JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">   

    <div class="box" id="bluebox">
        <p>DIV #1</p>
    </div>

    <div class="box" id="redbox">
        <p>DIV #2</p>
    </div>
    
</div>

CSS

body {
    display: table;
    position: absolute;
    height: 90%;
    width: 90%;
    border: 1px solid black; /* for demo purposes */
}
    
#container {
    display: table-cell;
    vertical-align: middle;
}

.box {
    width: 300px;
    padding: 5px;
    margin: 7px auto;   
    text-align: center;
}

#bluebox {
    background: aqua;
}

#redbox {
    background: red;
}