css 三角形空心三角形的简单实现

<style>   
#talkbubble {   
width: 120px;   
height: 80px;   
position: relative;   
-moz-border-radius: 10px;   
-webkit-border-radius: 10px;   
border-radius: 10px;   
border: 1px #808080 solid;   
background-color: #fff;   
}   
  
#talkbubble:before {   
content: " ";   
position: absolute;   
top: 100%;   
left: 50px;   
width: 0;   
height: 0;   
border-left: 15px solid transparent;   
border-top: 15px solid #808080;   
border-right: 15px solid transparent;   
}   
  
.inlayer:after {   
content: " ";   
position: absolute;   
top: 100%;   
left: 51px;   
width: 0;   
height: 0;   
border-left: 14px solid transparent;   
border-top: 14px solid #fff;   
border-right: 14px solid transparent;   
}   
  
#talkbubble:hover {   
background-color: #ff0000;   
}   
  
.inlayer:hover:after {   
width: 0;   
height: 0;   
border-left: 14px solid transparent;   
border-top: 14px solid #ff0000;   
border-right: 14px solid transparent;   
}   
</style>   
  
<!-- html -->   
<div id="talkbubble" class="inlayer">   
空心三角形   
</div>   

　　空心三角原理：主要利用元素伪类(:before,:after)实现

 另外附上 三角形向上的css的代码

.tip-em{
    width:12px;
    height:12px;
    position:absolute;
    left:80px;
    top:-10px;
    }
    .em1{
      position: absolute;   
      bottom: 100%;   
      left: 50px;   
      width: 0;   
      height: 0;   
      border-left: 15px solid transparent;   
      border-bottom: 15px solid #808080;   
      border-right: 15px solid transparent;  
    }
    .em2{
      position: absolute;   
      bottom: 100%;   
      left: 51px;   
      width: 0;   
      height: 0;   
      border-left: 14px solid transparent;   
      border-bottom: 14px solid #fff;   
      border-right: 14px solid transparent; 
    }