I am currently having an issue with exporting .pdfs for just a specific book. I have tried changing the CSS sheet and checked the pdf. export settings but this hasn’t fixed the issue yet.
I changed the page size to see what happens and it makes all the options bigger than specified. An 8.5" x 11" becomes 10" x 12.75". Can this issue be cause by something running in the background for this book?
Pressbooks Custom CSS is no longer maintained (and has been for almost a year—it’s been replaced with core functionality), and you’re running a two-year-old version of Pressbooks. Page sizes can be changed without issue on newer versions. I’m sorry, but I don’t think I can provide any help with this.