I'm literally just getting started but I made the following change in stylesheet.css (classic folder) to effect the change you describe

From:
#mainWrapper {
background-color: #ffffff;
text-align: left;
width: 750px;
vertical-align: top;
border: 1px solid #9a9a9a;
}


To:
#mainWrapper {
background-color: #ffffff;
text-align: left;
width: 1000px;
vertical-align: top;
border: 1px solid #9a9a9a;
}

Seems to have done the job