.page-about {
  --rail-w: 156px;
  --rail-gap: clamp(32px, 5vw, 88px);
  background: var(--c-ink);
  color: var(--c-cream);
  font-family: var(--font-body);
  font-size: var(--fs-base);
  line-height: 1.75;
  overflow-wrap: break-word;
}

.page-about p { margin: 0 0 1.1em; }
.page-about a { color: var(--c-blue-soft); text-decoration: none; }
.page-about a:hover { color: var(--c-neon); }

/* ============ 首屏 ============ */
.page-about .about-hero {
  position: relative;
  padding: calc(var(--header-h-sm) + 36px) 0 var(--sp-6);
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(120% 90% at 8% 0%, rgba(31, 78, 140, .30) 0%, transparent 58%),
    radial-gradient(80% 70% at 100% 12%, rgba(56, 224, 176, .08) 0%, transparent 62%);
}

@media (min-width: 860px) {
  .page-about .about-hero {
    padding: calc(var(--header-h) + 52px) 0 var(--sp-7);
  }
}

.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: var(--sp-5);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .12em;
  color: var(--c-cream-faint);
}

.page-about .breadcrumb a { color: var(--c-cream-faint); }
.page-about .breadcrumb a:hover { color: var(--c-neon); }
.page-about .breadcrumb-sep { color: var(--c-blue-soft); }

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

@media (min-width: 900px) {
  .page-about .hero-grid {
    grid-template-columns: 176px minmax(0, 1fr);
    gap: clamp(32px, 5vw, 80px);
    align-items: start;
  }
}

.page-about .hero-side {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

@media (min-width: 900px) {
  .page-about .hero-side {
    flex-direction: row;
    align-items: flex-start;
    gap: 18px;
  }
}

.page-about .hero-vert {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.3rem, 7vw, 3.4rem);
  line-height: 1.04;
  letter-spacing: .08em;
  color: var(--c-cream);
}

.page-about .hero-annot {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .18em;
  color: var(--c-blue-soft);
  white-space: nowrap;
}

@media (min-width: 900px) {
  .page-about .hero-vert {
    writing-mode: vertical-rl;
    text-orientation: upright;
    font-size: clamp(2.6rem, 4.2vw, 4rem);
    letter-spacing: .22em;
    padding-right: 18px;
    border-right: 1px solid var(--line-strong);
  }
  .page-about .hero-annot {
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    align-self: flex-end;
    padding-bottom: 4px;
  }
}

.page-about .hero-kicker {
  display: inline-block;
  margin-bottom: var(--sp-3);
  padding: 4px 11px;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .18em;
  color: var(--c-neon);
  border: 1px solid rgba(56, 224, 176, .34);
  border-radius: var(--radius);
}

.page-about .hero-lead {
  margin: 0 0 var(--sp-3);
  max-width: 26ch;
  font-size: var(--fs-lg);
  font-weight: 700;
  line-height: 1.42;
  color: var(--c-cream);
}

.page-about .hero-text {
  margin: 0;
  max-width: 64ch;
  color: var(--c-cream-dim);
}

.page-about .hero-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: 1px;
  margin: var(--sp-5) 0 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .hero-fact {
  background: var(--c-ink);
  padding: 16px 18px;
}

.page-about .hero-fact dt {
  margin: 0 0 4px;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .14em;
  color: var(--c-cream-faint);
}

.page-about .hero-fact dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-md);
  letter-spacing: .04em;
  color: var(--c-lemon);
}

/* ============ 主体骨架 ============ */
.page-about .about-body {
  padding-top: var(--sp-6);
  padding-bottom: var(--sp-7);
}

.page-about .about-body-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-5);
}

@media (min-width: 1060px) {
  .page-about .about-body-grid {
    grid-template-columns: var(--rail-w) minmax(0, 1fr);
    gap: var(--rail-gap);
  }
}

/* ============ 左侧索引轨 ============ */
.page-about .rail { display: none; }

@media (min-width: 1060px) {
  .page-about .rail { display: block; }
  .page-about .rail-inner {
    position: sticky;
    top: calc(var(--header-h-sm) + 34px);
  }
}

.page-about .rail-head {
  display: block;
  margin-bottom: var(--sp-3);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .22em;
  color: var(--c-cream-faint);
}

.page-about .rail-list {
  position: relative;
  margin: 0;
  padding: 0 0 0 18px;
  list-style: none;
}

.page-about .rail-list::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: linear-gradient(180deg, var(--c-blue-soft), rgba(56, 224, 176, .45) 58%, transparent);
}

.page-about .rail-list li { position: relative; }

.page-about .rail-list li::before {
  content: "";
  position: absolute;
  left: -18px;
  top: .74em;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--c-ink);
  box-shadow: inset 0 0 0 1px var(--c-blue-soft);
  transition: background .2s ease, box-shadow .2s ease;
}

.page-about .rail-list li:hover::before,
.page-about .rail-list li:focus-within::before {
  background: var(--c-neon);
  box-shadow: 0 0 0 3px rgba(56, 224, 176, .18);
}

.page-about .rail-link {
  display: block;
  padding: 5px 0;
  font-size: var(--fs-sm);
  color: var(--c-cream-dim);
  transition: color .2s ease;
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible { color: var(--c-cream); }

.page-about .rail-num {
  margin-right: 6px;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .06em;
  color: var(--c-blue-soft);
}

/* ============ 章节 ============ */
.page-about .chapter {
  padding: clamp(36px, 5vw, 74px) 0;
  border-top: 1px solid var(--line);
  scroll-margin-top: 96px;
}

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

.page-about .chapter-tag {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 var(--sp-2);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .2em;
  color: var(--c-cream-faint);
}

.page-about .chapter-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 26px;
  height: 20px;
  padding: 0 7px;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .06em;
  color: #A9BE9A;
  background: rgba(95, 113, 82, .22);
  border: 1px solid rgba(95, 113, 82, .6);
  border-radius: var(--radius);
}

.page-about .chapter-title {
  margin: 0 0 var(--sp-3);
  max-width: 24ch;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 1.05rem + 2.2vw, 2.7rem);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: .01em;
  color: var(--c-cream);
}

.page-about .chapter-body p {
  max-width: 66ch;
  color: var(--c-cream-dim);
}

.page-about .chapter-body strong {
  color: var(--c-lemon);
  font-weight: 700;
}

.page-about .chapter-footnote {
  max-width: 62ch;
  margin: var(--sp-4) 0 0;
  padding-left: 16px;
  border-left: 2px solid rgba(56, 224, 176, .5);
  font-size: var(--fs-sm);
  color: var(--c-cream-faint);
}

/* ============ 图片 ============ */
.page-about .shot {
  margin: var(--sp-5) 0 0;
}

.page-about .shot img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--line);
  background: var(--c-slate);
}

.page-about .shot figcaption,
.page-about .ring-visual figcaption {
  margin-top: 10px;
  font-size: var(--fs-xs);
  letter-spacing: .04em;
  color: var(--c-cream-faint);
}

/* ============ 团队分工 ============ */
.page-about .crew {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: var(--sp-4);
  background: var(--line);
  border: 1px solid var(--line);
}

@media (min-width: 760px) {
  .page-about .crew { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.page-about .crew-item {
  padding: 22px 20px 24px;
  background: var(--c-slate);
}

.page-about .crew-num {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: clamp(1.8rem, 1.2rem + 1.7vw, 2.6rem);
  line-height: 1;
  letter-spacing: .02em;
  color: var(--c-lemon);
}

.page-about .crew-name {
  margin: 0 0 8px;
  font-size: var(--fs-md);
  font-weight: 700;
  color: var(--c-cream);
}

.page-about .crew-desc {
  margin: 0;
  font-size: var(--fs-sm);
  color: var(--c-cream-dim);
}

.page-about .crew-note {
  margin: var(--sp-3) 0 0;
  max-width: 66ch;
  font-size: var(--fs-sm);
  color: var(--c-cream-faint);
}

/* ============ 整理流程 ============ */
.page-about .steps {
  display: grid;
  gap: var(--sp-2);
  margin: var(--sp-4) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .step {
  position: relative;
  padding: 22px 22px 22px 26px;
  background: var(--card);
  border: 1px solid var(--line);
  border-left: 2px solid var(--c-orange);
  border-radius: var(--radius);
}

.page-about .step:nth-child(2) { border-left-color: var(--c-blue-soft); }
.page-about .step:nth-child(3) { border-left-color: var(--c-neon); }

.page-about .step-title {
  margin: 0 0 6px;
  font-size: var(--fs-md);
  font-weight: 700;
  color: var(--c-cream);
}

.page-about .step-text {
  margin: 0;
  max-width: 62ch;
  font-size: var(--fs-sm);
  color: var(--c-cream-dim);
}

/* ============ 收录范围 ============ */
.page-about .scope-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-4);
  margin-top: var(--sp-4);
}

@media (min-width: 900px) {
  .page-about .scope-grid {
    grid-template-columns: minmax(220px, 340px) minmax(0, 1fr);
    gap: clamp(32px, 4vw, 64px);
    align-items: start;
  }
}

.page-about .ring-visual {
  position: relative;
  margin: 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 50% 50% 0 0;
  background: radial-gradient(circle at 50% 46%, rgba(31, 78, 140, .28), transparent 70%);
}

.page-about .ring-visual img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: 50%;
}

.page-about .ring-visual figcaption {
  margin-top: 14px;
  text-align: center;
}

.page-about .scope-body p {
  max-width: 62ch;
  color: var(--c-cream-dim);
}

.page-about .age-list {
  margin: var(--sp-4) 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.page-about .age-list > li {
  border-bottom: 1px solid var(--line);
}

.page-about .age-item {
  background: transparent;
}

.page-about .age-item summary {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
  font-size: var(--fs-sm);
  color: var(--c-cream-dim);
  transition: background .2s ease, color .2s ease;
}

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

.page-about .age-item summary::marker { content: ""; }

.page-about .age-item summary:hover {
  background: rgba(92, 141, 196, .10);
  color: var(--c-cream);
}

.page-about .age-item[open] summary {
  background: rgba(56, 224, 176, .08);
  box-shadow: inset 2px 0 0 var(--c-neon);
  color: var(--c-cream);
}

.page-about .age-code {
  min-width: 42px;
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  letter-spacing: .06em;
  color: var(--c-lemon);
}

.page-about .age-name {
  font-weight: 600;
  color: inherit;
}

.page-about .age-meta {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .08em;
  color: var(--c-cream-faint);
}

.page-about .age-detail {
  margin: 0;
  padding: 2px 16px 18px 70px;
  font-size: var(--fs-sm);
  color: var(--c-cream-faint);
}

/* ============ 协作参与 ============ */
.page-about .partner-figures {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  margin-top: var(--sp-5);
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .pf {
  padding: 20px 18px;
  background: var(--c-slate);
}

.page-about .pf-num {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 1rem + 1.5vw, 2.2rem);
  line-height: 1;
  letter-spacing: .02em;
  color: var(--c-lemon);
}

.page-about .pf-unit {
  font-size: .6em;
  margin-left: 2px;
  color: var(--c-cream-dim);
}

.page-about .pf-label {
  display: block;
  font-size: var(--fs-sm);
  color: var(--c-cream-faint);
  line-height: 1.6;
}

/* ============ 发展节点 ============ */
.page-about .nodes {
  position: relative;
  margin: var(--sp-5) 0 0;
  padding: 0 0 0 26px;
  list-style: none;
}

.page-about .nodes::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 12px;
  bottom: 16px;
  width: 1px;
  background: linear-gradient(180deg, var(--c-orange), var(--c-neon) 44%, rgba(242, 239, 231, .10));
}

.page-about .node {
  position: relative;
  padding-bottom: var(--sp-4);
}

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

.page-about .node-dot {
  position: absolute;
  left: -26px;
  top: .5em;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--c-ink);
  border: 1px solid var(--c-neon);
  transition: background .25s ease, box-shadow .25s ease;
}

.page-about .node:hover .node-dot,
.page-about .node:focus-within .node-dot {
  background: var(--c-neon);
  box-shadow: 0 0 0 5px rgba(56, 224, 176, .15);
}

.page-about .node-era {
  display: inline-block;
  margin-bottom: 8px;
  padding: 2px 9px;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .14em;
  color: #A9BE9A;
  background: rgba(95, 113, 82, .2);
  border: 1px solid rgba(95, 113, 82, .5);
  border-radius: var(--radius);
}

.page-about .node-title {
  margin: 0 0 6px;
  font-size: var(--fs-md);
  font-weight: 700;
  line-height: 1.4;
  color: var(--c-cream);
}

.page-about .node-note {
  margin: 0;
  max-width: 58ch;
  font-size: var(--fs-sm);
  color: var(--c-cream-faint);
  transition: color .25s ease;
}

.page-about .node:hover .node-note,
.page-about .node:focus-within .node-note {
  color: var(--c-cream-dim);
}

/* ============ 收束 ============ */
.page-about .closing {
  padding: clamp(64px, 10vw, 132px) 0 clamp(72px, 12vw, 152px);
  border-top: 1px solid var(--line);
  background:
    radial-gradient(90% 110% at 100% 100%, rgba(31, 78, 140, .26) 0%, transparent 62%);
}

.page-about .closing-kicker {
  margin: 0 0 var(--sp-2);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: .22em;
  color: var(--c-orange);
}

.page-about .closing-title {
  margin: 0 0 var(--sp-3);
  max-width: 24ch;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 1rem + 2.6vw, 3rem);
  font-weight: 800;
  line-height: 1.16;
  color: var(--c-cream);
}

.page-about .closing-text {
  max-width: 62ch;
  margin: 0;
  color: var(--c-cream-dim);
}

.page-about .closing-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: var(--sp-4);
}

.page-about .btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  font-size: var(--fs-sm);
  font-weight: 600;
  border-radius: var(--radius);
  border: 1px solid var(--line-strong);
  color: var(--c-cream);
  text-decoration: none;
  transition: background .2s ease, border-color .2s ease, color .2s ease;
}

.page-about .btn--primary {
  background: var(--c-orange);
  border-color: var(--c-orange);
  color: #FFF6F1;
}

.page-about .btn--primary:hover {
  background: #C8461F;
  border-color: #C8461F;
  color: #FFFFFF;
}

.page-about .btn--ghost:hover {
  border-color: var(--c-neon);
  color: var(--c-neon);
}

.page-about .btn:focus-visible,
.page-about .rail-link:focus-visible,
.page-about .age-item summary:focus-visible {
  outline: 1px solid var(--c-lemon);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: .001ms !important;
    animation-duration: .001ms !important;
  }
}