<!doctype html>
<html><head>
<title>div boxes</title>
<style>
div {
width: 400px;
height: 400px;
display: inline-block;
}
</style>
</head>
<body>
<div style="background-color: #FF0000;"></div> <!-- red -->
<div style="background-color: #00FF00;"></div> <!-- green -->
<div style="background-color: #0000FF;"></div> <!-- blue -->
<div style="background-color: #999999;"></div> <!-- gray -->
</body></html>