Was reminded from a thread posted under suggestions that several others have an issue with the new background here on the forum in regards to readability, as such I have posted a script to change this image for similar theme, but much easier to read on.
So this post is just to ensure that it does not get lost if other have a need for it:
Download the User script for changing board background
(zip-file, to allow attachment) - Tested with firefox & Chrome(thanks axoloth)
If you want to modify the script, I also left in some functionality for editing text or similar. You can also change the url if you want a different background than the one I've selected.
UPDATE as NoMoreAngel added his fixes: Get the full package here