It’s From the Lost Library, one of the rather nice template sets published by Lord Zsezse Works. The set consists of four cover designs and four page designs, in US Letter and A4 sizes. I’ll have to decide which size will work best.
I’m not certain whether or not I’ll use the graphics for any of the existing “Things” book and item lists. I do plan to upgrade the graphics on those at some point; I’d just like to use something a bit more modern, given that they are aimed at modern campaigns.
I do have a number of supplements that have needed formatting for a while which I am going to use the templates with.