BorderAlwaysInFront

public bool BorderAlwaysInFront { get; set; }

Document doc = new Document();

PageSetup pageSetup = doc.Sections[0].PageSetup;
pageSetup.BorderAlwaysInFront = false;
pageSetup.BorderDistanceFrom = PageBorderDistanceFrom.PageEdge;
pageSetup.BorderAppliesTo = PageBorderAppliesTo.FirstPage;

Border border = pageSetup.Borders[BorderType.Top];
border.LineStyle = LineStyle.Single;
border.LineWidth = 30;
border.Color = Color.Blue;
border.DistanceFromText = 0;

doc.Save(ArtifactsDir + "PageSetup.PageBorderProperties.docx");