提示框的指引三角

.allProductInfo{
        100px;
        height:100px;
        border:1px solid #ccc;
        position:relative;
        top:50px;
    }
          .allProductInfo:after{
     content: "";
    border- 11px;
    border-style: solid;
    border-color: rgba(132, 47, 47, 0);
    border-bottom-color: rgb(255, 255, 255);
    position: absolute;
    top: -20px;
    left: 2px;
    }
     .allProductInfo:before{
      content: "";
    border- 11px;
    border-style: solid;
    border-color: rgba(132, 47, 47, 0);
    border-bottom-color: #ccc;
    position: absolute;
    top: -22px;
    left: 2px;
    } 

<div class="allProductInfo">
    </div>