纯css制作带三角border篇(兼容所有浏览器)

<div class="arrow-up"></div>
<div class="arrow-down"></div>
<div class="arrow-left"></div>
<div class="arrow-right"></div>

.arrow-up {
width: 0;
height: 0;
border-left: 5px solid transparent;
border-right: 5px solid transparent;
_border-left: 5px solid white;
_border-right: 5px solid white;
border-bottom: 5px solid black;
overflow:hidden;
}
.arrow-down {
width: 0;
height: 0;
border-left: 20px solid transparent;
border-right: 20px solid transparent;
_border-left: 20px solid white;
_border-right: 20px solid white;
border-: 20px solid #f00;
overflow:hidden;
}
.arrow-right {
width: 0;
height: 0;
border-: 60px solid transparent;
border-bottom: 60px solid transparent;
_border-: 60px solid white;
_border-bottom: 60px solid white;
border-left: 60px solid green;
overflow:hidden;
}
.arrow-left {
width: 0;
height: 0;
border-: 10px solid transparent;
border-bottom: 10px solid transparent;
_border-: 10px solid white;
_border-bottom: 10px solid white;
border-right:10px solid blue;
overflow:hidden;
}