css-triangle 兼容IE6

css-triangle

.triangle_left,
.triangle_down,
.triangle_right,
.triangle_up{
  border:5px dashed transparent;
  width:0;
  height:0;
  font-size:0;
  overflow:hidden
}
.triangle_left{
  border-right:5px solid #000
}
.triangle_down{
  border-top:5px solid #000
}
.triangle_right{
  border-left:5px solid #000
}
.triangle_up{
  border-bottom:5px solid #000
}