如何修復IE7中的twitter引導按鈕佈局？

我有3個按鈕，在我的表格：如何修復IE7中的twitter引導按鈕佈局？

<form id="myform" class="form-horizontal" class="collapse in"> 
    <fieldset> 
    <div> 
     <div class="control-group"> 
     <label class="control-label" for="place-of-birth">Место рождения</label> 
     <div class="controls"> 
      <input type="text" class="input-xlarge" id="place-of-birth" name="place-of-birth" minlength="2" maxlength="80" autocomplete="off"> 
     </div> 
     </div> 
    </div>  
    <div class="form-actions"> 
     <button type="button" class="btn" data-toggle="modal" data-target="#modal-demo-search">Демо поиска</button> 
     <button type="button" class="btn" id="clear">Очистить форму</button> 
     <button type="button" class="btn btn-inverse" id="search" name="search" data-loading-text="Поиск...">Поиск</button> 
    </div> 
    </fieldset> 
</form>

Demo

在相同的屏幕尺寸，它看起來可怕的IE7（2線，無邊框）： IE7