.app-shell {
    display: flex;
    min-height: 100vh;
}

/* ========== Sidebar ========== */
.sidebar {
    width: var(--sidebar-width);
    background: linear-gradient(180deg, #1a1f3a 0%, #162040 50%, #0f172a 100%);
    color: var(--text-primary);
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    z-index: var(--z-sidebar);
    display: flex;
    flex-direction: column;
    transition: width var(--transition-normal), transform var(--transition-normal);
    border-right: 1px solid rgba(255, 255, 255, 0.06);
}

.sidebar-header {
    padding: var(--spacing-lg) var(--spacing-lg);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    flex-shrink: 0;
}

.sidebar-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.sidebar-logo > i {
    font-size: 1.8rem;
    color: var(--color-accent);
    filter: drop-shadow(0 0 8px rgba(78, 205, 196, 0.4));
}

.sidebar-logo-text h1 {
    font-size: 1.1rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    white-space: nowrap;
}

.sidebar-version {
    font-size: 0.7rem;
    font-family: var(--font-mono);
    color: var(--color-primary-light);
    background: rgba(102, 126, 234, 0.2);
    padding: 1px 6px;
    border-radius: var(--radius-sm);
}

/* ========== Sidebar Nav ========== */
.sidebar-nav {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md) 0;
}

.nav-list {
    display: flex;
    flex-direction: column;
    gap: 2px;
    padding: 0 var(--spacing-sm);
}

.nav-item {
    border-radius: var(--radius-md);
    overflow: hidden;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-md);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    font-weight: 500;
    font-size: 0.925rem;
    white-space: nowrap;
}

.nav-link i {
    font-size: 1.1rem;
    width: 22px;
    text-align: center;
    flex-shrink: 0;
}

.nav-link:hover {
    background: rgba(255, 255, 255, 0.06);
    color: var(--text-primary);
}

.nav-item.active .nav-link {
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
    color: white;
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

/* ========== Sidebar Footer ========== */
.sidebar-footer {
    padding: var(--spacing-md) var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    flex-shrink: 0;
}

.sidebar-status {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.8rem;
    color: var(--text-muted);
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: var(--radius-full);
    background: var(--text-muted);
    flex-shrink: 0;
}

.status-dot.online {
    background: var(--color-success);
    box-shadow: 0 0 6px rgba(16, 185, 129, 0.5);
    animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

/* ========== Main Wrapper ========== */
.main-wrapper {
    margin-left: var(--sidebar-width);
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    transition: margin-left var(--transition-normal);
}

/* ========== Topbar ========== */
.topbar {
    height: var(--topbar-height);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--spacing-xl);
    position: sticky;
    top: 0;
    z-index: var(--z-topbar);
    flex-shrink: 0;
}

.topbar-left {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.topbar-toggle {
    display: none;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    transition: all var(--transition-fast);
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
}

.topbar-toggle:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.topbar-breadcrumb {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.925rem;
    color: var(--text-secondary);
}

.breadcrumb-icon {
    color: var(--text-muted);
}

.breadcrumb-separator {
    color: var(--text-muted);
    margin: 0 var(--spacing-xs);
}

.breadcrumb-current {
    color: var(--text-primary);
    font-weight: 600;
}

.topbar-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.topbar-indicator {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    background: rgba(16, 185, 129, 0.1);
    font-size: 0.8rem;
    color: var(--color-success);
}

.topbar-btn {
    width: 38px;
    height: 38px;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    font-size: 1rem;
}

.topbar-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.topbar-user {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
    padding-left: var(--spacing-md);
    border-left: 1px solid var(--border-color);
}

.topbar-user i {
    font-size: 1.4rem;
    color: var(--color-primary);
}

/* ========== App Content ========== */
.app-content {
    flex: 1;
    padding: var(--spacing-xl);
    overflow-y: auto;
}

.page-view {
    display: none;
    animation: pageFadeIn 0.35s ease;
}

.page-view.active {
    display: block;
}

@keyframes pageFadeIn {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========== Page Placeholder ========== */
.page-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    color: var(--text-muted);
    text-align: center;
}

.page-placeholder i {
    font-size: 4rem;
    margin-bottom: var(--spacing-lg);
    color: var(--color-primary);
    opacity: 0.4;
}

.page-placeholder h2 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

.page-placeholder p {
    font-size: 0.95rem;
    color: var(--text-muted);
}

/* ========== Loading Overlay ========== */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 23, 42, 0.7);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: var(--z-overlay);
    backdrop-filter: blur(4px);
}

.loading-overlay.show {
    display: flex;
}

.loading-spinner-box {
    background: var(--bg-card);
    padding: var(--spacing-xl) var(--spacing-2xl);
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-xl);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto var(--spacing-md);
}

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

.loading-spinner-box p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* ========== Notification Container ========== */
.notification-container {
    position: fixed;
    top: calc(var(--topbar-height) + var(--spacing-md));
    right: var(--spacing-xl);
    z-index: var(--z-notification);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    pointer-events: none;
}

/* ========== Responsive ========== */
@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
    }

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

    .main-wrapper {
        margin-left: 0;
    }

    .topbar-toggle {
        display: flex;
    }
}

@media (max-width: 768px) {
    .app-content {
        padding: var(--spacing-md);
    }

    .topbar {
        padding: 0 var(--spacing-md);
    }

    .topbar-user span {
        display: none;
    }

    .topbar-indicator .indicator-text {
        display: none;
    }
}