Applying images in CSS

I am trying to create a function that allows for a member to rotate through multiple themes (as seen this tutorial here). I am also trying to apply custom images so that the category icons, reply button, quote button, and all the other forum icons are replaced with a different images for each theme. I have been trying to locate the CSS code for all of them because it is not in the basic CSS code for my Phpbb2 board. If anyone has access to a full list of CSS codes that detail changing those kind of mentioned icons above I would greatly appreciate the help.

I dont think this is possible.

I was able to change the background, banner, and navbar icons so I thought it would be possible to change the others. It is odd that I can't locate them by default in the basic CSS code for my forum though .

The basic CSS would change all of them, So i have no idea if you can do them individually