CSS - Effect for Transparent Images

Using CSS change the background colour behind transparent .gif images.
The changing background colours show through the transparent portions of the image.

Create an anchor with the following styles

Style:
.rollover a { display:block; width:32px; background-color: #FFFFFF}
.rollover a:hover { background-color: #990000;border:1px solid #990000;}

HTML:
[div class="rollover"]
[p]
[a href="#"][img src="image.gif" border="0"][/a]
[/p]
[/div]