JSFiddle - React, Tailwind, and code Playground

HTML

<div id="comment">I am a comment!</div>

CSS

#comment{
    position: relative;
    top: 20px;
    left: 20px;
    padding: 10px;
    width: 150px;
    height: 150px;
    background-color: #F0F0F0;
    border: 1px solid #D0D0D0;
    -webkit-box-shadow: 2px 2px 10px rgba(0, 0, 0, 0.1);
    -moz-box-shadow: 2px 2px 10px rgba(0, 0, 0, 0.1);
    box-shadow: 2px 2px 10px rgba(0, 0, 0, 0.1);
}
    #comment:after, #comment:before {
        border: solid transparent;
        content: ' ';
        height: 0;
        position: absolute;
        width: 0;
    }
    #comment:after {
        border-color: rgba(240, 240, 240, 0);
        border-bottom-color: #F0F0F0;
        border-width: 9px;
        top: -18px;
        left: 7px;
    }
    #comment:before {
        border-color: rgba(208, 208, 208, 0);
        border-bottom-color: #D0D0D0;
        border-width: 10px;
        top: -20px;
        left: 6px;
    }