:root {
            --primary-color: #007bff;
            --secondary-color: #6c757d;
            --success-color: #28a745;
            --danger-color: #dc3545;
            --dark-color: #343a40;
            --light-color: #f8f9fa;
        }

        body {
            background-color: #f8f9fa;
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
        }

        .navbar {
            box-shadow: 0 2px 4px rgba(0,0,0,0.1);
        }

        .upload-area {
            border: 2px dashed #dee2e6;
            border-radius: 10px;
            padding: 3rem 2rem;
            text-align: center;
            transition: all 0.3s ease;
            cursor: pointer;
            background-color: white;
        }

        .upload-area:hover {
            border-color: var(--primary-color);
            background-color: #f8f9fa;
        }

        .upload-area.dragover {
            border-color: var(--primary-color);
            background-color: #e3f2fd;
        }

        .upload-icon {
            font-size: 3rem;
            color: var(--secondary-color);
            margin-bottom: 1rem;
        }

        .file-input {
            display: none;
        }

        .file-info {
            background-color: white;
            border-radius: 10px;
            padding: 1rem;
            margin-top: 1rem;
            border-left: 4px solid var(--success-color);
        }

        .preview-area {
            background-color: white;
            padding: 2rem;
            min-height: 60vh;
        }

        .markdown-content h1,
        .markdown-content h2,
        .markdown-content h3,
        .markdown-content h4,
        .markdown-content h5,
        .markdown-content h6 {
            margin-top: 1.5rem;
            margin-bottom: 1rem;
            font-weight: 600;
            line-height: 1.25;
        }

        .markdown-content h1 {
            font-size: 2rem;
            border-bottom: 1px solid #eee;
            padding-bottom: 0.5rem;
        }

        .markdown-content h2 {
            font-size: 1.5rem;
            border-bottom: 1px solid #eee;
            padding-bottom: 0.3rem;
        }

        .markdown-content h3 { font-size: 1.25rem; }
        .markdown-content h4 { font-size: 1rem; }
        .markdown-content h5 { font-size: 0.875rem; }
        .markdown-content h6 { font-size: 0.85rem; }

        .markdown-content p {
            margin-bottom: 1rem;
            line-height: 1.6;
        }

        .markdown-content ul,
        .markdown-content ol {
            margin-bottom: 1rem;
            padding-left: 2rem;
        }

        .markdown-content li {
            margin-bottom: 0.25rem;
        }

        .markdown-content blockquote {
            border-left: 4px solid #ddd;
            padding-left: 1rem;
            margin: 1rem 0;
            color: #666;
            font-style: italic;
        }

        .markdown-content code {
            background-color: #f1f3f4;
            padding: 0.125rem 0.25rem;
            border-radius: 3px;
            font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
            font-size: 0.875em;
        }

        .markdown-content pre {
            background-color: #f8f9fa;
            border: 1px solid #e9ecef;
            border-radius: 6px;
            padding: 1rem;
            overflow-x: auto;
            margin: 1rem 0;
        }

        .markdown-content pre code {
            background-color: transparent;
            padding: 0;
        }

        .markdown-content a {
            color: var(--primary-color);
            text-decoration: none;
        }

        .markdown-content a:hover {
            text-decoration: underline;
        }

        .markdown-content hr {
            border: none;
            border-top: 1px solid #eee;
            margin: 2rem 0;
        }

        .btn-clear {
            transition: all 0.3s ease;
        }

        .footer {
            background-color: var(--dark-color);
            color: white;
            text-align: center;
            padding: 2rem 0;
            margin-top: 3rem;
        }

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

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @media (max-width: 768px) {
            .upload-area {
                padding: 2rem 1rem;
            }
            
            .preview-area {
                padding: 1rem;
            }
        }