.page-about {
  --about-rail-w: 176px;
  --about-card: rgba(255, 255, 255, 0.62);
  background: var(--ivory);
  color: var(--black);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  background: var(--ink);
  color: var(--ivory);
  padding: clamp(26px, 4vw, 48px) 0 clamp(44px, 7vw, 88px);
}

.page-about .breadcrumb {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: rgba(248, 246, 241, 0.62);
}

.page-about .breadcrumb a {
  color: var(--cyan);
  text-decoration: none;
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-hero__frame {
  position: relative;
  margin-top: clamp(18px, 3vw, 30px);
  border: 1px solid var(--line-dark);
  padding: clamp(20px, 4vw, 52px);
}

.page-about .about-hero__frame::before {
  content: "";
  position: absolute;
  top: -1px;
  left: -1px;
  width: 62px;
  height: 2px;
  background: var(--cyan);
}

.page-about .about-hero__frame::after {
  content: "";
  position: absolute;
  right: -1px;
  bottom: -1px;
  width: 2px;
  height: 42px;
  background: var(--amber);
}

.page-about .kicker {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .about-hero__title {
  margin: clamp(12px, 2vw, 20px) 0 0;
  max-width: 17ch;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.1rem, 5.2vw, 4.3rem);
  line-height: 1.04;
  letter-spacing: -0.02em;
  color: var(--ivory);
}

.page-about .about-hero__lede {
  margin: clamp(16px, 2.4vw, 26px) 0 0;
  max-width: 34em;
  font-size: clamp(1rem, 1.3vw, 1.125rem);
  line-height: 1.75;
  color: rgba(248, 246, 241, 0.82);
}

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: clamp(12px, 2vw, 28px);
  margin: clamp(24px, 4vw, 44px) 0 0;
  padding-top: clamp(16px, 2.4vw, 24px);
  border-top: 1px solid var(--line-dark);
}

.page-about .about-stat {
  display: flex;
  flex-direction: column-reverse;
  gap: 8px;
}

.page-about .about-stat dd {
  margin: 0;
  display: flex;
  align-items: baseline;
  gap: 6px;
}

.page-about .about-stat__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.7rem, 3.2vw, 2.5rem);
  line-height: 1;
  color: var(--amber);
}

.page-about .about-stat__unit {
  font-size: 0.8125rem;
  color: rgba(248, 246, 241, 0.7);
}

.page-about .about-stat__lb {
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: rgba(248, 246, 241, 0.62);
}

/* ---------- 整体双栏 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: 1fr;
  padding-block: clamp(28px, 4vw, 56px) clamp(48px, 7vw, 96px);
}

/* ---------- 左侧标尺 ---------- */
.page-about .about-rail {
  position: relative;
  margin-bottom: clamp(18px, 3vw, 30px);
}

.page-about .about-rail__scale {
  display: none;
}

.page-about .about-rail__list {
  display: flex;
  gap: 6px;
  margin: 0;
  padding: 0 0 4px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: none;
}

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

.page-about .about-rail__link {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 7px 10px;
  border: 1px solid var(--line-light);
  color: var(--slate);
  font-size: 0.75rem;
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.page-about .about-rail__no {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--slate);
  transition: color 0.2s var(--ease);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--ink);
  border-color: var(--cyan);
}

.page-about .about-rail__link:hover .about-rail__no,
.page-about .about-rail__link:focus-visible .about-rail__no {
  color: var(--amber);
}

.page-about .about-rail__top {
  display: none;
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  padding-block: clamp(28px, 4.2vw, 52px);
  scroll-margin-top: 88px;
}

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

.page-about .about-head {
  display: grid;
  gap: 6px;
  margin-bottom: clamp(14px, 2.2vw, 24px);
}

.page-about .section-no {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  color: var(--amber);
}

.page-about .about-h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.45rem, 2.8vw, 2.15rem);
  line-height: 1.18;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-p {
  max-width: 36em;
  margin: 0 0 1em;
  font-size: 1rem;
  line-height: 1.75;
  color: var(--black);
}

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

.page-about .about-p--tight {
  margin-top: 1em;
}

.page-about .about-p a {
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px solid var(--cyan);
}

.page-about .about-p a:hover,
.page-about .about-p a:focus-visible {
  border-bottom-color: var(--amber);
}

/* ---------- 矩阵表 ---------- */
.page-about .about-matrix-wrap {
  margin-top: clamp(16px, 2.4vw, 26px);
  overflow-x: auto;
  border: 1px solid var(--line-light);
  background: var(--sand);
}

.page-about .about-matrix {
  width: 100%;
  min-width: 460px;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.page-about .about-matrix caption {
  caption-side: top;
  padding: 12px 16px;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.04em;
  color: var(--slate);
  border-bottom: 1px solid rgba(15, 20, 24, 0.1);
}

.page-about .about-matrix th,
.page-about .about-matrix td {
  border: 1px solid rgba(15, 20, 24, 0.1);
  text-align: center;
  padding: 0;
}

.page-about .about-matrix thead th {
  padding: 10px 8px;
  background: var(--mist);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-matrix tbody th {
  padding: 12px 14px;
  text-align: left;
  font-weight: 700;
  white-space: nowrap;
  color: var(--ink);
  background: rgba(255, 255, 255, 0.42);
}

.page-about .mx-cell {
  position: relative;
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 2px;
  padding: 15px 6px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1rem;
  color: var(--ink);
  transition: transform 0.2s var(--ease), background-color 0.2s var(--ease);
}

.page-about .mx-u {
  font-size: 0.6875rem;
  color: var(--slate);
}

.page-about .mx-cell__note {
  position: absolute;
  left: 50%;
  bottom: calc(100% - 2px);
  transform: translate(-50%, 4px);
  padding: 4px 8px;
  background: var(--ink);
  color: var(--ivory);
  font-family: var(--font-body);
  font-size: 0.6875rem;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.18s var(--ease), transform 0.18s var(--ease);
  z-index: 3;
}

.page-about .mx-cell:hover {
  transform: scale(1.14);
  background: var(--mist);
  position: relative;
  z-index: 4;
}

.page-about .mx-cell:hover .mx-cell__note {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* ---------- 规则列表 ---------- */
.page-about .about-rules {
  margin: clamp(16px, 2.4vw, 24px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-rules li {
  position: relative;
  padding: 13px 0 13px 22px;
  border-top: 1px solid var(--line-light);
  font-size: 0.9375rem;
  line-height: 1.72;
  color: rgba(15, 20, 24, 0.82);
}

.page-about .about-rules li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 21px;
  width: 10px;
  height: 1px;
  background: var(--cyan);
}

.page-about .about-rules strong {
  color: var(--ink);
}

/* ---------- 图文分栏 ---------- */
.page-about .about-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(18px, 3vw, 40px);
  align-items: start;
}

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

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line-light);
  background: var(--ink-2);
  object-fit: cover;
}

.page-about .about-figure figcaption {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.05em;
  color: var(--slate);
}

.page-about .about-count {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 8px;
  margin: clamp(14px, 2vw, 20px) 0 0;
  font-size: 0.875rem;
  color: var(--slate);
}

.page-about .about-count__n {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(2rem, 3.6vw, 3rem);
  line-height: 1;
  color: var(--ink-2);
}

/* ---------- 三条线（深色块） ---------- */
.page-about .about-team {
  background: var(--ink-2);
  color: var(--ivory);
  padding: clamp(22px, 3.6vw, 44px);
}

.page-about .about-head--dark .about-h2 {
  color: var(--ivory);
}

.page-about .about-head--dark .section-no {
  color: var(--cyan);
}

.page-about .about-team .about-p {
  color: rgba(248, 246, 241, 0.82);
}

.page-about .about-figure--dark img {
  border-color: var(--line-dark);
}

.page-about .about-figure--dark figcaption {
  color: rgba(248, 246, 241, 0.6);
}

.page-about .about-lines {
  margin-top: clamp(14px, 2vw, 20px);
}

.page-about .about-line {
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  gap: 12px;
  padding: 13px 0;
  border-top: 1px solid rgba(248, 246, 241, 0.16);
}

.page-about .about-line__no {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cyan);
  padding-top: 3px;
}

.page-about .about-line__t {
  margin: 0 0 4px;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--ivory);
}

.page-about .about-line p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: rgba(248, 246, 241, 0.76);
}

.page-about .about-p--dark {
  margin-top: clamp(14px, 2vw, 20px);
}

/* ---------- 阶段 ---------- */
.page-about .about-figure--wide {
  margin-top: clamp(18px, 2.6vw, 26px);
}

.page-about .about-stages {
  display: grid;
  gap: 10px;
  margin-top: clamp(20px, 3vw, 32px);
}

.page-about .about-stage {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  padding: 18px clamp(16px, 2.4vw, 26px);
  background: var(--about-card);
  border-left: 3px solid var(--cyan);
}

.page-about .about-stage__when {
  justify-self: start;
  margin: 0;
  padding: 6px 10px;
  background: var(--mist);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.06em;
  color: var(--ink);
}

.page-about .about-stage__t {
  margin: 0 0 6px;
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .about-stage__body p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.72;
  color: rgba(15, 20, 24, 0.78);
}

/* ---------- 联系 ---------- */
.page-about .about-contact {
  margin-top: clamp(18px, 2.6vw, 28px);
  padding: clamp(18px, 3vw, 32px);
  background: var(--sand);
  border: 1px solid var(--line-light);
}

.page-about .about-contact .contact-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
  align-items: center;
  padding: 12px 0;
  border-top: 1px dashed rgba(15, 20, 24, 0.18);
}

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

.page-about .about-contact .contact-key {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  color: var(--slate);
}

.page-about .about-contact .contact-val {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 0.9375rem;
  color: var(--ink);
  overflow-wrap: anywhere;
}

.page-about .about-contact .copy-btn {
  justify-self: start;
}

.page-about .about-steps {
  margin: clamp(16px, 2.4vw, 24px) 0 0;
  padding: 0;
  list-style: none;
  counter-reset: about-step;
}

.page-about .about-steps li {
  counter-increment: about-step;
  position: relative;
  margin: 0;
  padding: 12px 0 12px 34px;
  border-top: 1px solid var(--line-light);
  font-size: 0.9375rem;
  line-height: 1.72;
  color: rgba(15, 20, 24, 0.82);
}

.page-about .about-steps li::before {
  content: counter(about-step, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 14px;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--amber);
}

.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: clamp(18px, 2.6vw, 28px);
}

.page-about .about-actions .btn {
  flex: 1 1 auto;
  text-align: center;
}

/* ---------- 中屏 ---------- */
@media (min-width: 640px) {
  .page-about .about-contact .contact-row {
    grid-template-columns: 96px minmax(0, 1fr) auto;
    gap: 14px;
  }

  .page-about .about-actions .btn {
    flex: 0 0 auto;
  }
}

@media (min-width: 860px) {
  .page-about .about-split {
    grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr);
  }

  .page-about .about-split--rev {
    grid-template-columns: minmax(0, 0.8fr) minmax(0, 1.2fr);
    align-items: start;
  }

  .page-about .about-stage {
    grid-template-columns: 104px minmax(0, 1fr);
    gap: 20px;
    align-items: start;
  }

  .page-about .about-stage:nth-child(odd) {
    margin-right: clamp(0px, 7%, 88px);
  }

  .page-about .about-stage:nth-child(even) {
    margin-left: clamp(0px, 7%, 88px);
    border-left-color: var(--amber);
  }
}

/* ---------- 桌面：左侧标尺 ---------- */
@media (min-width: 980px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    column-gap: clamp(30px, 4vw, 68px);
  }

  .page-about .about-rail {
    position: sticky;
    top: clamp(24px, 7vh, 76px);
    align-self: start;
    margin-bottom: 0;
  }

  .page-about .about-rail__scale {
    display: block;
    position: absolute;
    left: 0;
    top: 2px;
    width: 22px;
    height: 100%;
    color: rgba(108, 124, 138, 0.55);
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding: 0 0 0 30px;
  }

  .page-about .about-rail__link {
    width: 100%;
    padding: 11px 0;
    border: 0;
    border-bottom: 1px dashed var(--line-light);
    white-space: normal;
    font-size: 0.8125rem;
  }

  .page-about .about-rail__top {
    display: inline-flex;
    margin: 16px 0 0 30px;
    font-family: var(--font-mono);
    font-size: 0.6875rem;
    letter-spacing: 0.06em;
    color: var(--slate);
    text-decoration: none;
    border-bottom: 1px solid transparent;
  }

  .page-about .about-rail__top:hover,
  .page-about .about-rail__top:focus-visible {
    color: var(--ink);
    border-bottom-color: var(--cyan);
  }
}

/* ---------- 窄屏收尾 ---------- */
@media (max-width: 700px) {
  .page-about .mx-cell {
    padding: 12px 4px;
    font-size: 0.9375rem;
  }

  .page-about .mx-cell__note {
    display: none;
  }

  .page-about .mx-cell:hover {
    transform: none;
    background: transparent;
  }

  .page-about .about-matrix {
    min-width: 400px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .mx-cell,
  .page-about .mx-cell__note,
  .page-about .about-rail__link,
  .page-about .about-rail__no {
    transition: none;
  }
}
<<<END>>>