#contentcolumn{
  margin: 0 240px 0 240px; /*Margins for content column. Should be "0 RightColumnWidth 0 LeftColumnWidth*/
}

#leftcolumn{
  float: left;
  width: 240px; /*Width of left column in pixel*/
  margin-left: -980px; /*Set margin to that of -(MainContainerWidth)*/
}

#rightcolumn{
  float: left;
  width: 240px; /*Width of right column*/
  margin-left: -240px; /*Set left margin to -(RightColumnWidth)*/
}