Very sorry for the late reply, i don’t check this forum as much as github.
I’ve noted before that the image isn’t changed by this theme as that would include adding a new image. (at one point I had a background image included that consisted of a black background that I threw some white on in MS paint)
If you wish to change the image to something you’d like more, replace the file located at:
I suggest finding a tiled/pattern image from one of the many website background sites.
Alternatively don’t use the “boxed” appearance. From the pihole admin view, go to
Settings -> API/Web Interface -> Interface appearance and uncheck the “use boxed layout” option.