CSS border实现各个方向等腰直角三角

CSS代码：

 .border_cort, .border_corr, .border_corb, .border_corl {
     display: inline-block;
     width:;
     height:;
     border-width: 6px;
     overflow: hidden;
 }
 .border_cort {
     border-color: #333 transparent transparent;
     border-style: solid dotted dotted;
 }
 .border_corr {
     border-color: transparent #333 transparent transparent;
     border-style: dotted solid dotted dotted;
 }
 .border_corb {
     border-color: transparent transparent #333;
     border-style: dotted dotted solid;
 }
 .border_corl {
     border-color: transparent transparent transparent #333;
     border-style: dotted dotted dotted solid;
 }

HTML代码：

 <span class="border_cort"></span>   //下箭头
 <span class="border_corb"></span>  //上箭头
 <span class="border_corl"></span>  //右箭头
 <span class="border_corr"></span>  //左箭头