:root {
    /* Color Palette */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #10b981;
    --accent: #f59e0b;
    --danger: #ef4444;
    --warning: #f97316;
    --success: #22c55e;

    /* Neutrals */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;

    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --bg-dark: #111827;

    /* Text Colors */
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --text-inverse: #ffffff;

    /* Border */
    --border-color: #e5e7eb;
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 16px;
    --border-radius-xl: 24px;

    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;

    /* 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);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;

    /* Fonts */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', monospace;

    /* Font Sizes */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;

    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    color: var(--text-primary);
    background: var(--bg-secondary);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: var(--primary);
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
}

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

input,
select,
textarea {
    font-family: inherit;
    outline: none;
}

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

.sidebar {
    width: 280px;
    background: var(--bg-primary);
    border-right: 1px solid var(--border-color);
    padding: var(--spacing-lg);
    position: fixed;
    left: 0;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    z-index: var(--z-fixed);
    transition: transform var(--transition-base);
}

.main-content {
    flex: 1;
    margin-left: 280px;
    padding: var(--spacing-2xl);
    max-width: 1400px;
    width: 100%;
}

/* Logo & Branding */
.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    border-radius: var(--border-radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: var(--text-xl);
    font-weight: 700;
}

.logo-text {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
}

/* Navigation */
.nav-menu {
    list-style: none;
    margin-bottom: var(--spacing-xl);
}

.nav-item {
    margin-bottom: var(--spacing-xs);
}

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

.nav-link:hover {
    background: var(--bg-tertiary);
    color: var(--primary);
}

.nav-link.active {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.nav-icon {
    width: 20px;
    height: 20px;
    opacity: 0.8;
}

.nav-link.active .nav-icon {
    opacity: 1;
}

/* Header */
.page-header {
    margin-bottom: var(--spacing-2xl);
}

.page-title {
    font-size: var(--text-3xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.page-subtitle {
    font-size: var(--text-base);
    color: var(--text-secondary);
}

/* Stats Cards */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.stat-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--primary) 0%, var(--primary-light) 100%);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.stat-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-md);
}

.stat-label {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.stat-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--border-radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-lg);
    opacity: 0.8;
}

.stat-value {
    font-size: var(--text-3xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-change {
    font-size: var(--text-sm);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.stat-change.positive {
    color: var(--success);
}

.stat-change.negative {
    color: var(--danger);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 12px 24px;
    border-radius: var(--border-radius-md);
    font-weight: 600;
    font-size: var(--text-base);
    transition: all var(--transition-fast);
    border: none;
    cursor: pointer;
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--gray-300);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary);
    color: var(--primary);
}

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

.btn-sm {
    padding: 8px 16px;
    font-size: var(--text-sm);
}

.btn-lg {
    padding: 16px 32px;
    font-size: var(--text-lg);
}

.btn-icon {
    padding: 12px;
    width: 44px;
    height: 44px;
}

.btn-danger {
    background: var(--danger);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-danger:hover {
    background: #dc2626;
    /* Darker red */
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Cards */
.card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-lg);
}

.card-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.card-title {
    font-size: var(--text-xl);
    font-weight: 600;
    color: var(--text-primary);
}

.card-body {
    padding: var(--spacing-lg);
}

.card-footer {
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

/* Form Elements */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
    color: var(--text-primary);
    font-size: var(--text-sm);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    font-size: var(--text-base);
    transition: all var(--transition-fast);
    background: var(--bg-primary);
    color: var(--text-primary);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-textarea {
    resize: vertical;
    min-height: 100px;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
    }

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

    .main-content {
        margin-left: 0;
        padding: var(--spacing-lg);
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .page-title {
        font-size: var(--text-2xl);
    }
}

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

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn var(--transition-base) ease-out;
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(20px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.slide-in-right {
    animation: slideInRight var(--transition-base) ease-out;
}

/* Loading Spinner */
.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--gray-200);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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