JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="a"></div>
    <div id="b"></div>
</div>

<div id="container">
    <div id="c"></div>
    <div id="d"></div>
</div>

CSS

#container{width:100px; height:200px; border:solid 1px #000;}

#container div{float:left;}

#a, #b{width:50px; height:50px;}
#a{background:red;}
#b{background:yellow;}

#c, #d{width:48px; height:48px; border:solid 1px #000;}
#c{background:blue;}
#d{background:green;}