Did not see your reply, thanks :)

You can select Page Fit in the Zoom drop down menu and then use the left and right arrow keys to jump between pages. This should give you the wanted functionality. It’s not possible to do this with the mouse however.

Allow me to quote myself:

While Stirling PDF and PdfDing are both self-hosted web applications centered around PDF files, they still differ in their use case. Stirling PDF focuses on performing various operations like splitting, ropping and rotating on your PDFs. PdfDing however has a different focus, it is all about reading and organizing your PDFs. All features are added with the goal of improving the reading experience or making the management of your PDF collection simpler. PdfDing’s editing functionalities were added with the same idea in mind. You can add annotations, highlighting and drawings to PDFs, so that you can highlight or add information that will be beneficial to your reading experience.

No this is not possible right now.