Steps to reproduce: 1) Create a sample .html: <!DOCTYPE html> <html> <head> <style type="text/css"> .p { margin: 0px 0px 0px 28px; } </style> </head> <body> <p> <span>This text should be indented</span> </p> </body> </html> 2) Initialize the HTML provider: private static void InitHtmlFormatProvider() { htmlFormatProvider = new HtmlFormatProvider(); var htmlExportSettings = new HtmlExportSettings(); htmlExportSettings.DocumentExportLevel = DocumentExportLevel.Fragment; htmlFormatProvider.ExportSettings = htmlExportSettings; } 3) Import the sample .html file: private void importFromFile_Click(object sender, EventArgs e) { string text = File.ReadAllText(@"C:\Sample1.txt"); RadDocument document = htmlFormatProvider.Import(text); radRichTextBox1.Document = document; } 4) Export the imported document to .html file: private void exportToFile_Click(object sender, EventArgs e) { string html = htmlFormatProvider.Export(radRichTextBox1.Document); File.WriteAllText(@"C:\Sample2.txt", html); } Expected Result: margin: 0px 0px 0px 28px; Actual Result: margin: 0px 0px 0px 0px;