.page-about {
  --about-gap: clamp(24px, 4vw, 56px);
  --about-rule: 2px solid var(--line);
  --about-step-bg: #0B1424;
}

/* ---------- 面包屑与首屏 ---------- */

.page-about .breadcrumb {
  padding-top: clamp(16px, 3vw, 28px);
}

.page-about .about-hero {
  display: grid;
  gap: clamp(24px, 4vw, 48px);
  align-items: start;
  padding: clamp(20px, 3vw, 36px) 0 clamp(36px, 6vw, 72px);
}

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

.page-about .about-hero h1 {
  margin: 12px 0 0;
  font-size: clamp(1.95rem, 4.6vw, 3.3rem);
  line-height: 1.16;
  letter-spacing: -0.01em;
  font-weight: 800;
  color: var(--ink);
  max-width: 18ch;
}

.page-about .about-hero .lede {
  margin-top: clamp(16px, 2vw, 22px);
  max-width: 58ch;
  color: var(--muted);
  font-size: clamp(1rem, 1.1vw, 1.075rem);
  line-height: 1.78;
}

.page-about .about-em {
  color: var(--cyan);
  font-family: var(--font-mono);
  font-weight: 600;
  letter-spacing: 0.02em;
}

.page-about .about-hero__facts {
  margin: clamp(22px, 3vw, 32px) 0 0;
  display: grid;
  gap: 0;
  border: var(--about-rule);
  background: var(--panel);
  box-shadow: var(--shadow-hard-sm);
}

.page-about .about-hero__facts .data-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding: 11px 16px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__facts .data-row:last-child {
  border-bottom: none;
}

.page-about .about-hero__facts .data-row__key {
  color: var(--muted);
  font-size: 0.875rem;
}

.page-about .about-hero__facts .data-row__val {
  margin: 0;
  font-family: var(--font-mono);
  color: var(--amber);
  font-size: 0.9375rem;
  letter-spacing: 0.02em;
}

.page-about .about-hero .btn-row {
  margin-top: clamp(20px, 3vw, 28px);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .about-hero__figure {
  margin: 0;
  position: relative;
}

.page-about .about-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  border: var(--about-rule);
  box-shadow: var(--shadow-hard);
  background: var(--panel);
}

.page-about .about-hero__caption {
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.8125rem;
  line-height: 1.6;
}

/* ---------- 左索引 + 右正文 ---------- */

.page-about .about-body {
  display: grid;
  gap: clamp(24px, 4vw, 48px);
  padding-bottom: clamp(48px, 7vw, 96px);
}

.page-about .about-index {
  border-top: var(--about-rule);
  padding-top: 14px;
}

.page-about .about-index__title {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--muted);
}

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

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

.page-about .about-index__link {
  display: block;
  padding: 8px 13px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--dur-fast) ease, border-color var(--dur-fast) ease, background var(--dur-fast) ease;
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  color: var(--ink);
  border-color: var(--line-strong);
}

.page-about .about-index__link[aria-current="true"] {
  color: var(--cyan);
  border-color: var(--cyan);
  background: rgba(43, 231, 224, 0.08);
  box-shadow: inset 3px 0 0 var(--amber);
}

/* ---------- 章节通用 ---------- */

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

.page-about .about-section {
  padding: clamp(30px, 4vw, 52px) 0;
  border-top: var(--about-rule);
  scroll-margin-top: 120px;
}

.page-about .about-section:first-child {
  border-top: none;
  padding-top: 0;
}

.page-about .about-section .section-title {
  margin: 10px 0 0;
  max-width: 24ch;
  font-size: clamp(1.4rem, 2.6vw, 2.05rem);
  line-height: 1.24;
  letter-spacing: -0.005em;
  color: var(--ink);
}

.page-about .about-section__lead {
  margin: clamp(14px, 2vw, 20px) 0 0;
  max-width: 64ch;
  color: var(--muted);
  line-height: 1.78;
}

.page-about .about-section__note {
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 12px 16px;
  border-left: 3px solid var(--violet);
  background: rgba(138, 107, 255, 0.07);
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  max-width: 68ch;
}

.page-about .about-section__note a {
  color: var(--cyan);
}

/* ---------- 01 流程 ---------- */

.page-about .about-steps {
  list-style: none;
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
  counter-reset: about-step;
}

.page-about .about-step {
  position: relative;
  padding: 18px 18px 20px;
  border: var(--about-rule);
  background: var(--about-step-bg);
  box-shadow: var(--shadow-hard-sm);
}

.page-about .about-step__num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  color: var(--amber);
  border-bottom: 1px dashed var(--line-strong);
  padding-bottom: 4px;
}

.page-about .about-step__title {
  margin: 12px 0 0;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: 0.01em;
}

.page-about .about-step p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.72;
}

/* ---------- 02 覆盖 ---------- */

.page-about .about-map {
  margin: clamp(22px, 3vw, 32px) 0 0;
}

.page-about .about-map img {
  display: block;
  width: 100%;
  height: auto;
  border: var(--about-rule);
  box-shadow: var(--shadow-hard);
  background: var(--panel-2);
  object-fit: cover;
}

.page-about .about-map__caption {
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.8125rem;
  line-height: 1.6;
}

.page-about .about-zones {
  display: block;
  width: 100%;
  height: auto;
  margin-top: clamp(20px, 3vw, 28px);
  overflow: visible;
}

.page-about .about-zones__cell rect {
  fill: rgba(43, 231, 224, 0.05);
  stroke: var(--cyan);
  stroke-width: 1.5;
  transition: fill var(--dur-fast) ease;
}

.page-about .about-zones__cell--int rect {
  fill: rgba(255, 154, 46, 0.06);
  stroke: var(--amber);
}

.page-about .about-zones__cell:hover rect,
.page-about .about-zones__cell:focus-visible rect {
  fill: rgba(43, 231, 224, 0.2);
}

.page-about .about-zones__cell--int:hover rect,
.page-about .about-zones__cell--int:focus-visible rect {
  fill: rgba(255, 154, 46, 0.22);
}

.page-about .about-zones__cell:focus-visible {
  outline: 1px dashed var(--violet);
  outline-offset: 2px;
}

.page-about .about-zones__label {
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.1em;
  text-anchor: middle;
  fill: var(--muted);
  pointer-events: none;
  transition: fill var(--dur-fast) ease;
}

.page-about .about-zones__cell:hover .about-zones__label,
.page-about .about-zones__cell:focus-visible .about-zones__label {
  fill: var(--ink);
}

.page-about .about-coverage {
  margin-top: clamp(24px, 3vw, 34px);
  display: grid;
  gap: 16px;
}

.page-about .about-coverage__item {
  padding: 20px;
  border: var(--about-rule);
  background: var(--panel);
  box-shadow: var(--shadow-hard-sm);
}

.page-about .about-coverage__title {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: 0.01em;
}

.page-about .about-coverage__item p {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.74;
}

.page-about .about-coverage__tags {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* ---------- 03 六类节点 ---------- */

.page-about .about-nodes {
  margin-top: clamp(22px, 3vw, 32px);
  display: grid;
  gap: 14px;
}

.page-about .about-node {
  position: relative;
  padding: 18px 18px 20px;
  border: var(--about-rule);
  border-left-width: 4px;
  background: var(--panel);
  box-shadow: var(--shadow-hard-sm);
}

.page-about .about-node__badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 26px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  border: 1px solid currentColor;
  background: rgba(255, 255, 255, 0.03);
}

.page-about .about-node__title {
  margin: 12px 0 0;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-node p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.72;
}

.page-about .about-node--cyan {
  border-left-color: var(--cyan);
}
.page-about .about-node--cyan .about-node__badge {
  color: var(--cyan);
}

.page-about .about-node--amber {
  border-left-color: var(--amber);
}
.page-about .about-node--amber .about-node__badge {
  color: var(--amber);
}

.page-about .about-node--violet {
  border-left-color: var(--violet);
}
.page-about .about-node--violet .about-node__badge {
  color: var(--violet);
}

.page-about .about-node--green {
  border-left-color: var(--green);
}
.page-about .about-node--green .about-node__badge {
  color: var(--green);
}

.page-about .about-node--fault {
  border-left-color: var(--fault);
}
.page-about .about-node--fault .about-node__badge {
  color: var(--fault);
}

.page-about .about-node--steel {
  border-left-color: var(--line-strong);
}
.page-about .about-node--steel .about-node__badge {
  color: var(--muted);
}

/* ---------- 04 协作 ---------- */

.page-about .about-collab {
  margin-top: clamp(22px, 3vw, 32px);
  display: grid;
  gap: clamp(20px, 3vw, 34px);
  align-items: start;
}

.page-about .about-collab__figure {
  margin: 0;
}

.page-about .about-collab__figure img {
  display: block;
  width: 100%;
  height: auto;
  border: var(--about-rule);
  box-shadow: var(--shadow-hard);
  background: var(--panel-2);
  object-fit: cover;
}

.page-about .about-collab__caption {
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.8125rem;
  line-height: 1.6;
}

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

.page-about .about-collab__text > p {
  margin: 0 0 14px;
  max-width: 64ch;
  color: var(--muted);
  line-height: 1.78;
}

.page-about .about-collab__facts {
  margin: 0 0 16px;
  padding: 0;
  border: var(--about-rule);
  background: var(--panel);
}

.page-about .about-collab__facts .data-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 16px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-collab__facts .data-row:last-child {
  border-bottom: none;
}

.page-about .about-collab__facts .data-row__key {
  color: var(--muted);
  font-size: 0.875rem;
}

.page-about .about-collab__facts .data-row__val {
  margin: 0;
  font-family: var(--font-mono);
  color: var(--green);
  font-size: 0.9375rem;
}

.page-about .about-collab__link {
  color: var(--muted);
}

.page-about .about-collab__link a {
  color: var(--cyan);
}

/* ---------- 05 规模 ---------- */

.page-about .about-scale {
  margin-top: clamp(22px, 3vw, 32px);
  display: grid;
  gap: 0;
  border: var(--about-rule);
  background: var(--panel);
  box-shadow: var(--shadow-hard);
}

.page-about .about-scale__item {
  padding: 20px 20px 22px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-scale__item:last-child {
  border-bottom: none;
}

.page-about .about-scale__num {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--amber);
  line-height: 1.1;
}

.page-about .about-scale__unit {
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.page-about .about-scale__label {
  margin: 8px 0 0;
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: 0.02em;
}

.page-about .about-scale__desc {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.72;
}

.page-about .about-scale__bar {
  margin-top: 14px;
  display: grid;
  grid-template-columns: 4fr 3fr 2fr 1fr;
  gap: 4px;
  height: 8px;
}

.page-about .about-scale__fill {
  display: block;
  height: 100%;
}

.page-about .about-scale__fill--a {
  background: var(--cyan);
}
.page-about .about-scale__fill--b {
  background: var(--amber);
}
.page-about .about-scale__fill--c {
  background: var(--violet);
}
.page-about .about-scale__fill--d {
  background: var(--green);
}

/* ---------- 06 开始使用 ---------- */

.page-about .about-section--start {
  padding-bottom: clamp(20px, 3vw, 32px);
}

.page-about .about-start {
  margin-top: clamp(22px, 3vw, 32px);
  display: grid;
  gap: 14px;
}

.page-about .about-start__card {
  display: block;
  padding: 20px;
  border: var(--about-rule);
  background: var(--panel-2);
  box-shadow: var(--shadow-hard-sm);
  text-decoration: none;
  transition: transform var(--dur-fast) ease, border-color var(--dur-fast) ease, box-shadow var(--dur-fast) ease;
}

.page-about .about-start__card:hover,
.page-about .about-start__card:focus-visible {
  transform: translate(-2px, -2px);
  border-color: var(--cyan);
  box-shadow: 8px 8px 0 #03060C;
}

.page-about .about-start__tag {
  display: inline-block;
}

.page-about .about-start__title {
  margin: 14px 0 0;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-start__card p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.72;
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .about-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-nodes {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-coverage {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-start {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .about-scale__item {
    padding: 22px 24px 24px;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  }
  .page-about .about-collab {
    grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  }
  .page-about .about-scale {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-scale__item {
    border-bottom: 1px solid var(--line);
  }
  .page-about .about-scale__item:nth-child(2n) {
    border-left: 1px solid var(--line);
  }
  .page-about .about-scale__item:nth-last-child(-n + 2) {
    border-bottom: none;
  }
}

@media (min-width: 980px) {
  .page-about .about-body {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: clamp(32px, 5vw, 72px);
  }
  .page-about .about-index {
    position: sticky;
    top: 104px;
    align-self: start;
  }
  .page-about .about-index__list {
    flex-direction: column;
    overflow: visible;
    padding-bottom: 0;
  }
  .page-about .about-index__item {
    flex: none;
  }
  .page-about .about-index__link {
    white-space: normal;
  }
}

@media (min-width: 1100px) {
  .page-about .about-steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .about-nodes {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1240px) {
  .page-about .about-section--wide .about-scale {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-section--wide .about-scale__item {
    border-bottom: none;
    border-left: 1px solid var(--line);
  }
  .page-about .about-section--wide .about-scale__item:first-child {
    border-left: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index__link,
  .page-about .about-start__card,
  .page-about .about-zones__cell rect,
  .page-about .about-zones__label {
    transition: none;
  }
  .page-about .about-start__card:hover,
  .page-about .about-start__card:focus-visible {
    transform: none;
  }
}
<<<END>>>