PdfDocumentOptionsAutoResizePdfPageWidth Property

When true, the PDF page width follows the browser window width, HtmlViewerWidth times 0.75 points, and the HTML is drawn at HtmlViewerZoom, 100 percent unless set. The window width and the zoom are then not computed by the layout methods: the values set are used, 1024 pixels and 100 percent by default. Setting the property back to false restores the layout of the last layout method called. When false, the page has the size given by PdfPageSize and the HTML is laid out for that page. PageWidthFromBrowserWindow and SinglePageOfWidth set this property to true; the other layout methods set it to false. To make the page follow the browser window, prefer calling PageWidthFromBrowserWindow, which also sets the window width and the zoom. The default value is false

public bool AutoResizePdfPageWidth { get; set; }