<group class="span3" data-normal="" data-tablet="span3" data-stablet="">left</group>
<group class="span3" data-normal="" data-tablet="span3" data-stablet="" >right</group>

.span12 {
  width: 940px;
}
.span11 {
  width: 860px;
}
.span10 {
  width: 780px;
}
.span9 {
  width: 700px;
}
.span8 {
  width: 620px;
}
.span7 {
  width: 540px;
}
.span6 {
  width: 460px;
}
.span5 {
  width: 380px;
}
.span4 {
  width: 300px;
}
.span3 {
  width: 220px;
}
.span2 {
  width: 140px;
}
.span1 {
  width: 60px;
}