JSFiddle - React, Tailwind, and code Playground

HTML

<div id="grid">
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
    <div class="child"></div>
</div>

CSS

#grid{
    width: 100px;
    height: 100px;
    margin: 0px;
    padding: 0px;
    border: 0px;
}
.child{
    background-color: lightpink;
    width: 25px;
    height: 25px;
    display: inline-block;
    margin: 0px;
    border: 0px;
    padding: 0px;
}