/* ===== 页面专属：.page-about ===== */
.page-about {
  display: block;
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-lg) var(--space-md) var(--space-xl);
  color: var(--c-text);
  font-family: var(--font-body);
}

/* --- 面包屑 --- */
.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-xs);
  font-size: 0.85rem;
  color: var(--c-text-muted);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--c-border);
}
.page-about .breadcrumb a {
  color: var(--c-secondary);
  text-decoration: none;
  transition: opacity 0.2s;
}
.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus {
  opacity: 0.7;
  outline: 2px solid var(--c-secondary);
  outline-offset: 2px;
}
.page-about .breadcrumb .sep {
  user-select: none;
  opacity: 0.4;
}
.page-about .breadcrumb [aria-current="page"] {
  color: var(--c-text);
  font-weight: 500;
}

/* --- 页面标题区 --- */
.page-about .about-intro {
  position: relative;
  text-align: center;
  padding: var(--space-xl) var(--space-md) var(--space-lg);
  margin-bottom: var(--space-lg);
  overflow: hidden;
}
.page-about .intro-glow {
  position: absolute;
  top: -30%;
  left: 50%;
  transform: translateX(-50%);
  width: 300px;
  height: 300px;
  background: radial-gradient(circle, rgba(74,0,224,0.25) 0%, rgba(142,45,226,0.08) 60%, transparent 80%);
  border-radius: 50%;
  pointer-events: none;
  z-index: 0;
}
.page-about .about-intro h1 {
  position: relative;
  z-index: 1;
  font-family: var(--font-heading);
  font-weight: 700;
  letter-spacing: 0.06em;
  font-size: clamp(1.8rem, 5vw, 3rem);
  margin: 0 0 var(--space-sm);
  line-height: 1.1;
}
.page-about .about-intro p {
  position: relative;
  z-index: 1;
  font-size: 1rem;
  color: var(--c-text-muted);
  max-width: 540px;
  margin: 0 auto;
}

/* --- 章节索引导航 --- */
.page-about .about-index {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
  margin: var(--space-lg) auto var(--space-xl);
  padding: var(--space-sm) 0;
}
.page-about .index-item {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: var(--c-text);
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: 0.04em;
  transition: background 0.25s, box-shadow 0.25s, border-color 0.25s;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}
.page-about .index-item:hover,
.page-about .index-item:focus {
  background: var(--c-surface-hover);
  border-color: var(--c-secondary);
  box-shadow: 0 0 14px rgba(0,255,135,0.18);
  outline: none;
}
.page-about .index-num {
  font-family: var(--font-data);
  font-size: 1.1rem;
  color: var(--c-secondary);
  font-weight: 700;
  min-width: 1.4em;
  text-align: center;
}
.page-about .index-label {
  font-size: 0.9rem;
}

/* --- 章节分隔色带 --- */
.page-about .chapter-divider {
  height: 6px;
  margin: var(--space-lg) 0;
  background: var(--gradient-primary);
  border-radius: var(--radius-sm);
  transform: skewX(-2deg);
  opacity: 0.55;
  width: 100%;
}

/* --- 章节通用 --- */
.page-about .chapter {
  scroll-margin-top: calc(var(--header-h) + var(--space-md));
  margin: var(--space-lg) 0;
}

/* 章节编号（大号装饰） */
.page-about .chapter-number {
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: clamp(4rem, 12vw, 7rem);
  line-height: 1;
  color: var(--c-primary-start);
  opacity: 0.18;
  display: block;
  margin-bottom: var(--space-sm);
  user-select: none;
  letter-spacing: -0.03em;
  pointer-events: none;
}

/* 章节内部布局（移动端：竖排） */
.page-about .chapter-inner {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}
.page-about .chapter-body {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}
.page-about .chapter-text h2 {
  font-family: var(--font-heading);
  font-weight: 700;
  letter-spacing: 0.04em;
  font-size: clamp(1.3rem, 3.5vw, 2rem);
  margin: 0 0 var(--space-md);
  line-height: 1.2;
  color: var(--c-text);
}
.page-about .chapter-text p {
  font-size: 1rem;
  line-height: 1.6;
  margin: 0 0 var(--space-md);
  color: var(--c-text);
}
.page-about .chapter-text p:last-child {
  margin-bottom: 0;
}
.page-about .chapter-text .text-muted {
  color: var(--c-text-muted);
  font-size: 0.95rem;
}

/* --- 关注列表 --- */
.page-about .focus-list {
  list-style: none;
  padding: 0;
  margin: var(--space-md) 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}
.page-about .focus-list li {
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--c-text);
}
.page-about .focus-list .tag {
  flex-shrink: 0;
  margin-top: 2px;
}

/* --- 图片 --- */
.page-about .chapter-figure {
  margin: 0;
  width: 100%;
}
.page-about .figure-img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  object-fit: cover;
  border: 1px solid var(--c-border);
  box-shadow: var(--shadow-glow);
}
.page-about .chapter-figure-center {
  margin: var(--space-lg) auto 0;
  max-width: 440px;
  width: 100%;
}

/* --- 第三章（居中） --- */
.page-about .chapter-body-center {
  align-items: center;
  text-align: center;
}
.page-about .chapter-body-center .chapter-text {
  max-width: 640px;
}

/* --- 里程碑网格 --- */
.page-about .milestones-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
  width: 100%;
  margin: var(--space-lg) 0;
}
.page-about .milestone-card {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-md);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  transition: border-color 0.25s, box-shadow 0.25s;
}
.page-about .milestone-card:hover {
  border-color: var(--c-secondary);
  box-shadow: var(--shadow-neon);
}
.page-about .milestone-card .tag {
  align-self: flex-start;
  font-size: 0.8rem;
  padding: 0.2em 0.7em;
  border: 1px solid var(--c-secondary);
  border-radius: var(--radius-sm);
  color: var(--c-secondary);
  font-family: var(--font-heading);
  font-weight: 600;
  letter-spacing: 0.04em;
  background: rgba(0,255,135,0.06);
}
.page-about .milestone-card p {
  margin: 0;
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--c-text);
}
.page-about .milestone-card .text-data {
  font-family: var(--font-data);
  font-size: 1.1rem;
  color: var(--c-secondary);
  font-weight: 600;
}

/* --- 底部 --- */
.page-about .about-outro {
  margin-top: var(--space-xl);
  padding: var(--space-lg) 0;
  text-align: center;
  border-top: 1px solid var(--c-border);
}
.page-about .about-outro p {
  font-size: 1rem;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: var(--space-sm);
}
.page-about .about-outro .btn-outline {
  display: inline-block;
  padding: 0.45em 1.2em;
  border: 1px solid var(--c-primary-end);
  border-radius: var(--radius-md);
  color: var(--c-primary-end);
  text-decoration: none;
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 0.9rem;
  letter-spacing: 0.04em;
  transition: background 0.25s, color 0.25s, box-shadow 0.25s;
}
.page-about .about-outro .btn-outline:hover,
.page-about .about-outro .btn-outline:focus {
  background: var(--gradient-primary);
  color: #fff;
  box-shadow: var(--shadow-glow);
  outline: none;
  border-color: transparent;
}

/* ===== 桌面端媒体查询 ===== */
@media (min-width: 768px) {

  .page-about {
    padding: var(--space-lg) var(--space-xl) var(--space-xl);
  }

  /* 标题区 */
  .page-about .about-intro {
    padding: var(--space-xl) var(--space-lg) var(--space-lg);
  }
  .page-about .intro-glow {
    width: 480px;
    height: 480px;
    top: -40%;
  }

  /* 索引 */
  .page-about .about-index {
    gap: var(--space-lg);
  }
  .page-about .index-item {
    padding: var(--space-sm) var(--space-lg);
    font-size: 1rem;
  }

  /* 章节布局：左右并排 */
  .page-about .chapter-inner {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--space-lg);
  }
  .page-about .chapter-number {
    font-size: 7rem;
    margin-bottom: 0;
    min-width: 100px;
    opacity: 0.15;
  }
  .page-about .chapter-body {
    flex: 1;
    flex-direction: row;
    align-items: flex-start;
    gap: var(--space-xl);
  }
  .page-about .chapter-text {
    flex: 1 1 55%;
  }
  .page-about .chapter-figure {
    flex: 0 1 40%;
    max-width: 480px;
  }

  /* 第二章（图片在左） */
  .page-about .chapter-reverse .chapter-body {
    flex-direction: row-reverse;
  }
  .page-about .chapter-reverse .chapter-text {
    flex: 1 1 55%;
  }
  .page-about .chapter-reverse .chapter-figure {
    flex: 0 1 40%;
  }

  /* 第三章（居中窄版） */
  .page-about .chapter-center .chapter-body-center {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
  .page-about .chapter-center .chapter-figure-center {
    max-width: 400px;
  }

  /* 里程碑 2×2 */
  .page-about .milestones-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-md);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
  }
  .page-about .milestone-card {
    padding: var(--space-md) var(--space-lg);
  }

  /* 分隔线加宽 */
  .page-about .chapter-divider {
    height: 8px;
    margin: var(--space-xl) 0;
    opacity: 0.6;
  }
}

/* ===== 窄屏微调 ===== */
@media (max-width: 380px) {
  .page-about .about-index {
    gap: var(--space-sm);
  }
  .page-about .index-item {
    font-size: 0.8rem;
    padding: var(--space-xs) var(--space-sm);
  }
  .page-about .chapter-number {
    font-size: 3.2rem;
  }
  .page-about .milestone-card {
    padding: var(--space-sm) var(--space-md);
  }
}