ds_3col_stacked_fluid.css in Display Suite 7

.group-header {
  clear: both;
}

.group-left {
  width: 25%;
  float: left;
}

.group-middle {
  width: 100%;
  float: left;
}

.group-one-sidebar .group-middle {
  width: 75%;
}

.group-two-sidebars .group-middle {
  width: 50%;
}

.group-right {
  width: 25%;
  float: right;
}

.group-footer {
  clear: both;
}