.page-about {
  background: var(--zt-bg-deep);
  color: var(--zt-text);
  font-family: var(--zt-font-body);
  line-height: 1.7;
  overflow-x: hidden;
}

/* ===== 面包屑 ===== */
.page-about .pb-breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .5rem;
  font-family: var(--zt-font-data);
  font-size: .8125rem;
  letter-spacing: .04em;
  color: var(--zt-muted);
  text-transform: uppercase;
  margin-bottom: 1.25rem;
}
.page-about .pb-breadcrumb a {
  color: var(--zt-acid);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color .2s ease;
}
.page-about .pb-breadcrumb a:hover {
  border-color: var(--zt-acid);
}
.page-about .pb-breadcrumb__sep {
  color: var(--zt-muted);
}
.page-about .pb-breadcrumb [aria-current="page"] {
  color: var(--zt-text);
}

/* ===== 首屏 ===== */
.page-about .pb-hero {
  position: relative;
  padding: calc(var(--zt-header-h) + 3.5rem) 0 3.5rem;
}
.page-about .pb-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    repeating-linear-gradient(135deg, rgba(242, 246, 248, 0.03) 0 1px, transparent 1px 14px),
    linear-gradient(135deg, var(--zt-bg-card) 0%, var(--zt-bg-deep) 60%);
}
.page-about .pb-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 2.5rem;
}
.page-about .pb-hero__title {
  font-family: var(--zt-font-head);
  font-weight: 900;
  font-size: clamp(2.1rem, 5.5vw, 4.6rem);
  line-height: 1.1;
  margin: 0 0 1.5rem;
  letter-spacing: -0.02em;
}
.page-about .pb-hero__title-accent {
  color: var(--zt-acid);
}
.page-about .pb-hero__lead {
  max-width: 62ch;
  color: var(--zt-muted);
  font-size: 1rem;
  line-height: 1.85;
  margin: 0 0 1.75rem;
}
.page-about .pb-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: .875rem;
  margin-bottom: 2.25rem;
}
.page-about .pb-hero__stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: .75rem;
  max-width: 36rem;
}
.page-about .pb-hero__stat {
  border: 1px solid var(--zt-border);
  background: rgba(17, 30, 58, 0.7);
  padding: 1rem;
  box-shadow: 4px 4px 0 rgba(0, 0, 0, 0.35);
}
.page-about .pb-hero__stat-num {
  display: block;
  font-family: var(--zt-font-data);
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  font-weight: 700;
  color: var(--zt-acid);
  line-height: 1.1;
}
.page-about .pb-hero__stat-label {
  display: block;
  color: var(--zt-muted);
  font-size: .8125rem;
  margin-top: .25rem;
}
.page-about .pb-hero__visual {
  position: relative;
  border: 2px solid var(--zt-border-strong);
  background: var(--zt-bg-card);
  padding: .75rem;
  box-shadow: 10px 10px 0 rgba(0, 0, 0, 0.4);
}
.page-about .pb-hero__visual::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-top: 42px solid var(--zt-acid);
  border-left: 42px solid transparent;
}
.page-about .pb-hero__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .pb-hero__badge {
  position: absolute;
  left: 1.25rem;
  bottom: 1.25rem;
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  background: var(--zt-bg-deep);
  border: 1px solid var(--zt-acid);
  color: var(--zt-acid);
  font-family: var(--zt-font-data);
  font-size: .75rem;
  letter-spacing: .06em;
  padding: .5rem .9rem;
}
.page-about .pb-hero__badge-dot {
  width: .5rem;
  height: .5rem;
  border-radius: 50%;
  background: var(--zt-acid);
  box-shadow: 0 0 8px var(--zt-acid);
}

/* ===== 内容地图目录 ===== */
.page-about .pb-catalog {
  border-top: 2px solid var(--zt-border-strong);
  background: var(--zt-bg-card);
  padding: 3.5rem 0 4.5rem;
}
.page-about .pb-catalog__head {
  display: grid;
  gap: .25rem;
  margin-bottom: 2rem;
}
.page-about .pb-catalog__kicker {
  font-family: var(--zt-font-data);
  color: var(--zt-orange);
  font-size: .8125rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  font-weight: 700;
}
.page-about .pb-catalog__title {
  font-family: var(--zt-font-head);
  font-weight: 900;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  margin: 0;
}
.page-about .pb-catalog__sub {
  color: var(--zt-muted);
  font-size: .875rem;
}
.page-about .pb-catalog__list {
  display: grid;
  gap: .875rem;
}
.page-about .pb-catalog__item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 1.5rem;
  background: var(--zt-bg-deep);
  border: 1px solid var(--zt-border);
  color: var(--zt-text);
  text-decoration: none;
  box-shadow: 4px 4px 0 rgba(0, 0, 0, 0.35);
  transition: border-color .2s ease, transform .2s ease, box-shadow .2s ease;
}
.page-about .pb-catalog__item:hover {
  border-color: var(--zt-acid);
  transform: translateX(6px);
  box-shadow: 8px 8px 0 rgba(0, 0, 0, 0.3);
}
.page-about .pb-catalog__num {
  font-family: var(--zt-font-data);
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--zt-acid);
  min-width: 3ch;
}
.page-about .pb-catalog__cell {
  display: grid;
  gap: .15rem;
  flex: 1;
}
.page-about .pb-catalog__cell strong {
  font-weight: 900;
  font-size: 1rem;
}
.page-about .pb-catalog__cell small {
  color: var(--zt-muted);
  font-size: .8125rem;
}
.page-about .pb-catalog__arrow {
  color: var(--zt-orange);
  font-family: var(--zt-font-data);
  font-size: 1.25rem;
}

/* ===== 章节通用 ===== */
.page-about .pb-chapter {
  padding: 5rem 0;
}
.page-about .pb-chapter__grid {
  display: grid;
  gap: 2rem;
}
.page-about .pb-chapter__rail {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: .5rem;
}
.page-about .pb-chapter__num {
  font-family: var(--zt-font-data);
  font-weight: 700;
  font-size: 3rem;
  line-height: 1;
  color: var(--zt-acid);
}
.page-about .pb-chapter__rail-name {
  font-family: var(--zt-font-data);
  font-size: .8125rem;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: var(--zt-muted);
  border-left: 2px solid var(--zt-orange);
  padding-left: .75rem;
  padding-top: .25rem;
}
.page-about .pb-chapter__head {
  margin-bottom: 3rem;
}
.page-about .pb-chapter__kicker {
  display: inline-block;
  font-family: var(--zt-font-data);
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--zt-acid);
  border-bottom: 1px solid var(--zt-orange);
  padding-bottom: .25rem;
  margin-bottom: .75rem;
}
.page-about .pb-chapter__head h2 {
  font-family: var(--zt-font-head);
  font-weight: 900;
  font-size: clamp(2rem, 4vw, 3.5rem);
  line-height: 1.15;
  margin: 0 0 1rem;
}
.page-about .pb-chapter__intro {
  color: var(--zt-muted);
  font-size: 1rem;
  line-height: 1.85;
  max-width: 65ch;
  margin: 0;
}

/* ===== 01 起源章节 ===== */
.page-about .pb-origin__steps {
  display: grid;
  gap: 1.25rem;
}
.page-about .pb-origin__step {
  position: relative;
  border: 1px solid var(--zt-border);
  background: linear-gradient(135deg, rgba(17, 30, 58, 0.85), rgba(10, 20, 40, 0.7));
  padding: 1.75rem 1.5rem 1.5rem 2rem;
  box-shadow: var(--zt-shadow);
}
.page-about .pb-origin__step::before {
  content: "";
  position: absolute;
  left: .75rem;
  top: 1.5rem;
  bottom: 1.5rem;
  width: 3px;
  background: var(--zt-acid);
}
.page-about .pb-origin__step-top {
  display: flex;
  align-items: baseline;
  gap: .75rem;
  margin-bottom: .5rem;
}
.page-about .pb-origin__step-index {
  font-family: var(--zt-font-data);
  color: var(--zt-acid);
  font-weight: 700;
  font-size: .875rem;
}
.page-about .pb-origin__step-top h3 {
  font-size: 1.125rem;
  font-weight: 900;
  margin: 0;
}
.page-about .pb-origin__step p {
  margin: 0;
  color: var(--zt-muted);
  font-size: .9375rem;
  line-height: 1.8;
}
.page-about .pb-origin__trail {
  margin-top: 2rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .875rem;
  border-top: 1px dashed var(--zt-border-strong);
  border-bottom: 1px dashed var(--zt-border-strong);
  padding: 1.25rem 0;
}
.page-about .pb-origin__trail-rule {
  flex: 1;
  min-width: 2rem;
  height: 2px;
  background-image: linear-gradient(to right, var(--zt-acid) 0 6px, transparent 6px 12px);
  background-size: 12px 2px;
  background-repeat: repeat-x;
}
.page-about .pb-origin__trail-year {
  font-family: var(--zt-font-data);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--zt-acid);
}
.page-about .pb-origin__trail-text {
  color: var(--zt-muted);
  font-size: .875rem;
}

/* ===== 02 数据规模墙 ===== */
.page-about .pb-scale__layout {
  display: grid;
  gap: 2.5rem;
}
.page-about .pb-scale__stats {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}
.page-about .pb-scale__stat {
  position: relative;
  border: 1px solid var(--zt-border-strong);
  background: rgba(10, 20, 40, 0.55);
  padding: 1.75rem 1.5rem;
  box-shadow: var(--zt-shadow);
}
.page-about .pb-scale__stat::after {
  content: "";
  position: absolute;
  bottom: -.5rem;
  right: -.5rem;
  width: 1rem;
  height: 1rem;
  background: var(--zt-orange);
}
.page-about .pb-scale__num {
  display: block;
  font-family: var(--zt-font-data);
  font-size: clamp(3rem, 8vw, 5rem);
  font-weight: 700;
  color: var(--zt-acid);
  line-height: 1;
  margin-bottom: .5rem;
}
.page-about .pb-scale__label {
  display: block;
  font-weight: 900;
  font-size: 1rem;
  color: var(--zt-text);
  margin-bottom: .5rem;
}
.page-about .pb-scale__desc {
  margin: 0;
  color: var(--zt-muted);
  font-size: .875rem;
  line-height: 1.7;
}
.page-about .pb-scale__figure {
  margin: 0;
  padding: .75rem;
  border: 1px solid var(--zt-border-strong);
  background: var(--zt-bg-card);
  box-shadow: var(--zt-shadow);
}
.page-about .pb-scale__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .pb-scale__figure figcaption {
  padding: .75rem .25rem 0;
  font-family: var(--zt-font-data);
  font-size: .8125rem;
  color: var(--zt-muted);
}

/* ===== 03 版本演进时间线 ===== */
.page-about .pb-evolution__layout {
  display: grid;
  gap: 2.5rem;
}
.page-about .pb-evolution__timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2rem;
  position: relative;
}
.page-about .pb-evolution__timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--zt-acid) 0%, var(--zt-muted) 100%);
}
.page-about .pb-evolution__item {
  display: grid;
  grid-template-columns: 16px minmax(0, 1fr);
  gap: 1rem;
}
.page-about .pb-evolution__marker {
  width: 16px;
  height: 16px;
  margin-top: .3rem;
  background: var(--zt-acid);
  box-shadow: 0 0 0 4px var(--zt-bg-deep), 0 0 0 6px var(--zt-acid);
}
.page-about .pb-evolution__card {
  border: 1px solid var(--zt-border);
  background: var(--zt-bg-card);
  padding: 1.5rem;
  box-shadow: var(--zt-shadow);
}
.page-about .pb-evolution__tag {
  display: inline-block;
  font-family: var(--zt-font-data);
  font-weight: 700;
  font-size: .75rem;
  letter-spacing: .08em;
  color: var(--zt-bg-deep);
  background: var(--zt-acid);
  padding: .25rem .75rem;
  margin-right: .5rem;
  margin-bottom: .75rem;
  vertical-align: middle;
}
.page-about .pb-evolution__date {
  font-family: var(--zt-font-data);
  font-size: .8125rem;
  color: var(--zt-orange);
  vertical-align: middle;
}
.page-about .pb-evolution__card h3 {
  font-size: 1.125rem;
  font-weight: 900;
  margin: 0 0 .5rem;
}
.page-about .pb-evolution__card p {
  margin: 0;
  color: var(--zt-muted);
  font-size: .9375rem;
  line-height: 1.7;
}
.page-about .pb-evolution__figure {
  margin: 0;
  align-self: start;
  border: 1px solid var(--zt-border-strong);
  background: var(--zt-bg-card);
  padding: .75rem;
  box-shadow: var(--zt-shadow);
}
.page-about .pb-evolution__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .pb-evolution__figure figcaption {
  padding: .75rem .25rem 0;
  font-family: var(--zt-font-data);
  font-size: .8125rem;
  color: var(--zt-muted);
}

/* ===== 04 认证与合作 ===== */
.page-about .pb-trust__grid {
  display: grid;
  gap: 1.25rem;
}
.page-about .pb-trust__block {
  position: relative;
  border: 1px solid var(--zt-border-strong);
  background: rgba(10, 20, 40, 0.4);
  padding: 1.75rem 1.5rem;
  box-shadow: var(--zt-shadow);
}
.page-about .pb-trust__block::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-top: 28px solid var(--zt-acid);
  border-left: 28px solid transparent;
}
.page-about .pb-trust__block:nth-child(2)::after {
  border-top-color: var(--zt-orange);
}
.page-about .pb-trust__block-title {
  display: block;
  font-family: var(--zt-font-data);
  font-weight: 700;
  font-size: .875rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--zt-text);
  border-bottom: 1px solid var(--zt-border);
  padding-bottom: .75rem;
}
.page-about .pb-trust__list {
  list-style: none;
  margin: 1rem 0 0;
  padding: 0;
  display: grid;
  gap: .75rem;
}
.page-about .pb-trust__list li {
  position: relative;
  padding-left: 1.25rem;
  color: var(--zt-muted);
  font-size: .9375rem;
  line-height: 1.7;
}
.page-about .pb-trust__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .55rem;
  width: .5rem;
  height: .5rem;
  background: var(--zt-acid);
}

/* ===== 05 品牌手册式原则 ===== */
.page-about .pb-principles__list {
  display: grid;
  gap: 1rem;
}
.page-about .pb-principles__item {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  border: 1px solid var(--zt-border);
  background: rgba(94, 14, 45, 0.55);
  padding: 1.75rem 1.5rem;
  box-shadow: var(--zt-shadow);
  transition: border-color .2s ease;
}
.page-about .pb-principles__item:hover {
  border-color: var(--zt-acid);
}
.page-about .pb-principles__num {
  font-family: var(--zt-font-data);
  font-weight: 700;
  font-size: 2rem;
  color: var(--zt-acid);
  line-height: 1;
}
.page-about .pb-principles__content {
  flex: 1;
}
.page-about .pb-principles__content h3 {
  font-size: 1.25rem;
  font-weight: 900;
  margin: 0 0 .5rem;
}
.page-about .pb-principles__content p {
  margin: 0;
  color: var(--zt-muted);
  font-size: .9375rem;
  line-height: 1.7;
}
.page-about .pb-principles__arrow {
  font-family: var(--zt-font-data);
  font-size: 2rem;
  color: var(--zt-orange);
  line-height: 1;
}

/* ===== 收尾 ===== */
.page-about .pb-next {
  padding: 4.5rem 0;
  border-top: 1px solid var(--zt-border);
}
.page-about .pb-next__inner {
  display: grid;
  gap: 1rem;
  justify-items: start;
}
.page-about .pb-next__kicker {
  font-family: var(--zt-font-data);
  font-size: .75rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--zt-orange);
  font-weight: 700;
  margin: 0;
}
.page-about .pb-next h2 {
  font-family: var(--zt-font-head);
  font-weight: 900;
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  margin: 0;
}
.page-about .pb-next__lead {
  color: var(--zt-muted);
  font-size: .9375rem;
  margin: 0;
}
.page-about .pb-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: .875rem;
  margin-top: .5rem;
}

/* ===== 响应式平板 ===== */
@media (min-width: 768px) {
  .page-about .pb-hero__inner {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: center;
    gap: 3rem;
  }
  .page-about .pb-catalog__list {
    grid-template-columns: repeat(2, 1fr);
  }
  .page-about .pb-scale__stats {
    grid-template-columns: repeat(2, 1fr);
  }
  .page-about .pb-trust__grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .page-about .pb-trust__block:first-child {
    grid-row: span 2;
  }
  .page-about .pb-principles__item {
    flex-direction: row;
    align-items: center;
    gap: 2rem;
  }
  .page-about .pb-principles__num {
    min-width: 9ch;
    font-size: 2.5rem;
  }
  .page-about .pb-next__inner {
    justify-items: center;
    text-align: center;
  }
}

/* ===== 响应式桌面 ===== */
@media (min-width: 1024px) {
  .page-about .pb-chapter {
    padding: 7rem 0;
  }
  .page-about .pb-chapter__grid {
    grid-template-columns: 180px minmax(0, 1fr);
    gap: 3.5rem;
  }
  .page-about .pb-chapter__rail {
    position: sticky;
    top: calc(var(--zt-header-h) + 1.5rem);
    align-self: start;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 0;
  }
  .page-about .pb-chapter__num {
    font-size: 5rem;
  }
  .page-about .pb-catalog__list {
    grid-template-columns: repeat(5, 1fr);
  }
  .page-about .pb-catalog__item {
    flex-direction: column;
    align-items: flex-start;
    gap: .75rem;
    padding: 1.5rem 1.25rem;
  }
  .page-about .pb-catalog__arrow {
    align-self: flex-end;
  }
  .page-about .pb-catalog__item:hover {
    transform: translateY(-6px);
  }
  .page-about .pb-scale__layout {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    align-items: start;
  }
  .page-about .pb-scale__stat:nth-child(even) {
    margin-top: 2.5rem;
  }
  .page-about .pb-evolution__layout {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: start;
  }
  .page-about .pb-trust__block {
    padding: 2rem 1.75rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition: none !important;
    animation: none !important;
  }
}