Difference in full-screen display style for Pages/PDFs

I was just fiddling about with these 2 different file types, and noticed that in full screen, Pages thumbnails appear on the left against a grey column, whereas PDF thumbnails appear on the right, against a white column. I wondered why the difference, and personally find the former implementation much nicer to look at.

Pages documents are (usually) displayed by Appleā€™s Quick Look plugin for such documents and the thumbnails are part of the plugin.

A little OT but it involves PDF display. If I choose to view PDFs at 100% I wish that setting would remain after quitting and re-opening DT. It always defaults back to Zooming.
Something small, but annoying!