JSFiddle - React, Tailwind, and code Playground

HTML

<div class="example">
    <a href="http://example.com">
		<img src="http://www.trost-flash.com/wp-content/themes/BoomWPA/images/728.png" title="Test">
	</a>
</div>

CSS

div.example {
    position: fixed;
    bottom: 0;
    left: 50%;	
    margin-left: -364px;
    width: 728px;
    height: 90px;
    z-index: 500;
}

JavaScript

function getStyle(oElm, strCssRule){
    var strValue = "";
    if(document.defaultView && document.defaultView.getComputedStyle){
        strValue = document.defaultView.getComputedStyle(oElm, "").getPropertyValue(strCssRule);
    }
    else if(oElm.currentStyle){
        strCssRule = strCssRule.replace(/\-(\w)/g, function (strMatch, p1){
            return p1.toUpperCase();
        });
        strValue = oElm.currentStyle[strCssRule];
    }
    return strValue;
}
alert(getStyle(document.getElementsByClassName('example'), "height"));