.page-about {
  --about-index-w: 212px;
  --about-sticky: 96px;
  position: relative;
  overflow-x: clip;
  color: var(--text);
  padding-bottom: clamp(56px, 9vw, 104px);
}

/* 面包屑 */
.page-about .about-crumb {
  padding-top: clamp(16px, 3vw, 28px);
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  padding: clamp(22px, 4.5vw, 44px) 0 clamp(36px, 6vw, 72px);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -18%;
  right: -12%;
  width: min(640px, 92%);
  aspect-ratio: 1;
  background: radial-gradient(circle at 50% 50%, rgba(40, 224, 210, 0.16), transparent 66%);
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(28px, 5vw, 52px);
  align-items: center;
  min-width: 0;
}

.page-about .about-hero-copy {
  min-width: 0;
}

.page-about .about-hero h1 {
  margin: 14px 0 0;
  font-family: var(--font-display);
  font-size: clamp(2rem, 5.4vw, 3.45rem);
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: -0.032em;
  color: var(--text);
}

.page-about .about-h1-mark {
  color: var(--cyan-glow);
  position: relative;
}

.page-about .about-h1-mark::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0.06em;
  height: 2px;
  background: linear-gradient(90deg, rgba(40, 224, 210, 0.85), rgba(255, 138, 61, 0.35));
}

.page-about .about-hero-lead {
  margin: clamp(18px, 2.6vw, 22px) 0 0;
  max-width: 48ch;
  padding-left: 16px;
  border-left: 2px solid var(--orange);
  color: var(--text-dim);
  font-size: clamp(0.975rem, 1.6vw, 1.0625rem);
  line-height: 1.85;
}

.page-about .about-stats {
  margin: clamp(26px, 4vw, 38px) 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.page-about .about-stats li {
  background: var(--ink-850);
  padding: 15px 16px 17px;
  min-width: 0;
}

.page-about .stat-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.35rem, 3.2vw, 1.7rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--cyan-glow);
}

.page-about .stat-label {
  display: block;
  margin-top: 6px;
  font-size: 0.78rem;
  line-height: 1.5;
  color: var(--text-dim);
}

.page-about .about-hero-visual {
  min-width: 0;
}

.page-about .about-hero-art {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  background: linear-gradient(150deg, rgba(15, 46, 74, 0.92), rgba(6, 21, 37, 0.96));
}

/* 主体：索引 + 章节 */
.page-about .about-body {
  display: grid;
  gap: clamp(28px, 4vw, 48px);
  min-width: 0;
}

.page-about .about-index {
  min-width: 0;
  padding-top: 4px;
}

.page-about .about-index-title {
  margin: 0 0 12px;
  padding-left: 15px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--text-dim);
}

.page-about .about-index ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 10px;
}

.page-about .about-index a {
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding: 9px 10px 9px 13px;
  border-left: 2px solid var(--line);
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.85rem;
  line-height: 1.5;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease), background 0.25s var(--ease);
}

.page-about .about-index .idx-num {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--line);
  transition: color 0.25s var(--ease);
}

.page-about .about-index a:hover {
  color: var(--text);
  border-left-color: var(--cyan);
}

.page-about .about-index a:hover .idx-num {
  color: var(--cyan);
}

.page-about .about-index a[aria-current="location"] {
  color: var(--cyan-glow);
  border-left-color: var(--cyan);
  background: linear-gradient(90deg, var(--cyan-veil), transparent 92%);
}

.page-about .about-index a[aria-current="location"] .idx-num {
  color: var(--cyan);
}

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

/* 章节通用 */
.page-about .about-section {
  padding: clamp(32px, 5vw, 58px) 0;
  border-top: 1px solid var(--line-soft);
  scroll-margin-top: 96px;
}

.page-about .about-chapters > .about-section:first-child {
  border-top: 0;
  padding-top: clamp(6px, 2vw, 14px);
}

.page-about .about-sec-head {
  display: flex;
  align-items: baseline;
  gap: clamp(12px, 2vw, 18px);
  margin-bottom: clamp(16px, 2.4vw, 22px);
}

.page-about .about-sec-num {
  flex: none;
  font-family: var(--font-mono);
  font-size: clamp(1.85rem, 4.6vw, 2.75rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: rgba(40, 224, 210, 0.28);
}

.page-about .about-sec-head h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.34rem, 3.1vw, 1.9rem);
  font-weight: 700;
  line-height: 1.28;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .about-section p {
  margin: 0 0 15px;
  font-size: 0.975rem;
  line-height: 1.85;
  color: var(--text-dim);
}

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

/* 研究板摘要 */
.page-about .about-abstract {
  padding: 15px 18px;
  border-left: 2px solid var(--orange);
  background: linear-gradient(90deg, rgba(255, 138, 61, 0.11), transparent 74%);
  color: var(--text) !important;
  font-size: 0.975rem;
  line-height: 1.85;
}

.page-about .about-note {
  margin-top: clamp(20px, 3vw, 26px) !important;
  padding: 16px 18px;
  border: 1px solid var(--line-soft);
  background: var(--ink-850);
  font-size: 0.93rem !important;
  line-height: 1.85;
}

/* 细线网格卡片 */
.page-about .about-grid {
  display: grid;
  gap: 1px;
  margin: clamp(20px, 3vw, 28px) 0 0;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.page-about .about-grid > * {
  background: var(--ink-800);
  padding: 20px 18px 22px;
  min-width: 0;
}

.page-about .about-cell-k {
  display: block;
  margin-bottom: 9px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .about-grid h3 {
  margin: 0 0 9px;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.45;
  color: var(--text);
}

.page-about .about-grid p {
  margin: 0;
  font-size: 0.885rem;
  line-height: 1.78;
  color: var(--text-dim);
}

/* 图 */
.page-about .about-figure {
  margin: clamp(20px, 3vw, 28px) 0;
  border: 1px solid var(--line);
  background: linear-gradient(160deg, rgba(15, 46, 74, 0.85), rgba(6, 21, 37, 0.95));
  overflow: hidden;
}

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

.page-about .about-figure--square {
  max-width: 460px;
  margin-left: 0;
  margin-right: 0;
}

/* 步骤 */
.page-about .about-steps {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .about-steps li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: clamp(12px, 2vw, 20px);
  padding-top: 18px;
  border-top: 1px solid var(--line-soft);
}

.page-about .step-num {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--orange);
  padding-top: 4px;
  white-space: nowrap;
}

.page-about .about-steps h3 {
  margin: 0 0 8px;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.45;
  color: var(--text);
}

.page-about .about-steps p {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.82;
}

/* 阶段 */
.page-about .about-stages {
  display: grid;
  gap: 1px;
  margin-top: clamp(4px, 1.5vw, 10px);
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.page-about .about-stage {
  position: relative;
  min-width: 0;
  padding: 24px 18px 26px;
  background: linear-gradient(180deg, var(--ink-700), var(--ink-800));
}

.page-about .about-stage::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), rgba(40, 224, 210, 0.12));
}

.page-about .about-stage-step {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--orange-soft);
}

.page-about .about-stage h3 {
  margin: 11px 0 10px;
  font-size: 1.06rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--text);
}

.page-about .about-stage p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.8;
  color: var(--text-dim);
}

/* 选择理由 */
.page-about .about-reasons {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-reasons li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: clamp(12px, 2vw, 20px);
  padding: 18px 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-reasons li:last-child {
  border-bottom: 1px solid var(--line-soft);
}

.page-about .reason-num {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: rgba(40, 224, 210, 0.4);
}

.page-about .about-reasons h3 {
  margin: 0 0 7px;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
}

.page-about .about-reasons p {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.82;
}

/* 协作生态 */
.page-about .about-eco {
  display: grid;
  gap: clamp(20px, 3vw, 30px);
  margin-top: clamp(24px, 4vw, 34px);
  padding-top: clamp(20px, 3vw, 28px);
  border-top: 1px dashed var(--line);
}

.page-about .about-eco-copy {
  min-width: 0;
}

.page-about .about-eco-copy h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(1.1rem, 2.4vw, 1.3rem);
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--cyan-glow);
}

.page-about .about-eco-copy p {
  font-size: 0.93rem;
  line-height: 1.85;
}

.page-about .about-inline-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(40, 224, 210, 0.45);
  padding-bottom: 2px;
  font-size: 0.925rem;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}

.page-about .about-inline-link:hover {
  color: var(--cyan-glow);
  border-bottom-color: var(--cyan-glow);
}

/* CTA */
.page-about .about-cta {
  margin-top: clamp(28px, 4vw, 40px);
  padding: clamp(20px, 3.4vw, 30px);
  border: 1px solid var(--line);
  background:
    radial-gradient(circle at 100% 0%, rgba(255, 138, 61, 0.16), transparent 58%),
    linear-gradient(160deg, var(--ink-700), var(--ink-850));
}

.page-about .about-cta > p {
  margin: 0 0 18px;
  color: var(--text);
  font-size: 0.96rem;
  line-height: 1.8;
}

.page-about .about-cta-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* 响应式 */
@media (min-width: 720px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .about-grid--2 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .page-about .about-grid--4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .page-about .about-eco {
    grid-template-columns: minmax(0, 380px) minmax(0, 1fr);
    align-items: center;
  }
}

@media (min-width: 940px) {
  .page-about .about-hero-inner {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
  }

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

@media (min-width: 1024px) {
  .page-about .about-body {
    grid-template-columns: var(--about-index-w) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-index {
    position: sticky;
    top: var(--about-sticky);
    align-self: start;
  }

  .page-about .about-index ol {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index a,
  .page-about .about-inline-link {
    transition: none;
  }
}