The 'Graph lines' template only renders for the first page. After that, scrolling in any direction shows a blank background.

The Grid background, in black lines, might be easier on the eye if the lines were rather blue, as the graph lines are

Instead of blue, I think a lighter shade of black/gray would suffice.

Maybe some added transparency to the grid and graph lines will be good.

It might be an idea to include a blank template with the lines and grids, in case a user wants to revert to blank.

Or allow the user to choose their own colour for the lines/grids as well...