JSFiddle - React, Tailwind, and code Playground

HTML

<div class="ui-overlay">
    <div class="ui-overlay-content">
        content
    </div>
    <div class="arrow"></div>
</div>

CSS

body {
    padding: 20px;
}
.ui-overlay {
     padding-bottom: 10px;   
    position: relative;

}
.ui-overlay-content { 
    background: #999;
    color: #000;
    padding: 8px;
    border-radius: 4px; 
    border: 5px solid rgba(0, 0, 0, 0.2); 
    background-clip: padding-box; 
    height: 100px;
    width: 200px;
}
.arrow {
    border-color: #999 transparent transparent; 
    border-style: solid; 
    border-width: 10px 10px 0; 
    bottom: 5px; 
    left: 15px; 
    width: 0;
    height: 0;
    position: absolute;
   overflow: hidden; 
}