/* Vietnamese PhuocIT Offline Styling */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        :root {
            --primary-blue: #8daffa;
            --primary-green: #059669;
            --primary-purple: #7c3aed;
            --accent-orange: #ea580c;
            --text-primary: #1f2937;
            --text-secondary: #6b7280;
            --bg-gradient: linear-gradient(135deg, #e0f2fe 0%, #f0f9ff 50%, #ecfdf5 100%);
            --card-gradient: linear-gradient(145deg, #ffffff 0%, #fafbfc 100%);
            --header-gradient: linear-gradient(135deg, #1e40af 0%, #3b82f6 50%, #06b6d4 100%);
            --success-gradient: linear-gradient(135deg, #10b981 0%, #059669 100%);
            --warning-gradient: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
            --danger-gradient: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: var(--bg-gradient);
            min-height: 100vh;
            color: var(--text-primary);
            line-height: 1.6;
        }
        
        .app-container {
            display: flex;
            min-height: 100vh;
        }
        
        /* Sidebar Styles */
        .sidebar {
            width: 280px;
            background: white;
            box-shadow: 4px 0 20px rgba(0,0,0,0.1);
            display: flex;
            flex-direction: column;
            position: fixed;
            height: 100vh;
            z-index: 10;
        }
        
        .sidebar-header {
            background: var(--header-gradient);
            padding: 24px;
            color: white;
            text-align: center;
        }
        
        .logo {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 12px;
            margin-bottom: 8px;
        }
        
        .logo-icon {
            width: 48px;
            height: 48px;
            background: rgba(255,255,255,0.2);
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 24px;
        }
        
        .app-title {
            font-size: 22px;
            font-weight: bold;
            margin: 0;
        }
        
        .app-subtitle {
            font-size: 14px;
            opacity: 0.9;
        }
        
        .nav-menu {
            flex: 1;
            padding: 20px;
            overflow-y: auto;
        }
        
        .nav-section {
            margin-bottom: 24px;
        }
        
        .nav-section h3 {
            font-size: 14px;
            font-weight: 600;
            color: var(--text-secondary);
            margin-bottom: 12px;
            text-transform: uppercase;
            letter-spacing: 0.5px;
        }
        
        .nav-item {
            display: flex;
            align-items: center;
            padding: 12px 16px;
            margin-bottom: 4px;
            border-radius: 8px;
            cursor: pointer !important;
            transition: all 0.3s ease;
            text-decoration: none;
            color: var(--text-primary);
            pointer-events: auto !important;
            position: relative;
            z-index: 10;
        }
        
        .nav-item:hover {
            background: #f3f4f6;
            transform: translateX(4px);
        }
        
        .nav-item.active {
            background: var(--header-gradient);
            color: white;
            box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
        }
        
        .nav-item-icon {
            margin-right: 12px;
            font-size: 18px;
        }
        
        /* Main Content */
        .main-content {
            flex: 1;
            margin-left: 280px;
            display: flex;
            flex-direction: column;
        }
        
        .header {
            background: white;
            padding: 20px 32px;
            border-bottom: 1px solid #e5e7eb;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .header-title {
            font-size: 28px;
            font-weight: bold;
            color: var(--text-primary);
        }
        
        .header-subtitle {
            color: var(--text-secondary);
            margin-top: 4px;
        }
        
        .demo-badge {
            background: var(--success-gradient);
            color: white;
            padding: 8px 16px;
            border-radius: 20px;
            font-size: 14px;
            font-weight: 600;
            display: flex;
            align-items: center;
            gap: 8px;
            box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
        }
        
        .content {
            flex: 1;
            padding: 32px;
            max-width: 1200px;
            margin: 0 auto;
            width: 100%;
        }
        
        /* Stats Cards */
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 16px;
            margin-bottom: 24px;
        }
        
        .stat-card {
            background: var(--card-gradient);
            border-radius: 12px;
            padding: 16px;
            box-shadow: 0 4px 16px rgba(0,0,0,0.08);
            border: 1px solid rgba(255,255,255,0.2);
            position: relative;
            overflow: hidden;
            transition: all 0.3s ease;
        }
        
        .stat-card:hover {
            transform: translateY(-4px);
            box-shadow: 0 16px 48px rgba(0,0,0,0.12);
        }
        
        .stat-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 4px;
        }
        
        .stat-card.revenue::before {
            background: var(--success-gradient);
        }
        
        .stat-card.orders::before {
            background: var(--header-gradient);
        }
        
        .stat-card.customers::before {
            background: var(--warning-gradient);
        }
        
        .stat-card.products::before {
            background: var(--danger-gradient);
        }
        
        .stat-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 12px;
        }
        
        .stat-title {
            font-size: 12px;
            font-weight: 600;
            color: var(--text-secondary);
            text-transform: uppercase;
            letter-spacing: 0.5px;
        }
        
        .stat-icon {
            font-size: 20px;
            opacity: 0.7;
        }
        
        .stat-value {
            font-size: 24px;
            font-weight: bold;
            color: var(--text-primary);
            margin-bottom: 6px;
        }
        
        .stat-change {
            font-size: 12px;
            font-weight: 600;
        }
        
        .stat-change.positive {
            color: #059669;
        }
        
        .stat-change.negative {
            color: #dc2626;
        }
        
        /* Quick Actions */
        .quick-actions {
            background: white;
            border-radius: 12px;
            padding: 20px;
            box-shadow: 0 4px 16px rgba(0,0,0,0.08);
            margin-bottom: 24px;
        }
        
        .section-title {
            font-size: 18px;
            font-weight: bold;
            margin-bottom: 16px;
            color: var(--text-primary);
        }
        
        .action-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
            gap: 12px;
        }
        
        .action-button {
            background: var(--card-gradient);
            border: 2px solid transparent;
            border-radius: 10px;
            padding: 16px;
            cursor: pointer;
            transition: all 0.3s ease;
            text-decoration: none;
            color: var(--text-primary);
            display: flex;
            flex-direction: column;
            align-items: center;
            text-align: center;
        }
        
        .action-button:hover {
            border-color: var(--primary-blue);
            transform: translateY(-2px);
            box-shadow: 0 8px 24px rgba(37, 99, 235, 0.15);
        }
        
        .action-icon {
            font-size: 24px;
            margin-bottom: 8px;
        }
        
        .action-title {
            font-weight: 600;
            margin-bottom: 4px;
            font-size: 14px;
        }
        
        .action-desc {
            font-size: 11px;
            color: var(--text-secondary);
        }
        
        /* Recent Activity */
        .recent-activity {
            background: white;
            border-radius: 12px;
            padding: 20px;
            box-shadow: 0 4px 16px rgba(0,0,0,0.08);
        }
        
        .activity-item {
            display: flex;
            align-items: center;
            padding: 12px;
            border-radius: 8px;
            margin-bottom: 8px;
            transition: background 0.2s ease;
        }
        
        .activity-item:hover {
            background: #f9fafb;
        }
        
        .activity-icon {
            width: 32px;
            height: 32px;
            border-radius: 6px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-right: 12px;
            font-size: 14px;
        }
        
        .activity-icon.success {
            background: rgba(16, 185, 129, 0.1);
            color: #059669;
        }
        
        .activity-icon.warning {
            background: rgba(245, 158, 11, 0.1);
            color: #d97706;
        }
        
        .activity-icon.info {
            background: rgba(37, 99, 235, 0.1);
            color: #2563eb;
        }
        
        .activity-content {
            flex: 1;
        }
        
        .activity-title {
            font-weight: 600;
            margin-bottom: 2px;
            font-size: 14px;
        }
        
        .activity-desc {
            font-size: 12px;
            color: var(--text-secondary);
        }
        
        .activity-time {
            font-size: 11px;
            color: var(--text-secondary);
            text-align: right;
        }
        
        /* Mobile Menu Toggle */
        .mobile-menu-toggle {
            display: none;
            position: fixed;
            top: 20px;
            left: 20px;
            z-index: 1002;
            background: var(--primary-blue);
            color: white;
            border: none;
            border-radius: 8px;
            padding: 12px;
            font-size: 18px;
            cursor: pointer;
            box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
        }

        /* Mobile Overlay */
        .mobile-overlay {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: rgba(0,0,0,0.5);
            z-index: 1001;
        }

        /* Enhanced Responsive Design */
        @media (max-width: 1024px) {
            .sidebar {
                width: 260px;
            }
            
            .main-content {
                margin-left: 260px;
            }
            
            .action-grid {
                grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
            }
            
            .content {
                padding: 24px;
            }
        }

        @media (max-width: 768px) {
            .mobile-menu-toggle {
                display: block;
            }
            
            .sidebar {
                transform: translateX(-100%);
                transition: transform 0.3s ease;
                width: 280px;
                z-index: 1002;
            }
            
            .sidebar.open {
                transform: translateX(0);
            }
            
            .mobile-overlay.show {
                display: block;
            }
            
            .main-content {
                margin-left: 0;
            }
            
            .header {
                padding: 15px 20px;
                padding-left: 70px; /* Space for mobile menu button */
            }
            
            .header-title {
                font-size: 22px;
            }
            
            .stats-grid {
                grid-template-columns: 1fr;
                gap: 12px;
            }
            
            .action-grid {
                grid-template-columns: repeat(2, 1fr);
                gap: 8px;
            }
            
            .action-button {
                padding: 12px 8px;
                font-size: 12px;
            }
            
            .action-icon {
                font-size: 20px;
                margin-bottom: 6px;
            }
            
            .content {
                padding: 16px;
            }
            
            .demo-badge {
                display: none;
            }
        }

        @media (max-width: 480px) {
            .login-card {
                padding: 30px 20px;
                margin: 20px;
            }
            
            .login-logo {
                width: 60px;
                height: 60px;
                font-size: 24px;
            }
            
            .login-title {
                font-size: 24px;
            }
            
            .header-title {
                font-size: 18px;
            }
            
            .stats-grid {
                gap: 8px;
            }
            
            .stat-card {
                padding: 12px;
            }
            
            .stat-value {
                font-size: 20px;
            }
            
            .action-grid {
                grid-template-columns: 1fr;
            }
            
            .action-button {
                padding: 16px;
                flex-direction: row;
                text-align: left;
                gap: 12px;
            }
            
            .action-icon {
                margin-bottom: 0;
                font-size: 24px;
            }
            
            .content {
                padding: 12px;
            }
            
            .section-title {
                font-size: 16px;
            }
        }

        /* Table Responsive */
        @media (max-width: 768px) {
            .table-responsive {
                overflow-x: auto;
                -webkit-overflow-scrolling: touch;
            }
            
            table {
                min-width: 600px;
            }
            
            th, td {
                padding: 8px 6px;
                font-size: 12px;
            }
        }

        /* Modal Responsive */
        @media (max-width: 768px) {
            div[style*="position: fixed"][style*="z-index"] div[style*="width: 500px"],
            div[style*="position: fixed"][style*="z-index"] div[style*="width: 700px"],
            div[style*="position: fixed"][style*="z-index"] div[style*="max-width: 90vw"] {
                width: 95vw !important;
                max-width: 95vw !important;
                padding: 20px !important;
                margin: 10px !important;
            }
        }

        @media (max-width: 480px) {
            div[style*="position: fixed"][style*="z-index"] div[style*="padding: 32px"] {
                padding: 16px !important;
            }
            
            div[style*="position: fixed"][style*="z-index"] h3 {
                font-size: 16px !important;
                margin-bottom: 16px !important;
            }
            
            div[style*="position: fixed"][style*="z-index"] input,
            div[style*="position: fixed"][style*="z-index"] select,
            div[style*="position: fixed"][style*="z-index"] textarea {
                padding: 10px !important;
                font-size: 14px !important;
            }
            
            div[style*="position: fixed"][style*="z-index"] button {
                padding: 10px 16px !important;
                font-size: 14px !important;
            }
        }
        
        /* Loading States */
        .loading {
            display: inline-block;
            width: 20px;
            height: 20px;
            border: 3px solid #f3f3f3;
            border-top: 3px solid var(--primary-blue);
            border-radius: 50%;
            animation: spin 1s linear infinite;
        }
        
        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }
        
        .fade-in {
            animation: fadeIn 0.5s ease-in;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }
        
        /* Login Screen Styles */
        .login-container {
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            padding: 20px;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: var(--bg-gradient);
            z-index: 1000;
        }
        
        .login-card {
            background: white;
            border-radius: 20px;
            box-shadow: 0 20px 60px rgba(0,0,0,0.15);
            padding: 40px;
            width: 100%;
            max-width: 450px;
            position: relative;
            overflow: hidden;
        }
        
        .login-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 5px;
            background: var(--header-gradient);
        }
        
        .login-header {
            text-align: center;
            margin-bottom: 30px;
        }
        
        .login-logo {
            width: 80px;
            height: 80px;
            background: var(--header-gradient);
            border-radius: 20px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0 auto 20px;
            font-size: 32px;
            color: white;
        }
        
        .login-title {
            font-size: 28px;
            font-weight: bold;
            margin-bottom: 8px;
            color: var(--text-primary);
        }
        
        .login-subtitle {
            color: var(--text-secondary);
            font-size: 16px;
        }
        
        .login-form {
            margin-bottom: 20px;
        }
        
        .login-form .form-group {
            margin-bottom: 20px;
        }
        
        .login-form .form-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: var(--text-primary);
        }
        
        .login-form .form-group input {
            width: 100%;
            padding: 15px;
            border: 2px solid #e5e7eb;
            border-radius: 10px;
            font-size: 16px;
            transition: all 0.3s ease;
        }
        
        .login-form .form-group input:focus {
            outline: none;
            border-color: var(--primary-blue);
            box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
        }
        
        .login-button {
            width: 100%;
            padding: 15px;
            background: var(--header-gradient);
            color: white;
            border: none;
            border-radius: 10px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            margin-bottom: 20px;
        }
        
        .login-button:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(37, 99, 235, 0.3);
        }
        
        .login-info {
            background: #f8fafc;
            border: 1px solid #e2e8f0;
            border-radius: 10px;
            padding: 15px;
            text-align: center;
            font-size: 14px;
            color: var(--text-secondary);
        }
        
        .login-info strong {
            color: var(--text-primary);
        }
        
        .error-message {
            background: #fef2f2;
            border: 1px solid #fecaca;
            color: #dc2626;
            padding: 12px;
            border-radius: 8px;
            margin-bottom: 20px;
            text-align: center;
            display: none;
        }
        
        /* Hide main app initially */
        .app-container {
            display: none;
        }

        /* Enhanced Form Responsive Design */
        @media (max-width: 768px) {
            .form-row {
                flex-direction: column !important;
                gap: 15px !important;
            }
            
            .form-group {
                margin-bottom: 15px !important;
            }
            
            .form-group label {
                font-size: 14px !important;
                margin-bottom: 6px !important;
            }
            
            .form-group input,
            .form-group select,
            .form-group textarea {
                padding: 12px !important;
                font-size: 16px !important; /* Prevent zoom on iOS */
                border-radius: 8px !important;
            }
            
            .form-buttons {
                flex-direction: column !important;
                gap: 10px !important;
            }
            
            .form-buttons button {
                width: 100% !important;
                padding: 12px !important;
                font-size: 16px !important;
            }
        }

        /* Enhanced Table Responsive */
        @media (max-width: 768px) {
            .table-container {
                margin: 0 -16px !important;
            }
            
            table {
                font-size: 14px !important;
                border-collapse: collapse !important;
            }
            
            th {
                background: #f8fafc !important;
                font-size: 12px !important;
                font-weight: 600 !important;
                text-transform: uppercase !important;
                letter-spacing: 0.5px !important;
                padding: 10px 6px !important;
                border-bottom: 2px solid #e5e7eb !important;
            }
            
            td {
                padding: 10px 6px !important;
                border-bottom: 1px solid #f3f4f6 !important;
                vertical-align: top !important;
            }
            
            /* Card-style table for mobile */
            .mobile-card-table {
                display: none !important;
            }
        }

        @media (max-width: 480px) {
            .table-responsive table {
                display: none !important;
            }
            
            .mobile-card-table {
                display: block !important;
            }
            
            .mobile-card {
                background: white;
                border: 1px solid #e5e7eb;
                border-radius: 8px;
                padding: 15px;
                margin-bottom: 12px;
                box-shadow: 0 1px 3px rgba(0,0,0,0.1);
            }
            
            .mobile-card-header {
                font-weight: 600;
                color: var(--primary-blue);
                margin-bottom: 8px;
                padding-bottom: 8px;
                border-bottom: 1px solid #f3f4f6;
            }
            
            .mobile-card-row {
                display: flex;
                justify-content: space-between;
                align-items: center;
                padding: 4px 0;
                font-size: 14px;
            }
            
            .mobile-card-label {
                font-weight: 500;
                color: var(--text-secondary);
                flex: 1;
            }
            
            .mobile-card-value {
                flex: 2;
                text-align: right;
                font-weight: 500;
            }
        }

        /* Enhanced Modal Responsive */
        @media (max-width: 768px) {
            .modal-backdrop {
                padding: 10px !important;
            }
            
            .modal-content {
                width: calc(100vw - 20px) !important;
                max-width: none !important;
                max-height: calc(100vh - 20px) !important;
                margin: 0 !important;
                border-radius: 12px !important;
            }
            
            .modal-header {
                padding: 16px 20px !important;
                flex-direction: column !important;
                gap: 8px !important;
                text-align: center !important;
            }
            
            .modal-header h3 {
                font-size: 18px !important;
                margin: 0 !important;
            }
            
            .modal-body {
                padding: 20px !important;
                max-height: calc(70vh) !important;
                overflow-y: auto !important;
            }
            
            .modal-footer {
                padding: 16px 20px !important;
                flex-direction: column-reverse !important;
                gap: 10px !important;
            }
            
            .modal-footer button {
                width: 100% !important;
                padding: 12px !important;
                font-size: 16px !important;
            }
        }

        /* Print styles */
        @media print {
            .sidebar,
            .mobile-menu-toggle,
            .mobile-overlay,
            .header,
            .demo-badge,
            button:not(.print-button) {
                display: none !important;
            }
            
            .main-content {
                margin-left: 0 !important;
                width: 100% !important;
            }
            
            .content {
                padding: 0 !important;
                max-width: none !important;
            }
            
            body {
                background: white !important;
                font-size: 12px !important;
                line-height: 1.4 !important;
            }
        }

        /* High contrast mode support */
        @media (prefers-contrast: high) {
            :root {
                --text-primary: #000000;
                --text-secondary: #333333;
            }
            
            .nav-item:hover {
                background: #333333 !important;
                color: #ffffff !important;
            }
        }

        /* Reduced motion support */
        @media (prefers-reduced-motion: reduce) {
            * {
                animation-duration: 0.01ms !important;
                animation-iteration-count: 1 !important;
                transition-duration: 0.01ms !important;
            }
        }