JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <span>The max-width of this image is set to 80% but this browser thinks it is: <br> <b></b></span>
    <img src="http://farm5.staticflickr.com/4109/4949061167_8e9276e324_z.jpg">
</div>

CSS

body {
    text-align: center;
    padding: 50px;
}
div {
    width:10%;
    margin: 0 auto;
}
img {
    max-width: 80%;
}
span {
    display: block;
    margin: 0 10px 10px;
}
b {
    font-size: 25px;
}

JavaScript

$maxWidth = $('img').css('maxWidth');

$('span b').text($maxWidth);