JSFiddle - React, Tailwind, and code Playground

HTML

<div class="sidebar">
    <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">About</a></li>
        <li><a href="#">Work</a></li>
        <li><a href="#">Contact</a></li>
    </ul>
</div>
<div class="content"> 
    <a href="#"><img src="http://placehold.it/500x400" /></a>
    <a href="#"><img src="http://placehold.it/500x400" /></a>
    <a href="#"><img src="http://placehold.it/500x400" /></a>
    <a href="#"><img src="http://placehold.it/500x400" /></a>
    <a href="#"><img src="http://placehold.it/500x400" /></a>
    <a href="#"><img src="http://placehold.it/500x400" /></a>
</div>

CSS

html, body {
    margin: 0;
    padding: 0;
    background-color: red;
    font-family:'Open Sans', sans-serif;
}
.sidebar {
    background-color: #fff;
    width: 100px;
    height: 100%;
    position: fixed;
    text-align: center;
    padding: 50px 10px;
    transition: .15s;
}
.sidebar:hover {
    width: 200px;
    transition: .15s;
}
.sidebar:hover + .content {
    margin-left: 220px;
    transition: .15s;
}
.sidebar img {
    max-width: 100px;
    margin-bottom: 50px;
}
.sidebar ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}
.sidebar ul a {
    color: #000;
    text-decoration: none;
}
.sidebar ul a li {
    opacity: 1;
    transition: .15s;
}
.sidebar ul a li:hover {
    opacity: .6;
    transition: .15s;
}
.content {
    margin-left: 120px;
    transition: .15s;
}
.content a {display:inline-block;margin:0;max-width:25%;float:left;}
.content img {
    display:block;
    max-width:100%;
    margin: 0;
    padding: 0;
}