<!DOCTYPE html>
<html>
<title>Titre du document</title>
<head>
<style>
.box {
display: -webkit-box;
display: -moz-box;
display: -ms-flexbox;
display: -webkit-flex;
display: flex;
width: 310px;
height: 310px;
border: 2px solid green;
}
.box div {
width: 100px;
padding: 15px;
text-align: center;
color: #000000;
font-family: arial, sans-serif;
}
.green {
background-color: green;
}
.blue {
background-color: blue;
}
.gray {
background-color: gray;
}
.pink {
background-color: pink;
}
</style>
</head>