JSFiddle - React, Tailwind, and code Playground

HTML

<div class="ok">
<div class="box">1</div>
<div class="box">2</div>
<div class="box">3</div>
<div class="box">4</div>
    
</div>

CSS

.ok{
    margin:0px auto; /* ADDED */
    width:300px;
    background:red;
    height:100px;
    box-sizing:border-box;
}

.box{
    display:inline-block; 
    box-sizing:border-box;
    width:25%;
    border:2px solid blue;
    height:100%;
    float:left;
}