/// <summary>
 /// XDocument containing Xml content of the styles part
 /// </summary>
 public XDocument GetStylesDocument()
 {
     if (parentDocument.Document.WorkbookPart.WorkbookStylesPart != null)
     {
         return(parentDocument.GetXDocument(parentDocument.Document.WorkbookPart.WorkbookStylesPart));
     }
     else
     {
         return(null);
     }
 }