Hello,
the background is gray for the odd items, as you have noticed. You just have to use CSS to modify that color (or use transparent). Add the following code to your template's stylesheet:
.odd {
background-color: white !important;
}

Hello,
if you look at the source code, you can see that there is a class 'even' attached to each even item, 'odd' attached to each odd item. Override the CSS class .even to change the background color, the same way I have suggested in the previous post.