.page-about {
  --about-rail-w: 176px;
  --about-gap: clamp(28px, 4vw, 56px);
  --about-pad: clamp(20px, 3vw, 36px);
  --about-ink: var(--ink-900);
  --about-mist: var(--graphite-400);
}

/* 面包屑与首屏 */
.page-about .about-crumb {
  padding-top: clamp(18px, 3vw, 34px);
}

.page-about .about-hero {
  padding-top: clamp(26px, 4vw, 52px);
}

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

.page-about .about-hero__title {
  font-size: clamp(40px, 8vw, 84px);
  line-height: 1.04;
  letter-spacing: -0.02em;
  font-weight: 800;
  margin: 14px 0 0;
  color: var(--ink-900);
}

.page-about .about-hero__lead {
  max-width: 36em;
  margin: 22px 0 0;
  font-size: 17px;
  line-height: 1.8;
  color: var(--black-900);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.page-about .about-facts {
  margin: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--rule-soft);
  border: 1px solid var(--rule-soft);
  align-self: start;
}

.page-about .about-facts__row {
  background: var(--surface);
  padding: 16px 18px;
  display: grid;
  gap: 6px;
}

.page-about .about-facts__row dt {
  font-size: 13px;
  letter-spacing: 0.02em;
  color: var(--graphite-400);
}

.page-about .about-facts__row dd {
  margin: 0;
  font-size: 15px;
  color: var(--ink-900);
}

.page-about .about-facts__num {
  font-family: var(--font-mono);
  font-size: 26px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--sand-500);
}

/* 阶段长卷 */
.page-about .about-chron__head {
  margin-bottom: var(--about-gap);
}

.page-about .about-chron__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 40px);
}

.page-about .about-rail {
  order: -1;
}

.page-about .about-rail__cap {
  margin: 0 0 10px;
  color: var(--graphite-400);
}

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

.page-about .about-rail__node {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 13px;
  border: 1px solid var(--rule-soft);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.02em;
  color: var(--graphite-400);
  text-decoration: none;
  white-space: nowrap;
  transition: color 180ms var(--ease), border-color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .about-rail__node:hover,
.page-about .about-rail__node:focus-visible {
  color: var(--ink-900);
  border-color: var(--rule-strong);
}

.page-about .about-rail__node.is-active {
  color: var(--ink-900);
  border-color: var(--sand-500);
  background: var(--sand-200);
}

.page-about .about-chron__flow {
  display: grid;
  gap: clamp(24px, 3vw, 44px);
}

.page-about .about-stage {
  position: relative;
}

.page-about .about-stage__card {
  background: var(--surface);
  border: 1px solid var(--rule-soft);
  padding: var(--about-pad);
  clip-path: polygon(0 0, calc(100% - 22px) 0, 100% 22px, 100% 100%, 0 100%);
}

.page-about .about-stage:nth-child(even) .about-stage__card {
  clip-path: polygon(22px 0, 100% 0, 100% 100%, 0 100%, 0 22px);
}

.page-about .about-stage__head {
  display: grid;
  gap: 10px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--rule-soft);
}

.page-about .about-stage__no {
  color: var(--sand-500);
  letter-spacing: 0.06em;
}

.page-about .about-stage__title {
  margin: 0;
  font-size: clamp(24px, 3.4vw, 38px);
  line-height: 1.2;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--ink-900);
}

.page-about .about-stage__body {
  margin-top: 20px;
  display: grid;
  gap: 20px;
}

.page-about .about-stage__body p {
  margin: 0;
  max-width: 38em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--black-900);
}

.page-about .about-stage__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--rule-soft);
  border-top: 1px solid var(--rule-soft);
  border-bottom: 1px solid var(--rule-soft);
}

.page-about .about-stage__list li {
  background: var(--surface);
  padding: 14px 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--graphite-400);
}

.page-about .about-stage__list li .mono-label {
  color: var(--ink-700);
  margin-right: 10px;
}

.page-about .about-stage__media {
  margin: 22px 0 0;
}

/* 两条产品线 */
.page-about .about-lines__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 34px);
}

.page-about .about-line {
  display: grid;
  gap: 16px;
  padding: var(--about-pad);
  border: 1px solid var(--rule-soft);
  background: var(--surface);
}

.page-about .about-line--home {
  border-top: 3px solid var(--sand-500);
}

.page-about .about-line--com {
  background: var(--ink-900);
  border-color: var(--ink-900);
  color: var(--paper-100);
  border-top: 3px solid var(--signal-500);
}

.page-about .about-line__head {
  display: grid;
  gap: 8px;
  justify-items: start;
}

.page-about .about-line__title {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(26px, 3.6vw, 36px);
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--ink-900);
}

.page-about .about-line--com .about-line__title {
  color: var(--paper-100);
}

.page-about .about-line__count {
  color: var(--graphite-400);
}

.page-about .about-line--com .about-line__count {
  color: var(--sand-200);
}

.page-about .about-line__desc {
  margin: 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--black-900);
}

.page-about .about-line--com .about-line__desc {
  color: var(--paper-100);
}

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

.page-about .about-line__list li {
  position: relative;
  padding-left: 18px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--graphite-400);
}

.page-about .about-line--com .about-line__list li {
  color: var(--cool-300);
}

.page-about .about-line__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 8px;
  height: 1px;
  background: var(--sand-500);
}

.page-about .about-line--com .about-line__list li::before {
  background: var(--signal-500);
}

.page-about .about-line__scene {
  margin: 0;
  padding-top: 14px;
  border-top: 1px dashed var(--rule-soft);
  font-size: 14px;
  line-height: 1.7;
  color: var(--graphite-400);
}

.page-about .about-line--com .about-line__scene {
  border-top-color: rgba(235, 217, 180, 0.3);
  color: var(--sand-200);
}

.page-about .about-line__link {
  justify-self: start;
  font-size: 15px;
  color: var(--ink-700);
  text-decoration: none;
  border-bottom: 1px solid var(--sand-500);
  padding-bottom: 2px;
}

.page-about .about-line--com .about-line__link {
  color: var(--paper-100);
  border-bottom-color: var(--sand-500);
}

.page-about .about-line__link:hover,
.page-about .about-line__link:focus-visible {
  color: var(--signal-500);
  border-bottom-color: var(--signal-500);
}

/* 编号与报告组别 */
.page-about .about-code-block__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
}

.page-about .about-code-block__intro p {
  max-width: 36em;
  margin: 18px 0 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--black-900);
}

.page-about .about-code {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  gap: 8px;
  margin-top: 26px;
}

.page-about .about-code__seg {
  flex: 1 1 130px;
  display: grid;
  gap: 6px;
  padding: 14px 16px;
  background: var(--surface);
  border: 1px solid var(--rule-soft);
}

.page-about .about-code__seg span {
  font-family: var(--font-mono);
  font-size: 24px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--ink-900);
}

.page-about .about-code__seg em {
  font-style: normal;
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--graphite-400);
}

.page-about .about-code__seg--line {
  border-color: var(--sand-500);
}

.page-about .about-code__seg--line span {
  color: var(--sand-500);
}

.page-about .about-code__seg--serial {
  border-color: var(--signal-500);
}

.page-about .about-code__seg--serial span {
  color: var(--signal-500);
}

.page-about .about-code__dash {
  align-self: center;
  color: var(--cool-300);
  font-family: var(--font-mono);
}

.page-about .about-code__note {
  margin: 14px 0 0;
  color: var(--graphite-400);
  line-height: 1.7;
}

.page-about .about-grades {
  align-self: start;
  padding: var(--about-pad);
  background: var(--ink-700);
  border: 1px solid var(--ink-700);
  clip-path: polygon(0 0, calc(100% - 22px) 0, 100% 22px, 100% 100%, 0 100%);
  display: grid;
  gap: 16px;
}

.page-about .about-grades__cap {
  margin: 0;
  color: var(--sand-200);
}

.page-about .about-grade {
  display: grid;
  grid-template-columns: minmax(84px, auto) minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
}

.page-about .about-grade__name {
  font-size: 14px;
  color: var(--paper-100);
}

.page-about .about-grade__bar {
  display: block;
  height: 4px;
  background: rgba(246, 242, 233, 0.16);
  position: relative;
}

.page-about .about-grade__bar::after {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: calc(var(--w) * 10%);
  background: var(--signal-500);
}

.page-about .about-grade__num {
  color: var(--sand-500);
  font-size: 13px;
}

.page-about .about-grades__foot {
  margin: 4px 0 0;
  padding-top: 14px;
  border-top: 1px dashed rgba(235, 217, 180, 0.28);
  font-size: 14px;
  line-height: 1.75;
  color: var(--cool-300);
}

/* 培训支持 */
.page-about .about-training__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
}

.page-about .about-training__media figure {
  margin: 0;
}

.page-about .about-training__media-note {
  margin: 14px 0 0;
  color: var(--graphite-400);
  line-height: 1.7;
}

.page-about .about-training__list {
  display: grid;
  gap: 14px;
  align-content: start;
}

.page-about .about-course {
  border: 1px solid var(--rule-soft);
  background: var(--surface);
}

.page-about .about-course__btn {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 6px 14px;
  width: 100%;
  text-align: left;
  padding: 18px 20px;
  background: none;
  border: 0;
  cursor: pointer;
  color: var(--ink-900);
}

.page-about .about-course__idx {
  grid-row: 1 / span 2;
  color: var(--sand-500);
  align-self: start;
  padding-top: 3px;
}

.page-about .about-course__name {
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.page-about .about-course__obj {
  grid-column: 2;
  font-size: 13px;
  line-height: 1.6;
  color: var(--graphite-400);
}

.page-about .about-course__btn .disclosure__mark {
  grid-row: 1 / span 2;
  font-family: var(--font-mono);
  font-size: 20px;
  color: var(--sand-500);
  line-height: 1;
}

.page-about .about-course__panel {
  padding: 0 20px 20px 56px;
}

.page-about .about-course__panel p {
  margin: 0 0 10px;
  max-width: 34em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--black-900);
}

.page-about .about-course__panel .mono-label {
  color: var(--graphite-400);
  line-height: 1.7;
}

.page-about .about-training__foot {
  margin: 6px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--graphite-400);
}

.page-about .about-training__foot a {
  color: var(--ink-700);
  text-decoration: none;
  border-bottom: 1px solid var(--sand-500);
}

.page-about .about-training__foot a:hover,
.page-about .about-training__foot a:focus-visible {
  color: var(--signal-500);
  border-bottom-color: var(--signal-500);
}

/* 服务网络 */
.page-about .about-net__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
}

.page-about .about-net__intro p {
  max-width: 36em;
  margin: 18px 0 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--black-900);
}

.page-about .about-net__links {
  margin-top: 24px;
}

.page-about .about-net__figure {
  padding: var(--about-pad);
  border: 1px solid var(--rule-soft);
  background: var(--paper-100);
  align-self: start;
}

.page-about .about-net__map {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(18px, 1fr));
  gap: 8px;
}

.page-about .about-net__dot {
  display: block;
  aspect-ratio: 1 / 1;
  background: var(--steel-500);
  opacity: 0.35;
  transition: opacity 200ms var(--ease), transform 200ms var(--ease), background-color 200ms var(--ease);
}

.page-about .about-net__map .about-net__dot:nth-child(1),
.page-about .about-net__map .about-net__dot:nth-child(2),
.page-about .about-net__map .about-net__dot:nth-child(4) {
  background: var(--sand-500);
  opacity: 1;
}

.page-about .about-net__dot:hover {
  background: var(--signal-500);
  opacity: 1;
  transform: scale(1.18);
}

.page-about .about-net__legend {
  list-style: none;
  margin: 22px 0 0;
  padding: 18px 0 0;
  border-top: 1px dashed var(--rule-soft);
  display: grid;
  gap: 10px;
}

.page-about .about-net__legend li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--graphite-400);
}

.page-about .about-net__key {
  flex: none;
  width: 12px;
  height: 12px;
  margin-top: 6px;
}

.page-about .about-net__key--prov {
  background: var(--steel-500);
  opacity: 0.4;
}

.page-about .about-net__key--spot {
  background: var(--sand-500);
}

.page-about .about-net__key--node {
  background: var(--ink-900);
}

/* 使用周期 */
.page-about .about-life__steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--rule-soft);
  border-top: 1px solid var(--rule-soft);
  border-bottom: 1px solid var(--rule-soft);
}

.page-about .about-life__step {
  background: var(--surface);
  padding: 22px 4px;
  display: grid;
  gap: 10px;
  align-content: start;
}

.page-about .about-life__step:nth-child(3) {
  background: var(--ink-900);
}

.page-about .about-life__num {
  color: var(--sand-500);
}

.page-about .about-life__step:nth-child(3) .about-life__num {
  color: var(--sand-200);
}

.page-about .about-life__title {
  margin: 0;
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--ink-900);
}

.page-about .about-life__step:nth-child(3) .about-life__title {
  color: var(--paper-100);
}

.page-about .about-life__step p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--graphite-400);
}

.page-about .about-life__step:nth-child(3) p {
  color: var(--cool-300);
}

.page-about .about-cta {
  margin-top: clamp(32px, 5vw, 56px);
  padding: var(--about-pad);
  background: var(--ink-900);
  border-left: 4px solid var(--sand-500);
  display: grid;
  gap: 20px;
}

.page-about .about-cta__title {
  margin: 0;
  font-size: clamp(22px, 3vw, 30px);
  line-height: 1.3;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--paper-100);
}

.page-about .about-cta__text {
  margin: 12px 0 0;
  max-width: 40em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--cool-300);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

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

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

  .page-about .about-life__step:nth-child(3) {
    background: var(--surface);
  }

  .page-about .about-life__step:nth-child(3) .about-life__num {
    color: var(--sand-500);
  }

  .page-about .about-life__step:nth-child(3) .about-life__title {
    color: var(--ink-900);
  }

  .page-about .about-life__step:nth-child(3) p {
    color: var(--graphite-400);
  }

  .page-about .about-life__step:nth-child(odd) {
    padding-right: 24px;
  }

  .page-about .about-life__step:nth-child(even) {
    padding-left: 24px;
  }

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

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-chron__grid {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(28px, 4vw, 64px);
  }

  .page-about .about-rail {
    position: sticky;
    top: 112px;
    align-self: start;
  }

  .page-about .about-rail__cap {
    margin-bottom: 14px;
  }

  .page-about .about-rail__scale {
    display: grid;
    gap: 24px;
    overflow: visible;
    position: relative;
    padding-left: 0;
  }

  .page-about .about-rail__scale::before {
    content: "";
    position: absolute;
    left: 7px;
    top: 6px;
    bottom: 6px;
    width: 1px;
    background: var(--rule-soft);
  }

  .page-about .about-rail__node {
    border: 0;
    padding: 0;
    background: none;
    gap: 12px;
    align-items: center;
  }

  .page-about .about-rail__node::before {
    content: "";
    display: block;
    flex: none;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    border: 1px solid var(--rule-strong);
    background: var(--surface);
    position: relative;
    z-index: 1;
    transition: background-color 200ms var(--ease), border-color 200ms var(--ease);
  }

  .page-about .about-rail__node.is-active {
    background: none;
    color: var(--ink-900);
  }

  .page-about .about-rail__node.is-active::before {
    background: var(--signal-500);
    border-color: var(--signal-500);
  }

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

  .page-about .about-line--com {
    margin-top: 52px;
  }

  .page-about .about-code-block__grid {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-training__grid {
    grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
    align-items: start;
  }

  .page-about .about-net__grid {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: start;
  }

  .page-about .about-life__steps {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

  .page-about .about-life__step {
    padding: 26px 18px;
  }

  .page-about .about-life__step:nth-child(odd),
  .page-about .about-life__step:nth-child(even) {
    padding-left: 18px;
    padding-right: 18px;
  }
}

@media (min-width: 1180px) {
  .page-about .about-stage__card {
    padding: clamp(28px, 3vw, 44px);
  }

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

  .page-about .about-stage__media {
    max-width: 560px;
  }
}
<<<END>>>

.page-about {
  --w: 1rem;
}