:root {
  --sidebar-width: 280px;
  --sidebar-collapsed-width: 60px;
  --sidebar-bg: #1a1a1a;
  --sidebar-text: #e0e0e0;
  --sidebar-hover: #2a2a2a;
  --sidebar-active: #0066cc;
  --sidebar-border: #333;
  --sidebar-shadow: 0 2px 8px rgba(0,0,0,0.15);
  --transition: all 0.3s ease;
}

[data-theme="light"] {
  --sidebar-bg: #f8f9fa;
  --sidebar-text: #333;
  --sidebar-hover: #e9ecef;
  --sidebar-active: #0066cc;
  --sidebar-border: #dee2e6;
}

#app-sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--sidebar-border);
  box-shadow: var(--sidebar-shadow);
  z-index: 1000;
  transition: var(--transition);
  overflow: hidden;
}

#app-sidebar.collapsed {
  width: var(--sidebar-collapsed-width);
}

.sidebar-nav {
  height: 100%;
  overflow-y: auto;
  padding: 1rem 0;
}

.nav-header {
  display: flex;
  align-items: center;
  padding: 0 1rem 1rem;
  border-bottom: 1px solid var(--sidebar-border);
  margin-bottom: 1rem;
}

.nav-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--sidebar-text);
  margin: 0 0 0 0.5rem;
  white-space: nowrap;
  opacity: 1;
  transition: var(--transition);
}

.collapsed .nav-title {
  opacity: 0;
  width: 0;
  margin: 0;
}

.nav-toggle {
  background: none;
  border: none;
  color: var(--sidebar-text);
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 4px;
  transition: var(--transition);
}

.nav-toggle:hover {
  background: var(--sidebar-hover);
}

.nav-group {
  margin-bottom: 0.5rem;
}

.nav-group-header {
  display: flex;
  align-items: center;
  padding: 0.75rem 1rem;
  color: var(--sidebar-text);
  cursor: pointer;
  border: none;
  background: none;
  width: 100%;
  text-align: left;
  font-size: 0.875rem;
  font-weight: 500;
  transition: var(--transition);
}

.nav-group-header:hover {
  background: var(--sidebar-hover);
}

.nav-group-header:focus {
  outline: 2px solid var(--sidebar-active);
  outline-offset: -2px;
}

.nav-group-icon {
  width: 20px;
  height: 20px;
  margin-right: 0.75rem;
  flex-shrink: 0;
}

.nav-group-label {
  flex: 1;
  white-space: nowrap;
  opacity: 1;
  transition: var(--transition);
}

.collapsed .nav-group-label {
  opacity: 0;
  width: 0;
}

.nav-group-arrow {
  width: 16px;
  height: 16px;
  transition: transform 0.2s ease;
  opacity: 1;
}

.collapsed .nav-group-arrow {
  opacity: 0;
}

.nav-group.expanded .nav-group-arrow {
  transform: rotate(90deg);
}

.nav-group-items {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.nav-group.expanded .nav-group-items {
  max-height: 500px;
}

.nav-item {
  display: block;
  padding: 0.625rem 1rem 0.625rem 3rem;
  color: var(--sidebar-text);
  text-decoration: none;
  font-size: 0.875rem;
  transition: var(--transition);
  border-left: 3px solid transparent;
}

.nav-item:hover {
  background: var(--sidebar-hover);
  color: var(--sidebar-text);
}

.nav-item:focus {
  outline: 2px solid var(--sidebar-active);
  outline-offset: -2px;
}

.nav-item[aria-current="page"] {
  background: var(--sidebar-active);
  color: white;
  border-left-color: white;
}

.collapsed .nav-item {
  padding-left: 1rem;
  text-indent: -9999px;
}

/* Main content adjustment */
body {
  margin-left: var(--sidebar-width);
  transition: var(--transition);
}

body.sidebar-collapsed {
  margin-left: var(--sidebar-collapsed-width);
}

/* Mobile styles */
@media (max-width: 768px) {
  body {
    margin-left: 0;
  }
  
  body.sidebar-collapsed {
    margin-left: 0;
  }
  
  #app-sidebar {
    transform: translateX(-100%);
    width: var(--sidebar-width);
  }
  
  #app-sidebar.mobile-open {
    transform: translateX(0);
  }
  
  .mobile-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0,0,0,0.5);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
  }
  
  .mobile-overlay.active {
    opacity: 1;
    visibility: visible;
  }
}

/* Accessibility */
.nav-item:focus-visible,
.nav-group-header:focus-visible,
.nav-toggle:focus-visible {
  outline: 2px solid var(--sidebar-active);
  outline-offset: 2px;
}

/* Scrollbar styling */
.sidebar-nav::-webkit-scrollbar {
  width: 6px;
}

.sidebar-nav::-webkit-scrollbar-track {
  background: transparent;
}

.sidebar-nav::-webkit-scrollbar-thumb {
  background: var(--sidebar-border);
  border-radius: 3px;
}

.sidebar-nav::-webkit-scrollbar-thumb:hover {
  background: var(--sidebar-text);
}