:root {
    /* Color Palette - Light Mode (Default) */
    --primary: #4f46e5;
    --primary-light: #818cf8;
    --primary-dark: #3730a3;
    
    --bg-base: #f3f4f6;
    --bg-surface: #ffffff;
    --bg-surface-hover: #f9fafb;
    
    --text-main: #111827;
    --text-muted: #6b7280;
    
    --border-color: #e5e7eb;
    
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --info: #3b82f6;

    /* Glassmorphism */
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(255, 255, 255, 0.3);
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    
    /* Typography */
    --font-sans: 'Inter', system-ui, sans-serif;
    --font-heading: 'Poppins', sans-serif;
    
    /* Layout */
    --sidebar-width: 260px;
    --sidebar-collapsed-width: 80px;
    --header-height: 70px;
    --border-radius-md: 12px;
    --border-radius-lg: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Mode Theme */
[data-theme="dark"] {
    --bg-base: #0f172a;
    --bg-surface: #1e293b;
    --bg-surface-hover: #334155;
    
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    
    --border-color: #334155;
    
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-base);
    color: var(--text-main);
    line-height: 1.5;
    overflow-x: hidden;
    transition: background-color var(--transition), color var(--transition);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: inherit;
}

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

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--bg-surface);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: width var(--transition);
    z-index: 100;
}

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

.sidebar-header {
    height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
    font-family: var(--font-heading);
    color: var(--primary);
    overflow: hidden;
    white-space: nowrap;
}

.logo i {
    font-size: 1.75rem;
}

.sidebar.collapsed .logo span {
    display: none;
}

.toggle-btn {
    font-size: 1.5rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color var(--transition);
}

.toggle-btn:hover {
    color: var(--primary);
}

.sidebar-nav {
    flex: 1;
    padding: 1.5rem 0;
    overflow-y: auto;
}

.nav-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding: 0 1rem;
}

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

.nav-link {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.875rem 1rem;
    border-radius: var(--border-radius-md);
    color: var(--text-muted);
    font-weight: 500;
    transition: var(--transition);
    white-space: nowrap;
}

.nav-link i {
    font-size: 1.5rem;
    min-width: 1.5rem;
    text-align: center;
}

.nav-item:hover .nav-link {
    background-color: var(--bg-surface-hover);
    color: var(--text-main);
    transform: translateX(5px);
}

.nav-item.active .nav-link {
    background-color: var(--primary);
    color: white;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}

.sidebar.collapsed .nav-text {
    display: none;
}

.sidebar.collapsed .nav-link {
    justify-content: center;
    padding: 0.875rem 0;
}

.sidebar.collapsed .nav-item:hover .nav-link {
    transform: none;
}

.sidebar-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 1rem;
    overflow: hidden;
}

.avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
    border: 2px solid var(--primary-light);
}

.user-details {
    white-space: nowrap;
}

.user-details h4 {
    font-size: 0.875rem;
    color: var(--text-main);
}

.user-details p {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.sidebar.collapsed .user-details {
    display: none;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    position: relative;
}

/* Top Header */
.top-header {
    height: var(--header-height);
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
    z-index: 10;
}

.header-search {
    display: flex;
    align-items: center;
    background-color: var(--bg-base);
    border-radius: 20px;
    padding: 0.5rem 1rem;
    width: 300px;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.header-search:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.header-search i {
    color: var(--text-muted);
    font-size: 1.25rem;
}

.header-search input {
    border: none;
    background: none;
    outline: none;
    padding-left: 0.75rem;
    width: 100%;
    color: var(--text-main);
    font-family: inherit;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.action-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-surface);
    color: var(--text-muted);
    font-size: 1.25rem;
    border: 1px solid var(--border-color);
    transition: var(--transition);
    position: relative;
}

.action-btn:hover {
    color: var(--primary);
    background-color: var(--bg-base);
    transform: translateY(-2px);
}

.badge {
    position: absolute;
    top: -2px;
    right: -2px;
    background-color: var(--danger);
    color: white;
    font-size: 0.65rem;
    font-weight: bold;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--bg-surface);
}

/* View Container */
.view-container {
    flex: 1;
    overflow-y: auto;
    padding: 2rem;
    scroll-behavior: smooth;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-base);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.fade-in {
    animation: fadeIn 0.4s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

/* Common View Styles (Cards, Grid, etc.) */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.page-title {
    font-size: 1.75rem;
    color: var(--text-main);
}

.page-subtitle {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius-md);
    font-weight: 500;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-dark);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: absolute;
        height: 100%;
        transform: translateX(-100%);
    }
    
    .sidebar.mobile-open {
        transform: translateX(0);
        box-shadow: var(--shadow-lg);
    }
    
    .header-search {
        display: none;
    }
}