:root {
    --primary: #6366f1;
    --primary-light: #818cf8;
    --sidebar-bg: #1e293b;
    --page-bg: #f8fafc;
    --card-bg: rgba(255, 255, 255, 0.8);
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
    --radius: 16px;
    --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.04), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
    --glass: rgba(255, 255, 255, 0.7);
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --page-bg: #0f172a;
    --card-bg: rgba(30, 41, 59, 0.7);
    --text-main: #f1f5f9;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --glass: rgba(15, 23, 42, 0.6);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
    background: var(--page-bg);
    color: var(--text-main);
    min-height: 100vh;
    overflow-x: hidden;
}

/* Glassmorphism utility */
.glass {
    background: var(--glass);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

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

/* Sidebar */
.sidebar {
    width: 260px;
    background: var(--sidebar-bg);
    padding: 2rem 0;
    display: flex;
    flex-direction: column;
    position: fixed;
    height: 100vh;
    z-index: 1000;
    transition: var(--transition);
}

.sidebar-brand {
    padding: 0 1.5rem 2.5rem;
    font-size: 1.25rem;
    font-weight: 800;
    color: white;
    letter-spacing: 0.5px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav-item {
    padding: 0.85rem 1.5rem;
    color: #94a3b8;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 0.2rem 1rem;
    border-radius: 12px;
}

.nav-item:hover, .nav-item.active {
    color: white;
    background: rgba(255, 255, 255, 0.1);
}

.nav-item.active {
    background: var(--primary);
    color: white;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 2rem;
    transition: var(--transition);
}

.top-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 1rem 1.5rem;
    background: var(--glass);
    backdrop-filter: blur(8px);
    border-radius: 16px;
    border: 1px solid var(--border-color);
}

/* Cards & Stats */
.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    position: relative;
    overflow: hidden;
}

.stat-card::after {
    content: '';
    position: absolute;
    top: 0; right: 0; width: 4px; height: 100%;
    background: var(--primary);
}

.stat-label {
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 0.5rem;
}

.stat-value {
    font-size: 1.85rem;
    font-weight: 800;
    color: var(--text-main);
}

/* Forms */
input, select, textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-main);
    outline: none;
    transition: var(--transition);
    font-size: 0.9rem;
}

input:focus, select:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
    padding: 0.8rem 1.5rem;
    border-radius: 12px;
    font-weight: 600;
    transition: var(--transition);
    box-shadow: 0 4px 6px rgba(99, 102, 241, 0.2);
}

.btn-primary:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(99, 102, 241, 0.3);
}

/* Status Badges */
.status-badge {
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
}

.status-approved { background: #ecfdf5; color: #059669; }
.status-rejected { background: #fef2f2; color: #dc2626; }
.status-pending { background: #fffbeb; color: #d97706; }

/* Mobile Responsiveness Rules (Phase 4) */
@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
        box-shadow: 10px 0 30px rgba(0,0,0,0.1);
    }
    
    .sidebar.active {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
        padding: 1rem;
    }
    
    .top-bar {
        padding: 0.75rem 1rem;
    }
    
    .search-bar input {
        width: 150px;
    }
}

/* Skeleton Loading */
.skeleton {
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
    border-radius: 8px;
}

@keyframes skeleton-loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Scrollbar Customization */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 10px; }
::-webkit-scrollbar-thumb:hover { background: #94a3b8; }

/* Table to Card View on Mobile */
@media (max-width: 640px) {
    .data-table thead {
        display: none;
    }
    
    .data-table, .data-table tbody, .data-table tr, .data-table td {
        display: block;
        width: 100%;
    }
    
    .data-table tr {
        margin-bottom: 1rem;
        border: 1px solid var(--border-color);
        border-radius: 12px;
        padding: 1rem;
        background: white;
    }
    
    .data-table td {
        text-align: right;
        padding: 0.5rem 0;
        border: none;
        position: relative;
        padding-left: 50%;
    }
    
    .data-table td::before {
        content: attr(data-label);
        position: absolute;
        left: 0;
        width: 50%;
        text-align: left;
        font-weight: 700;
        color: var(--text-muted);
        font-size: 0.75rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
}

.hidden { display: none !important; }

/* Animation */
.view {
    animation: slideIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}