/* Sidebar Navigation */

.app-container {
  display: flex;
  height: 100vh;
  overflow: hidden;
}

/* Sidebar */
.sidebar {
  width: 320px;
  background: var(--bg-secondary);
  border-right: 2px solid var(--border-color);
  box-shadow: 2px 0 20px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  position: relative;
  z-index: 100;
}

.sidebar::after {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(180deg, var(--neon-cyan), var(--neon-magenta));
  opacity: 0.3;
  pointer-events: none;
}

/* Sidebar Header */
.sidebar-header {
  padding: var(--spacing-lg);
  border-bottom: 2px solid var(--border-color);
  background: var(--bg-tertiary);
  position: sticky;
  top: 0;
  z-index: 10;
}

.sidebar-title {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  background: linear-gradient(135deg, var(--neon-cyan), var(--neon-magenta));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-xs);
  text-shadow: 0 0 20px rgba(0, 243, 255, 0.3);
}

.sidebar-subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

/* Navigation Menu */
.nav-menu {
  padding: var(--spacing-md);
  flex: 1;
}

.nav-chapter {
  margin-bottom: var(--spacing-lg);
}

.nav-chapter-title {
  font-family: var(--font-heading);
  font-size: 0.875rem;
  color: var(--neon-purple);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  cursor: pointer;
  transition: all 0.3s ease;
}

.nav-chapter-title:hover {
  color: var(--neon-cyan);
}

.nav-chapter-title::before {
  content: '▶';
  display: inline-block;
  margin-right: var(--spacing-sm);
  transition: transform 0.3s ease;
  font-size: 0.75rem;
}

.nav-chapter.expanded .nav-chapter-title::before {
  transform: rotate(90deg);
}

.nav-sections {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
}

.nav-chapter.expanded .nav-sections {
  max-height: 1000px;
}

.nav-section {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  padding-left: calc(var(--spacing-lg) + var(--spacing-md));
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-left: var(--spacing-md);
  transition: all 0.3s ease;
  cursor: pointer;
  position: relative;
}

.nav-section::before {
  content: '';
  position: absolute;
  left: var(--spacing-sm);
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 6px;
  background: var(--text-muted);
  border-radius: 50%;
  transition: all 0.3s ease;
}

.nav-section:hover {
  color: var(--neon-cyan);
}

.nav-section:hover::before {
  background: var(--neon-cyan);
  box-shadow: 0 0 10px var(--neon-cyan);
}

.nav-section.active {
  color: var(--neon-cyan);
  background: rgba(0, 243, 255, 0.05);
  font-weight: 600;
}

.nav-section.active::before {
  background: var(--neon-cyan);
  width: 8px;
  height: 8px;
  box-shadow: 0 0 10px var(--neon-cyan);
}

/* Sidebar Footer */
.sidebar-footer {
  padding: var(--spacing-md);
  border-top: 2px solid var(--border-color);
  background: var(--bg-tertiary);
  font-size: 0.75rem;
  color: var(--text-muted);
  text-align: center;
}

.sidebar-footer a {
  color: var(--neon-cyan);
  font-weight: 600;
}

/* Main Content Area */
.main-content {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-xl);
  background: var(--bg-primary);
  position: relative;
}

.content-wrapper {
  max-width: 900px;
  margin: 0 auto;
}

/* Loading State */
.loading {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  color: var(--neon-cyan);
}

.loading::after {
  content: '';
  width: 40px;
  height: 40px;
  margin-left: var(--spacing-md);
  border: 4px solid var(--border-color);
  border-top-color: var(--neon-cyan);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Mobile Responsive */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    left: -320px;
    height: 100vh;
    transition: left 0.3s ease;
    z-index: 1000;
  }

  .sidebar.open {
    left: 0;
  }

  .main-content {
    width: 100%;
  }

  .menu-toggle {
    display: block;
    position: fixed;
    top: var(--spacing-md);
    left: var(--spacing-md);
    z-index: 999;
    background: var(--bg-secondary);
    border: 2px solid var(--neon-cyan);
    color: var(--neon-cyan);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: 8px;
    cursor: pointer;
    font-family: var(--font-heading);
    box-shadow: 0 0 20px rgba(0, 243, 255, 0.3);
  }

  .menu-toggle:hover {
    background: var(--neon-cyan);
    color: var(--bg-primary);
  }
}

@media (min-width: 769px) {
  .menu-toggle {
    display: none;
  }
}

/* Overlay for mobile */
.sidebar-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  z-index: 999;
}

@media (max-width: 768px) {
  .sidebar-overlay.active {
    display: block;
  }
}