[qpurser]

I did the following

used in the postbit_legacy:

<div class="bppostbit">
your code
</div>

added this to the additional.css:

.bppostbit {
margin-top: 2px;
padding: 3px;
background: url(images/SeamusLight/gradients/back6.png) top left repeat;
border: 1px solid #c4c4c4;
}

the background code is a small image I used to create a background inside each box. You can use also a color instead of a picture of course.
If you don't want any background just delete the "background" code.