.page-about {
  position: relative;
  background-color: var(--bg-body);
  color: var(--text-main);
  padding-bottom: var(--sp-8);
  overflow: hidden;
}

.page-about .container {
  position: relative;
  z-index: 1;
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumb {
  padding-top: var(--sp-5);
  margin-bottom: 0;
  padding-bottom: 0;
}

.page-about .breadcrumb a {
  color: var(--teal);
  text-underline-offset: 0.2rem;
  transition: color var(--ease);
}

.page-about .breadcrumb a:hover {
  color: var(--accent);
}

/* ---------- 章节基础 ---------- */
.page-about .section-marker {
  font-family: var(--font-body);
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: var(--sp-3);
}

.page-about .section-title {
  font-family: var(--font-title);
  font-size: 1.75rem;
  line-height: 1.2;
  margin: 0 0 var(--sp-3);
  color: var(--text-main);
}

.page-about .section-desc {
  font-family: var(--font-body);
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--text-muted);
  margin: 0;
}

/* ---------- A-01 起点 ---------- */
.page-about .about-story {
  position: relative;
  padding-top: var(--sp-6);
  margin-top: var(--sp-2);
  margin-bottom: var(--sp-7);
}

.page-about .about-story-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
}

.page-about .about-h1 {
  font-family: var(--font-title);
  font-size: 2rem;
  line-height: 1.15;
  margin: 0 0 var(--sp-4);
  color: var(--text-main);
}

.page-about .about-h1-sub {
  display: block;
  font-family: var(--font-note);
  font-size: 1.05rem;
  font-weight: 400;
  font-style: italic;
  color: var(--accent);
  margin-top: var(--sp-3);
  letter-spacing: 0.02em;
}

.page-about .about-lead {
  font-family: var(--font-note);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--amber);
  margin: 0 0 var(--sp-4);
}

.page-about .prose-block p {
  font-family: var(--font-body);
  font-size: 0.92rem;
  line-height: 1.85;
  color: var(--text-main);
  margin: 0 0 var(--sp-4);
}

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

/* ---------- 数据统计面板 ---------- */
.page-about .about-hero-stats {
  position: relative;
  padding: var(--sp-5);
  background-color: var(--bg-panel);
  box-shadow: var(--shadow-2);
}

.page-about .stats-label {
  font-family: var(--font-body);
  font-size: 0.7rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 0 0 var(--sp-4);
  padding-bottom: var(--sp-2);
  border-bottom: 1px solid var(--line-faint);
}

.page-about .stat-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-3);
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .stat-item {
  border-top: 1px solid var(--line-teal);
  padding-top: var(--sp-3);
}

.page-about .stat-item dt {
  font-family: var(--font-body);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-bottom: var(--sp-2);
}

.page-about .stat-item dd {
  margin: 0;
}

.page-about .stat-num {
  font-family: var(--font-title);
  font-size: 1.85rem;
  line-height: 1;
  color: var(--accent);
}

.page-about .stat-unit,
.page-about .stat-plus {
  font-family: var(--font-body);
  font-style: normal;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ---------- A-02 版本时间线 ---------- */
.page-about .about-verse {
  position: relative;
  padding-top: var(--sp-5);
  margin-bottom: var(--sp-7);
}

.page-about .about-verse::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(46, 196, 182, 0.07) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(46, 196, 182, 0.07) 1px, transparent 1px);
  background-size: 3rem 3rem;
  pointer-events: none;
  z-index: 0;
}

.page-about .about-verse > * {
  position: relative;
  z-index: 1;
}

.page-about .about-timeline {
  position: relative;
  list-style: none;
  margin: var(--sp-6) 0 0;
  padding: 0;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 0.35rem;
  top: 0;
  bottom: 0;
  width: 1px;
  background: linear-gradient(to bottom, var(--line-teal), var(--line-faint) 70%, transparent);
}

.page-about .tl-entry {
  position: relative;
  padding: 0 0 var(--sp-5) 1.75rem;
}

.page-about .tl-rail {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: var(--sp-3);
  margin-bottom: var(--sp-2);
}

.page-about .tl-ver {
  font-family: var(--font-body);
  font-weight: 700;
  letter-spacing: 0.06em;
}

.page-about .tl-zone {
  font-family: var(--font-body);
  font-size: 0.78rem;
  color: var(--text-muted);
}

.page-about .tl-dot {
  position: absolute;
  left: 0;
  top: 0.5rem;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--bg-body);
  border: 2px solid var(--teal);
  box-shadow: 0 0 0 3px rgba(46, 196, 182, 0.16), 0 0 0 1px rgba(46, 196, 182, 0.5);
}

.page-about .tl-card {
  border-left: 2px solid var(--line-teal);
  padding: var(--sp-4);
  background-color: var(--bg-panel);
  transition: transform var(--ease), border-color var(--ease), box-shadow var(--ease);
}

.page-about .tl-entry:hover .tl-card {
  transform: translateY(-3px);
  border-left-color: var(--teal);
  box-shadow: var(--shadow-2);
}

.page-about .tl-title {
  font-family: var(--font-body);
  font-size: 1rem;
  letter-spacing: 0.03em;
  margin: 0 0 var(--sp-2);
  color: var(--text-main);
}

.page-about .tl-text {
  font-family: var(--font-body);
  font-size: 0.85rem;
  line-height: 1.75;
  color: var(--text-muted);
  margin: 0 0 var(--sp-3);
}

.page-about .tl-more {
  margin-top: var(--sp-3);
  font-family: var(--font-body);
  font-size: 0.8rem;
  border-top: 1px dashed var(--line-teal);
  padding-top: var(--sp-3);
}

.page-about .tl-more summary {
  list-style: none;
  cursor: pointer;
  color: var(--teal);
  transition: color var(--ease);
}

.page-about .tl-more summary::-webkit-details-marker {
  display: none;
}

.page-about .tl-more summary::before {
  content: "+";
  display: inline-block;
  margin-right: 0.4rem;
  color: var(--amber);
  font-family: var(--font-body);
  transition: transform var(--ease);
}

.page-about .tl-more[open] summary::before {
  content: "−";
}

.page-about .tl-more summary:hover {
  color: var(--amber);
}

.page-about .tl-more p {
  margin-top: var(--sp-2);
  margin-bottom: 0;
  color: var(--text-muted);
  line-height: 1.7;
  font-size: 0.8rem;
}

/* ---------- 图注与图片通用 ---------- */
.page-about figure {
  margin: 0;
}

.page-about .about-growth,
.page-about .about-flow-figure,
.page-about .about-device-figure {
  margin: var(--sp-6) 0 0;
}

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

.page-about .about-growth figcaption,
.page-about .about-flow-figure figcaption,
.page-about .about-device-figure figcaption {
  font-family: var(--font-note);
  font-style: italic;
  font-size: 0.8rem;
  color: var(--text-muted);
  padding-top: var(--sp-2);
}

/* ---------- A-03 数据编辑流程 ---------- */
.page-about .about-workflow {
  margin-bottom: var(--sp-7);
}

.page-about .section-head-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-3);
  margin-bottom: var(--sp-4);
}

.page-about .about-steps {
  list-style: none;
  margin: var(--sp-5) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-4);
}

.page-about .step-card {
  padding: var(--sp-5);
  position: relative;
  background-color: var(--bg-panel);
}

.page-about .step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--accent);
  color: var(--bg-body);
  min-width: 2rem;
  height: 2rem;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 0.9rem;
  margin-bottom: var(--sp-4);
}

.page-about .step-title {
  font-family: var(--font-body);
  font-size: 1rem;
  letter-spacing: 0.02em;
  margin: 0 0 var(--sp-2);
  color: var(--text-main);
}

.page-about .step-text {
  font-family: var(--font-body);
  font-size: 0.85rem;
  line-height: 1.75;
  color: var(--text-muted);
  margin: 0;
}

/* ---------- A-04 和球迷的关系 ---------- */
.page-about .about-fan {
  margin-bottom: var(--sp-7);
}

.page-about .about-fan-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
  margin-top: var(--sp-5);
}

.page-about .about-fan-aside {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-4);
}

.page-about .fan-device-card,
.page-about .fan-save-card {
  padding: var(--sp-5);
  background-color: var(--bg-panel);
}

.page-about .fan-card-label {
  font-family: var(--font-body);
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 0 0 var(--sp-2);
}

.page-about .fan-card-title {
  font-family: var(--font-body);
  font-size: 1rem;
  margin: 0 0 var(--sp-3);
  color: var(--text-main);
}

.page-about .fan-card-text {
  font-family: var(--font-body);
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text-muted);
  margin: 0 0 var(--sp-4);
}

/* ---------- CTA ---------- */
.page-about .about-cta {
  margin-top: var(--sp-7);
}

.page-about .about-cta .alert {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
}

.page-about .about-cta .alert p {
  margin: 0;
  font-family: var(--font-body);
  font-size: 0.88rem;
  line-height: 1.7;
}

.page-about .about-cta a {
  text-underline-offset: 0.2rem;
}

/* ---------- 焦点可见性 ---------- */
.page-about a:focus-visible,
.page-about summary:focus-visible,
.page-about .btn:focus-visible {
  outline: 2px solid var(--neon);
  outline-offset: 2px;
}

/* ---------- 桌面端 ---------- */
@media (min-width: 800px) {
  .page-about .section-title {
    font-size: 2rem;
  }

  .page-about .about-story-grid {
    grid-template-columns: minmax(0, 1fr) minmax(18rem, 24rem);
    column-gap: var(--sp-7);
    align-items: start;
  }

  .page-about .about-h1 {
    font-size: 2.75rem;
  }

  .page-about .about-h1-sub {
    font-size: 1.2rem;
  }

  .page-about .stat-num {
    font-size: 2.35rem;
  }

  .page-about .about-timeline::before {
    left: 16.5rem;
  }

  .page-about .tl-entry {
    display: grid;
    grid-template-columns: 15rem 3rem 1fr;
    padding-left: 0;
  }

  .page-about .tl-rail {
    justify-content: flex-end;
    text-align: right;
    padding-top: 0.4rem;
    margin-bottom: 0;
  }

  .page-about .tl-dot {
    position: relative;
    left: auto;
    top: auto;
    justify-self: center;
    align-self: start;
    margin-top: 0.5rem;
  }

  .page-about .tl-card {
    margin-left: 0;
  }

  .page-about .section-head-split {
    grid-template-columns: 1fr 1fr;
    align-items: end;
  }

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

  .page-about .about-fan-grid {
    grid-template-columns: minmax(0, 1fr) minmax(18rem, 22rem);
    column-gap: var(--sp-7);
  }

  .page-about .about-fan-aside {
    grid-template-columns: 1fr;
  }
}

@media (min-width: 1100px) {
  .page-about .about-steps {
    grid-template-columns: repeat(4, 1fr);
  }
}