<form action="javascript:void(0);">
  <div>
      <input type="radio" name="square" value="left" />左
      <input type="radio" name="square" value="left" />右
  </div>
</form>
<div style="width : 230px">
     <div class="square left" style="float:left">左</div>
     <div class="square right" style="float:left">右</div>
     <div class="square left" style="float:left">左</div>
     <div class="square right" style="float:left">右</div>
</div>