Emacs-desktop insists on having 13-pixel scrollbars at startup

[Rahguzar]

>From info node `(emacs) Saving Emacs Sessions`

   When the desktop restores the frame and window configuration, it uses
the recorded values of frame parameters, disregarding any settings for
those parameters you have in your init file (*note Init File::).  This
means that frame parameters such as fonts and faces for the restored
frames will come from the desktop file, where they were saved when you
exited your previous Emacs session; any settings for those parameters in
your init file will be ignored.  To disable this, customize the value of
‘frameset-filter-alist’ to filter out the frame parameters you don’t
want to be restored; they will then be set according to your
customizations in the init file.

So you need to customize frameset-filter-alist