JSFiddle - React, Tailwind, and code Playground

HTML

<head>
<style>
        #container{
            width: 900px;
            height: 900px;
            text-align: center;
            display: inline-block;
            background-color: lightblue;
            
            display: flex;
            justify-content: center;
            align-items: center;
            
            gap: 5px;
        }

        .box{
            width: 200px;
            height: 200px;
            margin: 0 auto;
            display: inline-block;
            vertical-align: middle;
            background-color: lightgreen;
            border: 1px solid grey;
            margin: 10px;
        }

    </style>
</head>
<body>
    <div id="container">
        <div class="box">BOXES</div>
        <div class="box">BOXES</div>
        <div class="box">BOXES</div>
    </div>
</body>