<style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            line-height: 1.6;
            color: #333;
            background-color: #ffffff;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }
        
        h1 {
            text-align: center;
            font-size: 2.5rem;
            color: #1a365d;
            margin: 40px 0 20px;
            font-weight: 700;
        }
        
        .subtitle {
            text-align: center;
            font-size: 1.2rem;
            color: #4a5568;
            margin-bottom: 40px;
        }
        
        .converter-tool {
            background: #f8fafc;
            border-radius: 12px;
            padding: 40px;
            margin: 40px 0;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
            border: 1px solid #e2e8f0;
        }
        
        .upload-area {
            border: 3px dashed #cbd5e0;
            border-radius: 8px;
            padding: 60px 20px;
            text-align: center;
            background: #ffffff;
            margin-bottom: 30px;
            transition: all 0.3s ease;
            cursor: pointer;
        }
        
        .upload-area:hover {
            border-color: #3182ce;
            background: #f7fafc;
        }
        
        .upload-area.dragover {
            border-color: #3182ce;
            background: #ebf8ff;
        }
        
        .upload-icon {
            font-size: 3rem;
            color: #a0aec0;
            margin-bottom: 20px;
        }
        
        .upload-text {
            font-size: 1.2rem;
            color: #4a5568;
            margin-bottom: 10px;
        }
        
        .upload-subtext {
            color: #718096;
            font-size: 0.9rem;
        }
        
        .file-input {
            display: none;
        }
        
        .upload-btn {
            background: #3182ce;
            color: white;
            padding: 12px 24px;
            border: none;
            border-radius: 6px;
            font-size: 1rem;
            cursor: pointer;
            margin-top: 15px;
            transition: background 0.3s ease;
        }
        
        .upload-btn:hover {
            background: #2c5aa0;
        }
        
        .file-list {
            margin-top: 20px;
        }
        
        .file-item {
            background: #ffffff;
            border: 1px solid #e2e8f0;
            border-radius: 6px;
            padding: 15px;
            margin-bottom: 10px;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .file-info {
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .file-name {
            font-weight: 500;
            color: #2d3748;
        }
        
        .file-size {
            color: #718096;
            font-size: 0.9rem;
        }
        
        .remove-file {
            background: #e53e3e;
            color: white;
            border: none;
            padding: 5px 10px;
            border-radius: 4px;
            cursor: pointer;
            font-size: 0.8rem;
        }
        
        .conversion-options {
            display: flex;
            gap: 20px;
            margin-bottom: 30px;
            flex-wrap: wrap;
        }
        
        .option-group {
            flex: 1;
            min-width: 200px;
        }
        
        .option-label {
            display: block;
            margin-bottom: 8px;
            font-weight: 500;
            color: #2d3748;
        }
        
        .option-select {
            width: 100%;
            padding: 10px;
            border: 1px solid #cbd5e0;
            border-radius: 6px;
            font-size: 1rem;
        }
        
        .convert-btn {
            background: #38a169;
            color: white;
            padding: 15px 40px;
            border: none;
            border-radius: 8px;
            font-size: 1.1rem;
            font-weight: 600;
            cursor: pointer;
            width: 100%;
            transition: background 0.3s ease;
        }
        
        .convert-btn:hover {
            background: #2f855a;
        }
        
        .convert-btn:disabled {
            background: #a0aec0;
            cursor: not-allowed;
        }
        
        .progress-area {
            margin-top: 20px;
            display: none;
        }
        
        .progress-bar {
            width: 100%;
            height: 8px;
            background: #e2e8f0;
            border-radius: 4px;
            overflow: hidden;
        }
        
        .progress-fill {
            height: 100%;
            background: #38a169;
            width: 0%;
            transition: width 0.3s ease;
        }
        
        .progress-text {
            text-align: center;
            margin-top: 10px;
            color: #4a5568;
        }
        
        .features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 30px;
            margin: 60px 0;
        }
        
        .feature-card {
            background: #ffffff;
            padding: 30px;
            border-radius: 8px;
            border: 1px solid #e2e8f0;
            text-align: center;
        }
        
        .feature-title {
            font-size: 1.3rem;
            font-weight: 600;
            color: #1a365d;
            margin-bottom: 15px;
        }
        
        .feature-description {
            color: #4a5568;
            line-height: 1.6;
        }
        
        .content-section {
            margin: 60px 0;
        }
        
        .content-section h2 {
            font-size: 2rem;
            color: #1a365d;
            margin-bottom: 20px;
            border-bottom: 3px solid #3182ce;
            padding-bottom: 10px;
        }
        
        .content-section h3 {
            font-size: 1.5rem;
            color: #2d3748;
            margin: 30px 0 15px;
        }
        
        .content-section p {
            color: #4a5568;
            margin-bottom: 15px;
            line-height: 1.7;
        }
        
        .content-section ul {
            margin: 20px 0;
            padding-left: 30px;
        }
        
        .content-section li {
            color: #4a5568;
            margin-bottom: 8px;
            line-height: 1.6;
        }
        
        .faq-section {
            background: #f8fafc;
            padding: 40px;
            border-radius: 12px;
            margin: 60px 0;
        }
        
        .faq-item {
            margin-bottom: 20px;
            border: 1px solid #e2e8f0;
            border-radius: 8px;
            background: #ffffff;
        }
        
        .faq-question {
            padding: 20px;
            font-weight: 600;
            color: #1a365d;
            cursor: pointer;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .faq-question:hover {
            background: #f7fafc;
        }
        
        .faq-answer {
            padding: 0 20px 20px;
            color: #4a5568;
            line-height: 1.6;
            display: none;
        }
        
        .faq-answer.active {
            display: block;
        }
        
        .faq-toggle {
            font-size: 1.2rem;
            transition: transform 0.3s ease;
        }
        
        .faq-toggle.active {
            transform: rotate(180deg);
        }
        
        @media (max-width: 768px) {
            h1 {
                font-size: 2rem;
            }
            
            .converter-tool {
                padding: 20px;
            }
            
            .conversion-options {
                flex-direction: column;
            }
            
            .features-grid {
                grid-template-columns: 1fr;
            }
        }
    </style>
