/* Layout Base */
.app-container {
  display: flex;
  height: 100vh;
  overflow: hidden;
  background-color: var(--color-bg-secondary);
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--color-bg-secondary);
  border-right: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-base);
  z-index: 40;
}

.sidebar-header {
  padding: var(--space-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--color-border);
}

.sidebar-title {
  font-size: var(--text-lg);
  font-weight: var(--font-bold);
  color: var(--color-text-primary);
}

.sidebar-nav {
  flex: 1;
  padding: var(--space-2) 0;
  overflow-y: auto;
}

.nav-item {
  display: flex;
  align-items: center;
  padding: var(--space-2) var(--space-4);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.nav-item:hover, .nav-item.active {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text-primary);
}

.nav-icon {
  width: var(--icon-lg, 20px);
  height: var(--icon-lg, 20px);
  margin-right: var(--space-3);
}

.nav-text {
  font-size: var(--text-base);
  font-weight: var(--font-medium);
}

/* Main Content Area */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background-color: var(--color-bg-primary);
}

.top-bar {
  height: 48px;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 var(--space-4);
  background-color: var(--color-bg-primary);
}

.mobile-menu-btn {
  display: none;
  margin-right: var(--space-3);
}

.page-container {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-6) var(--space-10);
}

.page-header {
  margin-bottom: var(--space-6);
}

.page-title {
  font-size: var(--text-3xl);
  font-weight: var(--font-bold);
  color: var(--color-text-primary);
  line-height: 1.25;
  letter-spacing: -0.02em;
}

/* Mobile Breakpoint */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .mobile-menu-btn {
    display: flex;
  }

  .page-container {
    padding: var(--space-4);
  }

  .sidebar-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.4);
    z-index: 30;
    display: none;
  }
  
  .sidebar-overlay.open {
    display: block;
  }
}