Try
.oneColFixCtrHdr #sidebar1, #sidebar2, #mainContent {
text-align: center;
width: 200px;
padding-top: 0px;
padding-right: 30px;
padding-bottom: 0;
padding-left: 30px;
float: left;
}
.oneColFixCtrHdr #sidebar1 {
background-color: #FFF;
float: left;
width: 200px;
}
.oneColFixCtrHdr #sidebar2 {
background-color: #FFF;
float: right;
width: 200px;
}