JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test">Hallo!</div>
<input type="button" id="btn" value="show/hide">

CSS

.hidden {
  display: none;
  -webkit-transition: display .5s ease;
  -moz-transition: display .5s ease;
  -o-transition: display .5s ease;
}

.active {
  transition: display .5s ease;
  -webkit-transition: display .5s ease;
  -moz-transition: display .5s ease;
  -o-transition: display .5s ease;
}

#test {
    width: 100px;
    height: 40px;
    background: red;
}

JavaScript

$('#btn').on('click', function(){
    $('#test').fadeToggle('slow');
});