JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
</div>

CSS

#container{
    width:300px;
    border:1px solid black;
    
}
.box{
    float:left;/*Here is the change*/
    height:50px;
    width:50px;
    background-color:black;
    margin:0;
    padding:0;
}