JSFiddle - React, Tailwind, and code Playground

HTML

<div style="width:400px;">
	<div class="top">
	</div>
	<div class="bottom"></div>
</div>

CSS

.top {background-color: yellow;height: 20px;}
.bottom {background-color: white;height: 20px;}
.rounded {width: 20px;height:20px;float:left;background-color: yellow; margin-top: 10px;border-radius: 10px;}

JavaScript

var div = $("<div>", {class: 'rounded'});
for(var i=1; i<=20; i++) {
	div.clone().appendTo('.top');
}