No New Post Icon, Where?

This may be one really simple question, but here it goes.

I'm making a style for punBB and only one thing stumps me.

When a new post is made and a user logs on, the board then determines which forums and or posts have changed since the last visit and throws in the .inew class into the appropriate html markup. ok, I get that.

Now, the icons that appear in the default Oxygen style along with the few other styles that come with the install package, show absolutely no trace of background image styles. Kind of bizarre.

What's even more perplexing is there is no signs of images for these default forum icons. I don't get that. lol

Is there something I'm completely overlooking here? Is there an internal script that manipulates code to make a faux-pas Icon appear, either on or off?

Sure, when the active state .inew class is inserted into the html it's easy enough to put an image icon through the CSS, but how in the world is the default punBB managing to pull this off with no apparent images?

Thanks in Advance.