:root {
  --primary-color: #2563eb;
  --secondary-color: #64748b;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --info-color: #0ea5e9;
  --background-color: #f8fafc;
  --card-bg: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --border-color: #e2e8f0;
  --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 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);
}

body {
  background-color: var(--background-color);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--text-primary);
}

.sidebar { 
    background: linear-gradient(135deg, var(--card-bg) 0%, #f1f5f9 100%); 
    border-right: 1px solid var(--border-color); 
    min-height: 100vh; 
    position: sticky; 
    top: 0; 
}

.logo {
    max-height: 60px; 
    width: auto; 
    transition: transform 0.2s ease; 
}

.logo:hover { 
    transform: scale(1.02); 
}

.sidebar .nav-link { 
    color: var(--text-secondary); 
    font-weight: 500; 
    padding: 0.75rem 1.5rem; 
    margin: 0.25rem 0; 
    border-radius: 0.5rem; 
    transition: all 0.2s ease; 
    position: relative; 
}

.sidebar .nav-link:hover {
    background-color: rgba(37, 99, 235, 0.1);
    color: var(--primary-color); 
    transform: translateX(4px); 
}

.sidebar .nav-link.active { 
    background-color: var(--primary-color); 
    color: white; 
    box-shadow: var(--shadow); 
}

.sidebar .nav-link.active::before { 
    content: ''; 
    position: absolute; 
    left: 0; 
    top: 0; 
    height: 100%; 
    width: 3px; 
    background-color: white; 
    border-radius: 0 2px 2px 0; 
}

.navbar { 
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.95) !important; 
}

.main-content {
    padding: 2rem;
}

.page-header { 
    background: linear-gradient(135deg, var(--primary-color) 0%, #3b82f6 100%); color: white; 
    border-radius: 1rem; 
    padding: 2rem; 
    margin-bottom: 2rem; 
    box-shadow: var(--shadow-lg); 
}

.page-header h3 { 
    font-size: 2rem; 
    font-weight: 700; 
    margin: 0; 
}

.page-header .subtitle { 
    opacity: 0.9; 
    font-size: 1.1rem; 
    margin-top: 0.5rem; 
}

.table-card {
    background: var(--card-bg); 
    border: none; 
    border-radius: 1rem; 
    box-shadow: var(--shadow); 
    overflow: hidden; 
    position: relative; 
}

.table-card::before {
    content: ''; 
    position: absolute; 
    top: 0; 
    left: 0;
    right: 0; 
    height: 4px; 
    background: linear-gradient(90deg, var(--primary-color), #3b82f6);
}

.card-header-custom { 
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%); 
    border-bottom: 1px solid var(--border-color); 
    padding: 1.5rem; 
}

.card-header-custom h5 { 
    margin: 0; 
    font-weight: 600;
    color: var(--text-primary); 
}

.table { 
    margin: 0;
    border: none; 
}

.table thead th {
    background: linear-gradient(135deg, #f1f5f9 0%, #e2e8f0 100%); 
    border: none; 
    color: var(--text-primary); 
    font-weight: 600; 
    font-size: 0.875rem; 
    text-transform: uppercase; 
    letter-spacing: 0.05em; 
    padding: 1rem 1.5rem;
    border-bottom: 2px solid var(--border-color); 
}

.table tbody td { 
    padding: 1rem 1.5rem; 
    border: none; 
    border-bottom: 1px solid var(--border-color); 
    vertical-align: middle; 
}

.table tbody tr { 
    transition: all 0.2s ease;
}

.table tbody tr:hover {
    background-color: rgba(37, 99, 235, 0.03);
    transform: translateX(2px); 
}

.invoice-number { 
    color: var(--primary-color);
    font-weight: 600; 
}

.customer-name {
    color: var(--text-primary); 
    font-weight: 500; 
}

.invoice-date { 
    color: var(--text-secondary);
    font-size: 0.9rem; 
}

.invoice-total { 
    color: var(--success-color);
    font-weight: 600; 
    font-size: 1.05rem;
}

.btn { 
    border-radius: 0.5rem;
    font-weight: 500; 
    padding: 0.5rem 1rem;
    transition: all 0.2s ease;
    box-shadow: var(--shadow);
    border: none; 
}

.btn-primary { 
    background: linear-gradient(135deg, var(--primary-color), #3b82f6); 
    color:white; 
}

.btn-info { 
    background: linear-gradient(135deg, var(--info-color), #0284c7); 
    color: white;
}

.btn-warning { 
    background: linear-gradient(135deg, var(--warning-color), #d97706); 
    color: white; 
}

.btn-danger { 
    background: linear-gradient(135deg, #ef4444, #dc2626); 
    color: white; 
}

.btn-sm { 
    padding: 0.4rem 0.8rem; 
    font-size: 0.85rem; 
    margin: 0 0.25rem; 
}

.action-buttons { 
    display: flex; 
    gap: 0.25rem; 
    align-items: center;
}

.empty-state {
    text-align: center; 
    padding: 4rem 1rem; 
    color: var(--text-secondary); 
}

.empty-state i { 
    font-size: 4rem;
    margin-bottom: 1.5rem;
    opacity: 0.5; 
}

.empty-state h5 { 
    color: var(--text-primary); 
    margin-bottom: 0.5rem; 
}

.fade-in { 
    animation: fadeIn 0.5s ease-in;
}


@keyframes fadeIn {
    from { 
        opacity: 0; 
        transform: translateY(20px);
        } 
        to {
            opacity: 1;
            transform: translateY(0);
            } }
            
@media (max-width: 768px) { 
    .main-content { 
        padding: 1rem; 
    } 
    .page-header { 
        padding: 1.5rem;
        text-align: center;
        } 
        .page-header h3 {
            font-size: 1.5rem;
            } 
            .table-responsive { 
                border-radius: 0.5rem;
                } 
                .action-buttons { 
                    flex-direction: column;
                    gap: 0.5rem;
                    }
                    .btn-sm {
                        width: 100%;
                        } }