I finally got it to work, had to tweak the code a little to match up with my current skin.

Demo

Great hack!

I am trying to use a PNG image and have my forums background texture show through. I've tried adding the "transparent" property to the code, but that did not seem to work. Is there a way to make it where the part of the postbit that does not have an image applied via this mod not to be filled with a color, leaving it transparent?

You need to use a program like Gimp or Photoshop and 'erase the background' so that you see a tile checkboard under the image. Just use the eraser and erase eveything you don't want to show up.

Sorry, guess I did not explain that very well. I already have the transparent png image. My problem is, when I use the png image, the part that is transparent shows up black and not as the normal color for my site.

That's because your image is not transparent.

The image up there now is not transparent, as it does not display it correctly and cause that area to show as black. So, I replaced it with some thing that does work... a JPG.

would this work on 3.7?

Since its just some edits, im pretty sure it would work;)

cheers mate ill give it a go :)

I could use some help here.
I am using this one: https://vborg.vbsupport.ru/showthread.php?t=207742
and I want to have a special background for girls on my forums. So it is not based on a usergroup but on a field.

My coding skills are just too low for that - can someone tell me how to state the if statement for this one?