internal void setMarginAttribute(XName xName, float value)
{
XElement body = mainDoc.Root.Element(XName.Get("body", w.NamespaceName));
XElement sectPr = body.Element(XName.Get("sectPr", w.NamespaceName));
XElement pgMar = sectPr?.Element(XName.Get("pgMar", w.NamespaceName));
XAttribute top = pgMar?.Attribute(xName);
top?.SetValue(value * 20);
}