JSFiddle - React, Tailwind, and code Playground

HTML

<div id="seventyfive"><img src="http://winters.yorku.ca/wp-content/blogs.dir/271/files/2011/11/twitter-icon.png" /></div>

CSS

#seventyfive{
    position:absolute;
    font-size:100px;
    font-weight:bold;
}

JavaScript

(function pulse(back) {
    $('#seventyfive').animate(
        {
            'font-size': (back) ? '100px' : '140px',
            opacity: (back) ? 1 : 0.5
        }, 700, function(){pulse(!back)});
})(false);