Border-top on :before & :after

HTML

<div></div>
<div></div>
<div></div>

CSS

div {
   position: relative;
   border-top: 1px solid #fad400;
   background:#333;
   height:100px;
   width:50%;
   left:25%;
}
div:before {
   content: " ";
   position: absolute;
   right: 100%;
   width:100%;
   height:100%;
   background:#ccc;
   border-top: 1px solid red;
}
div:after {
   content: " ";
   position: absolute;
   right: 100%;
   width:100%;
   height:100%;
   background:#ccc;
   border-top: 1px solid red;
}