.page-about {
  --about-axis-w: 104px;
  --about-gap: 32px;
  background:
    repeating-linear-gradient(90deg, rgba(35, 196, 200, 0.05) 0 1px, transparent 1px 46px),
    var(--deep);
  color: var(--text);
  padding-bottom: 64px;
  overflow-x: hidden;
}

.page-about .breadcrumb {
  margin: 20px 0 22px;
  font-size: 13px;
  color: var(--muted);
}

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

.page-about .breadcrumb a:hover {
  text-decoration: underline;
}

.page-about .breadcrumb__sep {
  margin: 0 8px;
  color: var(--muted);
}

/* ---------- 首屏 ---------- */

.about-hero {
  border-bottom: var(--seam);
  padding-bottom: 26px;
}

.about-hero__eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--cyan);
  border: 1px solid rgba(35, 196, 200, 0.4);
  padding: 5px 10px;
}

.about-hero h1 {
  font-family: var(--font-sans);
  font-size: clamp(27px, 7vw, 52px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 16px 0 18px;
  max-width: 17em;
}

.about-hero h1 em {
  font-style: normal;
  color: var(--orange);
}

.about-hero .lede {
  max-width: 36em;
  margin: 0 0 26px;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.8;
}

.about-stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.about-stats li {
  background: var(--panel);
  padding: 14px 14px 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.about-stats__num {
  font-size: 26px;
  font-weight: 700;
  line-height: 1;
  color: var(--orange);
  letter-spacing: -0.02em;
}

.about-stats__label {
  font-size: 12px;
  color: var(--muted);
  letter-spacing: 0.04em;
}

/* ---------- 章节骨架 ---------- */

.about-section {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  padding: 26px 0 32px;
  border-bottom: var(--seam);
}

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

.about-axis__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.about-axis__year {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--orange);
}

.about-axis__tip {
  display: none;
}

.about-body {
  min-width: 0;
}

/* ---------- 面板 ---------- */

.about-card {
  position: relative;
  background: linear-gradient(158deg, var(--panel-2) 0%, var(--panel) 58%, var(--panel) 100%);
  border: 1px solid var(--line);
  border-left: 3px solid var(--orange);
  padding: 22px 18px 24px;
  transition: transform 120ms ease, border-color 120ms ease;
}

.about-card:hover {
  transform: translateY(-3px);
  border-color: var(--orange-soft);
}

.about-card__num {
  position: absolute;
  top: 12px;
  right: 16px;
  font-family: var(--font-mono);
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--orange);
  opacity: 0.75;
  pointer-events: none;
}

.about-card__title {
  font-family: var(--font-sans);
  font-size: 21px;
  font-weight: 900;
  line-height: 1.32;
  letter-spacing: -0.01em;
  margin: 0 0 14px;
  padding-right: 48px;
  max-width: 18em;
}

.about-card p {
  margin: 0 0 14px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
  max-width: 38em;
}

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

.about-card p strong {
  color: var(--text);
  font-weight: 800;
}

.about-figure {
  margin: 0 0 18px;
  border: 1px solid var(--line);
  background: var(--ink);
  overflow: hidden;
}

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

/* ---------- 四象限 ---------- */

.about-quad {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin-top: 6px;
}

.about-quad__item {
  background: var(--panel);
  border: 1px solid var(--line);
  border-top: 2px solid var(--cyan);
}

.about-quad__item[open] {
  border-top-color: var(--orange);
}

.about-quad__item summary {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 13px 14px;
  cursor: pointer;
  list-style: none;
  font-size: 15px;
  font-weight: 800;
  color: var(--text);
}

.about-quad__item summary::-webkit-details-marker {
  display: none;
}

.about-quad__item summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: -2px;
}

.about-quad__count {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  color: var(--orange-soft);
  border: 1px solid rgba(255, 138, 87, 0.4);
  padding: 2px 6px;
  flex: none;
}

.about-quad__item p {
  margin: 0;
  padding: 0 14px 16px;
  font-size: 13.5px;
  line-height: 1.78;
  color: var(--muted);
}

/* ---------- 时间轴 ---------- */

.about-timeline {
  list-style: none;
  margin: 4px 0 0;
  padding: 0;
  position: relative;
}

.about-timeline::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--cyan) 0%, rgba(35, 196, 200, 0.12) 100%);
}

.about-timeline__item {
  position: relative;
  padding: 0 0 22px 30px;
}

.about-timeline__item:last-child {
  padding-bottom: 0;
}

.about-timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 5px;
  width: 14px;
  height: 14px;
  background: var(--orange);
  box-shadow: 0 0 0 3px var(--panel);
}

.about-timeline__year {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--orange-soft);
}

.about-timeline__item h3 {
  margin: 5px 0 6px;
  font-size: 15.5px;
  font-weight: 800;
  line-height: 1.45;
  color: var(--text);
}

.about-timeline__item p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.78;
  color: var(--muted);
  max-width: 40em;
}

/* ---------- 生态 ---------- */

.about-eco {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
}

.about-eco__item {
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 12px;
  padding: 14px;
  background: var(--panel);
  border-left: 2px solid var(--cyan);
}

.about-eco__num {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--cyan);
}

.about-eco__item h3 {
  margin: 0 0 4px;
  font-size: 14.5px;
  font-weight: 800;
  color: var(--text);
  line-height: 1.4;
}

.about-eco__item p {
  margin: 0;
  font-size: 13px;
  line-height: 1.72;
  color: var(--muted);
}

/* ---------- 三条坚持 ---------- */

.about-pillars {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin-top: 4px;
}

.about-pillar {
  background: var(--panel);
  border-top: 2px solid var(--orange);
  padding: 16px 14px 18px;
}

.about-pillar h3 {
  margin: 0 0 8px;
  font-size: 15px;
  font-weight: 800;
  line-height: 1.4;
  color: var(--text);
}

.about-pillar p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.78;
  color: var(--muted);
  max-width: none;
}

/* ---------- 收口 ---------- */

.page-about .status-band {
  margin: 26px 0 0;
  padding: 16px 18px;
  background: var(--paper);
  color: var(--deep);
  border-left: 4px solid var(--orange);
}

.page-about .status-band p {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  font-weight: 700;
  max-width: 40em;
}

.about-next {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin-top: 26px;
  background: var(--line);
  border: 1px solid var(--line);
}

.about-next__link {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 14px 16px;
  background: var(--panel);
  text-decoration: none;
  color: var(--text);
  border-left: 2px solid transparent;
  transition: border-color 120ms ease, background-color 120ms ease;
}

.about-next__link:hover,
.about-next__link:focus-visible {
  border-left-color: var(--orange);
  background: var(--panel-2);
}

.about-next__link:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: -2px;
}

.about-next__title {
  font-size: 15px;
  font-weight: 800;
}

.about-next__note {
  font-size: 12px;
  color: var(--muted);
  line-height: 1.6;
}

/* ---------- 平板 ---------- */

@media (min-width: 620px) {
  .about-stats {
    grid-template-columns: repeat(4, 1fr);
  }

  .about-stats__num {
    font-size: 30px;
  }

  .about-card {
    padding: 26px 24px 28px;
  }

  .about-card__title {
    font-size: 24px;
    padding-right: 64px;
  }

  .about-quad {
    grid-template-columns: 1fr 1fr;
  }

  .about-eco {
    grid-template-columns: 1fr 1fr;
  }

  .about-pillars {
    grid-template-columns: 1fr 1fr;
  }

  .about-next {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ---------- 桌面：年份刻度脊柱 + 面板宽度递进 ---------- */

@media (min-width: 900px) {
  .page-about {
    padding-bottom: 88px;
  }

  .about-hero {
    padding-bottom: 34px;
  }

  .about-hero .lede {
    font-size: 16px;
  }

  .about-section {
    grid-template-columns: var(--about-axis-w) minmax(0, 1fr);
    gap: var(--about-gap);
    padding: 40px 0 48px;
  }

  .about-axis {
    display: block;
    position: relative;
    padding: 2px 0 0 24px;
  }

  .about-axis::before {
    content: "";
    position: absolute;
    left: 4px;
    top: 0;
    bottom: -48px;
    width: 2px;
    background: linear-gradient(180deg, var(--cyan) 0%, rgba(35, 196, 200, 0.12) 100%);
  }

  .about-axis::after {
    content: "";
    position: absolute;
    left: 0;
    top: 5px;
    width: 10px;
    height: 10px;
    background: var(--orange);
    box-shadow: 0 0 0 3px var(--deep);
  }

  .about-axis__label {
    display: block;
    margin-bottom: 5px;
  }

  .about-axis__year {
    display: block;
    font-size: 16px;
  }

  .about-axis__tip {
    display: block;
    margin-top: 10px;
    font-family: var(--font-mono);
    font-size: 11px;
    line-height: 1.55;
    color: var(--cyan);
    opacity: 0;
    transform: translateY(-4px);
    transition: opacity 140ms ease, transform 140ms ease;
  }

  .about-section:hover .about-axis__tip,
  .about-section:focus-within .about-axis__tip {
    opacity: 1;
    transform: none;
  }

  .about-body--narrow {
    max-width: 520px;
  }

  .about-body--mid {
    max-width: 680px;
  }

  .about-body--wide {
    max-width: 100%;
  }

  .about-pillars {
    grid-template-columns: repeat(3, 1fr);
  }

  .about-next {
    grid-template-columns: repeat(5, 1fr);
  }
}

@media (min-width: 1100px) {
  .about-card {
    padding: 30px 30px 32px;
  }

  .about-card__title {
    font-size: 26px;
  }

  .about-card p {
    font-size: 15px;
  }

  .about-timeline__item p,
  .about-quad__item p,
  .about-eco__item p,
  .about-pillar p {
    font-size: 13.5px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .about-card,
  .about-axis__tip,
  .about-next__link {
    transition: none;
  }

  .about-card:hover {
    transform: none;
  }

  .about-axis__tip {
    transform: none;
  }
}