.page-about {
  --rail-w: 76px;
  --about-pad: 28px;
}

/* 开篇 */
.page-about .about-intro {
  padding: var(--about-pad) 0 4px;
  border-top: 1px solid var(--line);
}

.page-about .about-intro h1 {
  margin: 14px 0 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: var(--fs-44);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ice);
  max-width: 20ch;
}

.page-about .about-intro .lead {
  margin: 18px 0 0;
  max-width: 64ch;
  font-size: var(--fs-17);
  line-height: var(--lh-body);
  color: rgba(234, 242, 255, 0.82);
}

.page-about .about-intro__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: 28px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-intro__stats .stat {
  background: var(--bg-stand);
  padding: 16px 18px;
}

.page-about .stat__value {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-22);
  font-weight: 700;
  color: var(--ice);
  letter-spacing: -0.01em;
}

.page-about .stat__label {
  display: block;
  margin-top: 6px;
  font-size: var(--fs-12);
  color: var(--muted);
  letter-spacing: 0.08em;
}

/* 主视觉 */
.page-about .about-hero {
  margin: 32px 0 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 7;
  object-fit: cover;
}

.page-about .about-hero__cap {
  padding: 12px var(--gutter);
  font-size: var(--fs-12);
  color: var(--muted);
  border-top: 1px solid var(--line);
  background: var(--bg-stand);
}

/* 版式骨架 */
.page-about .about-layout {
  display: grid;
  gap: 24px;
  margin-top: 32px;
}

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

.page-about .track__list {
  display: flex;
  gap: 10px;
  margin: 0;
  padding: 0 0 10px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

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

.page-about .track__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ice);
  font-size: var(--fs-12);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--t-fast), border-color var(--t-fast), background var(--t-fast);
}

.page-about .track__num {
  font-family: var(--font-mono);
  color: var(--cyan);
}

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

/* 章节 */
.page-about .stage {
  padding: 30px 0 40px;
  border-top: 1px solid var(--line);
}

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

.page-about .stage__head {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .stage__num {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  color: var(--cyan);
  letter-spacing: 0.14em;
}

.page-about .stage__year {
  font-family: var(--font-cond);
  font-size: var(--fs-12);
  color: var(--muted);
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.page-about .stage__title {
  flex: 1 0 100%;
  margin: 10px 0 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: var(--fs-30);
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--ice);
}

.page-about .stage__text p {
  margin: 16px 0 0;
  max-width: 60ch;
  font-size: var(--fs-15);
  line-height: var(--lh-body);
  color: rgba(234, 242, 255, 0.78);
}

.page-about .stage__note {
  margin: 22px 0 0;
  padding-left: 14px;
  border-left: 2px solid var(--orange);
  font-size: var(--fs-15);
  line-height: 1.7;
  color: rgba(234, 242, 255, 0.86);
}

/* 职能线 */
.page-about .lines {
  display: grid;
  gap: 1px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .lines__item {
  background: var(--panel);
  padding: 16px 18px;
}

.page-about .lines__head {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.page-about .lines__num {
  font-family: var(--font-mono);
  font-size: var(--fs-17);
  font-weight: 700;
  color: var(--cyan);
}

.page-about .lines__name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: var(--fs-17);
  color: var(--ice);
}

.page-about .lines__desc {
  margin: 8px 0 0;
  font-size: var(--fs-15);
  line-height: 1.7;
  color: rgba(234, 242, 255, 0.72);
}

/* 覆盖范围 */
.page-about .stage__grid {
  display: grid;
  gap: 24px;
  margin-top: 4px;
}

.page-about .facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: 24px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .fact {
  background: var(--bg-stand);
  padding: 14px 16px;
}

.page-about .fact__v {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--fs-22);
  font-weight: 700;
  color: var(--cyan);
}

.page-about .fact__k {
  display: block;
  margin-top: 6px;
  font-size: var(--fs-12);
  color: var(--muted);
}

.page-about .stage__figure {
  margin: 24px 0 0;
  border: 1px solid var(--line);
}

.page-about .stage__grid .stage__figure {
  margin-top: 0;
}

.page-about .stage__figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .stage__figure--tall img {
  aspect-ratio: 4 / 3;
}

.page-about .stage__figure--wide img {
  aspect-ratio: 3 / 2;
}

.page-about .stage__cap {
  padding: 10px 14px;
  border-top: 1px solid var(--line);
  background: var(--bg-stand);
  font-size: var(--fs-12);
  color: var(--muted);
}

/* 时间线 SVG */
.page-about .tl-wrap {
  margin-top: 24px;
  padding-bottom: 6px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-bottom: 1px solid var(--line);
}

.page-about .tl {
  display: block;
  width: 100%;
  min-width: 560px;
  height: auto;
  padding-bottom: 10px;
}

.page-about .tl__axis {
  stroke: var(--line);
  stroke-width: 1;
}

.page-about .tl__node circle {
  fill: var(--bg);
  stroke: var(--muted);
  stroke-width: 2;
}

.page-about .tl__node--now circle {
  fill: var(--cyan);
  stroke: var(--cyan);
}

.page-about .tl__num {
  font-family: var(--font-mono);
  font-size: 14px;
  fill: var(--muted);
}

.page-about .tl__name {
  font-family: var(--font-body);
  font-size: 15px;
  fill: var(--ice);
}

.page-about .tl__node--now .tl__name {
  fill: var(--cyan);
}

/* 阶段记录 */
.page-about .chrono {
  display: grid;
  gap: 1px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .chrono__item {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  padding: 16px 18px;
  background: var(--bg-stand);
}

.page-about .chrono__year {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  color: var(--orange);
  letter-spacing: 0.08em;
}

.page-about .chrono__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: var(--fs-17);
  color: var(--ice);
}

.page-about .chrono__desc {
  margin: 8px 0 0;
  max-width: 56ch;
  font-size: var(--fs-15);
  line-height: 1.7;
  color: rgba(234, 242, 255, 0.74);
}

/* 更新节奏 */
.page-about .rhythm {
  display: grid;
  gap: 1px;
  margin: 24px 0 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .rhythm__cell {
  padding: 18px;
  background: var(--panel);
}

.page-about .rhythm__k {
  display: inline-block;
  padding: 3px 10px;
  border: 1px solid var(--orange);
  color: var(--orange);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.08em;
}

.page-about .rhythm__v {
  margin: 12px 0 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: var(--fs-17);
  color: var(--ice);
}

.page-about .rhythm__desc {
  margin: 8px 0 0;
  font-size: var(--fs-15);
  line-height: 1.7;
  color: rgba(234, 242, 255, 0.74);
}

/* 移动端细节清单 */
.page-about .spec {
  display: grid;
  gap: 14px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .spec__item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--line);
}

.page-about .spec__item:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.page-about .spec__mark {
  flex: 0 0 auto;
  width: 10px;
  height: 10px;
  margin-top: 7px;
  background: var(--cyan);
}

.page-about .spec__text {
  font-size: var(--fs-15);
  line-height: 1.75;
  color: rgba(234, 242, 255, 0.8);
}

/* 收束 */
.page-about .about-cta {
  margin-top: 12px;
  padding: 34px 0 44px;
  background: var(--bg-stand);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-cta__grid {
  display: grid;
  gap: 28px;
}

.page-about .about-cta__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: var(--fs-22);
  color: var(--ice);
}

.page-about .about-cta__text {
  margin: 12px 0 0;
  max-width: 52ch;
  font-size: var(--fs-15);
  line-height: var(--lh-body);
  color: rgba(234, 242, 255, 0.76);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.page-about .btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  font-size: var(--fs-15);
  text-decoration: none;
}

.page-about .about-cta__col--stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-cta__col--stats .stat {
  background: var(--panel);
  padding: 16px 18px;
}

/* 触控与动效偏好 */
.page-about .track__link:focus-visible,
.page-about .btn:focus-visible {
  outline: 2px solid var(--cyan-soft);
  outline-offset: 2px;
}

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

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

  .page-about .facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .rhythm {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .chrono__item {
    grid-template-columns: 96px minmax(0, 1fr);
    gap: 18px;
  }

  .page-about .about-cta__grid {
    grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr);
    align-items: start;
  }
}

@media (min-width: 960px) {
  .page-about .about-intro {
    padding-top: 48px;
  }

  .page-about .about-layout {
    grid-template-columns: var(--rail-w) minmax(0, 1fr);
    gap: 40px;
    margin-top: 48px;
  }

  .page-about .track {
    position: sticky;
    top: 108px;
    align-self: start;
  }

  .page-about .track__list {
    flex-direction: column;
    gap: 26px;
    padding: 0 0 0 16px;
    overflow: visible;
    border-left: 1px solid var(--line);
  }

  .page-about .track__link {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
    min-height: 0;
    padding: 0;
    border: 0;
    background: none;
    white-space: normal;
  }

  .page-about .track__name {
    writing-mode: vertical-rl;
    font-size: var(--fs-12);
    letter-spacing: 0.16em;
    color: var(--muted);
  }

  .page-about .track__link:hover .track__name,
  .page-about .track__link:focus-visible .track__name {
    color: var(--cyan);
  }

  .page-about .stage__grid {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
    gap: 32px;
  }

  .page-about .stage__title {
    font-size: var(--fs-44);
  }

  .page-about .stage__text p {
    font-size: var(--fs-17);
  }

  .page-about .stage__figure--wide {
    margin-top: 28px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .track__link,
  .page-about .btn {
    transition: none;
  }
}
</main>