[Lynne]

In your style:

.outer_border {
border-left:5px solid #C0DDFF;
border-right:5px solid #C0DDFF;
margin-left:auto;
margin-right:auto;
width:772px;
}

In their style:

.outer_border {
border-left:5px solid #C0DDFF;
border-right:5px solid #C0DDFF;
margin-left:auto;
margin-right:auto;
width:962px;
}

So, you need to change that class. If you don't know where to do that, you'll have to ask wherever you got the style because that is not a default vbulletin class.