/* 容器：强化对比度与阴影 */
.custom-toc {
  background: #ffffff;
  border: 1px solid #d1d5db; /* 加深边框 */
  border-radius: 12px;
  margin: 2rem 0;
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  font-family: -apple-system, system-ui, sans-serif;
  overflow: hidden;
}

/* 标题栏：使用渐变背景增加质感 */
.toc-summary {
  list-style: none;
  outline: none;
  cursor: pointer;
  padding: 1.1rem 1.4rem;
  background: linear-gradient(to right, #f8fafc, #eff6ff); /* 轻微蓝色渐变 */
  border-bottom: 2px solid #e5e7eb;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.toc-summary:hover {
  background: linear-gradient(to right, #f1f5f9, #dbeafe);
}

/* 标题文字：加粗加深 */
.toc-title {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.2rem;
  font-weight: 800; /* 更粗的字重 */
  color: #1e3a8a; /* 深蓝色 */
}

/* 箭头图标 */
.toc-arrow {
  width: 20px;
  height: 20px;
  color: #3b82f6;
  transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

details[open] .toc-arrow {
  transform: rotate(180deg);
}

/* 内容展开动画 */
.toc-content {
  padding: 1.5rem;
  background-color: #fff;
  max-height: 800px; /* 限制高度防止过长 */
  overflow-y: auto;
}

details[open] .toc-content {
  animation: fadeInSlide 0.5s ease-out;
}



/* 列表根样式 */
.toc-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

/* 一级分类 (Part) */
.toc-item-main {
  margin-bottom: 1.2rem;
}

.toc-link-main {
  display: block;
  font-size: 1.1rem;
  font-weight: 700;
  color: #111827; /* 极深灰，接近纯黑 */
  text-decoration: none;
  padding: 6px 12px;
  border-left: 4px solid #2563eb; /* 明显的侧边条 */
  background: #f3f4f6;
  border-radius: 0 6px 6px 0;
  transition: all 0.2s;
}

.toc-link-main:hover {
  background: #2563eb;
  color: white;
  padding-left: 18px;
}

/* 二级分类 */
.toc-sublist {
  list-style: none;
  padding-left: 1.5rem;
  margin-top: 0.6rem;
}

.toc-sublist li {
  position: relative;
  padding: 4px 0;
}

.toc-sublist a {
  text-decoration: none;
  color: #4b5563;
  font-size: 1rem;
  line-height: 1.5;
  transition: all 0.2s;
  display: inline-block;
}

.toc-sublist a:hover {
  color: #2563eb;
  transform: translateX(5px); /* 悬停右移 */
  font-weight: 500;
}

/* 三级小标题：点缀式样式 */
.toc-sublist ul {
  list-style: none;
  padding-left: 1.2rem;
  border-left: 1px solid #e5e7eb;
  margin: 4px 0 8px 4px;
}

.toc-sublist ul a {
  font-size: 0.9rem;
  color: #6b7280;
}

.toc-sublist ul a::before {
  content: "•";
  margin-right: 8px;
  color: #d1d5db;
}

.toc-sublist ul a:hover {
  color: #3b82f6;
}

/* 隐藏默认箭头 */
.toc-summary::-webkit-details-marker { display: none; }

  @keyframes fadeInSlide {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
  }