Positioning pictures on the background of a page
A regular TikZ picture appears right where we put it in the document text. We can use a center environment for centering it and a figure environment to have a caption and a reference label and to let it float to a suitable place in the document for better page breaks.
We can even put a TikZ picture anywhere on a page without affecting the document text, placing it in the background. As we already know, we can use the overlay option so that it doesn’t block any space. The remember picture option from the previous section is even more important here: once you set this, TikZ stores picture positioning information in the .aux file. In the next compiler run, that information is read from the .aux file and used for final positioning. That’s the reason why we need to compile a second time to have the final positioning.
We can consider the page like a node with a rectangular shape, having precisely the page dimensions. TikZ...
