/* Navigation System */


/* Component-specific custom properties */
:root {
  /* Layout properties */
  --l-app-header-height: 4rem;
  --l-app-sidebar-width: 16rem;
  --l-app-sidebar-width-collapsed: 4rem;
  --l-app-transition: all var(--ds-duration-normal) var(--ds-ease-out);
  
  /* Top Bar */
  --l-topbar-background: var(--ds-color-surface);
  --l-topbar-border-color: var(--ds-color-border);
  --l-topbar-text-color: var(--ds-color-text);
  --l-topbar-shadow: var(--ds-shadow-s);
  --l-topbar-padding: var(--ds-space-m);
  --l-topbar-gap: var(--ds-space-m);
  
  /* Navigation */
  --l-nav-background: var(--ds-color-surface);
  --l-nav-border-color: var(--ds-color-border);
  --l-nav-text-color: var(--ds-color-text);
  --l-nav-padding: var(--ds-space-m);
  --l-nav-gap: var(--ds-space-xs);
  
  /* Nav Items */
  --l-nav-item-background: transparent;
  --l-nav-item-background-hover: var(--ds-color-surface-raised);
  --l-nav-item-background-active: var(--ds-color-accent-weak);
  --l-nav-item-text-color: var(--ds-color-text);
  --l-nav-item-text-color-active: var(--ds-color-accent);
  --l-nav-item-border-radius: var(--ds-radius-s);
  --l-nav-item-padding: var(--ds-space-s) var(--ds-space-m);
  --l-nav-item-font-size: var(--ds-font-size-m);
  --l-nav-item-font-weight: var(--ds-font-weight-normal);
  --l-nav-item-font-weight-active: var(--ds-font-weight-medium);
  
  /* Drawer (mobile) */
  --l-drawer-background: var(--ds-color-surface);
  --l-drawer-backdrop-background: rgba(0, 0, 0, 0.5);
  --l-drawer-shadow: var(--ds-shadow-modal);
  --l-drawer-width: 20rem;
  --l-drawer-z-index: var(--ds-z-modal);
  
  /* Brand */
  --l-brand-font-size: var(--ds-font-size-l);
  --l-brand-font-weight: var(--ds-font-weight-bold);
  --l-brand-text-color: var(--ds-color-text);
}

/* ========================================
   APP LAYOUT
   ======================================== */

.l-app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  background-color: var(--ds-color-background);
}

.l-app--with-sidebar {
  flex-direction: row;
}

.l-app--with-sidebar .l-app__main {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.l-app__header {
  position: sticky;
  top: 0;
  z-index: var(--ds-z-sticky);
  order: -1;
}

.l-app__sidebar {
  width: var(--l-app-sidebar-width);
  flex-shrink: 0;
  order: -2;
}

.l-app__main {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.l-app__content {
  flex: 1;
  padding: var(--ds-space-l);
}

/* ========================================
   TOP BAR
   ======================================== */

.l-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--l-topbar-gap);
  
  height: var(--l-app-header-height);
  padding: 0 var(--l-topbar-padding);
  
  background-color: var(--l-topbar-background);
  border-bottom: 1px solid var(--l-topbar-border-color);
  box-shadow: var(--l-topbar-shadow);
  color: var(--l-topbar-text-color);
}

.l-topbar__start {
  display: flex;
  align-items: center;
  gap: var(--l-topbar-gap);
  flex-shrink: 0;
}

.l-topbar__center {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 0;
}

.l-topbar__end {
  display: flex;
  align-items: center;
  gap: var(--ds-space-s);
  flex-shrink: 0;
}

/* Brand */
.l-topbar__brand {
  display: flex;
  align-items: center;
  gap: var(--ds-space-s);
  text-decoration: none;
  color: var(--l-brand-text-color);
  font-size: var(--l-brand-font-size);
  font-weight: var(--l-brand-font-weight);
  line-height: 1;
}

.l-topbar__brand:hover {
  color: var(--l-brand-text-color);
  text-decoration: none;
}

.l-topbar__brand-logo {
  width: 2rem;
  height: 2rem;
  flex-shrink: 0;
}

.l-topbar__brand-text {
  white-space: nowrap;
}

/* Mobile menu toggle */
.l-topbar__toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background: none;
  border: none;
  border-radius: var(--ds-radius-s);
  color: var(--l-topbar-text-color);
  cursor: pointer;
  transition: var(--l-app-transition);
}

.l-topbar__toggle:hover {
  background-color: var(--l-nav-item-background-hover);
}

.l-topbar__toggle:focus-visible {
  outline: 2px solid var(--ds-color-accent);
  outline-offset: 2px;
}

.l-topbar__toggle svg {
  width: 1.5rem;
  height: 1.5rem;
  fill: currentColor;
}

/* ========================================
   NAVIGATION
   ======================================== */

.l-nav {
  display: flex;
  flex-direction: column;
  height: 100%;
  background-color: var(--l-nav-background);
  border-right: 1px solid var(--l-nav-border-color);
  color: var(--l-nav-text-color);
}

.l-nav__header {
  padding: var(--l-nav-padding);
  border-bottom: 1px solid var(--l-nav-border-color);
  flex-shrink: 0;
}

.l-nav__body {
  flex: 1;
  padding: var(--l-nav-padding);
  overflow-y: auto;
  overscroll-behavior: contain;
}

.l-nav__footer {
  padding: var(--l-nav-padding);
  border-top: 1px solid var(--l-nav-border-color);
  flex-shrink: 0;
}

/* Navigation items container */
.l-nav__items {
  display: flex;
  flex-direction: column;
  gap: var(--l-nav-gap);
  list-style: none;
  margin: 0;
  padding: 0;
}

/* ========================================
   NAV ITEMS
   ======================================== */

.l-nav-item {
  display: block;
}

.l-nav-item__link {
  display: flex;
  align-items: center;
  gap: var(--ds-space-s);
  
  padding: var(--l-nav-item-padding);
  border-radius: var(--l-nav-item-border-radius);
  
  background-color: var(--l-nav-item-background);
  color: var(--l-nav-item-text-color);
  font-size: var(--l-nav-item-font-size);
  font-weight: var(--l-nav-item-font-weight);
  line-height: var(--ds-line-height-s);
  text-decoration: none;
  
  transition: var(--l-app-transition);
  cursor: pointer;
}

.l-nav-item__link:hover {
  background-color: var(--l-nav-item-background-hover);
  color: var(--l-nav-item-text-color);
  text-decoration: none;
}

.l-nav-item__link:focus-visible {
  outline: 2px solid var(--ds-color-accent);
  outline-offset: 2px;
}

/* Active state */
.l-nav-item--active .l-nav-item__link {
  background-color: var(--l-nav-item-background-active);
  color: var(--l-nav-item-text-color-active);
  font-weight: var(--l-nav-item-font-weight-active);
}

/* Disabled state */
.l-nav-item--disabled .l-nav-item__link {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* Nav item icon */
.l-nav-item__icon {
  width: 1.25rem;
  height: 1.25rem;
  flex-shrink: 0;
  fill: currentColor;
}

/* Nav item text */
.l-nav-item__text {
  flex: 1;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Nav item badge */
.l-nav-item__badge {
  margin-left: auto;
  flex-shrink: 0;
}

/* Nav item arrow (for expandable items) */
.l-nav-item__arrow {
  width: 1rem;
  height: 1rem;
  flex-shrink: 0;
  fill: currentColor;
  transition: var(--l-app-transition);
}

.l-nav-item--expanded .l-nav-item__arrow {
  transform: rotate(90deg);
}

/* ========================================
   NAV GROUPS
   ======================================== */

.l-nav-group {
  margin-bottom: var(--ds-space-m);
}

.l-nav-group__header {
  display: flex;
  align-items: center;
  gap: var(--ds-space-s);
  padding: var(--ds-space-xs) var(--ds-space-s);
  margin-bottom: var(--ds-space-xs);
  
  font-size: var(--ds-font-size-s);
  font-weight: var(--ds-font-weight-medium);
  color: var(--ds-color-text-weak);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.l-nav-group__items {
  display: flex;
  flex-direction: column;
  gap: var(--l-nav-gap);
  list-style: none;
  margin: 0;
  padding: 0;
}

/* Collapsible groups */
.l-nav-group--collapsible .l-nav-group__header {
  cursor: pointer;
  border-radius: var(--l-nav-item-border-radius);
  transition: var(--l-app-transition);
}

.l-nav-group--collapsible .l-nav-group__header:hover {
  background-color: var(--l-nav-item-background-hover);
}

.l-nav-group--collapsed .l-nav-group__items {
  display: none;
}

/* ========================================
   DRAWER (MOBILE)
   ======================================== */

.l-drawer {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: var(--l-drawer-z-index);
  
  width: var(--l-drawer-width);
  max-width: 90vw;
  
  background-color: var(--l-drawer-background);
  box-shadow: var(--l-drawer-shadow);
  
  transform: translateX(-100%);
  transition: var(--l-app-transition);
  
  overflow: hidden;
}

.l-drawer--open {
  transform: translateX(0);
}

.l-drawer__backdrop {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: calc(var(--l-drawer-z-index) - 1);
  
  background-color: var(--l-drawer-backdrop-background);
  backdrop-filter: blur(2px);
  
  opacity: 0;
  visibility: hidden;
  transition: var(--l-app-transition);
}

.l-drawer--open + .l-drawer__backdrop {
  opacity: 1;
  visibility: visible;
}

.l-drawer__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--l-nav-padding);
  border-bottom: 1px solid var(--l-nav-border-color);
}

.l-drawer__close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  background: none;
  border: none;
  border-radius: var(--ds-radius-s);
  color: var(--l-nav-text-color);
  cursor: pointer;
  transition: var(--l-app-transition);
}

.l-drawer__close:hover {
  background-color: var(--l-nav-item-background-hover);
}

.l-drawer__close svg {
  width: 1.5rem;
  height: 1.5rem;
  fill: currentColor;
}

.l-drawer__body {
  flex: 1;
  padding: var(--l-nav-padding);
  overflow-y: auto;
  overscroll-behavior: contain;
}

/* ========================================
   RESPONSIVE BEHAVIOR
   ======================================== */

/* Mobile adjustments */
@media (max-width: 768px) {
  .l-app--with-sidebar {
    flex-direction: column;
  }
  
  .l-app__sidebar {
    display: none;
  }
  
  .l-topbar__toggle {
    display: flex;
  }
  
  .l-topbar__brand-text {
    display: none;
  }
  
  .l-nav {
    display: none;
  }
}

/* Tablet adjustments */
@media (max-width: 1024px) {
  .l-app__sidebar {
    width: var(--l-app-sidebar-width-collapsed);
  }
  
  .l-nav-item__text {
    display: none;
  }
  
  .l-nav-item__badge {
    display: none;
  }
  
  .l-nav-group__header {
    display: none;
  }
  
  .l-nav__header,
  .l-nav__footer {
    padding: var(--ds-space-s);
  }
}

/* ========================================
   ACCESSIBILITY & INTERACTION STATES
   ======================================== */

/* High contrast mode support */
@media (prefers-contrast: high) {
  .l-topbar,
  .l-nav,
  .l-drawer {
    border-width: 2px;
  }
  
  .l-nav-item__link:focus-visible,
  .l-topbar__toggle:focus-visible {
    outline-width: 3px;
  }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  .l-topbar__toggle,
  .l-nav-item__link,
  .l-nav-item__arrow,
  .l-drawer,
  .l-drawer__backdrop {
    transition: none;
  }
}

/* Print styles */
@media print {
  .l-topbar,
  .l-nav,
  .l-drawer {
    display: none !important;
  }
  
  .l-app__content {
    padding: 0 !important;
  }
}

/* ========================================
   UTILITY CLASSES
   ======================================== */

/* Screen reader only text */
.l-nav .u-sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Body scroll lock (when drawer is open) */
.l-drawer-open {
  overflow: hidden;
  padding-right: var(--scrollbar-width, 0);
}