CSS 气泡

<style>

.tag{ width:300px; height:100px; border:5px solid #09F; position:relative; background-color:#FFF;margin-top:200px;}
.tag em{display:block; border-width:20px; position:absolute; bottom:100px; left:100px;border-style:solid dashed dashed; border-color: transparent transparent #09F;font-size:0; line-height:0;}
.tag span{
display:block;
border-width:20px; 
position:absolute; bottom:96px; 
left:100px;
border-style:solid dashed dashed;
border-color:transparent transparent #FFF;
font-size:0; 
line-height:0;
}
</style>


<div class="tag">
      <em></em>  
  <span></span>
  </br>
      &nbsp;&nbsp;是：CSS气泡框实现</br>
  &nbsp;&nbsp;否：CSS气泡框实现2
</div>