body {
    font-size: 10pt;
}
#leftcolumn {
    border: solid 1px blue;
    float: left;
    width: 150px;
}
#rightcolumn {
    border: solid 1px red;
    float: right;
    width: 200px;
}
#middlecolumn {
    border: solid 1px green;
    margin-left: 150px;
    margin-right: 200px;
}