public static int GetBorderIndex(SpreadsheetDocument document, Border b)
{
XElement border = b.GetXElement();
XDocument styles = document.WorkbookPart.WorkbookStylesPart.GetXDocument();
XElement borders = styles.Root.Element(S.borders);
int index = Array.FindIndex(borders.Elements(S.border).ToArray(),
z => XElement.DeepEquals(z, border));
if (index != -1)
return index;
borders.Add(border);
borders.Attribute(NoNamespace.count).Value = borders.Elements(S.border).Count().ToString();
document.WorkbookPart.WorkbookStylesPart.PutXDocument();
return borders.Elements(S.border).Count() - 1;
}