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

        :root {
            --primary: #2563eb;
            --primary-dark: #1d4ed8;
            --secondary: #7c3aed;
            --success: #10b981;
            --warning: #f59e0b;
            --danger: #ef4444;
            --info: #3b82f6;
            --light: #f8fafc;
            --dark: #1e293b;
            --gray: #64748b;
            --light-gray: #e2e8f0;
            --border-radius: 12px;
            --box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.05);
            --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            --gradient-primary: linear-gradient(135deg, #2563eb 0%, #7c3aed 100%);
        }

        body {
            background: linear-gradient(135deg, #f0f9ff 0%, #fef7ff 100%);
            color: var(--dark);
            line-height: 1.6;
            min-height: 100vh;
            padding-bottom: 60px;
        }

        .container {
            max-width: 1600px;
            margin: 0 auto;
            padding: 0 20px;
        }

        /* Header */
        header {
            background: var(--gradient-primary);
            color: white;
            padding: 1.5rem 0;
            box-shadow: 0 4px 20px rgba(37, 99, 235, 0.3);
            position: sticky;
            top: 0;
            z-index: 1000;
            backdrop-filter: blur(10px);
        }

        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 20px;
        }

        .logo {
            display: flex;
            align-items: center;
            gap: 15px;
        }

        .logo-icon {
            width: 50px;
            height: 50px;
            background: rgba(255, 255, 255, 0.2);
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.8rem;
        }

        .logo-text h1 {
            font-size: 1.8rem;
            font-weight: 700;
            line-height: 1.2;
        }

        .logo-text span {
            font-size: 0.9rem;
            opacity: 0.9;
            font-weight: 400;
        }

        .pro-badge {
            background: linear-gradient(45deg, #fbbf24, #f59e0b);
            color: #78350f;
            padding: 6px 16px;
            border-radius: 20px;
            font-size: 0.85rem;
            font-weight: 700;
            display: inline-flex;
            align-items: center;
            gap: 6px;
            margin-left: 10px;
        }

        .header-stats {
            display: flex;
            gap: 25px;
            font-size: 0.9rem;
        }

        .stat-item {
            display: flex;
            align-items: center;
            gap: 8px;
            opacity: 0.9;
        }

        .stat-item i {
            font-size: 1.1rem;
        }

        /* Main Layout */
        .app-container {
            display: grid;
            grid-template-columns: 280px 1fr;
            gap: 30px;
            margin-top: 30px;
        }

        @media (max-width: 1200px) {
            .app-container {
                grid-template-columns: 1fr;
            }
        }

        /* Sidebar */
        .sidebar {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 25px;
            height: fit-content;
            position: sticky;
            top: 110px;
        }

        .nav-menu {
            list-style: none;
            margin-bottom: 30px;
        }

        .nav-item {
            margin-bottom: 8px;
        }

        .nav-link {
            display: flex;
            align-items: center;
            gap: 12px;
            padding: 14px 16px;
            color: var(--dark);
            text-decoration: none;
            border-radius: 10px;
            transition: var(--transition);
            font-weight: 500;
        }

        .nav-link:hover {
            background: var(--light);
            color: var(--primary);
            transform: translateX(5px);
        }

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

        .nav-link i {
            width: 20px;
            text-align: center;
        }

        .feature-list {
            list-style: none;
            margin-top: 20px;
        }

        .feature-list li {
            padding: 10px 0;
            display: flex;
            align-items: center;
            gap: 10px;
            border-bottom: 1px solid var(--light-gray);
            font-size: 0.9rem;
        }

        .feature-list li:last-child {
            border-bottom: none;
        }

        .feature-list i {
            color: var(--success);
            font-size: 1rem;
        }

        /* Main Content */
        .main-content {
            display: flex;
            flex-direction: column;
            gap: 30px;
        }

        /* Dashboard */
        .dashboard-section {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 30px;
        }

        .section-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 25px;
            flex-wrap: wrap;
            gap: 15px;
        }

        .section-header h2 {
            color: var(--primary);
            font-size: 1.5rem;
            font-weight: 700;
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .section-header h2 i {
            color: var(--secondary);
        }

        .stats-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 20px;
            margin-bottom: 30px;
        }

        .stat-card {
            background: linear-gradient(135deg, #ffffff 0%, #f8fafc 100%);
            padding: 25px;
            border-radius: var(--border-radius);
            border: 1px solid var(--light-gray);
            transition: var(--transition);
            position: relative;
            overflow: hidden;
        }

        .stat-card:hover {
            transform: translateY(-5px);
            box-shadow: var(--box-shadow);
            border-color: var(--primary);
        }

        .stat-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 5px;
            height: 100%;
            background: var(--primary);
        }

        .stat-card h3 {
            font-size: 0.9rem;
            color: var(--gray);
            margin-bottom: 8px;
            text-transform: uppercase;
            letter-spacing: 0.5px;
            font-weight: 600;
        }

        .stat-card .value {
            font-size: 2.2rem;
            font-weight: 700;
            color: var(--dark);
            line-height: 1;
        }

        .stat-card .change {
            font-size: 0.85rem;
            margin-top: 8px;
            display: flex;
            align-items: center;
            gap: 5px;
        }

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

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

        /* Quick Actions */
        .quick-actions {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 15px;
            margin-top: 20px;
        }

        .action-btn {
            padding: 18px;
            background: var(--light);
            border: 2px solid var(--light-gray);
            border-radius: var(--border-radius);
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 10px;
            cursor: pointer;
            transition: var(--transition);
            text-align: center;
        }

        .action-btn:hover {
            background: white;
            border-color: var(--primary);
            transform: translateY(-3px);
        }

        .action-btn i {
            font-size: 2rem;
            color: var(--primary);
        }

        .action-btn span {
            font-weight: 600;
            color: var(--dark);
        }

        /* Bill Creation */
        .bill-creation-section {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 30px;
        }

        .tabs {
            display: flex;
            gap: 5px;
            background: var(--light-gray);
            padding: 5px;
            border-radius: 10px;
            margin-bottom: 25px;
        }

        .tab-btn {
            flex: 1;
            padding: 12px;
            border: none;
            background: transparent;
            border-radius: 8px;
            cursor: pointer;
            font-weight: 600;
            color: var(--gray);
            transition: var(--transition);
            text-align: center;
        }

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

        .form-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 20px;
            margin-bottom: 25px;
        }

        .form-group {
            display: flex;
            flex-direction: column;
        }

        .form-group label {
            font-weight: 600;
            margin-bottom: 8px;
            color: var(--dark);
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .form-group label i {
            color: var(--primary);
            font-size: 0.9rem;
        }

        .form-control {
            padding: 14px;
            border: 2px solid var(--light-gray);
            border-radius: 8px;
            font-size: 1rem;
            transition: var(--transition);
            background: white;
        }

        .form-control:focus {
            border-color: var(--primary);
            outline: none;
            box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
        }

        .form-control.has-error {
            border-color: var(--danger);
        }

        /* Bill Items Table */
        .table-container {
            overflow-x: auto;
            border-radius: var(--border-radius);
            border: 1px solid var(--light-gray);
            margin: 25px 0;
        }

        table {
            width: 100%;
            border-collapse: collapse;
            min-width: 800px;
        }

        thead {
            background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
        }

        th {
            padding: 16px;
            text-align: left;
            font-weight: 600;
            color: white;
            font-size: 0.9rem;
            text-transform: uppercase;
            letter-spacing: 0.5px;
        }

        tbody tr {
            border-bottom: 1px solid var(--light-gray);
            transition: var(--transition);
        }

        tbody tr:hover {
            background-color: rgba(37, 99, 235, 0.02);
        }

        td {
            padding: 16px;
            vertical-align: middle;
        }

        .action-buttons {
            display: flex;
            gap: 8px;
        }

        .btn-icon {
            width: 36px;
            height: 36px;
            border-radius: 8px;
            border: none;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: var(--transition);
            font-size: 0.9rem;
        }

        .btn-icon.edit {
            background: rgba(59, 130, 246, 0.1);
            color: var(--info);
        }

        .btn-icon.edit:hover {
            background: rgba(59, 130, 246, 0.2);
        }

        .btn-icon.delete {
            background: rgba(239, 68, 68, 0.1);
            color: var(--danger);
        }

        .btn-icon.delete:hover {
            background: rgba(239, 68, 68, 0.2);
        }

        /* Buttons */
        .btn-group {
            display: flex;
            gap: 15px;
            margin-top: 25px;
            flex-wrap: wrap;
        }

        .btn {
            padding: 14px 28px;
            border: none;
            border-radius: 10px;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 10px;
            font-size: 1rem;
        }

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

        .btn-primary:hover {
            background: var(--primary-dark);
            transform: translateY(-2px);
            box-shadow: 0 10px 20px rgba(37, 99, 235, 0.3);
        }

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

        .btn-success:hover {
            background: #0da271;
            transform: translateY(-2px);
        }

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

        .btn-warning:hover {
            background: #d97706;
            transform: translateY(-2px);
        }

        .btn-secondary {
            background: var(--light-gray);
            color: var(--dark);
        }

        .btn-secondary:hover {
            background: #d1d5db;
        }

        /* Bill Preview */
        .bill-preview-section {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 30px;
        }

        .preview-container {
            background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
            border-radius: var(--border-radius);
            padding: 40px;
            margin-top: 20px;
            border: 1px solid var(--light-gray);
        }

        .bill-header {
            text-align: center;
            margin-bottom: 40px;
            padding-bottom: 20px;
            border-bottom: 2px solid var(--primary);
        }

        .bill-header h1 {
            color: var(--primary);
            font-size: 2.5rem;
            margin-bottom: 10px;
        }

        .bill-meta {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 20px;
            margin-bottom: 30px;
        }

        .meta-item {
            background: white;
            padding: 15px;
            border-radius: 8px;
            border: 1px solid var(--light-gray);
        }

        .meta-item strong {
            color: var(--gray);
            font-size: 0.9rem;
            display: block;
            margin-bottom: 5px;
        }

        .meta-item span {
            color: var(--dark);
            font-weight: 600;
        }

        .amount-words {
            background: white;
            padding: 20px;
            border-radius: 8px;
            border-left: 4px solid var(--success);
            margin: 25px 0;
            font-style: italic;
            color: var(--dark);
        }

        .totals-section {
            background: white;
            padding: 25px;
            border-radius: var(--border-radius);
            border: 1px solid var(--light-gray);
            margin-top: 30px;
        }

        .total-row {
            display: flex;
            justify-content: space-between;
            padding: 12px 0;
            border-bottom: 1px solid var(--light-gray);
        }

        .total-row:last-child {
            border-bottom: none;
            font-size: 1.3rem;
            font-weight: 700;
            color: var(--primary);
        }

        /* Alerts */
        .alert {
            padding: 16px 20px;
            border-radius: 10px;
            margin-bottom: 20px;
            display: flex;
            align-items: center;
            gap: 12px;
            border-left: 4px solid;
        }

        .alert-warning {
            background: rgba(245, 158, 11, 0.1);
            border-left-color: var(--warning);
            color: #92400e;
        }

        .alert-success {
            background: rgba(16, 185, 129, 0.1);
            border-left-color: var(--success);
            color: #065f46;
        }

        .alert-danger {
            background: rgba(239, 68, 68, 0.1);
            border-left-color: var(--danger);
            color: #991b1b;
        }

        .alert-info {
            background: rgba(59, 130, 246, 0.1);
            border-left-color: var(--info);
            color: #1e40af;
        }

        /* Bill History */
        .bill-history-section {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 30px;
        }

        .history-filters {
            display: flex;
            gap: 15px;
            margin-bottom: 25px;
            flex-wrap: wrap;
        }

        .filter-group {
            flex: 1;
            min-width: 200px;
        }

        .bill-cards {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
            gap: 20px;
            margin-top: 20px;
        }

        .bill-card {
            background: white;
            border: 1px solid var(--light-gray);
            border-radius: var(--border-radius);
            padding: 25px;
            transition: var(--transition);
            position: relative;
            overflow: hidden;
        }

        .bill-card:hover {
            transform: translateY(-5px);
            border-color: var(--primary);
            box-shadow: var(--box-shadow);
        }

        .bill-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 5px;
            background: var(--primary);
        }

        .bill-card-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 15px;
        }

        .bill-id {
            font-weight: 700;
            color: var(--primary);
            font-size: 1.1rem;
        }

        .bill-status {
            padding: 6px 12px;
            border-radius: 20px;
            font-size: 0.8rem;
            font-weight: 600;
        }

        .status-paid {
            background: rgba(16, 185, 129, 0.1);
            color: var(--success);
        }

        .status-pending {
            background: rgba(245, 158, 11, 0.1);
            color: var(--warning);
        }

        .status-draft {
            background: rgba(100, 116, 139, 0.1);
            color: var(--gray);
        }

        .bill-card-body {
            margin: 15px 0;
        }

        .bill-amount {
            font-size: 1.8rem;
            font-weight: 700;
            color: var(--dark);
            margin: 10px 0;
        }

        /* Export Options */
        .export-section {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 30px;
        }

        .export-options {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 20px;
            margin-top: 25px;
        }

        .export-btn {
            padding: 20px;
            background: white;
            border: 2px solid var(--light-gray);
            border-radius: var(--border-radius);
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 15px;
            cursor: pointer;
            transition: var(--transition);
        }

        .export-btn:hover {
            border-color: var(--primary);
            transform: translateY(-5px);
            box-shadow: var(--box-shadow);
        }

        .export-btn i {
            font-size: 2.5rem;
        }

        .export-btn.pdf i {
            color: var(--danger);
        }

        .export-btn.excel i {
            color: var(--success);
        }

        .export-btn.json i {
            color: var(--warning);
        }

        .export-btn span {
            font-weight: 600;
            color: var(--dark);
            font-size: 1.1rem;
        }

        /* Footer */
        footer {
            margin-top: 60px;
            text-align: center;
            color: var(--gray);
            font-size: 0.9rem;
            padding-top: 30px;
            border-top: 1px solid var(--light-gray);
        }

        /* Modal */
        .modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.5);
            z-index: 2000;
            align-items: center;
            justify-content: center;
            padding: 20px;
        }

        .modal.active {
            display: flex;
        }

        .modal-content {
            background: white;
            border-radius: var(--border-radius);
            padding: 40px;
            max-width: 600px;
            width: 100%;
            max-height: 90vh;
            overflow-y: auto;
            position: relative;
            box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
        }

        .modal-close {
            position: absolute;
            top: 20px;
            right: 20px;
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: var(--gray);
            transition: var(--transition);
        }

        .modal-close:hover {
            color: var(--danger);
        }

        /* Responsive */
        @media (max-width: 768px) {
            .header-content {
                flex-direction: column;
                text-align: center;
                gap: 15px;
            }
            
            .header-stats {
                justify-content: center;
                flex-wrap: wrap;
            }
            
            .form-grid {
                grid-template-columns: 1fr;
            }
            
            .btn-group {
                flex-direction: column;
            }
            
            .btn {
                width: 100%;
            }
            
            .bill-cards {
                grid-template-columns: 1fr;
            }
            
            .tabs {
                flex-direction: column;
            }
            
            .history-filters {
                flex-direction: column;
            }
            
            .preview-container {
                padding: 20px;
            }
            
            .bill-header h1 {
                font-size: 1.8rem;
            }
            
            .export-options {
                grid-template-columns: 1fr;
            }
        }

        /* Animation */
        @keyframes slideIn {
            from {
                opacity: 0;
                transform: translateY(20px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .slide-in {
            animation: slideIn 0.3s ease-out;
        }

        /* AI Detection */
        .ai-detected {
            animation: pulse 1.5s ease-in-out;
            border-color: var(--success) !important;
            background: rgba(16, 185, 129, 0.05) !important;
        }

        @keyframes pulse {
            0% { transform: scale(1); }
            50% { transform: scale(1.02); }
            100% { transform: scale(1); }
        }

        /* Amount in Words */
        .amount-in-words {
            font-style: italic;
            color: var(--gray);
            margin-top: 10px;
            padding: 15px;
            background: rgba(16, 185, 129, 0.05);
            border-radius: 8px;
            border-left: 4px solid var(--success);
        }