写法
.triangle{
overflow: hidden;
width:0;
height:0;
border-width: 10px;
border-color: red transparent transparent transparent;
border-style: solid ;
}
在ie6下会有黑色边框 解决方案
.triangle{
overflow: hidden;
width:0;
height:0;
border-width: 10px;
border-color: red transparent transparent transparent;
border-style: solid dashed dashed dashed;
}