JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>

CSS

.test {
     width:100px;
     height:50px;
     float: left;
     clear:both; 
      border: 1px solid #000000;  
}

JavaScript

$('.test:eq(0)').css('backgroundColor', 'red');
//Same as:
//$('.test:nth-child(1)').css('backgroundColor', 'green');