page-about .annual-aside a:hover {
  color: var(--orange);
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  padding-top: clamp(22px, 3.5vw, 36px);
  border-top: 2px solid var(--ink);
}

.page-about .about-next h2 {
  font-family: var(--font-display);
  font-size: clamp(20px, 3.2vw, 28px);
  font-weight: 800;
  letter-spacing: 0.03em;
  margin: 0 0 16px;
  color: var(--ink);
}

.page-about .next-links {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line-light);
}

.page-about .next-link {
  display: grid;
  grid-template-columns: 26px 1fr;
  align-items: center;
  gap: 12px;
  background: var(--mist);
  padding: 14px 14px 15px;
  text-decoration: none;
  color: var(--ink);
  font-size: 15px;
  transition: background 200ms ease-out, color 200ms ease-out;
}

.page-about .next-idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--orange);
}

.page-about .next-link:hover {
  background: var(--ink);
  color: var(--mist);
}

.page-about .next-link:hover .next-idx {
  color: var(--mint);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

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

@media (min-width: 960px) {
  .page-about .hero-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    align-items: end;
    gap: clamp(28px, 4vw, 64px);
  }

  .page-about .hero-side {
    border-top: 1px solid var(--line-dark);
    padding-top: 20px;
  }

  .page-about .hero-stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px 24px;
  }

  .page-about .about-canvas {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h, 84px) + 24px);
    align-self: start;
    max-height: calc(100vh - var(--header-h, 84px) - 48px);
    overflow-y: auto;
  }

  .page-about .night-grid {
    grid-template-columns: minmax(0, 1fr) 280px;
  }

  .page-about .annual-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    gap: clamp(24px, 3vw, 44px);
  }

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

@media (min-width: 1200px) {
  .page-about .crew {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .shift-band rect,
  .page-about .next-link {
    transition: none;
  }
}
<<<END>>>