Printing content of WKWebView in macOS-App

A app for macOS which shows only a WKWebView. No buttons or textfields. Nothing. The url is fix and use our server. From a initial page you go to different pages. The pages are with css formatted to be printed. Some have one page, other more. Till 12 pages. I need the code to print this content when pressing command+p or by clicking File->Print. The print dialogue should be as it is for all standard applications on my Mac with the possibility to select the paper size and the option to print the background.