Smiley help

I’m trying to add smilies to my site but because I have a dark background they always show with a border around them. I’m using custom smilies plugin and have tried all kinds of fixes like using transparent pngs and colouring the background of each smiley the same as the site background it just doesn’t seem to work does any body know how to get around this.

You can see my problem at slooude.net at the moment there is a white background around them but thats not the problem (these images don’t have a transparent background) it’s the dark box around them i want to get rid of and when I make transparent pngs i just get dark box as a background.