/*= Sidebar navigation improvements =*/

/* Collapse behavior for sidebar */
.sidebar nav ul {
  transition: all 0.3s ease;
}

/* Part titles styling */
.sidebar nav > ul > li > .sidebar-item {
  font-weight: 600;
  color: #1e40af;
  border-bottom: 1px solid #e5e7eb;
  padding: 0.5rem 0;
}

/* Hide nested chapters by default */
.sidebar nav > ul > li > ul {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

/* Show nested chapters when parent is active */
.sidebar nav > ul > li.active > ul,
.sidebar nav > ul > li:hover > ul {
  max-height: 500px;
}

/* Chapter links styling */
.sidebar nav ul ul li a {
  padding-left: 1.5rem;
  font-size: 0.9rem;
  color: #6b7280;
  border-left: 2px solid transparent;
  transition: all 0.2s ease;
}

/* Active chapter highlighting */
.sidebar nav ul ul li.active > a,
.sidebar nav ul ul li a:hover {
  color: #1e40af;
  border-left-color: #1e40af;
  background-color: #f8fafc;
}

/* Smooth scrolling for sidebar */
.sidebar {
  scroll-behavior: smooth;
}

/* Better spacing */
.sidebar nav ul li {
  margin: 0.2rem 0;
}

/* Icons for parts */
.sidebar nav > ul > li > a::before {
  content: "📁";
  margin-right: 0.5rem;
}

/* Collapse indicator */
.sidebar nav > ul > li > a::after {
  content: "▶";
  float: right;
  transition: transform 0.3s ease;
}

.sidebar nav > ul > li.active > a::after,
.sidebar nav > ul > li:hover > a::after {
  transform: rotate(90deg);
}