JSFiddle - React, Tailwind, and code Playground
HTML
<script src="//code.jquery.com/jquery-1.12.0.min.js"></script>
<div id="wrapper">
<div class="content"></div>
</div>
CSS
#wrapper {
width: 80%;
padding: 25px;
}
.content {
width: 100%;
height: 200px;
border: 1px solid purple;
}
JavaScript
$(document).ready(function() {
var $content = $('.content');
$content.attr('width', '100%');
console.log('width: ', $content.width());
});