:root {
            --primary-color: #4361ee;
            --secondary-color: #3f37c9;
            --accent-color: #4cc9f0;
            --light-color: #f8f9fa;
            --dark-color: #212529;
            --success-color: #4bb543;
            --warning-color: #ff9500;
            --danger-color: #ff3b30;
        }
        
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            color: var(--dark-color);
            background-color: #f0f2f5;
            padding: 20px;
        }
        
        .container {
            max-width: 1000px;
            margin: 0 auto;
            background-color: white;
            padding: 30px;
            border-radius: 12px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
        }
        
        h1, h2, h3 {
            color: var(--primary-color);
        }
        
        h1 {
            text-align: center;
            margin-bottom: 30px;
            font-size: 2.2rem;
            position: relative;
            padding-bottom: 15px;
        }
        
        h1::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 50%;
            transform: translateX(-50%);
            width: 100px;
            height: 4px;
            background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
            border-radius: 2px;
        }
        
        .input-section, .preview-section {
            margin-bottom: 30px;
            padding: 25px;
            border-radius: 10px;
            background-color: white;
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
        }
        
        .form-group {
            margin-bottom: 20px;
        }
        
        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: var(--secondary-color);
        }
        
        input, select, textarea {
            width: 100%;
            padding: 12px;
            border: 1px solid #ddd;
            border-radius: 6px;
            font-size: 16px;
            transition: border 0.3s;
        }
        
        input:focus, select:focus, textarea:focus {
            border-color: var(--accent-color);
            outline: none;
            box-shadow: 0 0 0 3px rgba(76, 201, 240, 0.2);
        }
        
        button {
            padding: 12px 20px;
            border: none;
            border-radius: 6px;
            cursor: pointer;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.3s;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
        }
        
        button:hover {
            transform: translateY(-2px);
            box-shadow: 0 4px 8px rgba(0,0,0,0.1);
        }
        
        table {
            width: 100%;
            border-collapse: collapse;
            margin-top: 20px;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }
        
        th, td {
            padding: 12px 15px;
            text-align: left;
            border-bottom: 1px solid #e0e0e0;
        }
        
        th {
            background-color: var(--primary-color);
            color: white;
            font-weight: 600;
        }
        
        tr:nth-child(even) {
            background-color: #f9f9f9;
        }
        
        tr:hover {
            background-color: #f1f1f1;
        }
        
        .logo-container {
            display: flex;
            align-items: center;
            gap: 15px;
            margin-bottom: 20px;
        }
        
        .logo-preview {
            width: 80px;
            height: 80px;
            object-fit: contain;
            border: 1px dashed #ccc;
            border-radius: 8px;
            padding: 5px;
        }
        
        .bill-preview {
            background-color: white;
            padding: 25px;
            border-radius: 10px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
            margin-top: 20px;
        }
        
        .bill-header {
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            margin-bottom: 30px;
            gap: 20px;
        }
        
        .company-info {
            flex: 1;
            min-width: 250px;
        }
        
        .bill-info {
            text-align: right;
        }
        
        .bill-title {
            font-size: 28px;
            font-weight: bold;
            margin-bottom: 10px;
            color: var(--primary-color);
        }
        
        .bill-details {
            margin-bottom: 30px;
        }
        
        .bill-footer {
            margin-top: 50px;
            text-align: center;
            font-style: italic;
            color: #666;
            padding-top: 20px;
            border-top: 1px solid #eee;
        }
        
        .total-row {
            font-weight: bold;
            background-color: #f5f7ff;
        }
        
        .total-row td {
            border-top: 2px solid var(--primary-color);
            border-bottom: 2px solid var(--primary-color);
        }
        
        .action-buttons {
            display: flex;
            gap: 15px;
            margin-top: 25px;
            flex-wrap: wrap;
        }
        
        #addItem {
            background-color: var(--primary-color);
            color: white;
        }
        
        #addItem:hover {
            background-color: var(--secondary-color);
        }
        
        #clearAll {
            background-color: var(--danger-color);
            color: white;
        }
        
        #clearAll:hover {
            background-color: #e0352b;
        }
        
        #generateBill {
            background-color: var(--success-color);
            color: white;
            width: 100%;
        }
        
        #generateBill:hover {
            background-color: #3fa238;
        }
        
        #downloadBill {
            background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
            color: white;
        }
        
        #downloadBill:hover {
            background: linear-gradient(135deg, var(--secondary-color), #3ac2f0);
        }
        
        #printBill {
            background-color: var(--warning-color);
            color: white;
        }
        
        #printBill:hover {
            background-color: #e68a00;
        }
        
        .remove-item {
            background-color: transparent;
            color: var(--danger-color);
            padding: 5px;
            font-size: 18px;
            border-radius: 50%;
            width: 30px;
            height: 30px;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        
        .remove-item:hover {
            background-color: rgba(255, 59, 48, 0.1);
            transform: none;
            box-shadow: none;
        }
        
        .logo-svg {
            width: 80px;
            height: 80px;
        }
        
        #pdfContent {
            position: absolute;
            left: -9999px;
            width: 794px; /* A4 width in pixels at 96dpi */
            padding: 20px;
            background: white;
        }
        
        /* Responsive styles */
        @media (max-width: 768px) {
            .container {
                padding: 15px;
            }
            
            .input-section, .preview-section {
                padding: 15px;
            }
            
            h1 {
                font-size: 1.8rem;
            }
            
            .bill-header {
                flex-direction: column;
            }
            
            .bill-info {
                text-align: left;
            }
            
            th, td {
                padding: 8px 10px;
                font-size: 14px;
            }
            
            .action-buttons button {
                flex: 1;
                min-width: 120px;
            }
        }
        
        @media (max-width: 480px) {
            body {
                padding: 10px;
            }
            
            .container {
                padding: 10px;
            }
            
            h1 {
                font-size: 1.5rem;
            }
            
            input, select, textarea, button {
                padding: 10px;
            }
            
            .action-buttons {
                gap: 10px;
            }
            
            .action-buttons button {
                font-size: 14px;
            }
        }