如何为Triange正确添加框阴影？

Question

我想为三角形添加框阴影，但改为正方形。我尝试搜索此问题，但找不到任何东西

.speech-bubble {
      display:inline-block;
      padding:5px;
    	position: relative;
    	background: #dcf8c6;
    	border-radius: .4em;
      box-shadow: 0px 1px 1px #d0cbc4;
    }
    
    .speech-bubble:after {
    	content: '';
    	position: absolute;
    	right: 0;
    	top: 50%;
    	width: 0;
    	height: 0;
    	border: 5px solid transparent;
    	border-left-color: #dcf8c6;
    	border-right: 0;
    	margin-top: -5px;
    	margin-right: -5px;
      box-shadow: 0px 1px 1px #d0cbc4;
    }

<div class="speech-bubble"> Hello Mike! Could you please call me back </div>