CSS代码：
1 .border_cort, .border_corr, .border_corb, .border_corl {
2 display: inline-block;
3 width: 0;
4 height: 0;
5 border-width: 6px;
6 overflow: hidden;
7 }
8 .border_cort {
9 border-color: #333 transparent transparent;
10 border-style: solid dotted dotted;
11 }
12 .border_corr {
13 border-color: transparent #333 transparent transparent;
14 border-style: dotted solid dotted dotted;
15 }
16 .border_corb {
17 border-color: transparent transparent #333;
18 border-style: dotted dotted solid;
19 }
20 .border_corl {
21 border-color: transparent transparent transparent #333;
22 border-style: dotted dotted dotted solid;
23 }
HTML代码：
1 <span class="border_cort"></span> //下箭头
2 <span class="border_corb"></span> //上箭头
3 <span class="border_corl"></span> //右箭头
4 <span class="border_corr"></span> //左箭头
