.page-about {
  --about-measure: 34em;
  --about-step: clamp(0.9rem, 4.5vw, 4rem);
  display: block;
  overflow-x: clip;
}

/* ---------- 首屏：窄栏长文 + 右侧扫描线 ---------- */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(2rem, 6vw, 4.5rem) clamp(2.75rem, 8vw, 6rem);
  border-bottom: 1px solid var(--ink-line);
}

.page-about .about-hero::after {
  display: none;
}

.page-about .about-hero__inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(1.75rem, 5vw, 3.5rem);
  align-items: center;
}

.page-about .about-hero__lead {
  max-width: 38em;
}

.page-about .about-hero__kicker {
  margin: 1.25rem 0 0.75rem;
  font-size: var(--fs-12);
  letter-spacing: 0.14em;
  color: var(--teal);
}

.page-about .about-hero__title {
  margin: 0;
  font-family: var(--font-narrow);
  font-size: var(--fs-h1);
  font-weight: 300;
  line-height: 1.08;
  letter-spacing: -0.01em;
  color: var(--text-title);
}

.page-about .about-hero__text {
  margin-top: 1.5rem;
}

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

.page-about .about-hero__media .media__frame {
  border-radius: var(--radius-lg);
}

/* ---------- 边界声明 ---------- */
.page-about .about-stance {
  padding-block: clamp(2rem, 5vw, 3.25rem);
  border-bottom: 1px solid var(--ink-line);
}

.page-about .about-boundary {
  margin: 0;
  border-left: 2px solid var(--amber);
  padding-left: clamp(0.9rem, 2.5vw, 1.25rem);
  max-width: 38em;
  font-size: var(--fs-20);
  font-weight: 500;
  line-height: 1.7;
  color: var(--text-title);
}

.page-about .about-stance__note {
  margin: 1.5rem 0 0;
  max-width: var(--about-measure);
  font-size: var(--fs-14);
  color: var(--text-muted);
}

.page-about .about-copyline {
  display: block;
  width: 100%;
  margin-top: 0.75rem;
  padding: 0.85rem 1.1rem;
  border: 1px dashed var(--ink-line);
  border-radius: var(--radius-sm);
  background: var(--plate-soft);
  color: var(--text-body);
  font-family: var(--font-mono);
  font-size: var(--fs-14);
  line-height: 1.6;
  text-align: left;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-copyline:hover,
.page-about .about-copyline:focus-visible {
  border-color: var(--teal-line);
  color: var(--text-title);
}

.page-about .about-copyline:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 3px;
}

/* ---------- 章节头和索引色 ---------- */
.page-about .section__index {
  color: var(--teal);
  letter-spacing: 0.18em;
}

/* ---------- 三层私钥管理：阶梯缩进 ---------- */
.page-about .layers {
  list-style: none;
  margin: clamp(2rem, 5vw, 3rem) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(1.75rem, 5vw, 3rem);
}

.page-about .layer {
  position: relative;
  max-width: 40rem;
  padding-left: clamp(1.1rem, 4vw, 2.25rem);
  border-left: 1px solid var(--ink-line);
}

.page-about .layer::before {
  content: "";
  position: absolute;
  left: -1px;
  top: 0;
  width: 1px;
  height: 3.25rem;
  background: linear-gradient(180deg, var(--teal), transparent);
}

.page-about .layer:nth-child(2)::before {
  background: linear-gradient(180deg, var(--violet), transparent);
}

.page-about .layer:nth-child(3)::before {
  background: linear-gradient(180deg, var(--amber), transparent);
}

.page-about .layer__num {
  display: inline-block;
  font-size: var(--fs-12);
  letter-spacing: 0.16em;
  color: var(--text-muted);
}

.page-about .layer__title {
  margin: 0.6rem 0 0;
  font-family: var(--font-narrow);
  font-size: var(--fs-h3);
  font-weight: 500;
  line-height: 1.35;
  color: var(--text-title);
}

.page-about .layer__text {
  margin: 0.9rem 0 0;
  max-width: var(--about-measure);
  line-height: 1.85;
  color: var(--text-body);
}

.page-about .layer .disclosure {
  margin-top: 1.1rem;
}

.page-about .disclosure__body ul {
  margin: 0;
  padding-left: 1.1rem;
  display: grid;
  gap: 0.5rem;
}

.page-about .disclosure__body li {
  max-width: var(--about-measure);
  line-height: 1.8;
  color: var(--text-muted);
}

.page-about .about-layers__figure {
  margin: clamp(2.5rem, 7vw, 4rem) 0 0;
}

.page-about .about-layers__figure .media__frame {
  border-radius: var(--radius-lg);
}

/* ---------- 版本演进 ---------- */
.page-about .about-versions__figure {
  margin: clamp(2rem, 5vw, 3rem) 0 0;
}

.page-about .about-versions__figure .media__frame {
  border-radius: var(--radius-lg);
}

.page-about .versions {
  list-style: none;
  margin: clamp(2.25rem, 6vw, 3.5rem) 0 0;
  padding: 0 0 0 1.5rem;
  position: relative;
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .versions::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 0.7rem;
  bottom: 0.7rem;
  width: 1px;
  background: var(--ink-line);
}

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

.page-about .version__dot {
  position: absolute;
  left: -1.5rem;
  top: 0.6rem;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--ink-line);
}

.page-about .version[data-state="current"] .version__dot {
  background: var(--teal);
  box-shadow: 0 0 0 4px var(--teal-soft);
}

.page-about .version__main {
  max-width: 40rem;
}

.page-about .version__meta {
  margin: 0;
  font-size: var(--fs-14);
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.page-about .version[data-state="current"] .version__meta {
  color: var(--teal);
}

.page-about .version__title {
  margin: 0.45rem 0 0;
  font-family: var(--font-narrow);
  font-size: var(--fs-20);
  font-weight: 500;
  line-height: 1.4;
  color: var(--text-title);
}

.page-about .version__text {
  margin: 0.6rem 0 0;
  max-width: var(--about-measure);
  line-height: 1.8;
  color: var(--text-body);
}

.page-about .version .disclosure {
  margin-top: 0.9rem;
}

/* ---------- 团队 ---------- */
.page-about .about-team__grid {
  margin-top: clamp(2rem, 5vw, 3rem);
}

.page-about .about-team__card {
  display: flex;
  flex-direction: column;
}

.page-about .about-team__name {
  margin: 1rem 0 0;
  font-family: var(--font-narrow);
  font-size: var(--fs-20);
  font-weight: 500;
  line-height: 1.4;
  color: var(--text-title);
}

.page-about .about-team__text {
  margin: 0.8rem 0 0;
  line-height: 1.8;
  color: var(--text-body);
}

.page-about .about-team__list {
  list-style: none;
  margin: 1.25rem 0 0;
  padding: 0;
  display: grid;
  gap: 0.6rem;
}

.page-about .about-team__list li {
  position: relative;
  padding-left: 1rem;
  font-size: var(--fs-14);
  line-height: 1.7;
  color: var(--text-muted);
}

.page-about .about-team__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--teal);
}

/* ---------- 维护机制 ---------- */
.page-about .cadence {
  list-style: none;
  margin: clamp(2rem, 5vw, 3rem) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.25rem);
}

.page-about .cadence__item {
  padding-bottom: clamp(1.25rem, 3vw, 1.75rem);
  border-bottom: 1px solid var(--ink-line);
}

.page-about .cadence__num {
  margin: 0;
  font-size: var(--fs-12);
  letter-spacing: 0.16em;
  color: var(--violet);
}

.page-about .cadence__title {
  margin: 0.6rem 0 0;
  font-family: var(--font-narrow);
  font-size: var(--fs-20);
  font-weight: 500;
  color: var(--text-title);
}

.page-about .cadence__text {
  margin: 0.7rem 0 0;
  max-width: 36em;
  line-height: 1.85;
  color: var(--text-body);
}

.page-about .about-docs__prose {
  margin-top: clamp(1.75rem, 4vw, 2.5rem);
}

.page-about .about-docs__more {
  margin-top: 1.5rem;
}

/* ---------- 服务范围 ---------- */
.page-about .facts {
  margin: clamp(1.75rem, 4vw, 2.5rem) 0 0;
  border-top: 1px solid var(--ink-line);
}

.page-about .facts__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0.35rem;
  padding: 1.05rem 0;
  border-bottom: 1px solid var(--ink-line);
}

.page-about .facts__row dt {
  font-size: var(--fs-12);
  letter-spacing: 0.12em;
  color: var(--text-muted);
}

.page-about .facts__row dd {
  margin: 0;
  line-height: 1.75;
  color: var(--text-body);
}

.page-about .about-scope__icp {
  margin: 1.75rem 0 0;
  font-size: var(--fs-14);
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

/* ---------- 延伸入口 ---------- */
.page-about .about-next__title {
  margin: 0;
  font-family: var(--font-narrow);
  font-size: var(--fs-20);
  font-weight: 500;
  color: var(--text-title);
}

.page-about .about-next__list {
  list-style: none;
  margin: 1.25rem 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-next__list li {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0.3rem;
  padding: 1rem 0;
  border-top: 1px solid var(--ink-line);
}

.page-about .about-next__list a {
  font-size: var(--fs-16);
  font-weight: 500;
  color: var(--text-title);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-next__list a:hover,
.page-about .about-next__list a:focus-visible {
  color: var(--teal);
  border-bottom-color: var(--teal-line);
}

.page-about .about-next__list a:focus-visible {
  outline: 2px solid var(--mint);
  outline-offset: 3px;
}

.page-about .about-next__list span {
  font-size: var(--fs-14);
  line-height: 1.7;
  color: var(--text-muted);
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .facts__row {
    grid-template-columns: 8.5rem minmax(0, 1fr);
    gap: 1.25rem;
    align-items: baseline;
  }

  .page-about .about-next__list li {
    grid-template-columns: minmax(0, 12rem) minmax(0, 1fr);
    align-items: baseline;
    gap: 1.5rem;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    padding-right: clamp(1rem, 5vw, 3.5rem);
  }

  .page-about .about-hero::after {
    display: block;
    content: "";
    position: absolute;
    top: clamp(2rem, 6vw, 4.5rem);
    right: clamp(0.75rem, 3vw, 2rem);
    bottom: clamp(2.5rem, 7vw, 5rem);
    width: 1px;
    background: linear-gradient(180deg, transparent, var(--teal-line) 18%, var(--mint) 50%, var(--teal-line) 82%, transparent);
    opacity: 0.65;
  }

  .page-about .about-hero__inner {
    grid-template-columns: minmax(0, 1.02fr) minmax(0, 0.98fr);
    align-items: center;
  }

  .page-about .layer:nth-child(1) {
    margin-left: 0;
  }

  .page-about .layer:nth-child(2) {
    margin-left: var(--about-step);
  }

  .page-about .layer:nth-child(3) {
    margin-left: calc(var(--about-step) * 2);
  }

  .page-about .about-team__card--offset {
    margin-top: 2.5rem;
  }

  .page-about .cadence {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: clamp(1.5rem, 3vw, 2.5rem);
  }

  .page-about .cadence__item {
    border-bottom: none;
    border-top: 1px solid var(--ink-line);
    padding-top: 1.25rem;
    padding-bottom: 0;
  }
}

@media (min-width: 1180px) {
  .page-about .versions {
    padding-left: 2rem;
  }

  .page-about .version__dot {
    left: -2rem;
  }

  .page-about .versions::before {
    left: 4px;
  }
}

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