JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <div id="buttonContainer"><span id="buttonIcon">My</span><span id="buttonLabel">self</span></div>
    <div id="content">
        <div id="heading">Press Me</div>
        <div id="body">
            <div id="innerBody"></div>
        </div>
    </div>
</div>

CSS

#wrapper {
    margin: auto;
    background-color: blue;
    width: 470px;
    text-align: center;
    overflow: hidden;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.17);
    max-height: 400px;
    max-width: 600px;
    padding: 0;
}

#buttonContainer {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    align-content: center;
    flex-direction: column;
    margin: auto;
    width: 100px;
    height: 100px;
    color: white;
}

#buttonIcon {
    width: 36px;
    height: 36px;
    line-height: 36px;
    font-size: 35px;
    font-weight: bold;
    display: inline-block;
}

#buttonLabel {
    font-size: 20px;
}

#content {
    width: 100%;
    height: 100%;
    text-align: left;
    transform: translateY(0px);
}

#heading {
    color: white;
    text-align: right;
    margin: 10px;
    font-size: 17px;
}

#body {
    color: #000;
    color: rgba(0, 0, 0, 0.87);
    background-color: #FFF;
    width: 100%;
    max-height: 500px;
    padding: 10px 0;
    box-sizing: border-box;
}

#body.hide {
    transition: max-height 2s ease-in-out;
    max-height: 0;
}

#innerBody {
    height: 200px;
    background-color: orange;
}

JavaScript

var heading = document.getElementById('heading'),
    body = document.getElementById('body');

heading.addEventListener('click', hide);
body.addEventListener('transitionend', hideCallback);

function hide() {
    body.className = 'hide';
}

function hideCallback(e) {
    console.log(e.propertyName);
}