<!DOCTYPE html>
<html>
<head>
<style>
.flex-container {
display: flex;
justify-content: center;
align-items: center;
height: 300px;
background-color: DodgerBlue;
}
.flex-container > div {
background-color: #f1f1f1;
color: white;
width: 100px;
height: 100px;
}
</style>
</head>
<body>
<h1>Perfect Centering</h1>
<p>A flex container with both the justify-content and the align-items properties set to <em>center</em> will align the item(s) in the center (in both axis).</p>
<div class="flex-container">
<div></div>
</div>
</body>
</html>