css透明输入框（纯CSS实现气泡对话框尖角处理方案）

<li class="dialog-box">  
  <span class="bot"></span>  
  <span class="top"></span>  
</li>  

.dialog-box {  
  position: relative;  
  span {  
    width:0;   
    height:0;   
    font-size:0;   
    overflow:hidden;   
    position:absolute;  
    &.bot{  
      border-width: 15px;   
      border-style: solid dashed dashed;   
      border-color: transparent transparent #F9743A transparent;   
      left: 15px;   
      top: -29px;  
    }  
    &.top{  
      border-width:13px;   
      border-style:solid dashed dashed;   
      border-color:transparent transparent #fff transparent;   
      left:17px;   
      top:-25px;  
    }  
  }  
}