.page-about {
  --about-line-soft: rgba(30, 58, 107, 0.55);
  --about-paper-ink: #33476B;
  --about-paper-line: #C9D4E4;
  display: block;
  overflow-x: clip;
  background: var(--void);
  color: var(--ink);
}

.page-about .mono {
  font-family: var(--font-mono);
}

/* 面包屑 */
.page-about .about-crumb-bar {
  padding-block: 16px 14px;
  border-bottom: 1px solid var(--about-line-soft);
}

.page-about .crumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.12em;
  color: var(--mist);
}

.page-about .crumb-list li {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.page-about .crumb-list li + li::before {
  content: "/";
  color: var(--line);
}

.page-about .crumb-list a {
  color: var(--mist);
  text-decoration: none;
  transition: color 0.2s var(--ease);
}

.page-about .crumb-list a:hover,
.page-about .crumb-list a:focus-visible {
  color: var(--cyan);
}

.page-about .crumb-list [aria-current="page"] {
  color: var(--ink);
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(26px, 5vw, 56px) clamp(34px, 6vw, 72px);
  overflow: hidden;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: -12%;
  right: -12%;
  bottom: 12%;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--cyan-deep) 35%, var(--cyan) 70%, transparent);
  opacity: 0.5;
  transform: rotate(-8deg);
  pointer-events: none;
}

.page-about .hero-split {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(26px, 4vw, 44px);
}

.page-about .hero-eyebrow {
  margin: 0 0 16px;
  font-size: 11.5px;
  letter-spacing: 0.26em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .hero-copy h1 {
  margin: 0;
  font-size: clamp(30px, 6vw, 56px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ink);
  max-width: 14em;
}

.page-about .hero-lede {
  margin: clamp(18px, 2.4vw, 24px) 0 0;
  max-width: 48ch;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.9;
  color: var(--mist);
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(22px, 3vw, 30px);
}

.page-about .hero-facts {
  display: grid;
  gap: 16px;
  margin: clamp(26px, 4vw, 40px) 0 0;
  padding: clamp(18px, 3vw, 24px) 0 0;
  border-top: 2px solid var(--line);
  list-style: none;
}

.page-about .hero-facts li {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.page-about .hero-facts strong {
  font-family: var(--font-mono);
  font-size: clamp(22px, 2.6vw, 28px);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--gold);
}

.page-about .hero-facts span {
  font-size: 13px;
  line-height: 1.65;
  color: var(--mist);
}

.page-about .hero-visual {
  position: relative;
}

.page-about .hero-figure {
  margin: 0;
  border: 2px solid var(--line);
  background: var(--panel);
  box-shadow: var(--hard-shadow);
}

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

.page-about .hero-note {
  margin: 12px 0 0;
  font-size: 10.5px;
  letter-spacing: 0.2em;
  color: var(--mist);
}

/* 章节索引条 */
.page-about .about-toc {
  border-block: 2px solid var(--line);
  background: linear-gradient(90deg, rgba(14, 127, 126, 0.22), rgba(5, 10, 24, 0) 62%);
}

.page-about .toc-list {
  display: flex;
  margin: 0;
  padding: 0;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .toc-list::-webkit-scrollbar {
  display: none;
}

.page-about .toc-list li {
  flex: 0 0 auto;
}

.page-about .toc-list a {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 16px;
  font-size: 13px;
  white-space: nowrap;
  color: var(--mist);
  text-decoration: none;
  border-right: 1px solid var(--about-line-soft);
  transition: color 0.2s var(--ease), background 0.2s var(--ease);
}

.page-about .toc-list a:hover,
.page-about .toc-list a:focus-visible {
  color: var(--cyan);
  background: rgba(34, 224, 214, 0.08);
}

.page-about .toc-list .mono {
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--cyan-deep);
}

/* 01 主张 */
.page-about .framing-grid {
  display: grid;
  gap: clamp(24px, 4vw, 40px);
  margin-top: clamp(22px, 3.4vw, 34px);
}

.page-about .framing-prose p {
  margin: 0 0 18px;
  color: var(--mist);
  font-size: 16px;
  line-height: 1.9;
}

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

.page-about .framing-panel {
  display: grid;
  gap: 18px;
  align-content: start;
}

/* 02 原则 */
.page-about .principle-stack {
  margin-top: clamp(22px, 3.6vw, 40px);
}

.page-about .principle {
  display: grid;
  gap: 16px;
  padding: clamp(22px, 3.4vw, 34px) 0;
  border-top: 2px solid var(--line);
}

.page-about .principle:last-child {
  border-bottom: 2px solid var(--line);
}

.page-about .principle-head {
  padding-left: 18px;
  border-left: 2px solid var(--cyan);
}

.page-about .principle-num {
  display: block;
  margin-bottom: 10px;
  font-size: 12px;
  letter-spacing: 0.28em;
  color: var(--cyan);
}

.page-about .principle-name {
  margin: 0;
  font-size: clamp(20px, 3vw, 29px);
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .principle-body > p {
  margin: 0;
  max-width: 58ch;
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--mist);
}

.page-about .principle-more {
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px dashed var(--about-line-soft);
}

.page-about .principle-more > summary {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  list-style: none;
  cursor: pointer;
  border: 2px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--cyan);
  transition: color 0.2s var(--ease), background 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .principle-more > summary::-webkit-details-marker {
  display: none;
}

.page-about .principle-more > summary::before {
  content: "+";
  font-size: 14px;
  line-height: 1;
}

.page-about .principle-more[open] > summary::before {
  content: "–";
}

.page-about .principle-more > summary:hover,
.page-about .principle-more > summary:focus-visible {
  border-color: var(--cyan);
  background: rgba(34, 224, 214, 0.1);
}

.page-about .principle-more[open] > summary {
  color: var(--void);
  background: var(--cyan);
  border-color: var(--cyan);
}

.page-about .more-body {
  margin-top: 16px;
  color: var(--mist);
}

.page-about .more-body p {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.9;
}

.page-about .more-body ul {
  margin: 12px 0 0;
  padding-left: 18px;
  display: grid;
  gap: 8px;
  font-size: 15px;
  line-height: 1.8;
}

.page-about .more-body li::marker {
  color: var(--cyan);
}

/* 03 纸白带 */
.page-about .about-boundaries {
  padding-block: clamp(28px, 4.6vw, 52px);
}

.page-about .about-boundaries .eyebrow {
  margin: 0;
  color: var(--cyan-deep);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.24em;
}

.page-about .about-boundaries h2 {
  margin: 12px 0 0;
  font-size: clamp(26px, 4.4vw, 42px);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--panel-deep);
}

.page-about .boundary-lede {
  margin: 14px 0 0;
  max-width: 60ch;
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--about-paper-ink);
}

.page-about .boundary-grid {
  display: grid;
  gap: 20px;
  margin-top: clamp(24px, 4vw, 36px);
}

.page-about .boundary-col {
  padding: clamp(18px, 3vw, 26px);
  border: 2px solid var(--about-paper-line);
  background: #FFFFFF;
  box-shadow: 8px 8px 0 rgba(11, 27, 58, 0.1);
}

.page-about .boundary-col--wide {
  border-color: var(--panel);
}

.page-about .boundary-col h3 {
  margin: 0 0 14px;
  font-size: clamp(17px, 2vw, 20px);
  font-weight: 800;
  color: var(--panel-deep);
}

.page-about .boundary-col ul {
  margin: 0;
  padding-left: 16px;
  display: grid;
  gap: 10px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--about-paper-ink);
}

.page-about .boundary-col li::marker {
  color: var(--cyan-deep);
}

.page-about .boundary-figure {
  margin: clamp(24px, 4vw, 40px) 0 0;
  padding: 10px;
  border: 2px solid var(--panel);
  background: #FFFFFF;
  box-shadow: 10px 10px 0 rgba(11, 27, 58, 0.12);
}

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

.page-about .boundary-figure figcaption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--about-paper-ink);
}

.page-about .boundary-qa {
  margin-top: clamp(24px, 4vw, 36px);
  padding-top: 16px;
  border-top: 2px solid var(--panel);
  max-width: 70ch;
}

.page-about .boundary-qa > summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  gap: 10px;
  align-items: baseline;
  font-size: 16px;
  font-weight: 700;
  color: var(--panel-deep);
}

.page-about .boundary-qa > summary::-webkit-details-marker {
  display: none;
}

.page-about .boundary-qa > summary::before {
  content: "Q";
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--cyan-deep);
}

.page-about .qa-body {
  margin-top: 12px;
  font-size: 15px;
  line-height: 1.9;
  color: var(--about-paper-ink);
}

.page-about .qa-body p {
  margin: 0;
}

/* 04 时间线 */
.page-about .timeline-grid {
  display: grid;
  gap: clamp(26px, 4vw, 48px);
}

.page-about .timeline-intro .btn {
  margin-top: clamp(18px, 2.6vw, 26px);
}

.page-about .timeline {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 4px;
  border-left: 2px solid var(--line);
}

.page-about .tl-item {
  position: relative;
  margin-left: -2px;
  padding-left: 26px;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -6px;
  top: 20px;
  width: 10px;
  height: 10px;
  border: 2px solid var(--cyan);
  background: var(--void);
}

.page-about .tl-item.is-current::before {
  border-color: var(--gold);
  background: var(--gold);
  box-shadow: 0 0 0 4px rgba(242, 168, 59, 0.16);
}

.page-about .tl-node > summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 14px;
  padding: 10px 0;
  list-style: none;
  cursor: pointer;
}

.page-about .tl-node > summary::-webkit-details-marker {
  display: none;
}

.page-about .tl-ver {
  flex: 0 0 auto;
  padding: 3px 8px;
  border: 1px solid var(--line);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--cyan);
}

.page-about .tl-item.is-current .tl-ver {
  border-color: var(--gold);
  background: var(--gold);
  color: var(--void);
}

.page-about .tl-title {
  flex: 1 1 220px;
  font-size: clamp(15px, 1.9vw, 17px);
  line-height: 1.65;
  color: var(--ink);
  transition: color 0.2s var(--ease);
}

.page-about .tl-node > summary:hover .tl-title,
.page-about .tl-node[open] > summary .tl-title {
  color: var(--cyan);
}

.page-about .tl-body {
  padding: 2px 0 16px;
  border-bottom: 1px dashed var(--about-line-soft);
  max-width: 58ch;
}

.page-about .tl-body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--mist);
}

/* 05 团队与流程 */
.page-about .team-grid {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
  margin-top: clamp(22px, 3.6vw, 36px);
}

.page-about .crew {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0;
  align-content: start;
}

.page-about .crew li {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 14px;
  padding: 16px 0;
  border-top: 2px solid var(--line);
}

.page-about .crew li:last-child {
  border-bottom: 2px solid var(--line);
}

.page-about .crew-num {
  padding-top: 3px;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .crew-name {
  margin: 0 0 6px;
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .crew-desc {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .flow {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 14px;
  align-content: start;
}

.page-about .flow li {
  padding: 16px 18px;
  border: 2px solid var(--line);
  background: var(--panel);
  box-shadow: 6px 6px 0 rgba(3, 6, 15, 0.85);
}

.page-about .flow-num {
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--gold);
}

.page-about .flow h3 {
  margin: 10px 0 6px;
  font-size: 15.5px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .flow p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist);
}

/* 06 服务范围 */
.page-about .region-grid {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
  align-items: center;
}

.page-about .region-figure {
  margin: 0;
  padding: 12px;
  border: 2px solid var(--line);
  background: var(--panel-deep);
}

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

.page-about .region-lede {
  margin: 16px 0 0;
  max-width: 56ch;
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--mist);
}

.page-about .region-list {
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.page-about .region-list li {
  display: grid;
  grid-template-columns: 92px minmax(0, 1fr);
  gap: 12px;
  align-items: baseline;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--about-line-soft);
}

.page-about .region-list strong {
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.02em;
  color: var(--gold);
}

.page-about .region-list span {
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .region-copy .btn {
  margin-top: clamp(20px, 3vw, 28px);
}

/* 收束行动区 */
.page-about .about-cta {
  margin-top: clamp(36px, 6vw, 76px);
  padding-block: clamp(34px, 6vw, 68px);
  border-top: 2px solid var(--line);
  background: linear-gradient(120deg, var(--panel-deep), var(--panel) 58%, #0A2340);
}

.page-about .about-cta h2 {
  margin: 0;
  font-size: clamp(24px, 3.6vw, 36px);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-cta p {
  margin: 14px 0 0;
  max-width: 56ch;
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--mist);
}

.page-about .cta-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(22px, 3vw, 30px);
}

/* 平板 */
@media (min-width: 600px) {
  .page-about .hero-facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
  }

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

@media (min-width: 780px) {
  .page-about .boundary-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 28px;
  }

  .page-about .boundary-figure {
    max-width: 620px;
    margin-left: auto;
  }
}

/* 桌面 */
@media (min-width: 900px) {
  .page-about .hero-split {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: start;
  }

  .page-about .hero-visual {
    transform: translateY(-16px);
  }

  .page-about .framing-grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 3fr);
    gap: clamp(28px, 4vw, 52px);
  }

  .page-about .region-grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
  }
}

@media (min-width: 920px) {
  .page-about .principle {
    grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
    gap: clamp(24px, 4vw, 60px);
    align-items: start;
  }

  .page-about .principle:nth-child(even) .principle-body {
    transform: translateY(20px);
  }

  .page-about .timeline-grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 7fr);
    align-items: start;
    gap: clamp(28px, 4vw, 56px);
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about .about-hero::after {
    transform: none;
  }

  .page-about .principle:nth-child(even) .principle-body,
  .page-about .hero-visual {
    transform: none;
  }
}