<!doctype html>
<title>Example</title>
<style>
.wrapper {
display: flex;
align-items: center;
background-color: beige;
height: 100vh;
}
.wrapper > div {
padding: 20px;
font-size: 4vw;
color: white;
.red {
background: orangered;
.green {
background: yellowgreen;
.blue {
background: steelblue;
body {
margin: 0;
</style>
<div class="wrapper">
<div class="red">1</div>
<div class="green">2</div>
<div class="blue">3</div>
</div>