Cover: I like the cover very much especially as each module has its own colour. The different logo's for the different modules, while highlighting the specific module, is also a great idea.
On the other hand, we should try and fill the upper half of the cover as this is indeed very empty, maybe putting the title and logo at 1/3 from the top will improve it.
I am not so sure whether the "Get involved" should appear on the cover, as users/readers of the guides are looking for help and not yet there to help or to get involved.
Chapter: I fully agree that it is good to have a distict page at the start of each chapter, the lay-out is a bit too heavy for me: repating the logo for each module and a small background would do for me.
Pages: headers and footers are also too heavy for me, I would prefer that we just keep the footers the same as the present footers with the name of the chapter on one page and the name of the guide on the other page.
Back: great !!
Keep up the good work
Front covers for user guides: I like that you're using several bits from the v3.x design (different colours and graphics, especially), but the large empty area in the top half of the draft v4.0 cover looks strange to me, and the small LibreOffice logo in the top left gets a bit lost, I think. I prefer to have a larger LibreOffice logo in this blank area. Also, I'm dubious about the "Get involved" in the upper right, though not completely opposed to it.
Chapters: I assume these are intended for the cover pages of the stand-alone chapter files. I think they may be a bit too much when the chapters are compiled into a book, however.
Pages: I find the dark colours in the headers and footers are too distracting. And anyone printing these out on a personal printer is likely to be annoyed by the excess use of ink or toner.
Back covers: I like the concept, although for the print version (which is 6x9 inches, not A4) I would amend the text a bit. Also, the footer won't work on the print version because of the automatic placement of the barcode by the Lulu publishing service.
I expect to have some amended versions of these ready to show people soon.
Jean Hollis Weber